Nanomaterials

20 pages, 5268 KiB

Open AccessEditor’s ChoiceArticle

Conferring Antioxidant Activity to an Antibacterial and Bioactive Titanium Surface through the Grafting of a Natural Extract

by Francesca Gamna, Seiji Yamaguchi, Andrea Cochis, Sara Ferraris, Ajay. Kumar, Lia Rimondini and Silvia Spriano

Nanomaterials 2023, 13(3), 479; https://doi.org/10.3390/nano13030479 - 25 Jan 2023

Cited by 7 | Viewed by 2616

Abstract

The main unmet medical need of bone implants is multifunctional activity, including their ability to induce rapid and physiological osseointegration, counteract bacterial biofilm formation, and prevent in situ chronic inflammation at the same time. This research starts from an already developed c.p. titanium [...] Read more.

The main unmet medical need of bone implants is multifunctional activity, including their ability to induce rapid and physiological osseointegration, counteract bacterial biofilm formation, and prevent in situ chronic inflammation at the same time. This research starts from an already developed c.p. titanium surface with proven bioactive (in vitro hydroxyl apatite precipitation) and antibacterial activities, due to a calcium titanate layer with nano- and micro-scale roughness and loaded with iodine ions. Here, antioxidant ability was added to prevent chronic inflammation by grafting polyphenols of a green tea extract onto the surface, without compromising the other functionalities of the surface. The surface was characterized before and after functionalization through XPS analysis, zeta potential titrations, ion release measurements, in vitro bioactivity tests, SEM and fluorescence microscopy, and Folin–Ciocalteu and biological tests. The presence of grafted polyphenols as a homogeneous layer was proven. The grafted polyphenols maintained their antioxidant ability and were anchored to the surface through the linking action of Ca²⁺ ions added to the functionalizing solution. Iodine ion release, cytocompatibility towards human mesenchymal stem cells (hMSC), and antibacterial activity were maintained even after functionalization. The antioxidant ability of the functionalized surface was effective in preserving hMSC viability in a chemically induced pro-inflammatory environment, thus showing a scavenger activity towards toxic active species responsible for inflammation. Full article

(This article belongs to the Special Issue Nanostructured Biomaterials for Tissue Repair and Anti-infection)

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47 pages, 6170 KiB

Open AccessEditor’s ChoiceReview

The State of the Art and Challenges of In Vitro Methods for Human Hazard Assessment of Nanomaterials in the Context of Safe-by-Design

by Nienke Ruijter, Lya G. Soeteman-Hernández, Marie Carrière, Matthew Boyles, Polly McLean, Julia Catalán, Alberto Katsumiti, Joan Cabellos, Camilla Delpivo, Araceli Sánchez Jiménez, Ana Candalija, Isabel Rodríguez-Llopis, Socorro Vázquez-Campos, Flemming R. Cassee and Hedwig Braakhuis

Nanomaterials 2023, 13(3), 472; https://doi.org/10.3390/nano13030472 - 24 Jan 2023

Cited by 24 | Viewed by 6141

Abstract

The Safe-by-Design (SbD) concept aims to facilitate the development of safer materials/products, safer production, and safer use and end-of-life by performing timely SbD interventions to reduce hazard, exposure, or both. Early hazard screening is a crucial first step in this process. In this [...] Read more.

The Safe-by-Design (SbD) concept aims to facilitate the development of safer materials/products, safer production, and safer use and end-of-life by performing timely SbD interventions to reduce hazard, exposure, or both. Early hazard screening is a crucial first step in this process. In this review, for the first time, commonly used in vitro assays are evaluated for their suitability for SbD hazard testing of nanomaterials (NMs). The goal of SbD hazard testing is identifying hazard warnings in the early stages of innovation. For this purpose, assays should be simple, cost-effective, predictive, robust, and compatible. For several toxicological endpoints, there are indications that commonly used in vitro assays are able to predict hazard warnings. In addition to the evaluation of assays, this review provides insights into the effects of the choice of cell type, exposure and dispersion protocol, and the (in)accurate determination of dose delivered to cells on predictivity. Furthermore, compatibility of assays with challenging advanced materials and NMs released from nano-enabled products (NEPs) during the lifecycle is assessed, as these aspects are crucial for SbD hazard testing. To conclude, hazard screening of NMs is complex and joint efforts between innovators, scientists, and regulators are needed to further improve SbD hazard testing. Full article

(This article belongs to the Special Issue Risk Assessment of Nanomaterials Toxicity)

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11 pages, 6390 KiB

Open AccessEditor’s ChoiceArticle

Bulk Photovoltaic Current Mechanisms in All-Inorganic Perovskite Multiferroic Materials

by Jiazheng Chen, Guobin Ma, Boxiang Gong, Chaoyong Deng, Min Zhang, Kaixin Guo, Ruirui Cui, Yunkai Wu, Menglan Lv and Xu Wang

Nanomaterials 2023, 13(3), 429; https://doi.org/10.3390/nano13030429 - 20 Jan 2023

Cited by 10 | Viewed by 3083

Abstract

After the discovery of bulk photovoltaic effect more than half a century ago, ferro-electrical and magneto-optical experiments have provided insights into various related topics, revealing above bandgap open voltages and non-central symmetrical current mechanisms. However, the nature of the photon-generated carriers responses and [...] Read more.

After the discovery of bulk photovoltaic effect more than half a century ago, ferro-electrical and magneto-optical experiments have provided insights into various related topics, revealing above bandgap open voltages and non-central symmetrical current mechanisms. However, the nature of the photon-generated carriers responses and their microscopic mechanisms remain unclear. Here, all-inorganic perovskite Bi

_{0.85}

Gd

_{0.15}

Fe

_{1 - x}

Mn

_{x}

O

_{3}

thin films were prepared by a sol-gel process and the effects of Gd and Mn co-doped bismuth ferrites on their microtopography, grain boundries, multiferroic, and optical properties were studied. We discovered a simple “proof of principle” type new method that by one-step measuring the leakage current, one can demonstrate the value of photo generated current being the sum of ballistic current and shift current, which are combined to form the so-called bulk photovoltaic current, and can be related to the prototype intrinsic properties such as magneto-optical coupling and ferroelectric polarization. This result has significant potential influence on design principles for engineering multiferroic optoelectronic devices and future photovoltaic industry development. Full article

(This article belongs to the Special Issue Advanced Nanomaterials for Perovskite Solar Cells)

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18 pages, 4045 KiB

Open AccessEditor’s ChoiceArticle

Electrochemical Synthesis, Magnetic and Optical Characterisation of FePd Dense and Mesoporous Nanowires

by Deepti Raj, Gabriele Barrera, Federico Scaglione, Federica Celegato, Matteo Cialone, Marco Coïsson, Paola Tiberto, Jordi Sort, Paola Rizzi and Eva Pellicer

Nanomaterials 2023, 13(3), 403; https://doi.org/10.3390/nano13030403 - 19 Jan 2023

Cited by 1 | Viewed by 2973

Abstract

Dense and mesoporous FePd nanowires (NWs) with 45 to 60 at.% Pd content were successfully fabricated by template- and micelle-assisted pulsed potentiostatic electrodeposition using nanoporous anodic alumina and polycarbonate templates of varying pore sizes. An FePd electrolyte was utilized for obtaining dense NWs [...] Read more.

Dense and mesoporous FePd nanowires (NWs) with 45 to 60 at.% Pd content were successfully fabricated by template- and micelle-assisted pulsed potentiostatic electrodeposition using nanoporous anodic alumina and polycarbonate templates of varying pore sizes. An FePd electrolyte was utilized for obtaining dense NWs while a block copolymer, P-123, was added to this electrolyte as the micelle-forming surfactant to produce mesoporous NWs. The structural and magnetic properties of the NWs were investigated by electron microscopy, X-ray diffraction, and vibrating sample magnetometry. The as-prepared NWs were single phase with a face-centered cubic structure exhibiting 3.1 µm to 7.1 µm of length. Mesoporous NWs revealed a core-shell structure where the porosity was only witnessed in the internal volume of the NW while the outer surface remained non-porous. Magnetic measurements revealed that the samples displayed a soft ferromagnetic behavior that depended on the shape anisotropy and the interwire dipolar interactions. The mesoporous core and dense shell structure of the NWs were seen to be slightly affecting the magnetic properties. Moreover, mesoporous NWs performed excellently as SERS substrates for the detection of 4,4′-bipyridine, showing a low detection limit of 10⁻¹² M. The signal enhancement can be attributed to the mesoporous morphology as well as the close proximity of the embedded NWs being conducive to localized surface plasmon resonance. Full article

(This article belongs to the Special Issue New Challenges in Nanofilm and Nanowire Characterization)

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13 pages, 2598 KiB

Open AccessEditor’s ChoiceArticle

Smart Nanofiber Mesh with Locally Sustained Drug Release Enabled Synergistic Combination Therapy for Glioblastoma

by Yinuo Li, Yoshitaka Matsumoto, Lili Chen, Yu Sugawara, Emiho Oe, Nanami Fujisawa, Mitsuhiro Ebara and Hideyuki Sakurai

Nanomaterials 2023, 13(3), 414; https://doi.org/10.3390/nano13030414 - 19 Jan 2023

Cited by 8 | Viewed by 3221

Abstract

This study aims to propose a new treatment model for glioblastoma (GBM). The combination of chemotherapy, molecular targeted therapy and radiotherapy has been achieved in a highly simultaneous manner through the application of a safe, non-toxic, locally sustained drug-releasing composite Nanofiber mesh (NFM). [...] Read more.

This study aims to propose a new treatment model for glioblastoma (GBM). The combination of chemotherapy, molecular targeted therapy and radiotherapy has been achieved in a highly simultaneous manner through the application of a safe, non-toxic, locally sustained drug-releasing composite Nanofiber mesh (NFM). The NFM consisted of biodegradable poly(ε-caprolactone) with temozolomide (TMZ) and 17-allylamino-17-demethoxygeldanamycin (17AAG), which was used in radiation treatment. TMZ and 17AAG combination showed a synergistic cytotoxicity effect in the T98G cell model. TMZ and 17AAG induced a radiation-sensitization effect, respectively. The NFM containing 17AAG or TMZ, known as 17AAG-NFM and TMZ-NFM, enabled cumulative drug release of 34.1% and 39.7% within 35 days. Moreover, 17AAG+TMZ-NFM containing both drugs revealed a synergistic effect in relation to the NFM of a single agent. When combined with radiation, 17AAG+TMZ-NFM induced in an extremely powerful cytotoxic effect. These results confirmed the application of NFM can simultaneously allow multiple treatments to T98G cells. Each modality achieved a significant synergistic effect with the other, leading to a cascading amplification of the therapeutic effect. Due to the superior advantage of sustained drug release over a long period of time, NFM has the promise of clinically addressing the challenge of high recurrence of GBM post-operatively. Full article

(This article belongs to the Special Issue Biohybrid Nanofibers and Nanomaterial-Contained Fibers: Fabrication and Application)

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14 pages, 2218 KiB

Open AccessEditor’s ChoiceArticle

Magnetic Properties of Zig-Zag-Edged Hexagonal Nanohelicenes: A Quantum Chemical Study

by Vitaly Porsev and Robert Evarestov

Nanomaterials 2023, 13(3), 415; https://doi.org/10.3390/nano13030415 - 19 Jan 2023

Cited by 8 | Viewed by 1970

Abstract

The atomic structure and electronic and magnetic properties of two zig-zag-edged hexagonal nanohelicenes of the second type [1.2] and [2.2] were studied by the density functional theory. These objects possess a helical periodicity and belong to the fifth family of line symmetry groups [...] Read more.

The atomic structure and electronic and magnetic properties of two zig-zag-edged hexagonal nanohelicenes of the second type [1.2] and [2.2] were studied by the density functional theory. These objects possess a helical periodicity and belong to the fifth family of line symmetry groups in their global energy minimum. These nanohelicenes were shown by us to be diamagnetic metals that undergo spontaneous symmetry breaking into antiferromagnetic semiconductors as a result of the Mott–Hubbard metal-insulator transition. However, under some torsional stress, a reversible transformation to a diamagnetic metal can take place, which is promising for the use of nanohelicenes in electro-magneto-mechanical nanodevices. Full article

(This article belongs to the Section Theory and Simulation of Nanostructures)

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16 pages, 4936 KiB

Open AccessEditor’s ChoiceArticle

Graphene-Based Coating to Mitigate Biofilm Development in Marine Environments

by Francisca Sousa-Cardoso, Rita Teixeira-Santos, Ana Francisca Campos, Marta Lima, Luciana C. Gomes, Olívia S. G. P. Soares and Filipe J. Mergulhão

Nanomaterials 2023, 13(3), 381; https://doi.org/10.3390/nano13030381 - 18 Jan 2023

Cited by 12 | Viewed by 4614

Abstract

Due to its several economic and ecological consequences, biofouling is a widely recognized concern in the marine sector. The search for non-biocide-release antifouling coatings has been on the rise, with carbon-nanocoated surfaces showing promising activity. This work aimed to study the impact of [...] Read more.

Due to its several economic and ecological consequences, biofouling is a widely recognized concern in the marine sector. The search for non-biocide-release antifouling coatings has been on the rise, with carbon-nanocoated surfaces showing promising activity. This work aimed to study the impact of pristine graphene nanoplatelets (GNP) on biofilm development through the representative marine bacteria Cobetia marina and to investigate the antibacterial mechanisms of action of this material. For this purpose, a flow cytometric analysis was performed and a GNP/polydimethylsiloxane (PDMS) surface containing 5 wt% GNP (G5/PDMS) was produced, characterized, and assessed regarding its biofilm mitigation potential over 42 days in controlled hydrodynamic conditions that mimic marine environments. Flow cytometry revealed membrane damage, greater metabolic activity, and endogenous reactive oxygen species (ROS) production by C. marina when exposed to GNP 5% (w/v) for 24 h. In addition, C. marina biofilms formed on G5/PDMS showed consistently lower cell count and thickness (up to 43% reductions) than PDMS. Biofilm architecture analysis indicated that mature biofilms developed on the graphene-based surface had fewer empty spaces (34% reduction) and reduced biovolume (25% reduction) compared to PDMS. Overall, the GNP-based surface inhibited C. marina biofilm development, showing promising potential as a marine antifouling coating. Full article

(This article belongs to the Special Issue Nano-Enhanced Strategies for Biofouling and Biocorrosion Prevention)

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11 pages, 2416 KiB

Open AccessEditor’s ChoiceArticle

Pixelated Micropolarizer Array Based on Carbon Nanotube Films

by Hui Zhang, Yanji Yi, Yibin Wang, Huwang Hou, Ting Meng, Peng Zhang and Yang Zhao

Nanomaterials 2023, 13(3), 391; https://doi.org/10.3390/nano13030391 - 18 Jan 2023

Cited by 1 | Viewed by 1902

Abstract

A micropolarizer array (MPA) that can be integrated into a scientific camera is proposed as a real-time polarimeter that is capable of extracting the polarization parameters. The MPA is based on highly aligned carbon nanotube (CNT) films inspired by their typical anisotropy and [...] Read more.

A micropolarizer array (MPA) that can be integrated into a scientific camera is proposed as a real-time polarimeter that is capable of extracting the polarization parameters. The MPA is based on highly aligned carbon nanotube (CNT) films inspired by their typical anisotropy and selectivity for light propagation over a wide spectral range. The MPA contains a dual-tier CNT pixel plane with 0° and 45° orientations. The thickness of the dual-tier structure of the CNT-based MPA is limited to less than 2 μm with a pixel size of 7.45 μm × 7.45 μm. The degree of polarization of the CNT-MPA reached 93% at a 632 nm wavelength. The specific designs in structure and semiconductor fabrication procedures are described. Compared with customary MPAs, CNT-based MPA holds great potential in decreasing the cross-talk risk associated with lower film thickness and can be extended to a wide spectral range. Full article

(This article belongs to the Special Issue 2D Materials for Advanced Sensors: Fabrication and Applications)

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39 pages, 30620 KiB

Open AccessEditor’s ChoiceReview

Dynamics and Processes on Laser-Irradiated Surfaces

by Juergen Reif

Nanomaterials 2023, 13(3), 379; https://doi.org/10.3390/nano13030379 - 17 Jan 2023

Cited by 6 | Viewed by 3730

Abstract

The modification of solid surfaces via the impacts of intense laser pulses and the dynamics of the relevant processes are reviewed. We start with rather weak interactions on dielectric materials, based on non-linear absorption across the bandgap and resulting in low-level local effects [...] Read more.

The modification of solid surfaces via the impacts of intense laser pulses and the dynamics of the relevant processes are reviewed. We start with rather weak interactions on dielectric materials, based on non-linear absorption across the bandgap and resulting in low-level local effects like electron and individual ion emission. The role of such locally induced defects in the cumulative effect of incubation, i.e., the increase in efficiency with the increasing number of laser pulses, is addressed. At higher excitation density levels, due to easier laser–material coupling and higher laser fluence, the energy dissipation is considerable, leading to lattice destabilization, surface relaxation, ablation, and surface modification (e.g., laser-induced periodic surface structures). Finally, a short list of possible applications, namely in the field of wettability, is presented. Full article

(This article belongs to the Special Issue Dynamics and Processes at Laser-Irradiated Surfaces—A Themed Issue in Honor of the 70th Birthday of Professor Jürgen Reif)

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20 pages, 3843 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Uranium Removal from Aqueous Solutions by Aerogel-Based Adsorbents—A Critical Review

by Efthalia Georgiou, Grigorios Raptopoulos, Ioannis Anastopoulos, Dimitrios A. Giannakoudakis, Michael Arkas, Patrina Paraskevopoulou and Ioannis Pashalidis

Nanomaterials 2023, 13(2), 363; https://doi.org/10.3390/nano13020363 - 16 Jan 2023

Cited by 22 | Viewed by 4868

Abstract

Aerogels are a class of lightweight, nanoporous, and nanostructured materials with diverse chemical compositions and a huge potential for applications in a broad spectrum of fields. This has led the IUPAC to include them in the top ten emerging technologies in chemistry for [...] Read more.

Aerogels are a class of lightweight, nanoporous, and nanostructured materials with diverse chemical compositions and a huge potential for applications in a broad spectrum of fields. This has led the IUPAC to include them in the top ten emerging technologies in chemistry for 2022. This review provides an overview of aerogel-based adsorbents that have been used for the removal and recovery of uranium from aqueous environments, as well as an insight into the physicochemical parameters affecting the adsorption efficiency and mechanism. Uranium removal is of particular interest regarding uranium analysis and recovery, to cover the present and future uranium needs for nuclear power energy production. Among the methods used, such as ion exchange, precipitation, and solvent extraction, adsorption-based technologies are very attractive due to their easy and low-cost implementation, as well as the wide spectrum of adsorbents available. Aerogel-based adsorbents present an extraordinary sorption capacity for hexavalent uranium that can be as high as 8.8 mol kg^–1 (2088 g kg^–1). The adsorption data generally follow the Langmuir isotherm model, and the kinetic data are in most cases better described by the pseudo-second-order kinetic model. An evaluation of the thermodynamic data reveals that the adsorption is generally an endothermic, entropy-driven process (ΔH⁰, ΔS⁰ > 0). Spectroscopic studies (e.g., FTIR and XPS) indicate that the adsorption is based on the formation of inner-sphere complexes between surface active moieties and the uranyl cation. Regeneration and uranium recovery by acidification and complexation using carbonate or chelating ligands (e.g., EDTA) have been found to be successful. The application of aerogel-based adsorbents to uranium removal from industrial processes and uranium-contaminated waste waters was also successful, assuming that these materials could be very attractive as adsorbents in water treatment and uranium recovery technologies. However, the selectivity of the studied materials towards hexavalent uranium is limited, suggesting further developments of aerogel materials that could be modified by surface derivatization with chelating agents (e.g., salophen and iminodiacetate) presenting high selectivity for uranyl moieties. Full article

(This article belongs to the Special Issue Nanoscale Materials for Water Purification and Catalysis)

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13 pages, 2679 KiB

Open AccessEditor’s ChoiceArticle

Numerical and Experimental Study of Colored Magnetic Particle Mapping via Magnetoelectric Sensors

by Ron-Marco Friedrich, Mohammad Sadeghi and Franz Faupel

Nanomaterials 2023, 13(2), 347; https://doi.org/10.3390/nano13020347 - 14 Jan 2023

Cited by 6 | Viewed by 2499

Abstract

Colored imaging of magnetic nanoparticles (MNP) is a promising noninvasive method for medical applications such as therapy and diagnosis. This study investigates the capability of the magnetoelectric sensor and projected gradient descent (PGD) algorithm for colored particle detection. In the first step, the [...] Read more.

Colored imaging of magnetic nanoparticles (MNP) is a promising noninvasive method for medical applications such as therapy and diagnosis. This study investigates the capability of the magnetoelectric sensor and projected gradient descent (PGD) algorithm for colored particle detection. In the first step, the required circumstances for image reconstruction are studied via a simulation approach for different signal-to-noise ratios (SNR). The spatial accuracy of the reconstructed image is evaluated based on the correlation coefficient (CC) factor. The inverse problem is solved using the PGD method, which is adapted according to a nonnegativity constraint in the complex domain. The MNP characterizations are assessed through a magnetic particle spectrometer (MPS) for different types. In the experimental investigation, the real and imaginary parts of the MNP’s response are used to detect the spatial distribution and particle type, respectively. The experimental results indicate that the average phase difference for CT100 and ARA100 particles is 14 degrees, which is consistent with the MPS results and could satisfy the system requirements for colored imaging. The experimental evaluation showed that the magnetoelectric sensor and the proposed approach could be potential candidates for color bio-imaging applications. Full article

(This article belongs to the Special Issue Perspectives in Magnetoelectric and Magnetic Nanomaterials)

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10 pages, 2258 KiB

Open AccessEditor’s ChoiceArticle

Synthesis of Nanocrystalline PuO₂ by Hydrothermal and Thermal Decomposition of Pu(IV) Oxalate: A Comparative Study

by Viktoria Baumann, Karin Popa, Olaf Walter, Murielle Rivenet, Gérald Senentz, Bertrand Morel and Rudy J.M. Konings

Nanomaterials 2023, 13(2), 340; https://doi.org/10.3390/nano13020340 - 13 Jan 2023

Cited by 6 | Viewed by 12159

Abstract

In recent years, the hydrothermal conversion of actinide (IV) oxalates into nanometric actinide dioxides (AnO₂) has begun to be investigated as an alternative to the widely implemented thermal decomposition method. We present here a comparison between the hydrothermal and [...] Read more.

In recent years, the hydrothermal conversion of actinide (IV) oxalates into nanometric actinide dioxides (AnO₂) has begun to be investigated as an alternative to the widely implemented thermal decomposition method. We present here a comparison between the hydrothermal and the conventional thermal decomposition of Pu(IV) oxalate in terms of particle size, morphology and residual carbon content. A parametric study was carried out in order to define the temperature and time applied in the hydrothermal conversion of tetravalent Pu-oxalate into PuO₂ and to optimize the reaction conditions. Full article

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14 pages, 1996 KiB

Open AccessEditor’s ChoiceReview

Upscaling of Carbon-Based Perovskite Solar Module

by Maurizio Stefanelli, Luigi Vesce and Aldo Di Carlo

Nanomaterials 2023, 13(2), 313; https://doi.org/10.3390/nano13020313 - 12 Jan 2023

Cited by 23 | Viewed by 6593

Abstract

Perovskite solar cells (PSCs) and modules are driving the energy revolution in the coming photovoltaic field. In the last 10 years, PSCs reached efficiency close to the silicon photovoltaic technology by adopting low-cost solution processes. Despite this, the noble metal (such as gold [...] Read more.

Perovskite solar cells (PSCs) and modules are driving the energy revolution in the coming photovoltaic field. In the last 10 years, PSCs reached efficiency close to the silicon photovoltaic technology by adopting low-cost solution processes. Despite this, the noble metal (such as gold and silver) used in PSCs as a counter electrode made these devices costly in terms of energy, CO₂ footprint, and materials. Carbon-based perovskite solar cells (C-PSCs) and modules use graphite/carbon-black-based material as the counter electrode. The formulation of low-cost carbon-based inks and pastes makes them suitable for large area coating techniques and hence a solid technology for imminent industrialization. Here, we want to present the upscaling routes of carbon-counter-electrode-based module devices in terms of materials formulation, architectures, and manufacturing processes in order to give a clear vision of the scaling route and encourage the research in this green and sustainable direction. Full article

(This article belongs to the Special Issue Bio-Inspired Functional Nanomaterials)

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14 pages, 5939 KiB

Open AccessEditor’s ChoiceArticle

The Local and Electronic Structure Study of Lu_xGd_1−xVO₄ (0 ≤ x ≤ 1) Solid Solution Nanocrystals

by Yang Chen, Ziqing Li, Nianjing Ji, Chenxi Wei, Xiulan Duan and Huaidong Jiang

Nanomaterials 2023, 13(2), 323; https://doi.org/10.3390/nano13020323 - 12 Jan 2023

Viewed by 2381

Abstract

Rare-earth-doped mixed crystals have demonstrated tunable optical properties, and it is of great importance to study the structural characteristics of the mixed-crystal hosts. Herein, Lu_xGd_1-xVO₄ (0 ≤ x ≤ 1) solid solution nanocrystals were synthesized by a [...] Read more.

Rare-earth-doped mixed crystals have demonstrated tunable optical properties, and it is of great importance to study the structural characteristics of the mixed-crystal hosts. Herein, Lu_xGd_1-xVO₄ (0 ≤ x ≤ 1) solid solution nanocrystals were synthesized by a modified sol–gel method, with a pure crystalline phase and element composition. The X-ray diffraction (XRD) and Rietveld refinement results showed that Lu_xGd_1−xVO₄ nanocrystals are continuous solid solutions with a tetragonal zircon phase (space group I4₁/amd) and the lattice parameters strictly follow Vegard’s law. The detailed local structures were studied by extended X-ray absorption fine structure (EXAFS) spectra, which revealed that the average bond length of Gd-O fluctuates and decreases, while the average bond length of Lu-O gradually decreases with the increase in Lu content. Furthermore, the binding energy differences of core levels indicate that the covalent V-O bond is relatively stable, while the ionicity of the Lu-O bond decreases with the increasing x value, and the ionicity of the Gd-O bond fluctuates with small amplitude. The valence band structures were further confirmed by the first-principles calculations, indicating that the valence band is contributed to by the O 2p nonbonding state, localized Gd 4f and Lu 4f states, and the hybridized states between the bonding O 2p and V 3d. The binding energies of the Lu core and the valence levels tend to decrease gradually with the increase in Lu content. This work provides insight into the structural features of mixed-crystal hosts, which have been developed in recent years to improve laser performance by providing different positions for active ions to obtain inhomogeneous broadening spectra. Full article

(This article belongs to the Special Issue Optoelectronic Functional Nanomaterials and Devices)

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8 pages, 2345 KiB

Open AccessEditor’s ChoiceCommunication

High-Performance n-Type Bi₂Te₃ Thermoelectric Fibers with Oriented Crystal Nanosheets

by Min Sun, Pengyu Zhang, Guowu Tang, Dongdan Chen, Qi Qian and Zhongmin Yang

Nanomaterials 2023, 13(2), 326; https://doi.org/10.3390/nano13020326 - 12 Jan 2023

Cited by 10 | Viewed by 2709

Abstract

High-performance thermoelectric fibers with n-type bismuth telluride (Bi₂Te₃) core were prepared by thermal drawing. The nanosheet microstructures of the Bi₂Te₃ core were tailored by the whole annealing and Bridgman annealing processes, respectively. The influence of the [...] Read more.

High-performance thermoelectric fibers with n-type bismuth telluride (Bi₂Te₃) core were prepared by thermal drawing. The nanosheet microstructures of the Bi₂Te₃ core were tailored by the whole annealing and Bridgman annealing processes, respectively. The influence of the annealing processes on the microstructure and thermoelectric performance was investigated. As a result of the enhanced crystalline orientation of Bi₂Te₃ core caused by the above two kinds of annealing processes, both the electrical conductivity and thermal conductivity could be improved. Hence, the thermoelectric performance was enhanced, that is, the optimized dimensionless figure of merit (ZT) after the Bridgman annealing processes increased from 0.48 to about 1 at room temperature. Full article

(This article belongs to the Special Issue Advanced Nanoscale Materials for Thermoelectric Applications)

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13 pages, 2584 KiB

Open AccessEditor’s ChoiceArticle

Rational Optimization of Cathode Composites for Sulfide-Based All-Solid-State Batteries

by Artur Tron, Raad Hamid, Ningxin Zhang and Alexander Beutl

Nanomaterials 2023, 13(2), 327; https://doi.org/10.3390/nano13020327 - 12 Jan 2023

Cited by 12 | Viewed by 5863

Abstract

All-solid-state lithium-ion batteries with argyrodite solid electrolytes have been developed to attain high conductivities of 10⁻³ S cm⁻¹ in studies aiming at fast ionic conductivity of electrolytes. However, no matter how high the ionic conductivity of the electrolyte, the design of [...] Read more.

All-solid-state lithium-ion batteries with argyrodite solid electrolytes have been developed to attain high conductivities of 10⁻³ S cm⁻¹ in studies aiming at fast ionic conductivity of electrolytes. However, no matter how high the ionic conductivity of the electrolyte, the design of the cathode composite is often the bottleneck for high performance. Thus, optimization of the composite cathode formulation is of utmost importance. Unfortunately, many reports limit their studies to only a few parameters of the whole electrode formulation. In addition, different measurement setups and testing conditions employed for all-solid-state batteries make a comparison of results from mutually independent studies quite difficult. Therefore, a detailed investigation on different key parameters for preparation of cathodes employed in all-solid-state batteries is presented here. Employing a rational approach for optimization of composite cathodes using solid sulfide electrolytes elucidated the influence of different parameters on the cycling performance. First, powder electrodes made without binders are investigated to optimize several parameters, including the active materials’ particle morphology, the nature and amount of the conductive additive, the particle size of the solid electrolyte, as well as the active material-to-solid electrolyte ratio. Finally, cast electrodes are examined to determine the influence of a binder on cycling performance. Full article

(This article belongs to the Special Issue Sulfur Based Nanomaterials for Secondary Batteries)

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13 pages, 15211 KiB

Open AccessEditor’s ChoiceArticle

In Vitro Analysis of Superparamagnetic Iron Oxide Nanoparticles Coated with APTES as Possible Radiosensitizers for HNSCC Cells

by Clara Emer, Laura S. Hildebrand, Bernhard Friedrich, Rainer Tietze, Rainer Fietkau and Luitpold V. Distel

Nanomaterials 2023, 13(2), 330; https://doi.org/10.3390/nano13020330 - 12 Jan 2023

Cited by 2 | Viewed by 3183

Abstract

Superparamagnetic iron oxide nanoparticles (SPION) are being investigated for many purposes, e.g., for the amplification of ionizing radiation and for the targeted application of therapeutics. Therefore, we investigated SPIONs coated with (3-Aminopropyle)-Triethoxysilane (SPION-APTES) for their influence on different head and neck squamous cell [...] Read more.

Superparamagnetic iron oxide nanoparticles (SPION) are being investigated for many purposes, e.g., for the amplification of ionizing radiation and for the targeted application of therapeutics. Therefore, we investigated SPIONs coated with (3-Aminopropyle)-Triethoxysilane (SPION-APTES) for their influence on different head and neck squamous cell carcinoma (HNSCC) cell lines, as well as for their suitability as a radiosensitizer. We used 24-well microscopy and immunofluorescence microscopy for cell observation, growth curves to determine cytostatic effects, and colony formation assays to determine cytotoxicity. We found that the APTES-SPIONs were very well taken up by the HNSCC cells. They generally have a low cytotoxic effect, showing no significant difference in clonogenic survival between the control group and cells treated with 20 µg Fe/mL (p > 0.25) for all cell lines. They have a cytostatic effect on some cell lines cells (e.g., Cal33) that is visible across different radiation doses (1, 2, 8 Gy, p = 0.05). In Cal33, e.g., SPION-APTES raised the doubling time at 2 Gy from 24.53 h to 41.64 h. Importantly, these findings vary notably between the cell lines. However, they do not significantly alter the radiation effect: only one out of eight cell lines treated with SPION-APTES showed a significantly reduced clonogenic survival after ionizing radiation with 2 Gy, and only two showed significantly reduced doubling times. Thus, although the APTES-SPIONs do not qualify as a radiosensitizer, we were still able to vividly demonstrate and analyze the effect that the APTES-SPIONs have on various cell lines as a contribution to further functionalization. Full article

(This article belongs to the Section Biology and Medicines)

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12 pages, 2089 KiB

Open AccessEditor’s ChoiceArticle

Dietary Transfer of Zinc Oxide Nanoparticles Induces Locomotive Defects Associated with GABAergic Motor Neuron Damage in Caenorhabditis elegans

by Chun Ming How and Chi-Wei Huang

Nanomaterials 2023, 13(2), 289; https://doi.org/10.3390/nano13020289 - 10 Jan 2023

Cited by 12 | Viewed by 2492

Abstract

The widespread use of zinc oxide nanoparticles (ZnO-NPs) and their release into the environment have raised concerns about the potential toxicity caused by dietary transfer. However, the toxic effects and the mechanisms of dietary transfer of ZnO-NPs have rarely been investigated. We employed [...] Read more.

The widespread use of zinc oxide nanoparticles (ZnO-NPs) and their release into the environment have raised concerns about the potential toxicity caused by dietary transfer. However, the toxic effects and the mechanisms of dietary transfer of ZnO-NPs have rarely been investigated. We employed the bacteria-feeding nematode Caenorhabditis elegans as the model organism to investigate the neurotoxicity induced by exposure to ZnO-NPs via trophic transfer. Our results showed that ZnO-NPs accumulated in the intestine of C. elegans and also in Escherichia coli OP50 that they ingested. Additionally, impairment of locomotive behaviors, including decreased body bending and head thrashing frequencies, were observed in C. elegans that were fed E. coli pre-treated with ZnO-NPs, which might have occurred because of damage to the D-type GABAergic motor neurons. However, these toxic effects were not apparent in C. elegans that were fed E. coli pre-treated with zinc chloride (ZnCl₂). Therefore, ZnO-NPs particulates, rather than released Zn ions, damage the D-type GABAergic motor neurons and adversely affect the locomotive behaviors of C. elegans via dietary transfer. Full article

(This article belongs to the Special Issue Nanoparticles in the Environment and Nanotoxicology)

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13 pages, 4226 KiB

Open AccessEditor’s ChoiceArticle

In Situ Grown Mesoporous Structure of Fe-Dopant@NiCoO_X@NF Nanoneedles as an Efficient Supercapacitor Electrode Material

by Yedluri Anil Kumar, Ganesh Koyyada, Dasha Kumar Kulurumotlakatla, Jae Hong Kim, Md Moniruzzaman, Salem Alzahmi and Ihab M. Obaidat

Nanomaterials 2023, 13(2), 292; https://doi.org/10.3390/nano13020292 - 10 Jan 2023

Cited by 6 | Viewed by 3570

Abstract

In this study, we designed mixed metal oxides with doping compound nano-constructions as efficient electrode materials for supercapacitors (SCs). We successfully prepared the Fe-dopant with NiCoO_x grown on nickel foam (Fe-dopant@NiCoO_x@NF) through a simple hydrothermal route with annealing procedures. This [...] Read more.

In this study, we designed mixed metal oxides with doping compound nano-constructions as efficient electrode materials for supercapacitors (SCs). We successfully prepared the Fe-dopant with NiCoO_x grown on nickel foam (Fe-dopant@NiCoO_x@NF) through a simple hydrothermal route with annealing procedures. This method provides an easy route for the preparation of high activity SCs for energy storage. Obtained results revealed that the Fe dopant has successfully assisted NiCoO_x lattices. The electrochemical properties were investigated in a three-electrode configuration. As a composite electrode for SC characteristics, the Fe-dopant@NiCoO_x@NF exhibits notable electrochemical performances with very high specific capacitances of 1965 F g⁻¹ at the current density of 0.5 A g⁻¹, and even higher at 1296 F g⁻¹ and 30 A g⁻¹, respectively, which indicate eminent and greater potential for SCs. Moreover, the Fe-dopant@NiCoO_x@NF nanoneedle composite obtains outstanding cycling performances of 95.9% retention over 4500 long cycles. The improved SC activities of Fe-dopant@NiCoO_x@NF nanoneedles might be ascribed to the synergistic reactions of the ternary mixed metals, Fe-dopant, and the ordered nanosheets grown on NF. Thus, the Fe-dopant@NiCoO_x@NF nanoneedle composite with unique properties could lead to promising SC performance. Full article

(This article belongs to the Special Issue Advanced Functional Nanomaterials for Energy Storage Applications, Volume II)

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12 pages, 9453 KiB

Open AccessEditor’s ChoiceArticle

Supercurrent in Bi₄Te₃ Topological Material-Based Three-Terminal Junctions

by Jonas Kölzer, Abdur Rehman Jalil, Daniel Rosenbach, Lisa Arndt, Gregor Mussler, Peter Schüffelgen, Detlev Grützmacher, Hans Lüth and Thomas Schäpers

Nanomaterials 2023, 13(2), 293; https://doi.org/10.3390/nano13020293 - 10 Jan 2023

Cited by 11 | Viewed by 3266

Abstract

In this paper, in an in situ prepared three-terminal Josephson junction based on the topological insulator Bi

_{4}

Te

_{3}

and the superconductor Nb the transport properties are studied. The differential resistance maps as a function of two bias currents reveal extended areas [...] Read more.

In this paper, in an in situ prepared three-terminal Josephson junction based on the topological insulator Bi

_{4}

Te

_{3}

and the superconductor Nb the transport properties are studied. The differential resistance maps as a function of two bias currents reveal extended areas of Josephson supercurrent, including coupling effects between adjacent superconducting electrodes. The observed dynamics for the coupling of the junctions is interpreted using a numerical simulation of a similar geometry based on a resistively and capacitively shunted Josephson junction model. The temperature dependency indicates that the device behaves similar to prior experiments with single Josephson junctions comprising topological insulators’ weak links. Irradiating radio frequencies to the junction, we find a spectrum of integer Shapiro steps and an additional fractional step, which is interpreted with a skewed current–phase relationship. In a perpendicular magnetic field, we observe Fraunhofer-like interference patterns in the switching currents. Full article

(This article belongs to the Special Issue Topological Materials in Low Dimensions)

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19 pages, 6251 KiB

Open AccessEditor’s ChoiceArticle

Photocatalytic Degradation of Crystal Violet Dye under Visible Light by Fe-Doped TiO₂ Prepared by Reverse-Micelle Sol–Gel Method

by Antonietta Mancuso, Nicola Blangetti, Olga Sacco, Francesca Stefania Freyria, Barbara Bonelli, Serena Esposito, Diana Sannino and Vincenzo Vaiano

Nanomaterials 2023, 13(2), 270; https://doi.org/10.3390/nano13020270 - 8 Jan 2023

Cited by 54 | Viewed by 6197

Abstract

A reverse-micelle sol–gel method was chosen for the preparation of Fe-doped TiO₂ samples that were employed in the photodegradation of the crystal violet dye under visible light irradiation in a batch reactor. The dopant amount was varied to assess the optimal photocatalyst [...] Read more.

A reverse-micelle sol–gel method was chosen for the preparation of Fe-doped TiO₂ samples that were employed in the photodegradation of the crystal violet dye under visible light irradiation in a batch reactor. The dopant amount was varied to assess the optimal photocatalyst composition towards the target dye degradation. The photocatalysts were characterized through a multi-technique approach, envisaging XRPD and QPA as obtained by Rietveld refinement, FE-SEM analysis, DR UV−vis spectroscopy, N₂ adsorption/desorption isotherms measurement at −196 °C, ζ-potential measurement, and XPS analysis. The physical-chemical characterization showed that the adopted synthesis method allows obtaining NPs with uniform shape and size and promotes the introduction of Fe into the titania matrix, finally affecting the relative amounts of the three occurring polymorphs of TiO₂ (anatase, rutile and brookite). By increasing the Fe content, the band gap energy decreases from 3.13 eV (with undoped TiO₂) to 2.65 eV (with both 2.5 and 3.5 wt.% nominal Fe contents). At higher Fe content, surface Fe oxo-hydroxide species occur, as shown by DR UV-vis and XP spectroscopies. All the Fe-doped TiO₂ photocatalysts were active in the degradation and mineralization of the target dye, showing a TOC removal higher than the undoped sample. The photoactivity under visible light was ascribed both to the band-gap reduction (as confirmed by phenol photodegradation) and to dye sensitization of the photocatalyst surface (as confirmed by photocatalytic tests carried out using different visible-emission spectra LEDs). The main reactive species involved in the dye degradation were determined to be positive holes. Full article

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18 pages, 2191 KiB

Open AccessEditor’s ChoiceReview

Recent Strategies for High-Performing Indoor Perovskite Photovoltaics

by Kelvian T. Mularso, Ji-Young Jeong, Gill Sang Han and Hyun Suk Jung

Nanomaterials 2023, 13(2), 259; https://doi.org/10.3390/nano13020259 - 7 Jan 2023

Cited by 11 | Viewed by 5498

Abstract

The development of digital technology has made our lives more advanced as a society familiar with the Internet of Things (IoT). Solar cells are among the most promising candidates for power supply in IoT sensors. Perovskite photovoltaics (PPVs), which have already attained 25% [...] Read more.

The development of digital technology has made our lives more advanced as a society familiar with the Internet of Things (IoT). Solar cells are among the most promising candidates for power supply in IoT sensors. Perovskite photovoltaics (PPVs), which have already attained 25% and 40% power conversion efficiencies for outdoor and indoor light, respectively, are the best candidates for self-powered IoT system integration. In this review, we discuss recent research progress on PPVs under indoor light conditions, with a focus on device engineering to achieve high-performance indoor PPVs (Id-PPVs), including bandgap optimization and defect management. Finally, we discuss the challenges of Id-PPVs development and its interpretation as a potential research direction in the field. Full article

(This article belongs to the Special Issue New Horizon in Perovskite Nanocrystals)

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13 pages, 2379 KiB

Open AccessEditor’s ChoiceArticle

Wearable and Washable MnO₂−Zn Battery Packaged by Vacuum Sealing

by Jun Ho Noh, Myoungeun Oh, Sunjin Kang, Hyeong Seok Lee, Yeong Jun Hong, Chaeyeon Park, Raeyun Lee and Changsoon Choi

Nanomaterials 2023, 13(2), 265; https://doi.org/10.3390/nano13020265 - 7 Jan 2023

Cited by 4 | Viewed by 3223

Abstract

Batteries are used in all types of electronic devices from conventional to advanced devices. Currently, batteries are evolving in the direction of extremely personalized yarn− or textile−structured textronic systems. However, the absence of a protective layer on such batteries is a critical limitation [...] Read more.

Batteries are used in all types of electronic devices from conventional to advanced devices. Currently, batteries are evolving in the direction of extremely personalized yarn− or textile−structured textronic systems. However, the absence of a protective layer on such batteries is a critical limitation to their practical use. In this study, we developed a wearable and washable MnO₂−Zn textile battery that maintains its electrochemical capacity under various external environmental conditions through a vacuum−sealed packaging. The packaged textile battery was fabricated by vacuuming a polymer envelope containing the battery, followed by heat sealing with a vacuum packaging machine. The interior and exterior regions of the textile battery are completely separated by the packaging sheath to preclude leakage and intrusion of substances. The resulting packaged textile battery exhibits stable capacity retention performance under varying temperature and humidity; mechanical deformations due to bending, twisting, rubbing, and pressing; and several mechanical, chemical, and their combined washing cycles. On the basis of these demonstrations, we expect that our vacuum−packaged textile battery will offer new possibilities for practical and convenient use of textronics. Full article

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14 pages, 3545 KiB

Open AccessEditor’s ChoiceArticle

K_xCo_1.5−0.5xFe(CN)₆/rGO with Dual−Active Sodium Ion Storage Site as Superior Anode for Sodium Ion Battery

by Gang Zhou, Mincong Fan, Lei Wang, Xianglin Li, Danqing Liu and Feng Gao

Nanomaterials 2023, 13(2), 264; https://doi.org/10.3390/nano13020264 - 7 Jan 2023

Cited by 4 | Viewed by 2411

Abstract

The unique and open large frame structures of prussian blue analogues (PBA) enables it for accommodating a large number of cations (Na⁺, K⁺, Ca²⁺, etc.), thus, PBA are considered as promising electrode materials for the rechargeable battery. [...] Read more.

The unique and open large frame structures of prussian blue analogues (PBA) enables it for accommodating a large number of cations (Na⁺, K⁺, Ca²⁺, etc.), thus, PBA are considered as promising electrode materials for the rechargeable battery. However, due to the chemical composition, there are still many alkaline metal ions in the gap within the framework, which puts multivalent metals in PBA in a low valence state and affects the sodium storage performance. To improve the valence of metal ions in PBA materials, precursors prepared by co−precipitation method and hydrothermal method are used to synthesis K_xCo_1.5−0.5xFe(CN)₆ through further chemical oxidation. Through the introducing of reduced graphene oxide (rGO) with excellent conductivity by a simple physical mixing method, the cycle stability and rate performance of the PBA material can be further improved. The K_0.5Co_1.2Fe(CN)₆·2H₂O/rGO anode prepared with 2 h hydrothermal time and further chemical oxidation, named as KCoHCP−H2−EK/rGO, exhibits a super electrochemical performance, delivering initial charge/discharge capacities of 846.7/1445.0 mAh·g⁻¹, and a capacity retention of 58.2% after 100 cycles at a current density of 100 mA·g⁻¹. The KCoHCP−H2−EK/rGO outstanding electrochemical behaviors are attributed to the unique dual−active site structure properties and the improved surface conductance of materials by rGO components. Full article

(This article belongs to the Special Issue Functional Micro-/Nanostructures: Advanced Fabrication and Application)

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10 pages, 1719 KiB

Open AccessEditor’s ChoiceArticle

Capacitive NO₂ Detection Using CVD Graphene-Based Device

by Wonbin Ju and Sungbae Lee

Nanomaterials 2023, 13(2), 243; https://doi.org/10.3390/nano13020243 - 5 Jan 2023

Cited by 3 | Viewed by 2281

Abstract

A graphene-based capacitive NO₂ sensing device was developed by utilizing the quantum capacitance effect. We have used a graphene field-effect transistor (G-FET) device whose geometrical capacitance is enhanced by incorporating an aluminum back-gate electrode with a naturally oxidized aluminum surface as an [...] Read more.

A graphene-based capacitive NO₂ sensing device was developed by utilizing the quantum capacitance effect. We have used a graphene field-effect transistor (G-FET) device whose geometrical capacitance is enhanced by incorporating an aluminum back-gate electrode with a naturally oxidized aluminum surface as an insulating layer. When the graphene, the top-side of the device, is exposed to NO₂, the quantum capacitance of graphene and, thus, the measured capacitance of the device, changed in accordance with NO₂ concentrations ranging from 1–100 parts per million (ppm). The operational principle of the proposed system is also explained with the changes in gate voltage-dependent capacitance of the G-FET exposed to various concentrations of NO₂. Further analyses regarding carrier density changes and potential variances under various concentrations of NO₂ are also presented to strengthen the argument. The results demonstrate the feasibility of capacitive NO₂ sensing using graphene and the operational principle of capacitive NO₂ sensing. Full article

(This article belongs to the Special Issue Mechanical Properties and Applications of Graphene and Layered Nanocomposites)

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14 pages, 6255 KiB

Open AccessEditor’s ChoiceArticle

Effect of Polyphenols on the Ice-Nucleation Activity of Ultrafine Bubbles

by Tsutomu Uchida and Yukiharu Fukushi

Nanomaterials 2023, 13(1), 205; https://doi.org/10.3390/nano13010205 - 2 Jan 2023

Cited by 2 | Viewed by 3121

Abstract

Ultrafine bubbles (UFBs) in water provide a large amount of gas and a large gas–liquid interfacial area, and can release energy through their collapse. Such features may promote ice nucleation. Here, we examined the nucleation of ice in solutions containing polyphenols and UFBs. [...] Read more.

Ultrafine bubbles (UFBs) in water provide a large amount of gas and a large gas–liquid interfacial area, and can release energy through their collapse. Such features may promote ice nucleation. Here, we examined the nucleation of ice in solutions containing polyphenols and UFBs. To reduce the likelihood of nucleation occurring on the container walls over that in previous studies, we used a much larger sample volume of 1 mL. In our experiments, UFBs (when present) had a number concentration of 10⁸ mL⁻¹. We quantified changes to the nucleation activity by examining the shift in the cumulative freezing (nucleation) probability distribution. Compared to pure water, this freezing curve shifts approximately 0.6 °C higher with the UFBs. Then, to the water, we added three polyphenols (tannic acid TA, tea catechin TC, and oligonol OLG), chosen because they had been reported to reduce the ice-nucleation activity of heterogeneous ice nuclei (e.g., AgI). We found experimentally that, without UFBs, all polyphenols instead shift the pure-water freezing curve to a higher temperature. Then, when UFBs are added, the additional temperature shift in the freezing curve is slightly higher for OLG, essentially unchanged for TA, and slightly lower for TC. To help to explain these differences, we examined the UFB size distributions using dynamic light scattering and freeze-fractured replicas with transmission electron microscopy, finding that OLG and TC alter the UFBs, but that TA does not. Full article

(This article belongs to the Special Issue Nanobubbles and Their Applications)

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10 pages, 2935 KiB

Open AccessEditor’s ChoiceArticle

Improved Electrical Properties of EHD Jet-Patterned MoS₂ Thin-Film Transistors with Printed Ag Electrodes on a High-k Dielectric

by Thi Thu Thuy Can and Woon-Seop Choi

Nanomaterials 2023, 13(1), 194; https://doi.org/10.3390/nano13010194 - 1 Jan 2023

Cited by 6 | Viewed by 3310

Abstract

Electrohydrodynamic (EHD) jet printing is known as a versatile method to print a wide viscosity range of materials that are impossible to print by conventional inkjet printing. Hence, with the understanding of the benefits of EHD jet printing, solution-based MoS₂ and a [...] Read more.

Electrohydrodynamic (EHD) jet printing is known as a versatile method to print a wide viscosity range of materials that are impossible to print by conventional inkjet printing. Hence, with the understanding of the benefits of EHD jet printing, solution-based MoS₂ and a high-viscosity Ag paste were EHD jet-printed for electronic applications in this work. In particular, printed MoS₂ TFTs with a patterned Ag source and drain were successfully fabricated with low-k silica (SiO₂) and high-k alumina (Al₂O₃) gate dielectrics, respectively. Eventually, the devices based on Al₂O₃ exhibited much better electrical properties compared to the ones based on SiO₂. Interestingly, an improvement of around one order of magnitude in hysteresis was achieved for devices after changing the gate insulator from SiO₂ to Al₂O₃. In effect, the results of this work for the printed MoS₂ and the printed Ag source and drains for TFTs demonstrate a new approach for jet printing in the fabrication of electronic devices. Full article

(This article belongs to the Special Issue 2D Semiconducting Materials for Device Applications)

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16 pages, 5060 KiB

Open AccessEditor’s ChoiceArticle

Photodetection Properties of MoS₂, WS₂ and Mo_xW_1-xS₂ Heterostructure: A Comparative Study

by Maryam Al Qaydi, Ahmed Kotbi, Nitul S. Rajput, Abdellatif Bouchalkha, Mimoun El Marssi, Guillaume Matras, Chaouki Kasmi and Mustapha Jouiad

Nanomaterials 2023, 13(1), 24; https://doi.org/10.3390/nano13010024 - 21 Dec 2022

Cited by 10 | Viewed by 4627

Abstract

Layered transition metals dichalcogenides such as MoS₂ and WS₂ have shown a tunable bandgap, making them highly desirable for optoelectronic applications. Here, we report on one-step chemical vapor deposited MoS₂, WS₂ and Mo_xW_1-xS₂ [...] Read more.

Layered transition metals dichalcogenides such as MoS₂ and WS₂ have shown a tunable bandgap, making them highly desirable for optoelectronic applications. Here, we report on one-step chemical vapor deposited MoS₂, WS₂ and Mo_xW_1-xS₂ heterostructures incorporated into photoconductive devices to be examined and compared in view of their use as potential photodetectors. Vertically aligned MoS₂ nanosheets and horizontally stacked WS₂ layers, and their heterostructure form Mo_xW_1-xS₂, exhibit direct and indirect bandgap, respectively. To analyze these structures, various characterization methods were used to elucidate their properties including Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectrometry and high-resolution transmission electron microscopy. While all the investigated samples show a photoresponse in a broad wavelength range between 400 nm and 700 nm, the vertical MoS₂ nanosheets sample exhibits the highest performances at a low bias voltage of 5 V. Our findings demonstrate a responsivity and a specific detectivity of 47.4 mA W⁻¹ and 1.4 × 10¹¹ Jones, respectively, achieved by Mo_xW_1-xS₂. This study offers insights into the use of a facile elaboration technique for tuning the performance of Mo_xW_1-xS₂ heterostructure-based photodetectors. Full article

(This article belongs to the Special Issue Advances in Nanostructured Semiconductors and Heterojunctions)

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15 pages, 4473 KiB

Open AccessEditor’s ChoiceArticle

Shear Bond Strength and Color Stability of Novel Antibacterial Nanofilled Dental Adhesive Resins

by Qing Hong, Alexandra C. Pierre-Bez, Matheus Kury, Mark E. Curtis, Rochelle D. Hiers, Fernando L. Esteban Florez and John C. Mitchell

Nanomaterials 2023, 13(1), 1; https://doi.org/10.3390/nano13010001 - 20 Dec 2022

Cited by 9 | Viewed by 3068

Abstract

Experimental adhesives containing co-doped metaloxide nanoparticles were demonstrated to display strong and long-term antibacterial properties against Streptococcus mutans biofilms. The present study represents an effort to characterize the shear-bond strength (SBS) and color stability (CS) of these novel biomaterials. Experimental adhesives were obtained [...] Read more.

Experimental adhesives containing co-doped metaloxide nanoparticles were demonstrated to display strong and long-term antibacterial properties against Streptococcus mutans biofilms. The present study represents an effort to characterize the shear-bond strength (SBS) and color stability (CS) of these novel biomaterials. Experimental adhesives were obtained by dispersing nitrogen and fluorine co-doped titanium dioxide nanoparticles (NF_TiO₂, 10%, 20% or 30%, v/v%) into OptiBond Solo Plus (OPTB). Dentin surfaces were wet-polished (600-Grit). Specimens (n = 5/group) of Tetric EvoCeram were fabricated and bonded using either OPTB or experimental (OPTB + NF_TiO₂) adhesives. Specimens were stored in water (37 °C) for twenty-four hours (T1), three months (T2), and six months (T3). At T1, T2, or T3, specimens were removed from water storage and were tested for SBS. Disc-shaped specimens (n = 10/group; d = 6.0 mm, t = 0.5 mm) of adhesives investigated were fabricated and subjected to thermocycling (10,000 cycles, 5–55 °C, 15 s dwell time). Specimens’ colors were determined with a VITA Easyshade^® V spectrophotometer (after every 1000 cycles). SBS data was analyzed using two-way ANOVA and post-hoc Tukey tests, while CS data was analyzed using one-way ANOVA and post-hoc Tukey tests (α = 0.05). Mean values of SBS ranged from 16.39 ± 4.20 MPa (OPTB + 30%NF_TiO₂) to 19.11 ± 1.11 MPa (OPTB), from 12.99 ± 2.53 MPa (OPTB + 30% NF_TiO₂) to 14.87 ± 2.02 (OPTB) and from 11.37 ± 1.89 (OPTB + 20% NF_TiO₂) to 14.19 ± 2.24 (OPTB) after twenty-four hours, three months, and six months of water storage, respectively. Experimental materials had SBS values that were comparable (p > 0.05) to those from OPTB independently of nanoparticle concentration or time-point considered. Experimental materials with higher NF_TiO₂ concentrations had less intense color variations and were more color stable than OPTB even after 10,000 thermocycles. In combination, the results reported have demonstrated that experimental adhesives can establish strong and durable bonds to human dentin while displaying colors that are more stable, thereby suggesting that the antibacterial nanotechnology investigated can withstand the harsh conditions within the oral cavity without compromising the esthetic component of dental restorations. Full article

(This article belongs to the Special Issue Synthesis and Application of Nanoparticles in Novel Composites)

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16 pages, 6500 KiB

Open AccessEditor’s ChoiceArticle

Insights into the Stability of Graphene Oxide Aqueous Dispersions

by Codrut Costinas, Catalin Alexandru Salagean, Liviu Cosmin Cotet, Monica Baia, Milica Todea, Klara Magyari and Lucian Baia

Nanomaterials 2022, 12(24), 4489; https://doi.org/10.3390/nano12244489 - 19 Dec 2022

Cited by 13 | Viewed by 2896

Abstract

Understanding graphene oxide’s stability (or lack thereof) in liquid solvents is critical for fine-tuning the material’s characteristics and its potential involvement in future applications. In this work, through the use of structural and surface investigations, the alteration of the structural and edge-surface properties [...] Read more.

Understanding graphene oxide’s stability (or lack thereof) in liquid solvents is critical for fine-tuning the material’s characteristics and its potential involvement in future applications. In this work, through the use of structural and surface investigations, the alteration of the structural and edge-surface properties of 2D graphene oxide nanosheets was monitored over a period of eight weeks by involving DLS, zeta potential, XRD, XPS, Raman and FT-IR spectroscopy techniques. The samples were synthesized as an aqueous suspension by an original modified Marcano-Tour method centred on the sono-chemical exfoliation of graphite. Based on the acquired experimental results and the available literature, a phenomenological explanation of the two underlying mechanisms responsible for the meta-stability of graphene oxide aqueous dispersions is proposed. It is based on the cleavage of the carbon bonds in the first 3–4 weeks, while the bonding of oxygen functional groups on the carbon lattice occurs, and the transformation of epoxide and hydroxyl groups into adsorbed water molecules in a process driven by the availability of hydrogen in graphene oxide nanosheets. Full article

(This article belongs to the Special Issue Synthesis, Modification and Application of Graphene)

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11 pages, 2429 KiB

Open AccessEditor’s ChoiceArticle

Biocompatibility, Bioactivity, and Antibacterial Behaviour of Cerium-Containing Bioglass^®

by Sílvia R. Gavinho, Ana Sofia Pádua, Isabel Sá-Nogueira, Jorge C. Silva, João P. Borges, Luis C. Costa and Manuel Pedro F. Graça

Nanomaterials 2022, 12(24), 4479; https://doi.org/10.3390/nano12244479 - 18 Dec 2022

Cited by 32 | Viewed by 3711

Abstract

The main reason for the increased use of dental implants in clinical practice is associated with aesthetic parameters. Implants are also presented as the only technique that conserves and stimulates natural bone. However, there are several problems associated with infections, such as peri-implantitis. [...] Read more.

The main reason for the increased use of dental implants in clinical practice is associated with aesthetic parameters. Implants are also presented as the only technique that conserves and stimulates natural bone. However, there are several problems associated with infections, such as peri-implantitis. This disease reveals a progressive inflammatory action that affects the hard and soft tissues surrounding the implant, leading to implant loss. To prevent the onset of this disease, coating the implant with bioactive glasses has been suggested. In addition to its intrinsic function of promoting bone regeneration, it is also possible to insert therapeutic ions, such as cerium. Cerium has several advantages when the aim is to improve osseointegration and prevent infectious problems with dental implant placement. It promotes increased growth and the differentiation of osteoblasts, improves the mechanical properties of bone, and prevents bacterial adhesion and proliferation that may occur on the implant surface. This antibacterial effect is due to its ability to disrupt the cell wall and membrane of bacteria, thus interfering with vital metabolic functions such as respiration. In addition, its antioxidant effect reverses oxidative stress after implantation in bone. In this work, Bioglass 45S5 with CeO₂ with different percentages (0.25, 0.5, 1, and 2 mol%) was developed by the melt-quenching method. The materials were analyzed in terms of morphological, structural, and biological (cytotoxicity, bioactivity, and antibacterial activity) properties. The addition of cerium did not promote structural changes to the bioactive glass, which shows no cytotoxicity for the Saos-2 cell line up to 25 mg/mL of extract concentration for all cerium contents. For the maximum cerium concentration (2 mol%) the bioactive glass shows an evident inhibitory effect for Escherichia coli and Streptococcus mutans bacteria. Furthermore, all samples showed the beginning of the deposition of a CaP-rich layer on the surface of the material after 24 h. Full article

(This article belongs to the Special Issue Nanobiotechnologies in Environment and Medicine)

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19 pages, 5643 KiB

Open AccessEditor’s ChoiceArticle

3D Nanoprinting of All-Metal Nanoprobes for Electric AFM Modes

by Lukas Matthias Seewald, Jürgen Sattelkow, Michele Brugger-Hatzl, Gerald Kothleitner, Hajo Frerichs, Christian Schwalb, Stefan Hummel and Harald Plank

Nanomaterials 2022, 12(24), 4477; https://doi.org/10.3390/nano12244477 - 17 Dec 2022

Cited by 8 | Viewed by 2874

Abstract

3D nanoprinting via focused electron beam induced deposition (FEBID) is applied for fabrication of all-metal nanoprobes for atomic force microscopy (AFM)-based electrical operation modes. The 3D tip concept is based on a hollow-cone (HC) design, with all-metal material properties and apex radii in [...] Read more.

3D nanoprinting via focused electron beam induced deposition (FEBID) is applied for fabrication of all-metal nanoprobes for atomic force microscopy (AFM)-based electrical operation modes. The 3D tip concept is based on a hollow-cone (HC) design, with all-metal material properties and apex radii in the sub-10 nm regime to allow for high-resolution imaging during morphological imaging, conductive AFM (CAFM) and electrostatic force microscopy (EFM). The study starts with design aspects to motivate the proposed HC architecture, followed by detailed fabrication characterization to identify and optimize FEBID process parameters. To arrive at desired material properties, e-beam assisted purification in low-pressure water atmospheres was applied at room temperature, which enabled the removal of carbon impurities from as-deposited structures. The microstructure of final HCs was analyzed via scanning transmission electron microscopy—high-angle annular dark field (STEM-HAADF), whereas electrical and mechanical properties were investigated in situ using micromanipulators. Finally, AFM/EFM/CAFM measurements were performed in comparison to non-functional, high-resolution tips and commercially available electric probes. In essence, we demonstrate that the proposed all-metal HCs provide the resolution capabilities of the former, with the electric conductivity of the latter onboard, combining both assets in one design. Full article

(This article belongs to the Special Issue Nanomaterials Fabricated by Electron-Beam-Induced Deposition and Related Processes)

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35 pages, 2188 KiB

Open AccessEditor’s ChoiceReview

Mechanisms of Antifungal Properties of Metal Nanoparticles

by Yael N. Slavin and Horacio Bach

Nanomaterials 2022, 12(24), 4470; https://doi.org/10.3390/nano12244470 - 16 Dec 2022

Cited by 92 | Viewed by 10412

Abstract

The appearance of resistant species of fungi to the existent antimycotics is challenging for the scientific community. One emergent technology is the application of nanotechnology to develop novel antifungal agents. Metal nanoparticles (NPs) have shown promising results as an alternative to classical antimycotics. [...] Read more.

The appearance of resistant species of fungi to the existent antimycotics is challenging for the scientific community. One emergent technology is the application of nanotechnology to develop novel antifungal agents. Metal nanoparticles (NPs) have shown promising results as an alternative to classical antimycotics. This review summarizes and discusses the antifungal mechanisms of metal NPs, including combinations with other antimycotics, covering the period from 2005 to 2022. These mechanisms include but are not limited to the generation of toxic oxygen species and their cellular target, the effect of the cell wall damage and the hyphae and spores, and the mechanisms of defense implied by the fungal cell. Lastly, a description of the impact of NPs on the transcriptomic and proteomic profiles is discussed. Full article

(This article belongs to the Special Issue Development of Nanomaterials for Biomedical Applications)

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20 pages, 2945 KiB

Open AccessEditor’s ChoiceArticle

Towards Improved Humidity Sensing Nanomaterials via Combined Electron and NH₃ Treatment of Carbon-Rich FEBID Deposits

by Hannah Boeckers, Petra Swiderek and Markus Rohdenburg

Nanomaterials 2022, 12(24), 4455; https://doi.org/10.3390/nano12244455 - 15 Dec 2022

Cited by 3 | Viewed by 2298

Abstract

Focused Electron Beam Induced Deposition (FEBID) is a unique tool to produce nanoscale materials. The resulting deposits can be used, for instance, as humidity or strain sensors. The humidity sensing concept relies on the fact that FEBID using organometallic precursors often yields deposits [...] Read more.

Focused Electron Beam Induced Deposition (FEBID) is a unique tool to produce nanoscale materials. The resulting deposits can be used, for instance, as humidity or strain sensors. The humidity sensing concept relies on the fact that FEBID using organometallic precursors often yields deposits which consist of metal nanoparticles embedded in a carbonaceous matrix. The electrical conductivity of such materials is altered in the presence of polar molecules such as water. Herein, we provide evidence that the interaction with water can be enhanced by incorporating nitrogen in the deposit through post-deposition electron irradiation in presence of ammonia (NH₃). This opens the perspective to improve and tune the properties of humidity sensors fabricated by FEBID. As a proof-of-concept experiment, we have prepared carbonaceous deposits by electron irradiation of adsorbed layers of three different precursors, namely, the aliphatic hydrocarbon n-pentane, a simple alkene (2-methyl-2-butene), and the potential Ru FEBID precursor bis(ethylcyclopentadienyl)ruthenium(II). In a subsequent processing step, we incorporated C-N bonds in the deposit by electron irradiation of adsorbed NH₃. To test the resulting material with respect to its potential humidity sensing capabilities, we condensed sub-monolayer quantities of water (H₂O) on the deposit and evaluated their thermal desorption behavior. The results confirm that the desorption temperature of H₂O decisively depends on the degree of N incorporation into the carbonaceous residue which, in turn, depends on the chemical nature of the precursor used for deposition of the carbonaceous layer. We thus anticipate that the sensitivity of a FEBID-based humidity sensor can be tuned by a precisely timed post-deposition electron and NH₃ processing step. Full article

(This article belongs to the Special Issue Nanomaterials Fabricated by Electron-Beam-Induced Deposition and Related Processes)

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14 pages, 4899 KiB

Open AccessEditor’s ChoiceArticle

Electrical Contact Resistance of Large-Area Graphene on Pre-Patterned Cu and Au Electrodes

by Tomáš Blecha, Zuzana Vlčková Živcová, Farjana J. Sonia, Martin Mergl, Oleksandr Volochanskyi, Michal Bodnár, Pavel Rous, Kenichiro Mizohata, Martin Kalbáč and Otakar Frank

Nanomaterials 2022, 12(24), 4444; https://doi.org/10.3390/nano12244444 - 14 Dec 2022

Cited by 4 | Viewed by 4186

Abstract

Contact resistance between electrically connected parts of electronic elements can negatively affect their resulting properties and parameters. The contact resistance is influenced by the physicochemical properties of the connected elements and, in most cases, the lowest possible value is required. The issue of [...] Read more.

Contact resistance between electrically connected parts of electronic elements can negatively affect their resulting properties and parameters. The contact resistance is influenced by the physicochemical properties of the connected elements and, in most cases, the lowest possible value is required. The issue of contact resistance is also addressed in connection with the increasingly frequently used carbon allotropes. This work aimed to determine the factors that influence contact resistance between graphene prepared by chemical vapour deposition and pre-patterned Cu and Au electrodes onto which graphene is subsequently transferred. It was found that electrode surface treatment methods affect the resistance between Cu and graphene, where contact resistance varied greatly, with an average of 1.25 ± 1.54 kΩ, whereas for the Au electrodes, the deposition techniques did not influence the resulting contact resistance, which decreased by almost two orders of magnitude compared with the Cu electrodes, to 0.03 ± 0.01 kΩ. Full article

(This article belongs to the Special Issue Nanofabrication and Nanomanipulation in Graphene)

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20 pages, 2617 KiB

Open AccessEditor’s ChoiceArticle

Interaction of Colloidal Gold Nanoparticles with Urine and Saliva Biofluids: An Exploratory Study

by Maria António, Tânia Lima, Rui Vitorino and Ana L. Daniel-da-Silva

Nanomaterials 2022, 12(24), 4434; https://doi.org/10.3390/nano12244434 - 13 Dec 2022

Cited by 5 | Viewed by 2726

Abstract

The use of gold nanoparticles for drug delivery, photothermal or photodynamic therapy, and biosensing enhances the demand for knowledge about the protein corona formed on the surface of nanoparticles. In this study, gold nanospheres (AuNSs), gold nanorods (AuNRs), and gold nanoflowers (AuNFs) were [...] Read more.

The use of gold nanoparticles for drug delivery, photothermal or photodynamic therapy, and biosensing enhances the demand for knowledge about the protein corona formed on the surface of nanoparticles. In this study, gold nanospheres (AuNSs), gold nanorods (AuNRs), and gold nanoflowers (AuNFs) were incubated with saliva or urine. After the interaction, the surface of gold nanoparticles was investigated using UV-VIS spectroscopy, zeta potential, and dynamic light scattering. The shifting of the localized surface plasmon resonance (LSPR) band, the increase in hydrodynamic diameter, and the changes in the surface charge of nanoparticles indicated the presence of biomolecules on the surface of AuNSs, AuNRs, and AuNFs. The incubation of AuNFs with saliva led to nanoparticle aggregation and minimal protein adsorption. AuNSs and AuNRs incubated in saliva were analyzed through liquid chromatography with tandem mass spectrometry (LC-MS/MS) to identify the 96 proteins adsorbed on the surface of the gold nanoparticles. Among the 20 most abundant proteins identified, 14 proteins were common in both AuNSs and AuNRs. We hypothesize that the adsorption of these proteins was due to their high sulfur content, allowing for their interaction with gold nanoparticles via the Au-S bond. The presence of distinct proteins on the surface of AuNSs or AuNRs was also investigated and possibly related to the competition between proteins present on the external layers of corona and gold nanoparticle morphology. Full article

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9 pages, 3650 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Enhanced Field-Effect Control of Single-Layer WS₂ Optical Features by hBN Full Encapsulation

by Anna Di Renzo, Onur Çakıroğlu, Felix Carrascoso, Hao Li, Giuseppe Gigli, Kenji Watanabe, Takashi Taniguchi, Carmen Munuera, Aurora Rizzo, Andres Castellanos-Gomez, Rosanna Mastria and Riccardo Frisenda

Nanomaterials 2022, 12(24), 4425; https://doi.org/10.3390/nano12244425 - 12 Dec 2022

Cited by 1 | Viewed by 2881

Abstract

The field-effect control of the electrical and optical properties of two-dimensional (2D) van der Waals semiconductors (vdW) is one important aspect of this novel class of materials. Thanks to their reduced thickness and decreased screening, electric fields can easily penetrate in a 2D [...] Read more.

The field-effect control of the electrical and optical properties of two-dimensional (2D) van der Waals semiconductors (vdW) is one important aspect of this novel class of materials. Thanks to their reduced thickness and decreased screening, electric fields can easily penetrate in a 2D semiconductor and thus modulate their charge density and their properties. In literature, the field effect is routinely used to fabricate atomically thin field-effect transistors based on 2D semiconductors. Apart from the tuning of the electrical transport, it has been demonstrated that the field effect can also be used to modulate the excitonic optical emission of 2D transition metal dichalcogenides such as MoS₂ or WSe₂. In this paper, we present some recent experiments on the field-effect control of the optical and excitonic properties of the monolayer WS₂. Using the deterministic transfer of van der Waals materials, we fabricate planar single-layer WS₂ devices contacted by a gold electrode and partially sandwiched between two insulating hexagonal boron nitride (hBN) flakes. Thanks to the planar nature of the device, we can optically access both the hBN encapsulated and the unencapsulated WS₂ regions and compare the field-effect control of the exciton population in the two cases. We find that the encapsulation strongly increases the range of tunability of the optical emission of WS₂, allowing us to tune the photoluminescence emission from excitons-dominated to trions-dominated. We also discuss how the full encapsulation of WS₂ with hBN helps reduce spurious hysteretic effects in the field-effect control of the optical properties, similar to what has been reported for 2D vdW field-effect transistors. Full article

(This article belongs to the Special Issue Advances in Semiconductor Nano-Structures)

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19 pages, 4737 KiB

Open AccessEditor’s ChoiceArticle

Effective Antibacterial/Photocatalytic Activity of ZnO Nanomaterials Synthesized under Low Temperature and Alkaline Conditions

by Sujeong Kim, Hyerim Park, Sadanand Pandey, Daewon Jeong, Chul-Tae Lee, Jeong Yeon Do, Sun-Min Park and Misook Kang

Nanomaterials 2022, 12(24), 4417; https://doi.org/10.3390/nano12244417 - 11 Dec 2022

Cited by 13 | Viewed by 2493

Abstract

The purpose of this study was to evaluate the surface properties of ZnO nanomaterials based on their ability to photodegrade methyl blue dye (MB) and to show their antibacterial properties against different types of Gram-positive bacteria (Bacillus manliponensis, Micrococcus luteus, [...] Read more.

The purpose of this study was to evaluate the surface properties of ZnO nanomaterials based on their ability to photodegrade methyl blue dye (MB) and to show their antibacterial properties against different types of Gram-positive bacteria (Bacillus manliponensis, Micrococcus luteus, Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli). In this study, ZnO nanomaterials were synthesized rapidly and easily in the presence of 1–4 M NaOH at a low temperature of 40 °C within 4 h. It was found that the ZnO nanomaterials obtained from the 1.0 M (ZnO–1M) and 2.0 M (ZnO–2M) aqueous solutions of NaOH had spherical and needle-shaped forms, respectively. As the concentration of NaOH increased, needle thickness increased and the particles became rod-like. Although the ZnO nanomaterial shapes were different, the bandgap size remained almost unchanged. However, as the NaOH concentration increased, the energy position of the conduction band shifted upward. Photo current curves and photoluminescence intensities suggested that the recombination between photoexcited electrons and holes was low in the ZnO–4M materials prepared in 4.0 M NaOH solution; however, charge transfer was easy. ∙O₂⁻ radicals were generated more than ∙OH radicals in ZnO–4M particles, showing stronger antibacterial activity against both Gram-positive and Gram-negative bacteria and stronger decomposition ability on MB dye. The results of this study suggest that on the ZnO nanomaterial surface, ∙O₂⁻ radicals generated are more critical for antibacterial activity than particle shape. Full article

(This article belongs to the Special Issue Synthesis of Nanomaterials as Electrocatalysis, Photocatalysis and Thermal Catalysis)

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33 pages, 21104 KiB

Open AccessEditor’s ChoiceArticle

Micromagnetic Design of Skyrmionic Materials and Chiral Magnetic Configurations in Patterned Nanostructures for Neuromorphic and Qubit Applications

by Roxana-Alina One, Sever Mican, Angela-Georgiana Cimpoeșu, Marius Joldos, Romulus Tetean and Coriolan Viorel Tiușan

Nanomaterials 2022, 12(24), 4411; https://doi.org/10.3390/nano12244411 - 10 Dec 2022

Cited by 4 | Viewed by 3303

Abstract

Our study addresses the problematics of magnetic skyrmions, nanometer-size vortex-like swirling topological defects, broadly studied today for applications in classic, neuromorphic and quantum information technologies. We tackle some challenging issues of material properties versus skyrmion stability and manipulation within a multiple-scale modeling framework, [...] Read more.

Our study addresses the problematics of magnetic skyrmions, nanometer-size vortex-like swirling topological defects, broadly studied today for applications in classic, neuromorphic and quantum information technologies. We tackle some challenging issues of material properties versus skyrmion stability and manipulation within a multiple-scale modeling framework, involving complementary ab-initio and micromagnetic frameworks. Ab-initio calculations provide insight into the anatomy of the magnetic anisotropy, the Dzyaloshinskii–Moriya asymmetric exchange interaction (DMI) and their response to a gating electric field. Various multi-layered heterostructures were specially designed to provide electric field tunable perpendicular magnetization and sizeable DMI, which are required for skyrmion occurrence. Landau–Lifshitz–Gilbert micromagnetic calculations in nanometric disks allowed the extraction of material parameter phase diagrams in which magnetic textures were classified according to their topological charge. We identified suitable ranges of magnetic anisotropy, DMI and saturation magnetization for stabilizing skyrmionic ground states or writing/manipulating them using either a spin-transfer torque of a perpendicular current or the electric field. From analyzing the different contributions to the total magnetic free energy, we point out some critical properties influencing the skyrmions’ stability. Finally, we discuss some experimental issues related to the choice of materials or the design of novel magnetic materials compatible with skyrmionic applications. Full article

(This article belongs to the Special Issue New Achievements in Nanostructured and Low Dimensional Materials and Systems)

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13 pages, 2991 KiB

Open AccessEditor’s ChoiceArticle

Hydrogenated Amorphous Silicon-Based Nanomaterials as Alternative Electrodes to Graphite for Lithium-Ion Batteries

by Rocío Barrio, Nieves González, Álvaro Portugal, Carmen Morant and José Javier Gandía

Nanomaterials 2022, 12(24), 4400; https://doi.org/10.3390/nano12244400 - 9 Dec 2022

Cited by 2 | Viewed by 2402

Abstract

Graphite is the material most used as an electrode in commercial lithium-ion batteries. On the other hand, it is a material with low energy capacity, and it is considered a raw critical material given its large volume of use. In the current energy [...] Read more.

Graphite is the material most used as an electrode in commercial lithium-ion batteries. On the other hand, it is a material with low energy capacity, and it is considered a raw critical material given its large volume of use. In the current energy context, we must promote the search for alternative materials based on elements that are abundant, sustainable and that have better performance for energy storage. We propose thin materials based on silicon, which has a storage capacity eleven times higher than graphite. Nevertheless, due to the high-volume expansion during lithiation, it tends to crack, limiting the life of the batteries. To solve this problem, hydrogenated amorphous silicon has been researched, in the form of thin film and nanostructures, since, due to its amorphous structure, porosity and high specific surface, it could better absorb changes in volume. These thin films were grown by plasma-enhanced chemical vapor deposition, and then the nanowires were obtained by chemical etching. The compositional variations of films deposited at different temperatures and the incorporation of dopants markedly influence the stability and longevity of batteries. With these optimized electrodes, we achieved batteries with an initial capacity of 3800 mAhg⁻¹ and 82% capacity retention after 50 cycles. Full article

(This article belongs to the Special Issue Application of Nanomaterials for Electrochemical Energy Conversion and Storage Devices)

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15 pages, 3093 KiB

Open AccessEditor’s ChoiceArticle

Mechanically Enhanced Nanocrystalline Cellulose/Reduced Graphene Oxide/Polyethylene Glycol Electrically Conductive Composite Film

by Pengbo Xie, Ying Ge, Yida Wang, Jing Zhou, Yuanyuan Miao and Zhenbo Liu

Nanomaterials 2022, 12(24), 4371; https://doi.org/10.3390/nano12244371 - 8 Dec 2022

Cited by 7 | Viewed by 2497

Abstract

Traditional conductive materials do not meet the increasing requirements of electronic products because of such materials’ high rigidity, poor flexibility, and slow biodegradation after disposal. Preparing flexible conductive materials with excellent mechanical properties is an active area of research. The key to flexible [...] Read more.

Traditional conductive materials do not meet the increasing requirements of electronic products because of such materials’ high rigidity, poor flexibility, and slow biodegradation after disposal. Preparing flexible conductive materials with excellent mechanical properties is an active area of research. The key to flexible conductive materials lies in the combination of the polymer matrix and conductive components. This combination can be achieved by making a film of renewable nano-microcrystalline cellulose (NCC) and reduced graphene oxide (rGO) with excellent electrical conductivity—by simple filtration and introducing polyethylene glycol (PEG) to enhance the functionality of the composite film. Graphene imparted conductivity to the composite film, which reached 5.67 S·m⁻¹. A reinforced NCC/rGO/PEG-4 composite film with a thickness of only 21 μm exhibited a tensile strength of 30.56 MPa, which was 83% higher than that of the sample without PEG (16.71 MPa), and toughness of 727.18 kJ·m⁻³, which was about 132% higher than that of the control sample (NCC/rGO, 313.86 kJ·m⁻³). This ultra-thin conductive composite film—which can be prepared simply, consists of environmentally sustainable and biodegradable raw materials, and exhibits excellent mechanical properties—has substantial potential for applications in e.g., flexible electronic wearable devices, electrodes, and capacitors. Full article

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12 pages, 5293 KiB

Open AccessEditor’s ChoiceArticle

Green Extraction of Graphene from Natural Mineral Shungite

by Anastasia Novikova and Alina Karabchevsky

Nanomaterials 2022, 12(24), 4356; https://doi.org/10.3390/nano12244356 - 7 Dec 2022

Cited by 8 | Viewed by 2458

Abstract

Conventional fabrication methods to produce graphene are cumbersome, expensive, and not ecologically friendly. This is due to the fact that the processing of a large volume of raw materials requires large amounts of acids and alkalis which, in turn, require special disposal. Therefore, [...] Read more.

Conventional fabrication methods to produce graphene are cumbersome, expensive, and not ecologically friendly. This is due to the fact that the processing of a large volume of raw materials requires large amounts of acids and alkalis which, in turn, require special disposal. Therefore, it is necessary to develop new technologies or to refine existing ones for the production of graphene—and to create new, ecologically-safe and effective methods. Here, we utilized physical sonication to extract graphene films from natural mineral shungite rock. From our study of the structure of shungite by Raman spectrometry and X-ray phase analysis, we found that shungite is characterized by graphite-like mineral structures. Transmission electron microscopy images obtained from the processed material revealed graphene films—with surfaces as small as 200 nanometers long and several layers wide. Our green method of fabicating graphene can be widely used in a variety of fields, from electro-optics to ecology, to list a few. Full article

(This article belongs to the Special Issue 2D Materials for Advanced Sensors: Fabrication and Applications)

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13 pages, 4997 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Antiviral Properties against SARS-CoV-2 of Nanostructured ZnO Obtained by Green Combustion Synthesis and Coated in Waterborne Acrylic Coatings

by Julia de O. Primo, Jamille de S. Correa, Dienifer F. L. Horsth, Arkaprava Das, Marcin Zając, Polona Umek, Ruddy Wattiez, Fauze J. Anaissi, Rob C. A. Onderwater and Carla Bittencourt

Nanomaterials 2022, 12(23), 4345; https://doi.org/10.3390/nano12234345 - 6 Dec 2022

Cited by 9 | Viewed by 2980

Abstract

The COVID-19 pandemic has increased the need for developing disinfectant surfaces as well as reducing the spread of infections on contaminated surfaces and the contamination risk from the fomite route. The present work reports on the antiviral activity of coatings containing ZnO particles [...] Read more.

The COVID-19 pandemic has increased the need for developing disinfectant surfaces as well as reducing the spread of infections on contaminated surfaces and the contamination risk from the fomite route. The present work reports on the antiviral activity of coatings containing ZnO particles obtained by two simple synthesis routes using Aloe vera (ZnO-aloe) or cassava starch (ZnO-starch) as reaction fuel. After detailed characterization using XRD and NEXAFS, the obtained ZnO particles were dispersed in a proportion of 10% with two different waterborne acrylic coatings (binder and commercial white paint) and brushed on the surface of polycarbonates (PC). The cured ZnO/coatings were characterized by scanning electron microscopes (SEM) and energy-dispersive X-ray spectroscopy (EDS). Wettability tests were performed. The virucidal activity of the ZnO particles dispersed in the waterborne acrylic coating was compared to a reference control sample (PC plates). According to RT-PCR results, the ZnO-aloe/coating displays the highest outcome for antiviral activity against SARS-CoV-2 using the acrylic binder, inactivating >99% of the virus after 24 h of contact relative to reference control. Full article

(This article belongs to the Special Issue Applications of Nanomaterials in Diagnostics and Therapeutics)

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14 pages, 3264 KiB

Open AccessEditor’s ChoiceArticle

Postproduction Approach to Enhance the External Quantum Efficiency for Red Light-Emitting Diodes Based on Silicon Nanocrystals

by Hiroyuki Yamada, Junpei Watanabe, Kazuhiro Nemoto, Hong-Tao Sun and Naoto Shirahata

Nanomaterials 2022, 12(23), 4314; https://doi.org/10.3390/nano12234314 - 5 Dec 2022

Cited by 9 | Viewed by 2574

Abstract

Despite bulk crystals of silicon (Si) being indirect bandgap semiconductors, their quantum dots (QDs) exhibit the superior photoluminescence (PL) properties including high quantum yield (PLQY > 50%) and spectral tunability in a broad wavelength range. Nevertheless, their low optical absorbance character inhibits the [...] Read more.

Despite bulk crystals of silicon (Si) being indirect bandgap semiconductors, their quantum dots (QDs) exhibit the superior photoluminescence (PL) properties including high quantum yield (PLQY > 50%) and spectral tunability in a broad wavelength range. Nevertheless, their low optical absorbance character inhibits the bright emission from the SiQDs for phosphor-type light emitting diodes (LEDs). In contrast, a strong electroluminescence is potentially given by serving SiQDs as an emissive layer of current-driven LEDs with (Si-QLEDs) because the charged carriers are supplied from electrodes unlike absorption of light. Herein, we report that the external quantum efficiency (EQE) of Si-QLED was enhanced up to 12.2% by postproduction effect which induced by continuously applied voltage at 5 V for 9 h. The active layer consisted of SiQDs with a diameter of 2.0 nm. Observation of the cross-section of the multilayer QLEDs device revealed that the interparticle distance between adjacent SiQDs in the emissive layer is reduced to 0.95 nm from 1.54 nm by “post-electric-annealing”. The shortened distance was effective in promoting charge injection into the emission layer, leading improvement of the EQE. Full article

(This article belongs to the Special Issue Low-Dimensional Semiconductor Materials: Fabrication, Characterization and Applications)

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21 pages, 4805 KiB

Open AccessEditor’s ChoiceArticle

Conducting Electrospun Nanofibres: Monitoring of Iodine Doping of P3HT through Infrared (IRAV) and Raman (RaAV) Polaron Spectroscopic Features

by Alessia Arrigoni, Luigi Brambilla, Chiara Castiglioni and Chiara Bertarelli

Nanomaterials 2022, 12(23), 4308; https://doi.org/10.3390/nano12234308 - 4 Dec 2022

Cited by 5 | Viewed by 2621

Abstract

Aligned polymer nanofibres are prepared by means of the electrospinning of a chlorobenzene solution containing regioregular poly(3-hexyltiophene-2,5-diyl), P3HT, and poly(ethylene oxide), PEO. The PEO scaffold is easily dissolved with acetonitrile, leaving pure P3HT fibres, which do not show structural modification. Polymer fibres, either [...] Read more.

Aligned polymer nanofibres are prepared by means of the electrospinning of a chlorobenzene solution containing regioregular poly(3-hexyltiophene-2,5-diyl), P3HT, and poly(ethylene oxide), PEO. The PEO scaffold is easily dissolved with acetonitrile, leaving pure P3HT fibres, which do not show structural modification. Polymer fibres, either with or without the PEO supporting polymer, are effectively doped by exposure to iodine vapours. Doping is monitored following the changes in the doping-induced vibrational bands (IRAVs) observed in the infrared spectra and by means of Raman spectroscopy. Molecular orientation inside the fibres has been assessed by means of IR experiments in polarised light, clearly demonstrating that electrospinning induces the orientation of the polymer chains along the fibre axis as well as of the defects introduced by doping. This work illustrates a case study that contributes to the fundamental knowledge of the vibrational properties of the doping-induced defects—charged polarons—of P3HT. Moreover, it provides experimental protocols for a thorough spectroscopic characterisation of the P3HT nanofibres, and of doped conjugated polymers in general, opening the way for the control of the material structure when the doped polymer is confined in a one-dimensional architecture. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Nanofibers)

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11 pages, 2547 KiB

Open AccessEditor’s ChoiceArticle

Silver Nanoparticle Chains for Ultra-Long-Range Plasmonic Waveguides for Nd³⁺ Fluorescence

by Javier Fernández-Martínez, Sol Carretero-Palacios, Pablo Molina, Jorge Bravo-Abad, Mariola O. Ramírez and Luisa E. Bausá

Nanomaterials 2022, 12(23), 4296; https://doi.org/10.3390/nano12234296 - 3 Dec 2022

Cited by 2 | Viewed by 2066

Abstract

Plasmonic waveguides have been shown to be a promising approach to confine and transport electromagnetic energy beyond the diffraction limit. However, ohmic losses generally prevent their integration at micrometric or millimetric scales. Here, we present a gain-compensated plasmonic waveguide based on the integration [...] Read more.

Plasmonic waveguides have been shown to be a promising approach to confine and transport electromagnetic energy beyond the diffraction limit. However, ohmic losses generally prevent their integration at micrometric or millimetric scales. Here, we present a gain-compensated plasmonic waveguide based on the integration of linear chains of Ag nanoparticles on an optically active Nd³⁺-doped solid-state gain medium. By means of dual confocal fluorescence microscopy, we demonstrate long-range optical energy propagation due to the near-field coupling between the plasmonic nanostructures and the Nd³⁺ ions. The subwavelength fluorescence guiding is monitored at distances of around 100 µm from the excitation source for two different emission ranges centered at around 900 nm and 1080 nm. In both cases, the guided fluorescence exhibits a strong polarization dependence, consistent with the polarization behavior of the plasmon resonance supported by the chain. The experimental results are interpreted through numerical simulations in quasi-infinite long chains, which corroborate the propagation features of the Ag nanoparticle chains at both excitation (λ_exc = 590 nm) and emission wavelengths. The obtained results exceed by an order of magnitude that of previous reports on electromagnetic energy transport using linear plasmonic chains. The work points out the potential of combining Ag nanoparticle chains with a small interparticle distance (~2 nm) with rare-earth-based optical gain media as ultra-long-range waveguides with extreme light confinement. The results offer new perspectives for the design of integrated hybrid plasmonic–photonic circuits based on rare-earth-activated solid-state platforms. Full article

(This article belongs to the Special Issue Nano-Optics and Nano-Optoelectronics: Challenges and Future Trends)

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11 pages, 1959 KiB

Open AccessEditor’s ChoiceArticle

Dynamic Light Scattering Plus Scanning Electron Microscopy: Usefulness and Limitations of a Simplified Estimation of Nanocellulose Dimensions

by Quim Tarrés, Roberto Aguado, Justin O. Zoppe, Pere Mutjé, Núria Fiol and Marc Delgado-Aguilar

Nanomaterials 2022, 12(23), 4288; https://doi.org/10.3390/nano12234288 - 2 Dec 2022

Cited by 19 | Viewed by 3914

Abstract

Measurements of nanocellulose size usually demand very high-resolution techniques and tedious image processing, mainly in what pertains to the length of nanofibers. Aiming to ease the process, this work assesses a relatively simple method to estimate the dimensions of nanocellulose particles with an [...] Read more.

Measurements of nanocellulose size usually demand very high-resolution techniques and tedious image processing, mainly in what pertains to the length of nanofibers. Aiming to ease the process, this work assesses a relatively simple method to estimate the dimensions of nanocellulose particles with an aspect ratio greater than 1. Nanocellulose suspensions, both as nanofibers and as nanocrystals, are subjected to dynamic light scattering (DLS) and to field-emission scanning electron microscopy (FE-SEM). The former provides the hydrodynamic diameter, as long as the scatter angle and the consistency are adequate. Assays with different angles and concentrations compel us to recommend forward scattering (12.8°) and concentrations around 0.05–0.10 wt %. Then, FE-SEM with magnifications of ×5000–×20,000 generally suffices to obtain an acceptable approximation for the actual diameter, at least for bundles. Finally, length can be estimated by a simple geometric relationship. Regardless of whether they are collected from FE-SEM or DLS, size distributions are generally skewed to lower diameters. Width distributions from FE-SEM, in particular, are well fitted to log-normal functions. Overall, while this method is not valid for the thinnest fibrils or for single, small nanocrystals, it can be useful in lieu of very high-resolution techniques. Full article

(This article belongs to the Special Issue Cellulose Nanomaterials and Nanocomposites)

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11 pages, 2277 KiB

Open AccessEditor’s ChoiceArticle

Analysis of Electrochemical Performance with Dispersion Degree of CNTs in Electrode According to Ultrasonication Process and Slurry Viscosity for Lithium-Ion Battery

by Jaehong Choi, Chaewon Lee, Sungwoo Park, Tom James Embleton, Kyungmok Ko, Mina Jo, Kashif Saleem Saqib, Jeongsik Yun, Minki Jo, Yoonkook Son and Pilgun Oh

Nanomaterials 2022, 12(23), 4271; https://doi.org/10.3390/nano12234271 - 1 Dec 2022

Cited by 10 | Viewed by 5256

Abstract

Lithium-ion batteries (LIBs) continue to dominate the battery market with their efficient energy storage abilities and their ongoing development. However, at high charge/discharge C-rates their electrochemical performance decreases significantly. To improve the power density properties of LIBs, it is important to form a [...] Read more.

Lithium-ion batteries (LIBs) continue to dominate the battery market with their efficient energy storage abilities and their ongoing development. However, at high charge/discharge C-rates their electrochemical performance decreases significantly. To improve the power density properties of LIBs, it is important to form a uniform electron transfer network in the cathode electrode via the addition of conductive additives. Carbon nanotubes (CNTs) with high crystallinity, high electrical conductivity, and high aspect ratio properties have gathered significant interest as cathode electrode conductive additives. However, due to the high aggregational properties of CNTs, it is difficult to form a uniform network for electron transfer within the electrode. In this study, to help fabricate electrodes with well-dispersed CNTs, various electrodes were prepared by controlling (i) the mixing order of the conductive material, binder, and active material, and (ii) the sonication process of the CNTs/NMP solution before the electrode slurry preparation. When the binder was mixed with a well sonicated CNTs/NMP solution, the CNTs uniformly adsorbed to the then added cathode material of LiNi_0.6Co_0.2Mn_0.2O₂ and were well-dispersed to form a flowing uniform network. This electrode fabrication process achieved > 98.74% capacity retention after 50 cycles at 5C via suppressed polarization at high current densities and a more reversible H1-M phase transition of the active material. Our study presents a novel design benchmark for the fabricating of electrodes applying well-dispersed CNTs, which can facilitate the application of LIBs in high current density applications. Full article

(This article belongs to the Special Issue Advanced Functional Nanomaterials for Efficient Energy Conversion and Storage)

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12 pages, 2617 KiB

Open AccessEditor’s ChoiceArticle

Dual-Wavelength Forward-Enhanced Directional Scattering and Second Harmonic Enhancement in Open-Hole Silicon Nanoblock

by Xinghua Wang, Yunbao Zheng, Min Ouyang, Haihua Fan, Qiaofeng Dai and Haiying Liu

Nanomaterials 2022, 12(23), 4259; https://doi.org/10.3390/nano12234259 - 30 Nov 2022

Cited by 1 | Viewed by 2009

Abstract

Nanostructures with appropriate sizes can limit light-matter interaction and support electromagnetic multipole resonance. The interaction between light and nanostructures is intimately related to manipulating the direction of scattered light in the far field as well as the electromagnetic field in the near field. [...] Read more.

Nanostructures with appropriate sizes can limit light-matter interaction and support electromagnetic multipole resonance. The interaction between light and nanostructures is intimately related to manipulating the direction of scattered light in the far field as well as the electromagnetic field in the near field. In this paper, we demonstrate dual-wavelength directional forward-scattering enhancement in an individual open-hole silicon nanoblock (OH-SiNB) and simultaneously achieve bulk and surface electromagnetic field localization. The second harmonic generation is enhanced using electromagnetic field localization on the square hole surface. Numerical simulations reveal that the resonance modes, at λ₁ = 800 nm and λ₂ = 1190 nm, approximately satisfy the Kerker condition. In the near field, the magnetic dipole modes at dual wavelength all satisfy the boundary condition that the normal component of the electric displacement is continuous on the square holes surface, thus obtaining the surface electromagnetic field localization. Moreover, highly efficient second harmonic generation can be achieved at dual wavelengths using the surface electromagnetic field localization and the increased surface area of the square holes. Our results provide a new strategy for the integration of nanoantennas and nonlinear optoelectronic devices in optical chips. Full article

(This article belongs to the Section Nanophotonics Materials and Devices)

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9 pages, 3312 KiB

Open AccessEditor’s ChoiceArticle

Surface Oxidation of Cu₂O Nanoparticles by Adsorbed Ammonia

by Siwoo Lee, Ji Won Jang and Young Bok Ryu

Nanomaterials 2022, 12(23), 4242; https://doi.org/10.3390/nano12234242 - 29 Nov 2022

Cited by 1 | Viewed by 2235

Abstract

Copper-based nanoparticles have been intensively studied owing to their superior antibacterial activity. In this study, cuprous oxide (Cu₂O) nanoparticles were synthesized using two different methods. In particular, two methods for synthesizing copper oxide from NaOH, namely, with and without the addition [...] Read more.

Copper-based nanoparticles have been intensively studied owing to their superior antibacterial activity. In this study, cuprous oxide (Cu₂O) nanoparticles were synthesized using two different methods. In particular, two methods for synthesizing copper oxide from NaOH, namely, with and without the addition of NH₃, were used to adjust the morphology of the nanoparticles. The nanoparticles from the NH₃ and NaOH samples possessed an octahedral morphology. The crystal structure of the samples was confirmed by X-ray diffraction. The size distribution of the NH₃ sample was narrower than that of the NaOH sample. Furthermore, the average size of the NH₃ sample was smaller than that of the NaOH sample. Unexpectedly, the antibacterial activity of the NH₃ sample was found to be lower than that of the NaOH sample. X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy revealed that the adsorbed NH₃ caused the surface oxidation of Cu₂O nanoparticles with azide (N₃) formation on surface. Full article

(This article belongs to the Section Biology and Medicines)

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