Nanomaterials

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 1952

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 2128

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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15 pages, 8896 KiB

Open AccessEditor’s ChoiceArticle

On-Chip Reconfigurable and Ultracompact Silicon Waveguide Mode Converters Based on Nonvolatile Optical Phase Change Materials

by Yedeng Fei, Yin Xu, Dongmei Huang, Yue Dong, Bo Zhang, Yi Ni and P. K. A. Wai

Nanomaterials 2022, 12(23), 4225; https://doi.org/10.3390/nano12234225 - 28 Nov 2022

Cited by 6 | Viewed by 2736

Abstract

Reconfigurable mode converters are essential components in efficient higher-order mode sources for on-chip multimode applications. We propose an on-chip reconfigurable silicon waveguide mode conversion scheme based on the nonvolatile and low-loss optical phase change material antimony triselenide (Sb₂Se₃). The [...] Read more.

Reconfigurable mode converters are essential components in efficient higher-order mode sources for on-chip multimode applications. We propose an on-chip reconfigurable silicon waveguide mode conversion scheme based on the nonvolatile and low-loss optical phase change material antimony triselenide (Sb₂Se₃). The key mode conversion region is formed by embedding a tapered Sb₂Se₃ layer into the silicon waveguide along the propagation direction and further cladding with graphene and aluminum oxide layers as the microheater. The proposed device can achieve the TE₀-to-TE₁ mode conversion and reconfigurable conversion (no mode conversion) depending on the phase state of embedded Sb₂Se₃ layer, whereas such function could not be realized according to previous reports. The proposed device length is only 2.3 μm with conversion efficiency (CE) = 97.5%, insertion loss (IL) = 0.2 dB, and mode crosstalk (CT) = −20.5 dB. Furthermore, the proposed device scheme can be extended to achieve other reconfigurable higher-order mode conversions. We believe the proposed reconfigurable mode conversion scheme and related devices could serve as the fundamental building blocks to provide higher-order mode sources for on-chip multimode photonics. Full article

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

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17 pages, 15925 KiB

Open AccessEditor’s ChoiceArticle

Towards Wireless Detection of Surface Modification of Silicon Nanowires by an RF Approach

by Florian Requena, Samuel Ahoulou, Nicolas Barbot, Darine Kaddour, Jean-Marie Nedelec, Thierry Baron and Etienne Perret

Nanomaterials 2022, 12(23), 4237; https://doi.org/10.3390/nano12234237 - 28 Nov 2022

Cited by 3 | Viewed by 1578

Abstract

This paper shows the possibility to detect the presence of grafted molecules on the surface of silicon nanowires with a wireless RF radar approach based on the measurement of the backscattered signal of a resonant structure on which the nanowires are deposited. The [...] Read more.

This paper shows the possibility to detect the presence of grafted molecules on the surface of silicon nanowires with a wireless RF radar approach based on the measurement of the backscattered signal of a resonant structure on which the nanowires are deposited. The measured resonance frequency allows the determination of the intrinsic properties related to temperature and humidity variations, which can be related to the presence of the grafted molecules. Several functionalizations of nanowires have been realized and characterized. For the first time, an RF approach is used to detect significant differences related to the presence of grafted molecules on the surface of nanowires. In addition to detecting their presence, the obtained results show the potential of the radar approach to identify the type of functionalization of nanowires. A set of six different grafted molecules (including octadecyltrichlorosilane, ethynylpyrene, N3) was tested and correctly separated with the proposed approach. Various measurements of the same samples showed a good repeatability which made the approach compatible with the possibility of differentiating the molecules with each other by radar reading. Moreover, discussions about the application of such functionalizations are made to increase the sensibility of sensors using a radar approach. Full article

(This article belongs to the Special Issue Functional Nanomaterials for Sensing and Detection)

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13 pages, 3193 KiB

Open AccessEditor’s ChoiceArticle

Valorization of Sugarcane By-Products through Synthesis of Biogenic Amorphous Silica Microspheres for Sustainable Cosmetics

by Joana R. Costa, Ana Paula Capeto, Carla F. Pereira, Sílvia S. Pedrosa, Inês F. Mota, João da Silva Burgal, Ana I. Pintado, Manuela E. Pintado, Catarina S. S. Oliveira, Patrícia Costa and Ana Raquel Madureira

Nanomaterials 2022, 12(23), 4201; https://doi.org/10.3390/nano12234201 - 26 Nov 2022

Cited by 11 | Viewed by 2598

Abstract

Ashes from sugarcane by-product incineration were used to synthesize silica powders through alkaline hot extraction, followed by ethanol/acid precipitation or the sol–gel method. Both production methods allowed amorphous spherical silica microparticles with sizes ranging from 1–15 μm and 97% purity to be obtained. [...] Read more.

Ashes from sugarcane by-product incineration were used to synthesize silica powders through alkaline hot extraction, followed by ethanol/acid precipitation or the sol–gel method. Both production methods allowed amorphous spherical silica microparticles with sizes ranging from 1–15 μm and 97% purity to be obtained. Water absorption ranged from 135–155 mL/100 g and 150–250 mL/100 g for precipitated silica and silica gel, respectively, while oil absorption ranged from 305 to 390 and from 250 to 350 mL/100 g. The precipitation with ethanol allowed the recovery of 178 g silica/kg ash, with a lab process cost of EUR 28.95/kg, while the sol-gel process showed a yield of 198 g silica/kg ash with a cost of EUR 10.89/kg. The experimental data suggest that ash from sugarcane by-products is a promising source to be converted into a competitive value-added product, minimizing the environmental impact of disposal problems. Full article

(This article belongs to the Special Issue Micro and Nanomaterials in Cosmetics)

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16 pages, 4193 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Development and Characterisation of a Whole Hybrid Sol-Gel Optofluidic Platform for Biosensing Applications

by Emma MacHugh, Graceson Antony, Arun Kumar Mallik, Alicja Kaworek, Declan McCormack, Brendan Duffy and Mohamed Oubaha

Nanomaterials 2022, 12(23), 4192; https://doi.org/10.3390/nano12234192 - 25 Nov 2022

Cited by 3 | Viewed by 2080

Abstract

This work outlines, for the first time, the fabrication of a whole hybrid sol-gel optofluidic platform by integrating a microfluidic biosensor platform with optical waveguides employing a standard photolithography process. To demonstrate the suitability of this new hybrid sol-gel optofluidic platform, optical and [...] Read more.

This work outlines, for the first time, the fabrication of a whole hybrid sol-gel optofluidic platform by integrating a microfluidic biosensor platform with optical waveguides employing a standard photolithography process. To demonstrate the suitability of this new hybrid sol-gel optofluidic platform, optical and bio-sensing proof-of-concepts are proposed. A photoreactive hybrid sol-gel material composed of a photopolymerisable organically modified silicon alkoxide and a transition metal complex was prepared and used as the fabrication material for the entire optofluidic platform, including the optical waveguides, the sensing areas, and the microfluidic device. The most suitable sol-gel materials chosen for the fabrication of the cladding and core of the waveguides showed a RIC of 3.5 × 10⁻³ and gave thicknesses between 5.5 and 7 μm. The material was optimised to simultaneously meet the photoreactive properties required for the photolithography fabrication process and the optical properties needed for the effective optical operability of the microstructured waveguides at 532 and 633 nm with an integrated microfluidic device. The optical proof-of-concept was performed using a fluorescent dye (Atto 633) and recording its optical responses while irradiated with a suitable optical excitation. The biosensing capability of the platform was assessed using a polyclonal primary IgG mouse antibody and a fluorescent labelled secondary IgG anti-mouse antibody. A limit of detection (LOD) of 50 ug/mL was achieved. A correlation between the concentration of the dye and the emission fluorescence was evidenced, thus clearly demonstrating the feasibility of the proposed hybrid sol-gel optofluidic platform concept. The successful integration and operability of optical and microfluidic components in the same optofluidic platform is a novel concept, particularly where the sol-gel fabrication material is concerned. Full article

(This article belongs to the Special Issue Eco-Friendly Microdevice Printing Techniques with Functional Nano/Biomaterials)

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15 pages, 1589 KiB

Open AccessEditor’s ChoiceArticle

Effect of Silica-Based Nanomaterials on Seed Germination and Seedling Growth of Rice (Oryza sativa L.)

by Yaqi Jiang, Jie Yang, Mingshu Li, Yuanbo Li, Pingfan Zhou, Quanlong Wang, Yi Sun, Guikai Zhu, Qibin Wang, Peng Zhang, Yukui Rui and Iseult Lynch

Nanomaterials 2022, 12(23), 4160; https://doi.org/10.3390/nano12234160 - 24 Nov 2022

Cited by 23 | Viewed by 3565

Abstract

The application of nanomaterials (NMs) in agriculture has become a global concern in recent years. However, studies on their effects on plants are still limited. Here, we conducted a seed germination experiment for 5 days and a hydroponics experiment for 14 days to [...] Read more.

The application of nanomaterials (NMs) in agriculture has become a global concern in recent years. However, studies on their effects on plants are still limited. Here, we conducted a seed germination experiment for 5 days and a hydroponics experiment for 14 days to study the effects of silicon dioxide NMs(nSiO₂) and silicon carbide NMs(nSiC) (0,10, 50, 200 mg/L) on rice (Oryza sativa L.). Bulk SiO₂ (bSiO₂) and sodium silicate (Na₂SiO₃) were used as controls. The results showed that nSiO₂ and nSiC increased the shoot length (11–37%, 6–25%) and root length (17–87%, 59–207%) of germinating seeds, respectively, compared with the control. Similarly, inter-root exposure to nSiO₂, bSiO_2, and nSiC improved the activity of aboveground catalase (10–55%, 31–34%, and 13–51%) and increased the content of trace elements magnesium, copper, and zinc, thus promoting the photosynthesis of rice. However, Na₂SiO₃ at a concentration of 200 mg/L reduced the aboveground and root biomass of rice by 27–51% and 4–17%, respectively. This may be because excess silicon not only inhibited the activity of root antioxidant enzymes but also disrupted the balance of mineral elements. This finding provides a new basis for the effect of silica-based NMs promotion on seed germination and rice growth. Full article

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11 pages, 2068 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

High-Reliability Perovskite Quantum Dots Using Atomic Layer Deposition Passivation for Novel Photonic Applications

by Tzu-Yi Lee, Tsau-Hua Hsieh, Wen-Chien Miao, Konthoujam James Singh, Yiming Li, Chang-Ching Tu, Fang-Chung Chen, Wen-Chung Lu and Hao-Chung Kuo

Nanomaterials 2022, 12(23), 4140; https://doi.org/10.3390/nano12234140 - 23 Nov 2022

Cited by 8 | Viewed by 3105

Abstract

In this study, we propose highly stable perovskite quantum dots (PQDs) coated with Al₂O₃ using atomic layer deposition (ALD) passivation technology. This passivation layer effectively protects the QDs from moisture infiltration and oxidation as well as from high temperatures and [...] Read more.

In this study, we propose highly stable perovskite quantum dots (PQDs) coated with Al₂O₃ using atomic layer deposition (ALD) passivation technology. This passivation layer effectively protects the QDs from moisture infiltration and oxidation as well as from high temperatures and any changes in the material characteristics. They exhibit excellent wavelength stability and reliability in terms of current variation tests, long-term light aging tests, and temperature/humidity tests (60°/90%). A white-light system has been fabricated by integrating a micro-LED and red phosphor exhibiting a high data transmission rate of 1 Gbit/s. These results suggest that PeQDs treated with ALD passivation protection offer promising prospects in full-color micro-displays and high-speed visible-light communication (VLC) applications. Full article

(This article belongs to the Special Issue Quantum Dots and Micro-LED Display 2.0)

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14 pages, 13242 KiB

Open AccessEditor’s ChoiceArticle

Mechanical Characterization of Two-Segment Free-Standing ZnO Nanowires Using Lateral Force Microscopy

by János Volk, János Radó, Zsófia Baji and Róbert Erdélyi

Nanomaterials 2022, 12(23), 4120; https://doi.org/10.3390/nano12234120 - 22 Nov 2022

Viewed by 1499

Abstract

Mechanical characterization of quasi one-dimensional nanostructures is essential for the design of novel nanoelectromechanical systems. However, the results obtained on basic mechanical quantities, such as Young’s modulus and fracture strength, show significant standard deviation in the literature. This is partly because of diversity [...] Read more.

Mechanical characterization of quasi one-dimensional nanostructures is essential for the design of novel nanoelectromechanical systems. However, the results obtained on basic mechanical quantities, such as Young’s modulus and fracture strength, show significant standard deviation in the literature. This is partly because of diversity in the quality of the nanowire, and partly because of inappropriately performed mechanical tests and simplified mechanical models. Here we present orientation-controlled bending and fracture studies on wet chemically grown vertical ZnO nanowires, using lateral force microscopy. The lateral force signal of the atomic force microscope was calibrated by a diamagnetic levitation spring system. By acquiring the bending curves of 14 nanowires, and applying a two-segment mechanical model, an average bending modulus of 108 ± 17 GPa was obtained, which was 23% lower than the Young’s modulus of bulk ZnO in the [0001] direction. It was also found that the average fracture strain and stress inside the nanowire was above 3.1 ± 0.3 % and 3.3 ± 0.3 GPa, respectively. However, the fracture of the nanowires was governed by the quality of the nanowire/substrate interface. The demonstrated technique is a relatively simple and productive way for the accurate mechanical characterization of vertical nanowire arrays. Full article

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

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12 pages, 3085 KiB

Open AccessEditor’s ChoiceArticle

Ethanol Electrooxidation at 1–2 nm AuPd Nanoparticles

by Juliette W. Strasser and Richard M. Crooks

Nanomaterials 2022, 12(22), 4093; https://doi.org/10.3390/nano12224093 - 21 Nov 2022

Cited by 3 | Viewed by 1655

Abstract

We report a systematic study of the electrocatalytic properties and stability of a series of 1–2 nm Au, Pd, and AuPd alloy nanoparticles (NPs) for the ethanol oxidation reaction (EOR). Following EOR electrocatalysis, NP sizes and compositions were characterized using aberration-corrected scanning transmission [...] Read more.

We report a systematic study of the electrocatalytic properties and stability of a series of 1–2 nm Au, Pd, and AuPd alloy nanoparticles (NPs) for the ethanol oxidation reaction (EOR). Following EOR electrocatalysis, NP sizes and compositions were characterized using aberration-corrected scanning transmission electron microscopy (ac-STEM) and energy dispersive spectroscopy (EDS). Two main findings emerge from this study. First, alloyed AuPd NPs exhibit enhanced electrocatalytic EOR activity compared to either monometallic Au or Pd NPs. Specifically, NPs having a 3:1 ratio of Au:Pd exhibit an ~8-fold increase in peak current density compared to Pd NPs, with an onset potential shifted ~200 mV more to the negative compared to Au NPs. Second, the size and composition of AuPd alloy NPs do not (within experimental error) change following 1.0 or 2.0 h chronoamperometry experiments, while monometallic Au NPs increase in size from 2 to 5 nm under the same conditions. Notably, this report demonstrates the importance of post-catalytic ac-STEM/EDS characterization for fully evaluating NP activity and stability, especially for 1–2 nm NPs that may change in size or structure during electrocatalysis. Full article

(This article belongs to the Special Issue Nanomaterials and Nanotechnology for Electrocatalytic Applications)

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17 pages, 4515 KiB

Open AccessEditor’s ChoiceArticle

Cascade Förster Resonance Energy Transfer Studies for Enhancement of Light Harvesting on Dye-Sensitized Solar Cells

by Mulugeta Tesema Efa, Jheng-Chang Huang and Toyoko Imae

Nanomaterials 2022, 12(22), 4085; https://doi.org/10.3390/nano12224085 - 20 Nov 2022

Cited by 5 | Viewed by 2144

Abstract

This work reports cascade Förster resonance energy transfer (FRET)-based n-type (ZnO) and p-type (NiO) dye-sensitized solar cells (DSSCs), discussing approaches to enhance their overall performance. Although DSSCs suffer from poorer performance than other solar cells, the use of composites with carbon dot (Cdot) [...] Read more.

This work reports cascade Förster resonance energy transfer (FRET)-based n-type (ZnO) and p-type (NiO) dye-sensitized solar cells (DSSCs), discussing approaches to enhance their overall performance. Although DSSCs suffer from poorer performance than other solar cells, the use of composites with carbon dot (Cdot) can enhance the power conversion efficiency (PCE) of DSSCs. However, further improvements are demanded through molecular design to stimulate DSSCs. Here, a photosensitized system based on a cascade FRET was induced alongside the conventional photosensitizer dye (N719). To N719 in a DSSC is transferred the energy cascaded through donor fluorescence materials (pyrene, 3-acetyl-7-N,N-diethyl-coumarin or coumarin and acridine orange), and this process enhances the light-harvesting properties of the sensitizers in the DSSC across a broad region of the solar spectrum. PCE values of 10.7 and 11.3% were achieved for ZnO/Cdot and NiO/Cdot DSSCs, respectively. These high PCE values result from the energy transfer among multi-photosensitizers (cascade FRET fluorophores, N719, and Cdot). Moreover, Cdot can play a role in intensifying the adsorption of dyes and discouraging charge recombination on the semiconductor. The present results raise expectations that a significant improvement in photovoltaic performance can be attained of DSSCs exploiting the cascade FRET photonics phenomenon. Full article

(This article belongs to the Special Issue Quantum Materials for Photonic Devices)

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22 pages, 4191 KiB

Open AccessEditor’s ChoiceReview

Application of Peptides in Construction of Nonviral Vectors for Gene Delivery

by Yujie Yang, Zhen Liu, Hongchao Ma and Meiwen Cao

Nanomaterials 2022, 12(22), 4076; https://doi.org/10.3390/nano12224076 - 19 Nov 2022

Cited by 8 | Viewed by 2672

Abstract

Gene therapy, which aims to cure diseases by knocking out, editing, correcting or compensating abnormal genes, provides new strategies for the treatment of tumors, genetic diseases and other diseases that are closely related to human gene abnormalities. In order to deliver genes efficiently [...] Read more.

Gene therapy, which aims to cure diseases by knocking out, editing, correcting or compensating abnormal genes, provides new strategies for the treatment of tumors, genetic diseases and other diseases that are closely related to human gene abnormalities. In order to deliver genes efficiently to abnormal sites in vivo to achieve therapeutic effects, a variety of gene vectors have been designed. Among them, peptide-based vectors show superior advantages because of their ease of design, perfect biocompatibility and safety. Rationally designed peptides can carry nucleic acids into cells to perform therapeutic effects by overcoming a series of biological barriers including cellular uptake, endosomal escape, nuclear entrance and so on. Moreover, peptides can also be incorporated into other delivery systems as functional segments. In this review, we referred to the biological barriers for gene delivery in vivo and discussed several kinds of peptide-based nonviral gene vectors developed for overcoming these barriers. These vectors can deliver different types of genetic materials into targeted cells/tissues individually or in combination by having specific structure–function relationships. Based on the general review of peptide-based gene delivery systems, the current challenges and future perspectives in development of peptidic nonviral vectors for clinical applications were also put forward, with the aim of providing guidance towards the rational design and development of such systems. Full article

(This article belongs to the Special Issue Nanomaterials for Chemical Engineering)

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20 pages, 5067 KiB

Open AccessEditor’s ChoiceArticle

High-Performance Room-Temperature NO₂ Gas Sensor Based on Au-Loaded SnO₂ Nanowires under UV Light Activation

by Bo Zhang, Shuai Zhang, Yi Xia, Pingping Yu, Yin Xu, Yue Dong, Qufu Wei and Jing Wang

Nanomaterials 2022, 12(22), 4062; https://doi.org/10.3390/nano12224062 - 18 Nov 2022

Cited by 17 | Viewed by 3181

Abstract

Optical excitation is widely acknowledged as one of the most effective means of balancing sensor responses and response/recovery properties at room temperature (RT, 25 °C). Moreover, noble metals have been proven to be suitable as photosensitizers for optical excitation. Localized surface plasmon resonance [...] Read more.

Optical excitation is widely acknowledged as one of the most effective means of balancing sensor responses and response/recovery properties at room temperature (RT, 25 °C). Moreover, noble metals have been proven to be suitable as photosensitizers for optical excitation. Localized surface plasmon resonance (LSPR) determines the liberalization of quasi-free electrons in noble metals under light irradiation, and numerous injected electrons in semiconductors will greatly promote the generation of chemisorbed oxygen, thus elevating the sensor response. In this study, pure SnO₂ and Au/SnO₂ nanowires (NWs) were successfully synthesized through the electrospinning method and validated using XRD, EDS, HRTEM, and XPS. Although a Schottky barrier led to a much higher initial resistance of the Au/SnO₂ composite compared with pure SnO₂ at RT in the dark, the photoinduced resistance of the Au/SnO₂ composite became lower than that of pure SnO₂ under UV irradiation with the same intensity, which confirmed the effect of LSPR. Furthermore, when used as sensing materials, a detailed comparison between the sensing properties of pure SnO₂ and Au/SnO₂ composite toward NO₂ in the dark and under UV irradiation highlighted the crucial role of the LSPR effects. In particular, the response of Au/SnO₂ NWs toward 5 ppm NO₂ could reach 65 at RT under UV irradiation, and the response/recovery time was only 82/42 s, which far exceeded those under Au modification-only or optical excitation-only. Finally, the gas-sensing mechanism corresponding to the change in sensor performance in each case was systematically proposed. Full article

(This article belongs to the Topic Advanced Nanomaterials for Sensing Applications)

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11 pages, 4958 KiB

Open AccessEditor’s ChoiceArticle

Omnidirectional Triboelectric Nanogenerator for Wide-Speed-Range Wind Energy Harvesting

by Qiman Wang, Wenhao Li, Kun Wang, Yitao Liao, Junjie Zheng, Xiongtu Zhou, Jianpu Lin, Yongai Zhang and Chaoxing Wu

Nanomaterials 2022, 12(22), 4046; https://doi.org/10.3390/nano12224046 - 17 Nov 2022

Cited by 5 | Viewed by 2568

Abstract

The environmentally friendly harvesting of wind energy is an effective technique for achieving carbon neutrality and a green economy. In this work, a core–shell triboelectric nanogenerator (CS-TENG) for harvesting wind energy is demonstrated and the device structure parameters are optimized. The core–shell structure [...] Read more.

The environmentally friendly harvesting of wind energy is an effective technique for achieving carbon neutrality and a green economy. In this work, a core–shell triboelectric nanogenerator (CS-TENG) for harvesting wind energy is demonstrated and the device structure parameters are optimized. The core–shell structure enables the CS-TENG to respond sensitively to wind from any direction and generate electrical output on the basis of the vertical contact–separation mode. A single device can generate a maximum power density of 0.14 W/m³ and can power 124 light-emitting diodes. In addition, wind energy can be harvested even at a wind speed as low as 2.3 m/s by paralleling CS-TENGs of different sizes. Finally, a self-powered water quality testing system that uses the CS-TENG as its power supply is built. The CS-TENG exhibits the advantages of a simple structure, environmentally friendly materials, low cost, and simple fabrication process. These features are of considerable significance for the development of green energy harvesting devices. Full article

(This article belongs to the Special Issue Nanogenerators and Self-Powered Systems)

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12 pages, 1023 KiB

Open AccessEditor’s ChoiceArticle

Hydrogenated Boron Phosphide THz-Metamaterial-Based Biosensor for Diagnosing COVID-19: A DFT Coupled FEM Study

by Chunjian Tan, Shaogang Wang, Huiru Yang, Qianming Huang, Shizhen Li, Xu Liu, Huaiyu Ye and Guoqi Zhang

Nanomaterials 2022, 12(22), 4024; https://doi.org/10.3390/nano12224024 - 16 Nov 2022

Cited by 4 | Viewed by 2091

Abstract

Recent reports focus on the hydrogenation engineering of monolayer boron phosphide and simultaneously explore its promising applications in nanoelectronics. Coupling density functional theory and finite element method, we investigate the bowtie triangle ring microstructure composed of boron phosphide with hydrogenation based on structural [...] Read more.

Recent reports focus on the hydrogenation engineering of monolayer boron phosphide and simultaneously explore its promising applications in nanoelectronics. Coupling density functional theory and finite element method, we investigate the bowtie triangle ring microstructure composed of boron phosphide with hydrogenation based on structural and performance analysis. We determine the carrier mobility of hydrogenated boron phosphide, reveal the effect of structural and material parameters on resonance frequencies, and discuss the variation of the electric field at the two tips. The results suggest that the mobilities of electrons for hydrogenated BP monolayer in the armchair and zigzag directions are 0.51 and 94.4 cm²·V

^{- 1}

·s

^{- 1}

, whereas for holes, the values are 136.8 and 175.15 cm²·V

^{- 1}

·s

^{- 1}

. Meanwhile, the transmission spectra of the bowtie triangle ring microstructure can be controlled by adjusting the length of the bowtie triangle ring microstructure and carrier density of hydrogenated BP. With the increasing length, the transmission spectrum has a red-shift and the electric field at the tips of equilateral triangle rings is significantly weakened. Furthermore, the theoretical sensitivity of the BTR structure reaches 100 GHz/RIU, which is sufficient to determine healthy and COVID-19-infected individuals. Our findings may open up new avenues for promising applications in the rapid diagnosis of COVID-19. Full article

(This article belongs to the Special Issue Computational Modeling and Simulation for Nanomaterials, Nanotechnology, and Nanoscience - II)

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23 pages, 4588 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Targeting Ultrasmall Gold Nanoparticles with cRGD Peptide Increases the Uptake and Efficacy of Cytotoxic Payload

by Richard D. Perrins, Lee-Anne McCarthy, Angela Robinson, Kelly L. Spry, Valentin Cognet, Avelino Ferreira, John Porter, Cristina Espinosa Garcίa, Miguel Ángel Rodriguez, Diana Lopez, Ibon Perera, Kelly Conlon, Africa Barrientos, Tom Coulter, Alessandro Pace, Sarah J. M. Hale, Enrico Ferrari and Csanad Z. Bachrati

Nanomaterials 2022, 12(22), 4013; https://doi.org/10.3390/nano12224013 - 15 Nov 2022

Cited by 7 | Viewed by 3660

Abstract

Cyclic arginyl-glycyl-aspartic acid peptide (cRGD) peptides show a high affinity towards αVβ3 integrin, a receptor overexpressed in many cancers. We aimed to combine the versatility of ultrasmall gold nanoparticles (usGNP) with the target selectivity of cRGD peptide for the directed delivery of a [...] Read more.

Cyclic arginyl-glycyl-aspartic acid peptide (cRGD) peptides show a high affinity towards αVβ3 integrin, a receptor overexpressed in many cancers. We aimed to combine the versatility of ultrasmall gold nanoparticles (usGNP) with the target selectivity of cRGD peptide for the directed delivery of a cytotoxic payload in a novel design. usGNPs were synthesized with a modified Brust-Schiffrin method and functionalized via amide coupling and ligand exchange and their uptake, intracellular trafficking, and toxicity were characterized. Our cRGD functionalized usGNPs demonstrated increased cellular uptake by αVβ3 integrin expressing cells, are internalized via clathrin-dependent endocytosis, accumulated in the lysosomes, and when loaded with mertansine led to increased cytotoxicity. Targeting via cRGD functionalization provides a mechanism to improve the efficacy, tolerability, and retention of therapeutic GNPs. Full article

(This article belongs to the Special Issue Nanomaterials for Applied Nanotechnology and Nanoscience)

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13 pages, 2698 KiB

Open AccessEditor’s ChoiceArticle

Influence of Cocatalysts (Ni, Co, and Cu) and Synthesis Method on the Photocatalytic Activity of Exfoliated Graphitic Carbon Nitride for Hydrogen Production

by Adeem Ghaffar Rana, Michael Schwarze, Minoo Tasbihi, Xavier Sala, Jordi García-Antón and Mirjana Minceva

Nanomaterials 2022, 12(22), 4006; https://doi.org/10.3390/nano12224006 - 14 Nov 2022

Cited by 5 | Viewed by 2880

Abstract

Exfoliated graphitic carbon nitride (ex-g-CN) was synthesized and loaded with non-noble metals (Ni, Cu, and Co). The synthesized catalysts were tested for hydrogen production using a 300-W Xe lamp equipped with a 395 nm cutoff filter. A noncommercial double-walled quartz-glass reactor irradiated from [...] Read more.

Exfoliated graphitic carbon nitride (ex-g-CN) was synthesized and loaded with non-noble metals (Ni, Cu, and Co). The synthesized catalysts were tested for hydrogen production using a 300-W Xe lamp equipped with a 395 nm cutoff filter. A noncommercial double-walled quartz-glass reactor irradiated from the side was used with a 1 g/L catalyst in 20 mL of a 10 vol% triethanolamine aqueous solution. For preliminary screening, the metal-loaded ex-g-CN was synthesized using the incipient wetness impregnation method. The highest hydrogen production was observed on the Ni-loaded ex-g-CN, which was selected to assess the impact of the synthesis method on hydrogen production. Ni-loaded ex-g-CN was synthesized using different synthesis methods: incipient wetness impregnation, colloidal deposition, and precipitation deposition. The catalysts were characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption using the Brunauer–Emmett–Teller method, and transmission electron microscopy. The Ni-loaded ex-g-CN synthesized using the colloidal method performed best with a hydrogen production rate of 43.6 µmol h⁻¹ g⁻¹. By contrast, the catalysts synthesized using the impregnation and precipitation methods were less active, with 28.2 and 10.1 µmol h⁻¹ g⁻¹, respectively. The hydrogen production performance of the suspended catalyst (440 µmol m⁻² g⁻¹) showed to be superior to that of the corresponding immobilized catalyst (236 µmol m⁻² g⁻¹). Full article

(This article belongs to the Special Issue Environmental Remediation by Photocatalytic Functional Nanomaterials)

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22 pages, 4560 KiB

Open AccessEditor’s ChoiceArticle

Influence of Tartrate Ligand Coordination over Luminescence Properties of Chiral Lanthanide-Based Metal–Organic Frameworks

by Uxua Huizi-Rayo, Xuban Gastearena, Ana M. Ortuño, Juan M. Cuerva, Antonio Rodríguez-Diéguez, Jose Angel García, Jesus Ugalde, Jose Manuel Seco, Eider San Sebastian and Javier Cepeda

Nanomaterials 2022, 12(22), 3999; https://doi.org/10.3390/nano12223999 - 13 Nov 2022

Cited by 2 | Viewed by 2775

Abstract

The present work reports on a detailed discussion about the synthesis, characterization, and luminescence properties of three pairs of enantiopure 3D metal–organic frameworks (MOFs) with general formula {[Ln₂(L/D-tart)₃(H₂O)₂]·3H₂O}_n (3D_Ln-L/D, where [...] Read more.

The present work reports on a detailed discussion about the synthesis, characterization, and luminescence properties of three pairs of enantiopure 3D metal–organic frameworks (MOFs) with general formula {[Ln₂(L/D-tart)₃(H₂O)₂]·3H₂O}_n (3D_Ln-L/D, where Ln = Sm(III), Eu(III) or Gd(III), and L/D-tart = L- or D-tartrate), and ten pairs of enantiopure 2D coordination polymers (CPs) with general formula [Ln(L/D-Htart)₂(OH)(H₂O)₂]_n (2D_Ln-L/D, where Ln = Y(III), Sm(III), Eu(III), Gd(III), Tb(III), Dy(III), Ho(III), Er(III), Tm(III) or Yb(III), and L/D-Htart = hydrogen L- or D-tartrate) based on single-crystal X-ray structures. Enantiopure nature of the samples has been further corroborated by Root Mean Square Deviation (RMSD) as well as by circular dichroism (CD) spectra. Solid-state emission spectra of Eu(III), Tb(III), and Dy(III)-based compounds confirm the occurrence of ligand-to-metal charge transfers in view of the characteristic emissions for these lanthanide ions, and emission decay curves were also recorded to estimate the emission lifetimes for the reported compounds. A complete theoretical study was accomplished to better understand the energy transfers occurring in the Eu-based counterparts, which allows for explaining the different performances of 3D-MOFs and 2D-layered compounds. As inferred from the colorimetric diagrams, emission characteristics of Eu-based 2D CPs depend on the temperature, so their luminescent thermometry has been determined on the basis of a ratiometric analysis between the ligand-centered and Eu-centered emission. Finally, a detailed study of the polarized luminescence intensity emitted by the samples is also accomplished to support the occurrence of chiro-optical activity. Full article

(This article belongs to the Special Issue Lanthanide-Doped Luminescent Nanomaterials: Design, Synthesis, Optical Properties and Applications)

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10 pages, 2287 KiB

Open AccessEditor’s ChoiceArticle

Complete Solution-Processed Semitransparent and Flexible Organic Solar Cells: A Success of Polyimide/Ag-Nanowires- and PH1000-Based Electrodes with Plasmonic Enhanced Light Absorption

by Jing Wang, Xiangfei Liang, Jianing Xie, Xiaolong Yin, Jinhao Chen, Tianfu Gu, Yueqi Mo, Jianqing Zhao, Shumei Liu, Donghong Yu, Jibin Zhang and Lintao Hou

Nanomaterials 2022, 12(22), 3987; https://doi.org/10.3390/nano12223987 - 12 Nov 2022

Cited by 6 | Viewed by 2561

Abstract

Organic solar cells (OSCs) have been widely studied due to the advantages of easy fabrication, low cost, light weight, good flexibility and sufficient transparency. In this work, flexible and semitransparent OSCs were successfully fabricated with the adoption of both polyimide/silver nanowires (PI/AgNW) and [...] Read more.

Organic solar cells (OSCs) have been widely studied due to the advantages of easy fabrication, low cost, light weight, good flexibility and sufficient transparency. In this work, flexible and semitransparent OSCs were successfully fabricated with the adoption of both polyimide/silver nanowires (PI/AgNW) and a conducting polymer PEDOT:PSS named PH1000 as the transparent conductive electrodes (TCEs). It is demonstrated that PI/AgNW is more suitable as a cathode rather than an anode in the viewpoint of its work function, photovoltaic performance, and simulations of optical properties. It is also found that the light incidence from PH1000 TCE can produce more plasmonic-enhanced photon absorption than the PI/AgNW electrode does, resulting in more high power conversion efficiency. Moreover, a high light transmittance of 33.8% and a decent efficiency of 3.88% are achieved for the whole all-flexible semitransparent device with only 9% decrease of resistance in PI/AgNW after 3000 bending cycles. This work illustrates that PI/AgNW has great potential and bright prospect in large-area OSC applications in the future. Full article

(This article belongs to the Special Issue Nanotechnology and Renewable Energy)

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22 pages, 2994 KiB

Open AccessEditor’s ChoiceArticle

Lanthanide(III) Ions and 5-Methylisophthalate Ligand Based Coordination Polymers: An Insight into Their Photoluminescence Emission and Chemosensing for Nitroaromatic Molecules

by Oier Pajuelo-Corral, Laura Razquin-Bobillo, Sara Rojas, Jose Angel García, Duane Choquesillo-Lazarte, Alfonso Salinas-Castillo, Ricardo Hernández, Antonio Rodríguez-Diéguez and Javier Cepeda

Nanomaterials 2022, 12(22), 3977; https://doi.org/10.3390/nano12223977 - 11 Nov 2022

Cited by 5 | Viewed by 2670

Abstract

The work presented herein reports on the synthesis, structural and physico-chemical characterization, luminescence properties and luminescent sensing activity of a family of isostructural coordination polymers (CPs) with the general formula [Ln₂(μ₄-5Meip)₃(DMF)]_n (where Ln(III) = Sm ( [...] Read more.

The work presented herein reports on the synthesis, structural and physico-chemical characterization, luminescence properties and luminescent sensing activity of a family of isostructural coordination polymers (CPs) with the general formula [Ln₂(μ₄-5Meip)₃(DMF)]_n (where Ln(III) = Sm (1_Sm), Eu (2_Eu), Gd (3_Gd), Tb (4_Tb) and Yb (5_Yb) and 5Meip = 5-methylisophthalate, DMF = N,N-dimethylmethanamide). Crystal structures consist of 3D frameworks tailored by the linkage between infinite lanthanide(III)-carboxylate rods by means of the tetradentate 5Meip ligands. Photoluminescence measurements in solid state at variable temperatures reveal the best-in-class properties based on the capacity of the 5Meip ligand to provide efficient energy transfers to the lanthanide(III) ions, which brings intense emissions in both the visible and near-infrared (NIR) regions. On the one hand, compound 5_Yb displays characteristic lanthanide-centered bands in the NIR with sizeable intensity even at room temperature. Among the compounds emitting in the visible region, 4_Tb presents a high QY of 63%, which may be explained according to computational calculations. At last, taking advantage of the good performance as well as high chemical and optical stability of 4_Tb in water and methanol, its sensing capacity to detect 2,4,6-trinitrophenol (TNP) among other nitroaromatic-like explosives has been explored, obtaining high detection capacity (with K_sv around 10⁵ M⁻¹), low limit of detection (in the 10⁻⁶–10⁻⁷ M) and selectivity among other molecules (especially in methanol). Full article

(This article belongs to the Special Issue Theoretical Calculation and Molecular Modeling of Nanomaterials)

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17 pages, 2416 KiB

Open AccessEditor’s ChoiceArticle

Surface Versus Bulk State Transitions in Inkjet-Printed All-Inorganic Perovskite Quantum Dot Films

by Thilini K. Ekanayaka, Dylan Richmond, Mason McCormick, Shashank R. Nandyala, Halle C. Helfrich, Alexander Sinitskii, Jon M. Pikal, Carolina C. Ilie, Peter A. Dowben and Andrew J. Yost

Nanomaterials 2022, 12(22), 3956; https://doi.org/10.3390/nano12223956 - 10 Nov 2022

Cited by 3 | Viewed by 2166

Abstract

The anion exchange of the halides, Br and I, is demonstrated through the direct mixing of two pure perovskite quantum dot solutions, CsPbBr₃ and CsPbI₃, and is shown to be both facile and result in a completely alloyed single phase [...] Read more.

The anion exchange of the halides, Br and I, is demonstrated through the direct mixing of two pure perovskite quantum dot solutions, CsPbBr₃ and CsPbI₃, and is shown to be both facile and result in a completely alloyed single phase mixed halide perovskite. Anion exchange is also observed in an interlayer printing method utilizing the pure, unalloyed perovskite solutions and a commercial inkjet printer. The halide exchange was confirmed by optical absorption spectroscopy, photoluminescent spectroscopy, X-ray diffraction, and X-ray photoemission spectroscopy characterization and indicates that alloying is thermodynamically favorable, while the formation of a clustered alloy is not favored. Additionally, a surface-to-bulk photoemission core level transition is observed for the Cs 4d photoemission feature, which indicates that the electronic structure of the surface is different from the bulk. Time resolved photoluminescence spectroscopy indicates the presence of multiple excitonic decay features, which is argued to originate from states residing at surface and bulk environments. Full article

(This article belongs to the Section Synthesis, Interfaces and Nanostructures)

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11 pages, 3128 KiB

Open AccessEditor’s ChoiceArticle

Bowtie Nanoantenna Coupled Metal-Oxide-Silicon (p-Doped) Diode for 28.3 THz IR Rectification

by Nasim Al Islam and Sangjo Choi

Nanomaterials 2022, 12(22), 3940; https://doi.org/10.3390/nano12223940 - 9 Nov 2022

Cited by 3 | Viewed by 2370

Abstract

Low-temperature waste heat in the infrared (IR) wavelength region offers an opportunity to harvest power from waste energy and requires further investigation in order to find efficient conversion techniques. Although grating-coupled metal-oxide-semiconductor (MOS) diode devices offer efficient conversion from low and moderate-temperature thermal [...] Read more.

Low-temperature waste heat in the infrared (IR) wavelength region offers an opportunity to harvest power from waste energy and requires further investigation in order to find efficient conversion techniques. Although grating-coupled metal-oxide-semiconductor (MOS) diode devices offer efficient conversion from low and moderate-temperature thermal sources, the integration of such diodes with a nanoantenna structure has yet to be explored. We propose a bowtie nanoantenna coupled with a p-doped MOS diode for IR to direct current (DC) conversion without any bias voltage at 28.3 THz. The nanoantenna was designed and optimized to provide maximum field enhancement in a 4 nm-thick oxide layer at the resonant frequency. The device was fabricated following the complementary MOS (CMOS) fabrication process and measured in a custom DC and optical characterization setup using a 10.6 μm wavelength CO₂ laser. The results reveal two different types of devices with linear and nonlinear I-V curves having kΩ and MΩ zero-bias resistance, respectively. The linear device generates a micron-level open-circuit voltage (V_oc) with clear polarization dependence from the laser input, but the nonlinear case suffers from a weak noise-like signal. Finally, we analyze two types of devices using thermoelectric and tunneling effects and discuss the future direction of nanoantenna-integrated MOS devices for efficient IR harvesters. Full article

(This article belongs to the Special Issue Nanomaterials for Photonics: Advances and Applications)

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11 pages, 517 KiB

Open AccessEditor’s ChoiceArticle

Electrical Conductive Properties of 3D-Printed Concrete Composite with Carbon Nanofibers

by Guido Goracci, David M. Salgado, Juan J. Gaitero and Jorge S. Dolado

Nanomaterials 2022, 12(22), 3939; https://doi.org/10.3390/nano12223939 - 8 Nov 2022

Cited by 8 | Viewed by 2191

Abstract

Electrical conductive properties in cement-based materials have received attention in recent years due to their key role in many innovative application (i.e., energy harvesting, deicing systems, electromagnetic shielding, and self-health monitoring). In this work, we explore the use 3D printing as an alternative [...] Read more.

Electrical conductive properties in cement-based materials have received attention in recent years due to their key role in many innovative application (i.e., energy harvesting, deicing systems, electromagnetic shielding, and self-health monitoring). In this work, we explore the use 3D printing as an alternative method for the preparation of electrical conductive concretes. With this aim, the conductive performance of cement composites with carbon nanofibers (0, 1, 2.5, and 4 wt%) was explored by means of a combination of thermogravimetric analysis (TGA) and dielectric spectroscopy (DS) and compared with that of specimens prepared with the traditional mold method. The combination of TGA and DS gave us a unique insight into the electrical conductive properties, measuring the specimens’ performance while monitoring the amount in water confined in the porous network. Experimental evidence of an additional contribution to the electrical conductivity due to sample preparation is provided. In particular, in this work, a strong correlation between water molecules in interconnected pores and the

σ (ω)

values is shown, originating, mainly, from the use of the 3D printing technique. Full article

(This article belongs to the Special Issue Nanostructured Materials for Energy Applications)

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15 pages, 2590 KiB

Open AccessEditor’s ChoiceArticle

Design and Development of Magnetic Iron Core Gold Nanoparticle-Based Fluorescent Multiplex Assay to Detect Salmonella

by Xinyi Zhao, Gwendoline Smith, Bilal Javed, Garret Dee, Yurii K. Gun’ko, James Curtin, Hugh J. Byrne, Christine O’Connor and Furong Tian

Nanomaterials 2022, 12(21), 3917; https://doi.org/10.3390/nano12213917 - 7 Nov 2022

Cited by 10 | Viewed by 3096

Abstract

Salmonella is a bacterial pathogen which is one of the leading causes of severe illnesses in humans. The current study involved the design and development of two methods, respectively using iron oxide nanoparticle (IONP) and iron core gold nanoparticle (ICGNP), conjugated with the [...] Read more.

Salmonella is a bacterial pathogen which is one of the leading causes of severe illnesses in humans. The current study involved the design and development of two methods, respectively using iron oxide nanoparticle (IONP) and iron core gold nanoparticle (ICGNP), conjugated with the Salmonella antibody and the fluorophore, 4-Methylumbelliferyl Caprylate (4-MUCAP), used as an indicator, for its selective and sensitive detection in contaminated food products. Twenty double-blind beverage samples, spiked with Salmonella enteritidis, Staphylococcus aureus, and Escherichia coli, were prepared in sterile Eppendorf^® tubes at room temperature. The gold layer and spikes of ICGNPs increased the surface areas. The ratio of the surface area is 0.76 (IONPs/ICGNPs). The comparative sensitivity and specificity of the IONP-based and the ICGNP-based methods to detect Salmonella were determined. The ICGNP method shows the limit of detection is 32 Salmonella per mL. The ICGNPs had an 83.3% sensitivity and a 92.9% specificity value for the presence and detection of Salmonella. The IONP method resulted in a limit of detection of 150 Salmonella per mL, and a 66.7% sensitivity and 83.3% specificity for the presence and detection of Salmonella. The higher surface area of ICGNPs increases the efficiency of detection. The monitoring of Salmonella can thus be achieved by a rapid magnetic fluorescent assay using a smartphone for image capture and analyze, providing quantitative results. The findings from the present study would help to detect Salmonella rapidly in water. It can improve the microbial quality of water and food safety due to the presence of Salmonella in the water environment. Full article

(This article belongs to the Special Issue Nanostructured Materials and Their Composites for Biosensing Applications)

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13 pages, 15815 KiB

Open AccessEditor’s ChoiceArticle

Fe₃O₄-Nanoparticle-Doped Epoxy Resin as a Detachable Adhesive by Electromagnetic Heating for GFRP Single-Lap Joints

by Xoan F. Sánchez-Romate, Antonio del Bosque, Anabel Crespo, Rafael Alonso, María Sánchez and Alejandro Ureña

Nanomaterials 2022, 12(21), 3913; https://doi.org/10.3390/nano12213913 - 6 Nov 2022

Cited by 2 | Viewed by 2026

Abstract

An adhesive based on a Fe₃O₄-nanoparticle (MNP)-doped epoxy resin was proposed for the development of detachable adhesive joints with GFRP substrates. The analysis of cryofractures showed that the increasing MNP content promotes a higher presence of larger aggregates and [...] Read more.

An adhesive based on a Fe₃O₄-nanoparticle (MNP)-doped epoxy resin was proposed for the development of detachable adhesive joints with GFRP substrates. The analysis of cryofractures showed that the increasing MNP content promotes a higher presence of larger aggregates and a lower sedimentation of nanoparticles due to the higher viscosity of the mixture. In this regard, the inclusion of expandable microspheres (MS) induces a more uniform dispersion of MNPs, reducing their sedimentation. The capability of the proposed adhesives for electromagnetic (EM) heating was also evaluated, with increases in temperature of around 100 °C at 750 A, enough to reach the T_g of the polymer required to facilitate the adhesive detachment, which is around 80 °C. Finally, the lap shear strength (LSS) of 14 and 20 wt.% MNP samples was evaluated in a single-lap shear joint with simultaneous EM heating. The LSS values were reduced by 60–80% at 750 A, thus promoting successful adhesive joint detachment under EM heating. Full article

(This article belongs to the Section Nanocomposite Materials)

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12 pages, 2934 KiB

Open AccessEditor’s ChoiceArticle

Reduced Thermal Conductivity in Nanostructured AgSbTe₂ Thermoelectric Material, Obtained by Arc-Melting

by Javier Gainza, Federico Serrano-Sánchez, Oscar J. Dura, Norbert M. Nemes, Jose Luis Martínez, María Teresa Fernández-Díaz and José Antonio Alonso

Nanomaterials 2022, 12(21), 3910; https://doi.org/10.3390/nano12213910 - 5 Nov 2022

Cited by 5 | Viewed by 2767

Abstract

AgSbTe₂ intermetallic compound is a promising thermoelectric material. It has also been described as necessary to obtain LAST and TAGS alloys, some of the best performing thermoelectrics of the last decades. Due to the random location of Ag and Sb atoms in [...] Read more.

AgSbTe₂ intermetallic compound is a promising thermoelectric material. It has also been described as necessary to obtain LAST and TAGS alloys, some of the best performing thermoelectrics of the last decades. Due to the random location of Ag and Sb atoms in the crystal structure, the electronic structure is highly influenced by the atomic ordering of these atoms and makes the accurate determination of the Ag/Sb occupancy of paramount importance. We report on the synthesis of polycrystalline AgSbTe₂ by arc-melting, yielding nanostructured dense pellets. SEM images show a conspicuous layered nanostructuration, with a layer thickness of 25–30 nm. Neutron powder diffraction data show that AgSbTe₂ crystalizes in the cubic Pm-3m space group, with a slight deficiency of Te, probably due to volatilization during the arc-melting process. The transport properties show some anomalies at ~600 K, which can be related to the onset temperature for atomic ordering. The average thermoelectric figure of merit remains around ~0.6 from ~550 up to ~680 K. Full article

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

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10 pages, 5196 KiB

Open AccessEditor’s ChoiceArticle

Influence of Group-IVA Doping on Electronic and Optical Properties of ZnS Monolayer: A First-Principles Study

by Bin Liu, Wan-Sheng Su and Bi-Ru Wu

Nanomaterials 2022, 12(21), 3898; https://doi.org/10.3390/nano12213898 - 4 Nov 2022

Cited by 3 | Viewed by 2326

Abstract

Element doping is a universal way to improve the electronic and optical properties of two-dimensional (2D) materials. Here, we investigate the influence of group−ⅣA element (C, Si, Ge, Sn, and Pb) doping on the electronic and optical properties of the ZnS monolayer with [...] Read more.

Element doping is a universal way to improve the electronic and optical properties of two-dimensional (2D) materials. Here, we investigate the influence of group−ⅣA element (C, Si, Ge, Sn, and Pb) doping on the electronic and optical properties of the ZnS monolayer with a tetragonal phase by using first-principles calculations. The results indicate that the doping atoms tend to form tetrahedral structures with neighboring S atoms. In these doped models, the formation energies are all negative, indicating that the formation processes of the doped models will release energy. The formation energy is smallest for C−doped ZnS and gradually increases with the metallicity of the doping element. The doped ZnS monolayer retains a direct band gap, with this band gap changing little in other element doping cases. Moreover, intermediate states are observed that are induced by the sp³ hybridization from the doping atoms and S atoms. Such intermediate states expand the optical absorption range into the visible spectrum. Our findings provide an in-depth understanding of the electronic and optical properties of the ZnS monolayer and the associated doping structures, which is helpful for application in optoelectronic devices. Full article

(This article belongs to the Special Issue First-Principles Investigations of Low-Dimensional Nanomaterials)

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13 pages, 2215 KiB

Open AccessEditor’s ChoiceArticle

Cancer Diagnosis Using Terahertz-Graphene-Metasurface-Based Biosensor with Dual-Resonance Response

by Chunjian Tan, Shaogang Wang, Shizhen Li, Xu Liu, Jia Wei, Guoqi Zhang and Huaiyu Ye

Nanomaterials 2022, 12(21), 3889; https://doi.org/10.3390/nano12213889 - 3 Nov 2022

Cited by 45 | Viewed by 3278

Abstract

Owing to the outstanding physical properties of graphene, its biosensing applications implemented by the terahertz metasurface are widely concerned and studied. Here, we present a novel design of the graphene metasurface, which consists of an individual graphene ring and an H-shaped graphene structure. [...] Read more.

Owing to the outstanding physical properties of graphene, its biosensing applications implemented by the terahertz metasurface are widely concerned and studied. Here, we present a novel design of the graphene metasurface, which consists of an individual graphene ring and an H-shaped graphene structure. The graphene metasurface exhibits a dual-resonance response, whose resonance frequency strongly varies with the geometrical parameters of the proposed metasurface, the carrier density of graphene, and the analyte composition. The transparency window, including width and position, can be artificially controlled by adjusting the geometrical parameters or the Fermi energy. Furthermore, the sensing parameters of the graphene metasurface for cancerous and normal cells are investigated, focusing on two factors, namely cell quantity and position on the metasurface. The simulated results clearly show that the theoretical sensitivity, figure of merit, and quantity of the graphene metasurface for breast cells reach 1.21 THz/RIU, 2.75 RIU

^{- 1}

, and 2.43, respectively. Our findings may open up new avenues for promising applications in the diagnosis of cancers. Full article

(This article belongs to the Topic Advances and Applications of 2D Materials, 2nd Volume)

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22 pages, 4019 KiB

Open AccessEditor’s ChoiceReview

Recent Development of Carbon-Nanotube-Based Solar Heat Absorption Devices and Their Application

by Saiful Islam and Hiroshi Furuta

Nanomaterials 2022, 12(21), 3871; https://doi.org/10.3390/nano12213871 - 2 Nov 2022

Cited by 10 | Viewed by 4723

Abstract

Population growth and the current global weather patterns have heightened the need to optimize solar energy harvesting. Solar-powered water filtration, electricity generation, and water heating have gradually multiplied as viable sources of fresh water and power generation, especially for isolated places without access [...] Read more.

Population growth and the current global weather patterns have heightened the need to optimize solar energy harvesting. Solar-powered water filtration, electricity generation, and water heating have gradually multiplied as viable sources of fresh water and power generation, especially for isolated places without access to water and energy. The unique thermal and optical characteristics of carbon nanotubes (CNTs) enable their use as efficient solar absorbers with enhanced overall photothermal conversion efficiency under varying solar light intensities. Due to their exceptional optical absorption efficiency, low cost, environmental friendliness, and natural carbon availability, CNTs have attracted intense scientific interest in the production of solar thermal systems. In this review study, we evaluated CNT-based water purification, thermoelectric generation, and water heating systems under varying solar levels of illumination, ranging from domestic applications to industrial usage. The use of CNT composites or multilayered structures is also reviewed in relation to solar heat absorber applications. An aerogel containing CNTs was able to ameliorate water filtering performance at low solar intensities. CNTs with a Fresnel lens improved thermoelectric output power at high solar intensity. Solar water heating devices utilizing a nanofluid composed of CNTs proved to be the most effective. In this review, we also aimed to identify the most relevant challenges and promising opportunities in relation to CNT-based solar thermal devices. Full article

(This article belongs to the Special Issue State-of-the-Art 2D and Carbon Nanomaterials in Japan)

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43 pages, 4139 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Recent Advances in the Development of Lipid-, Metal-, Carbon-, and Polymer-Based Nanomaterials for Antibacterial Applications

by Ruohua Ren, Chiaxin Lim, Shiqi Li, Yajun Wang, Jiangning Song, Tsung-Wu Lin, Benjamin W. Muir, Hsien-Yi Hsu and Hsin-Hui Shen

Nanomaterials 2022, 12(21), 3855; https://doi.org/10.3390/nano12213855 - 1 Nov 2022

Cited by 38 | Viewed by 4783

Abstract

Infections caused by multidrug-resistant (MDR) bacteria are becoming a serious threat to public health worldwide. With an ever-reducing pipeline of last-resort drugs further complicating the current dire situation arising due to antibiotic resistance, there has never been a greater urgency to attempt to [...] Read more.

Infections caused by multidrug-resistant (MDR) bacteria are becoming a serious threat to public health worldwide. With an ever-reducing pipeline of last-resort drugs further complicating the current dire situation arising due to antibiotic resistance, there has never been a greater urgency to attempt to discover potential new antibiotics. The use of nanotechnology, encompassing a broad range of organic and inorganic nanomaterials, offers promising solutions. Organic nanomaterials, including lipid-, polymer-, and carbon-based nanomaterials, have inherent antibacterial activity or can act as nanocarriers in delivering antibacterial agents. Nanocarriers, owing to the protection and enhanced bioavailability of the encapsulated drugs, have the ability to enable an increased concentration of a drug to be delivered to an infected site and reduce the associated toxicity elsewhere. On the other hand, inorganic metal-based nanomaterials exhibit multivalent antibacterial mechanisms that combat MDR bacteria effectively and reduce the occurrence of bacterial resistance. These nanomaterials have great potential for the prevention and treatment of MDR bacterial infection. Recent advances in the field of nanotechnology are enabling researchers to utilize nanomaterial building blocks in intriguing ways to create multi-functional nanocomposite materials. These nanocomposite materials, formed by lipid-, polymer-, carbon-, and metal-based nanomaterial building blocks, have opened a new avenue for researchers due to the unprecedented physiochemical properties and enhanced antibacterial activities being observed when compared to their mono-constituent parts. This review covers the latest advances of nanotechnologies used in the design and development of nano- and nanocomposite materials to fight MDR bacteria with different purposes. Our aim is to discuss and summarize these recently established nanomaterials and the respective nanocomposites, their current application, and challenges for use in applications treating MDR bacteria. In addition, we discuss the prospects for antimicrobial nanomaterials and look forward to further develop these materials, emphasizing their potential for clinical translation. Full article

(This article belongs to the Special Issue Advanced Nanomaterials in Biomedical Application)

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7 pages, 2426 KiB

Open AccessEditor’s ChoiceReview

Role of Interdiffusion and Segregation during the Life of Indium Gallium Arsenide Quantum Dots, from Cradle to Grave

by Thomas Walther

Nanomaterials 2022, 12(21), 3850; https://doi.org/10.3390/nano12213850 - 31 Oct 2022

Cited by 4 | Viewed by 1841

Abstract

This article summarizes our understanding of the interplay between diffusion and segregation during epitaxial growth of InGaAs and InAs quantum dots. These quantum dots form spontaneously on flat GaAs (001) single-crystalline substrates by the so-called Stranski-Krastanow growth mechanism once a sufficient amount of [...] Read more.

This article summarizes our understanding of the interplay between diffusion and segregation during epitaxial growth of InGaAs and InAs quantum dots. These quantum dots form spontaneously on flat GaAs (001) single-crystalline substrates by the so-called Stranski-Krastanow growth mechanism once a sufficient amount of indium has accumulated on the surface. Initially a perfectly flat wetting layer is formed. This strained layer then starts to roughen as strain increases, leading first to small, long-range surface undulations and then to tiny coherent islands. These continue to grow, accumulating indium both from the underlying wetting layer by lateral indium segregation and from within these islands by vertical segregation, which for InGaAs deposition results in an indium-enriched InGaAs alloy in the centre of the quantum dots. For pure InAs deposition, interdiffusion also results in an InGaAs alloy. Further deposition can lead to the formation of misfit dislocations that nucleate at the edges of the islands and are generally sought to be avoided. Overgrowth by GaAs or InGaAs alloys with low indium content commences preferentially between the islands, avoiding their strained edges, which initially leads to trench formation. Further deposition is necessary to cap these quantum dots effectively and to re-gain an almost flat surface that can then be used for subsequent deposition of multiple layers of quantum dots as needed for many optoelectronic devices. Full article

(This article belongs to the Special Issue Transmission Electron Microscopy for Nanomaterials Research Advances)

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10 pages, 3766 KiB

Open AccessEditor’s ChoiceArticle

Hot Electron Extraction in SWCNT/TiO₂ for Photocatalytic H₂ Evolution from Water

by Masahiro Yamagami, Tomoyuki Tajima, Zihao Zhang, Jun Kano, Ki-ichi Yashima, Takana Matsubayashi, Huyen Khanh Nguyen, Naoto Nishiyama, Tomoya Hayashi and Yutaka Takaguchi

Nanomaterials 2022, 12(21), 3826; https://doi.org/10.3390/nano12213826 - 29 Oct 2022

Cited by 4 | Viewed by 2609

Abstract

Single-walled carbon nanotube (SWCNT)/TiO₂ hybrids were synthesized using 1,10-bis(decyloxy)decane-core PAMAM dendrimer as a molecular glue. Upon photoirradiation of a water dispersion of SWCNT/TiO₂ hybrids with visible light (λ > 422 nm), the hydrogen evolution reaction proceeded at a rate of 0.95 [...] Read more.

Single-walled carbon nanotube (SWCNT)/TiO₂ hybrids were synthesized using 1,10-bis(decyloxy)decane-core PAMAM dendrimer as a molecular glue. Upon photoirradiation of a water dispersion of SWCNT/TiO₂ hybrids with visible light (λ > 422 nm), the hydrogen evolution reaction proceeded at a rate of 0.95 mmol/h·g in the presence of a sacrificial agent (1-benzyl-1,4-dihydronicotinamide, BNAH). External quantum yields (EQYs) of the hydrogen production reaction photosensitized by (6,5), (7,5), and (8,3) tubes were estimated to be 5.5%, 3.6%, and 2.2%, respectively, using monochromatic lights corresponding to their E₂₂ absorptions (570 nm, 650 nm, and 680 nm). This order of EQYs (i.e., (6,5) > (7,5) > (8,3)SWCNTs) exhibited the dependence on the C₂ energy level of SWCNT for EQY and proved the hot electron extraction pathway. Full article

(This article belongs to the Special Issue State-of-the-Art 2D and Carbon Nanomaterials in Japan)

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13 pages, 4181 KiB

Open AccessEditor’s ChoiceArticle

Fabrication of Cu Micromembrane as a Flexible Electrode

by Bo-Yao Sun, Wai-Hong Cheang, Shih-Cheng Chou, Jung-Chih Chiao and Pu-Wei Wu

Nanomaterials 2022, 12(21), 3829; https://doi.org/10.3390/nano12213829 - 29 Oct 2022

Cited by 1 | Viewed by 1899

Abstract

A Cu micromembrane is successfully fabricated and validated as a porous flexible electrode. The Cu micromembrane is prepared by functionalizing individual polypropylene (PP) fibers in a polypropylene micromembrane (PPMM) using a mixture of polydopamine (PDA) and polyethyleneimine (PEI). The mixture of PDA and [...] Read more.

A Cu micromembrane is successfully fabricated and validated as a porous flexible electrode. The Cu micromembrane is prepared by functionalizing individual polypropylene (PP) fibers in a polypropylene micromembrane (PPMM) using a mixture of polydopamine (PDA) and polyethyleneimine (PEI). The mixture of PDA and PEI provides adhesive, wetting, and reducing functionalities that facilitate subsequent Ag activation and Cu electroless plating. Scanning electron microscopy reveals conformal deposition of Cu on individual PP fibers. Porometer analysis indicates that the porous nature of PPMM is properly maintained. The Cu micromembrane demonstrates impressive electrical conductivities in both the X direction (1.04 ± 0.21 S/cm) and Z direction (2.99 ± 0.54 × 10⁻³ S/cm). In addition, its tensile strength and strain are better than those of pristine PPMM. The Cu micromembrane is flexible and mechanically robust enough to sustain 10,000 bending cycles with moderate deterioration. Thermogravimetric analysis shows a thermal stability of 400 °C and an effective Cu loading of 5.36 mg/cm². Cyclic voltammetric measurements reveal that the Cu micromembrane has an electrochemical surface area of 277.8 cm² in a 1 cm² geometric area (a roughness factor of 227.81), a value that is 45 times greater than that of planar Cu foil. Full article

(This article belongs to the Special Issue Latest Advances in Inorganic Nanomaterials)

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17 pages, 4229 KiB

Open AccessEditor’s ChoiceArticle

Photocatalytic Hydrogen Production from Glycerol Aqueous Solutions as Sustainable Feedstocks Using Zr-Based UiO-66 Materials under Simulated Sunlight Irradiation

by Celia M. Rueda-Navarro, Belén Ferrer, Herme G. Baldoví and Sergio Navalón

Nanomaterials 2022, 12(21), 3808; https://doi.org/10.3390/nano12213808 - 28 Oct 2022

Cited by 16 | Viewed by 3231

Abstract

There is an increasing interest in developing cost-effective technologies to produce hydrogen from sustainable resources. Herein we show a comprehensive study on the use of metal–organic frameworks (MOFs) as heterogeneous photocatalysts for H₂ generation from photoreforming of glycerol aqueous solutions under simulated [...] Read more.

There is an increasing interest in developing cost-effective technologies to produce hydrogen from sustainable resources. Herein we show a comprehensive study on the use of metal–organic frameworks (MOFs) as heterogeneous photocatalysts for H₂ generation from photoreforming of glycerol aqueous solutions under simulated sunlight irradiation. The list of materials employed in this study include some of the benchmark Zr-MOFs such as UiO-66(Zr)-X (X: H, NO₂, NH₂) as well as MIL-125(Ti)-NH₂ as the reference Ti-MOF. Among these solids, UiO-66(Zr)-NH₂ exhibits the highest photocatalytic H₂ production, and this observation is attributed to its adequate energy level. The photocatalytic activity of UiO-66(Zr)-NH₂ can be increased by deposition of small Pt NPs as the reference noble metal co-catalyst within the MOF network. This photocatalyst is effectively used for H₂ generation at least for 70 h without loss of activity. The crystallinity of MOF and Pt particle size were maintained as revealed by powder X-ray diffraction and transmission electron microscopy measurements, respectively. Evidence in support of the occurrence of photoinduced charge separation with Pt@UiO-66(Zr)-NH₂ is provided from transient absorption and photoluminescence spectroscopies together with photocurrent measurements. This study exemplifies the possibility of using MOFs as photocatalysts for the solar-driven H₂ generation using sustainable feedstocks. Full article

(This article belongs to the Special Issue Carbon-Based Nanomaterials for Visible-Light Photocatalysis and Photoelectrocatalysis)

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23 pages, 6604 KiB

Open AccessEditor’s ChoiceArticle

Adsorption of Peptides onto Carbon Nanotubes Grafted with Poly(ethylene Oxide) Chains: A Molecular Dynamics Simulation Study

by Zuzana Benková, Peter Čakánek and Maria Natália D. S. Cordeiro

Nanomaterials 2022, 12(21), 3795; https://doi.org/10.3390/nano12213795 - 27 Oct 2022

Cited by 3 | Viewed by 1890

Abstract

Carbon nanotubes (CNTs) display exceptional properties that predispose them to wide use in technological or biomedical applications. To remove the toxicity of CNTs and to protect them against undesired protein adsorption, coverage of the CNT sidewall with poly(ethylene oxide) (PEO) is often considered. [...] Read more.

Carbon nanotubes (CNTs) display exceptional properties that predispose them to wide use in technological or biomedical applications. To remove the toxicity of CNTs and to protect them against undesired protein adsorption, coverage of the CNT sidewall with poly(ethylene oxide) (PEO) is often considered. However, controversial results on the antifouling effectiveness of PEO layers have been reported so far. In this work, the interactions of pristine CNT and CNT covered with the PEO chains at different grafting densities with polyglycine, polyserine, and polyvaline are studied using molecular dynamics simulations in vacuum, water, and saline environments. The peptides are adsorbed on CNT in all investigated systems; however, the adsorption strength is reduced in aqueous environments. Save for one case, addition of NaCl at a physiological concentration to water does not appreciably influence the adsorption and structure of the peptides or the grafted PEO layer. It turns out that the flexibility of the peptide backbone allows the peptide to adopt more asymmetric conformations which may be inserted deeper into the grafted PEO layer. Water molecules disrupt the internal hydrogen bonds in the peptides, as well as the hydrogen bonds formed between the peptides and the PEO chains. Full article

(This article belongs to the Section 2D and Carbon Nanomaterials)

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16 pages, 6096 KiB

Open AccessEditor’s ChoiceArticle

Photocatalytic Investigation of Aerosol-Assisted Atmospheric Pressure Plasma Deposited Hybrid TiO₂ Containing Nanocomposite Coatings

by Chiara Lo Porto, Massimo Dell’Edera, Ilaria De Pasquale, Antonella Milella, Francesco Fracassi, Maria Lucia Curri, Roberto Comparelli and Fabio Palumbo

Nanomaterials 2022, 12(21), 3758; https://doi.org/10.3390/nano12213758 - 26 Oct 2022

Cited by 4 | Viewed by 1885

Abstract

We report on the aerosol-assisted atmospheric-pressure plasma deposition onto a stainless-steel woven mesh of a thin nanocomposite coating based on TiO₂ nanoparticles hosted in a hybrid organic–inorganic matrix, starting from nanoparticles dispersed in a mixture of hexamethyldisiloxane and isopropyl alcohol. The stainless-steel [...] Read more.

We report on the aerosol-assisted atmospheric-pressure plasma deposition onto a stainless-steel woven mesh of a thin nanocomposite coating based on TiO₂ nanoparticles hosted in a hybrid organic–inorganic matrix, starting from nanoparticles dispersed in a mixture of hexamethyldisiloxane and isopropyl alcohol. The stainless-steel mesh was selected as an effective support for the possible future technological application of the coating for photocatalytically assisted water depollution. The prepared coatings were thoroughly investigated from the chemical and morphological points of view and were demonstrated to be photocatalytically active in the degradation of an organic molecule, used as a pollutant model, in water upon UV light irradiation. In order to optimize the photocatalytic performance, different approaches were investigated for the coating’s realization, namely (i) the control of the deposition time and (ii) the application of a postdeposition O₂ plasma treatment on the pristine coatings. Both strategies were found to be able to increase the photocatalytic activity, and, remarkably, their combination resulted in a further enhancement of the photoactivity. Indeed, the proposed combined approach allowed a three-fold increase in the kinetic constant of the degradation reaction of the model dye methylene blue with respect to the pristine coating. Interestingly, the chemical and morphological characterizations of all the prepared coatings were able to account for the enhancement of the photocatalytic performance. Indeed, the presence of the TiO₂ nanoparticles on the outmost surface of the film confirmed the accessibility of the photocatalytic sites in the nanocomposite and reasonably explained the enhanced photocatalytic performance. In addition, the sustained photoactivity (>5 cycles of use) of the nanocomposites was demonstrated. Full article

(This article belongs to the Special Issue Unconventional and Green Approaches for the Synthesis of Crystalline Inorganic Materials)

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14 pages, 2230 KiB

Open AccessEditor’s ChoiceArticle

On the Development of Nanocomposite Covalent Associative Networks Based on Polycaprolactone and Reduced Graphite Oxide

by Alberto Vallin, Daniele Battegazzore, Giacomo Damonte, Alberto Fina and Orietta Monticelli

Nanomaterials 2022, 12(21), 3744; https://doi.org/10.3390/nano12213744 - 25 Oct 2022

Cited by 7 | Viewed by 1860

Abstract

In this work, the development of nanocomposite systems based on reduced graphite oxide (rGO) was combined with the development of crosslinked materials characterized by dynamic covalent bonds, i.e., a covalent associative network, starting from ad-hoc synthesized hydroxyl terminated polycaprolactone (PCL-OH). The crosslinking reaction [...] Read more.

In this work, the development of nanocomposite systems based on reduced graphite oxide (rGO) was combined with the development of crosslinked materials characterized by dynamic covalent bonds, i.e., a covalent associative network, starting from ad-hoc synthesized hydroxyl terminated polycaprolactone (PCL-OH). The crosslinking reaction was carried out using methylenediphenyl diisocyanate (MDI) to create systems capable of bond exchanges via transesterification and transcarbamoylation reactions, in the presence of stannous octoate as a catalyst. The above materials were prepared at two different temperatures (120 and 200 °C) and two PCL-OH:MDI ratios. FT-IR measurements proved the formation of urethane bonds in all the prepared samples. Crosslinking was demonstrated by contacting the samples with a solvent capable of dissolving the star-shaped PCL. These tests showed a significant increase in the crosslinked fraction with increasing the temperature and the PCL-OH:MDI ratio. In order to evidence the effect of crosslinking on rGO dispersion and the final properties of the material, a nanocomposite sample was also prepared using a linear commercial PCL, with the nanofiller mixed under the same conditions used to develop the crosslinked systems. The dispersion of rGO, which was investigated using FE-SEM measurements, was similar in the different systems prepared, indicating that the crosslinking process had a minor effect on the dispersibility of the nanofiller. As far as the thermal properties are concerned, the DSC measurements of the prepared samples showed that the crosslinking leads to a decrease in the crystallinity of the polymer, a phenomenon which was particularly evident in the sample prepared at 200 °C with a PCL-OH: MDI ratio of 1:1.33 and was related to the decrease in the polymer chain mobility. Moreover, rGO was found to act as a nucleating agent and increase the crystallization temperature of the nanocomposite sample based on linear commercial PCL, while the contribution of rGO in the crosslinked nanocomposite samples was minor. Rheological measurements confirmed the crosslinking of the PCL-OH system which generates a solid-like behavior depending on the PCL-OH:MDI ratio used. The presence of rGO during crosslinking generated a further huge increase in the viscosity of the melt with a remarkable solid-like behavior, confirming a strong interaction between rGO and crosslinked PCL. Finally, the prepared nanocomposites exhibited self-healing and recyclability properties, thus meeting the requirements for sustainable materials. Full article

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15 pages, 3754 KiB

Open AccessEditor’s ChoiceArticle

Electrostatic and Environmental Control of the Trion Fine Structure in Transition Metal Dichalcogenide Monolayers

by Yaroslav V. Zhumagulov, Alexei Vagov, Dmitry R. Gulevich and Vasili Perebeinos

Nanomaterials 2022, 12(21), 3728; https://doi.org/10.3390/nano12213728 - 24 Oct 2022

Cited by 2 | Viewed by 2261

Abstract

Charged excitons or trions are essential for optical spectra in low-dimensional doped monolayers (ML) of transitional metal dichalcogenides (TMDC). Using a direct diagonalization of the three-body Hamiltonian, we calculate the low-lying trion states in four types of TMDC MLs as a function of [...] Read more.

Charged excitons or trions are essential for optical spectra in low-dimensional doped monolayers (ML) of transitional metal dichalcogenides (TMDC). Using a direct diagonalization of the three-body Hamiltonian, we calculate the low-lying trion states in four types of TMDC MLs as a function of doping and dielectric environment. We show that the fine structure of the trion is the result of the interplay between the spin-valley fine structure of the single-particle bands and the exchange interaction. We demonstrate that by variations of the doping and dielectric environment, the fine structure of the trion energy can be tuned, leading to anticrossing of the bright and dark states, with substantial implications for the optical spectra of the TMDC ML. Full article

(This article belongs to the Special Issue Recent Advances in Optical Spectroscopy of Layered Materials)

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19 pages, 7216 KiB

Open AccessEditor’s ChoiceArticle

Optical Force of Bessel Pincer Light-Sheets Beam on a Dielectric Sphere of Arbitrary Size

by Shu Zhang, Bing Wei, Qun Wei, Renxian Li, Shiguo Chen and Ningning Song

Nanomaterials 2022, 12(21), 3723; https://doi.org/10.3390/nano12213723 - 23 Oct 2022

Cited by 2 | Viewed by 1570

Abstract

In the framework of Generalized Lorenz–Mie theory (GLMT), based on the expansion results of electromagnetic field radiation components of Bessel pincer light sheets beam acting on dielectric particles of arbitrary size, the expression of radiation force components in a Cartesian coordinate system is [...] Read more.

In the framework of Generalized Lorenz–Mie theory (GLMT), based on the expansion results of electromagnetic field radiation components of Bessel pincer light sheets beam acting on dielectric particles of arbitrary size, the expression of radiation force components in a Cartesian coordinate system is obtained by using the Maxwell stress tensor method. On the one hand, the effects of the refractive index and the equivalent radius of spherical particles on the distribution of radiation force are discussed; On the other hand, the influence of beam scaling parameter and beam order of Bessel pincer light sheets beam on the distribution of radiation force are investigated. The results indicate that the changes of particle’s refractive index and effective radius only affect the distribution of radiation force. However, the beam scaling parameter and beam order of Bessel pincer light sheets beam have a very sharp impact on the convergence position, distribution range and bending degree far away from the wave source of the radiation force. Single-beam optical tweezers using the self-focusing and self-bending Bessel pincer light-sheets beam are crucial for applications such as single molecule biophysics, optical manipulation and particle separation/clearing. Full article

(This article belongs to the Special Issue Research of Photonics at the Nanometer Scale)

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9 pages, 1702 KiB

Open AccessEditor’s ChoiceArticle

Design of Reflective Polarization Rotator in Silicon Waveguide

by Li-Ying Liu, Hong-Chang Huang, Chu-Wen Chen, Fu-Li Hsiao, Yu-Chieh Cheng and Chii-Chang Chen

Nanomaterials 2022, 12(20), 3694; https://doi.org/10.3390/nano12203694 - 21 Oct 2022

Cited by 3 | Viewed by 2970

Abstract

In this work, we investigate theoretically the reflective polarization rotator in a silicon waveguide formed by periodically arranged rectangular air holes. The etched air holes generate the large birefringence for the waveguide. The effective refractive index of the non-etched waveguide is isotropic. The [...] Read more.

In this work, we investigate theoretically the reflective polarization rotator in a silicon waveguide formed by periodically arranged rectangular air holes. The etched air holes generate the large birefringence for the waveguide. The effective refractive index of the non-etched waveguide is isotropic. The structure can be regarded as a stack of alternating birefringent waveplates and isotropic material similar to the folded Šolc filter. The band structure of the stack of birefringent waveplates with isotropic background is calculated to confirm the fact that high reflection peaks in the reflection spectra of the waveguide result from the photonic bandgap. The polarization extinction ratio for the reflected light is 15.8 dB. The highest reflectivity of the device is 93.1%, and the device length is 9.21 μm. An ultra-wide operation bandwidth from 1450.3 to 1621.8 nm can be achieved. Full article

(This article belongs to the Special Issue Nanophotonics and Integrated Optics Devices)

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10 pages, 23224 KiB

Open AccessEditor’s ChoiceArticle

Biofilm Degradation by Seashell-Derived Calcium Hydroxide and Hydrogen Peroxide

by Yuuki Hata, Yuta Bouda, Sumiyo Hiruma, Hiromi Miyazaki and Shingo Nakamura

Nanomaterials 2022, 12(20), 3681; https://doi.org/10.3390/nano12203681 - 20 Oct 2022

Cited by 6 | Viewed by 2511

Abstract

Microbial cells and self-produced extracellular polymeric substances assembled to form biofilms that are difficult to remove from surfaces, causing problems in various fields. Seashell-derived calcium hydroxide, a sustainable inorganic material, has shown high bactericidal activity even for biofilms due to its alkalinity. However, [...] Read more.

Microbial cells and self-produced extracellular polymeric substances assembled to form biofilms that are difficult to remove from surfaces, causing problems in various fields. Seashell-derived calcium hydroxide, a sustainable inorganic material, has shown high bactericidal activity even for biofilms due to its alkalinity. However, its biofilm removal efficacy is relatively low. Herein, we report a biofilm degradation strategy that includes two environmentally friendly reagents: seashell-derived calcium hydroxide and hydrogen peroxide. A biofilm model of Escherichia coli was prepared in vitro, treated with calcium hydroxide–hydrogen peroxide solutions, and semi-quantified by the crystal violet stain method. The treatment significantly improved biofilm removal efficacy compared with treatments by calcium hydroxide alone and hydrogen peroxide alone. The mechanism was elucidated from calcium hydroxide–hydrogen peroxide solutions, which suggested that perhydroxyl anion and hydroxyl radical generated from hydrogen peroxide, as well as the alkalinity of calcium hydroxide, enhanced biofilm degradation. This study showed that concurrent use of other reagents, such as hydrogen peroxide, is a promising strategy for improving the biofilm degradation activity of seashell-derived calcium hydroxide and will contribute to developing efficient biofilm removal methods. Full article

(This article belongs to the Special Issue Nano Geochemistry: Risk Assessment and Green Environmental Applications)

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11 pages, 5258 KiB

Open AccessEditor’s ChoiceArticle

Laser-Induced Forward Transferred Optical Scattering Nanosilica for Transparent Displays

by Ruo-Zhou Li, Mingqing Yang, Lvjiu Guo, Ke Qu, Tong Jian, Ying Yu and Jing Yan

Nanomaterials 2022, 12(20), 3674; https://doi.org/10.3390/nano12203674 - 19 Oct 2022

Cited by 4 | Viewed by 2487

Abstract

Laser printing has become a promising alternative for large-scale fabrication of functional devices. Here, laser-induced forward transfer (LIFT) of nanosilica was successfully achieved using a lower-cost nanosecond laser with a center wavelength of 1064 nm. To enhance the light absorption of silica, a [...] Read more.

Laser printing has become a promising alternative for large-scale fabrication of functional devices. Here, laser-induced forward transfer (LIFT) of nanosilica was successfully achieved using a lower-cost nanosecond laser with a center wavelength of 1064 nm. To enhance the light absorption of silica, a small amount of graphene oxide (GO) was added to the fumed silica. Investigations were conducted to give an insight into the role of GO in the LIFT process. Pattern deposition was achieved with a minimum line width of 221 μm. The scattering can be tuned from ~2.5% to ~17.5% by changing the laser fluence. The patternable transparent display based on laser transferred nanosilica (LTNS) film was also demonstrated, showing its capability to deliver information on multiple levels. This LIFT based technique promotes fast, flexible, and low-cost manufacturing of scattering-based translucent screens or patterns for transparent displays. Full article

(This article belongs to the Special Issue Scalable Fabrication Techniques for Nanostructures and Nanomaterials Facing Cutting-Edge Applications in Electronics, Energy, and Environment)

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11 pages, 10475 KiB

Open AccessEditor’s ChoiceArticle

Electric-Field Control in Phosphorene-Based Heterostructures

by Calin-Andrei Pantis-Simut, Amanda Teodora Preda, Nicolae Filipoiu, Alaa Allosh and George Alexandru Nemnes

Nanomaterials 2022, 12(20), 3650; https://doi.org/10.3390/nano12203650 - 18 Oct 2022

Cited by 4 | Viewed by 2313

Abstract

Phosphorene is a graphene-like material with an intermediate band gap, in contrast to zero-gap graphene and large-gap dichalcogenides or hexagonal boron nitride (hBN), which makes it more suitable for nanoelectronic devices. However, inducing band-gap modulation in freestanding phosphorene nanoribbons (PNRs) is problematic, as [...] Read more.

Phosphorene is a graphene-like material with an intermediate band gap, in contrast to zero-gap graphene and large-gap dichalcogenides or hexagonal boron nitride (hBN), which makes it more suitable for nanoelectronic devices. However, inducing band-gap modulation in freestanding phosphorene nanoribbons (PNRs) is problematic, as high in-plane electric fields are necessary to close the gap. We perform here a detailed investigation concerning the substrate influence on the electric-field control exerted by an external gate, using the density functional theory–non-equilibrium Green’s functions (DFT-NEGF) framework. It is established that the interaction with a hexagonal boron nitride supporting layer significantly enhances the gap modulation. Furthermore, we address the issue of contacting the PNRs, by using conducting graphene nanoribbons embedded in the support hBN layer. Within this setup, a measurable spin polarization is achieved owing to the anti-ferromagnetic coupling between the edges of the graphene nanoribbons. Full article

(This article belongs to the Special Issue Applied Physics and Nanomaterials)

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11 pages, 2578 KiB

Open AccessEditor’s ChoiceArticle

B-Site Fe/Re Cation-Ordering Control and Its Influence on the Magnetic Properties of Sr₂FeReO₆ Oxide Powders

by Zhuowei Wang, Qingkai Tang, Zhiwei Wu, Kang Yi, Jiayuan Gu and Xinhua Zhu

Nanomaterials 2022, 12(20), 3640; https://doi.org/10.3390/nano12203640 - 17 Oct 2022

Cited by 4 | Viewed by 1894

Abstract

Double-perovskite oxide Sr₂FeReO₆ (SFRO) powders have promising applications in spintronics due to their half-metallicity and high Curie temperature. However, their magnetic properties suffer from the existence of anti-site defects (ASDs). Here, we report on the synthesis of SFRO powders by [...] Read more.

Double-perovskite oxide Sr₂FeReO₆ (SFRO) powders have promising applications in spintronics due to their half-metallicity and high Curie temperature. However, their magnetic properties suffer from the existence of anti-site defects (ASDs). Here, we report on the synthesis of SFRO powders by the sol–gel process. The B-site cationic ordering degree (η) and its influence on magnetic properties are investigated. The results demonstrate that the η value is well controlled by the annealing temperature, which is as high as 85% when annealing at 1100 °C. However, the annealing atmospheres (e.g., N₂ or Ar) have little effect on the η value. At room temperature, the SFRO powders crystallize in a tetragonal crystal structure (space group I4/m). They have a relatively uniform morphology and the molar ratios of Sr, Fe, and Re elements are close to 2:1:1. XPS spectra identified that Sr, Fe, and Re elements presented as Sr²⁺, Fe³⁺, and Re⁵⁺ ions, respectively, and the O element presented as O^2-. The SFRO samples annealed at 1100 °C in N₂, exhibiting the highest saturation magnetization (M_S = 2.61 μ_B/f.u. at 2 K), which was ascribed to their smallest ASD content (7.45%) with an anti-phase boundary-like morphology compared to those annealed at 1000 °C (ASDs = 10.7%) or 1200 °C (ASDs = 10.95%). Full article

(This article belongs to the Section Synthesis, Interfaces and Nanostructures)

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13 pages, 3248 KiB

Open AccessEditor’s ChoiceArticle

Transfer Learning for Modeling Plasmonic Nanowire Waveguides

by Aoning Luo, Yuanjia Feng, Chunyan Zhu, Yipei Wang and Xiaoqin Wu

Nanomaterials 2022, 12(20), 3624; https://doi.org/10.3390/nano12203624 - 16 Oct 2022

Cited by 3 | Viewed by 1835

Abstract

Retrieving waveguiding properties of plasmonic metal nanowires (MNWs) through numerical simulations is time- and computational-resource-consuming, especially for those with abrupt geometric features and broken symmetries. Deep learning provides an alternative approach but is challenging to use due to inadequate generalization performance and the [...] Read more.

Retrieving waveguiding properties of plasmonic metal nanowires (MNWs) through numerical simulations is time- and computational-resource-consuming, especially for those with abrupt geometric features and broken symmetries. Deep learning provides an alternative approach but is challenging to use due to inadequate generalization performance and the requirement of large sets of training data. Here, we overcome these constraints by proposing a transfer learning approach for modeling MNWs under the guidance of physics. We show that the basic knowledge of plasmon modes can first be learned from free-standing circular MNWs with computationally inexpensive data, and then reused to significantly improve performance in predicting waveguiding properties of MNWs with various complex configurations, enabling much smaller errors (~23–61% reduction), less trainable parameters (~42% reduction), and smaller sets of training data (~50–80% reduction) than direct learning. Compared to numerical simulations, our model reduces the computational time by five orders of magnitude. Compared to other non-deep learning methods, such as the circular-area-equivalence approach and the diagonal-circle approximation, our approach enables not only much higher accuracies, but also more comprehensive characterizations, offering an effective and efficient framework to investigate MNWs that may greatly facilitate the design of polaritonic components and devices. Full article

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19 pages, 4074 KiB

Open AccessEditor’s ChoiceArticle

The Complexity of Comparative Adsorption of C₆ Hydrocarbons (Benzene, Cyclohexane, n-Hexane) at Metal–Organic Frameworks

by Christian Jansen, Nabil Assahub, Alex Spieß, Jun Liang, Alexa Schmitz, Shanghua Xing, Serkan Gökpinar and Christoph Janiak

Nanomaterials 2022, 12(20), 3614; https://doi.org/10.3390/nano12203614 - 15 Oct 2022

Cited by 16 | Viewed by 3410

Abstract

The relatively stable MOFs Alfum, MIL-160, DUT-4, DUT-5, MIL-53-TDC, MIL-53, UiO-66, UiO-66-NH₂, UiO-66(F)₄, UiO-67, DUT-67, NH₂-MIL-125, MIL-125, MIL-101(Cr), ZIF-8, ZIF-11 and ZIF-7 were studied for their C₆ sorption properties. An understanding of the uptake of the [...] Read more.

The relatively stable MOFs Alfum, MIL-160, DUT-4, DUT-5, MIL-53-TDC, MIL-53, UiO-66, UiO-66-NH₂, UiO-66(F)₄, UiO-67, DUT-67, NH₂-MIL-125, MIL-125, MIL-101(Cr), ZIF-8, ZIF-11 and ZIF-7 were studied for their C₆ sorption properties. An understanding of the uptake of the larger C₆ molecules cannot simply be achieved with surface area and pore volume (from N₂ sorption) but involves the complex micropore structure of the MOF. The maximum adsorption capacity at p p₀⁻¹ = 0.9 was shown by DUT-4 for benzene, MIL-101(Cr) for cyclohexane and DUT-5 for n-hexane. In the low-pressure range from p p₀⁻¹ = 0.1 down to 0.05 the highest benzene uptake is given by DUT-5, DUT-67/UiO-67 and MIL-101(Cr), for cyclohexane and n-hexane by DUT-5, UiO-67 and MIL-101(Cr). The highest uptake capacity at p p₀⁻¹ = 0.02 was seen with MIL-53 for benzene, MIL-125 for cyclohexane and DUT-5 for n-hexane. DUT-5 and MIL-101(Cr) are the MOFs with the widest pore window openings/cross sections but the low-pressure uptake seems to be controlled by a complex combination of ligand and pore-size effect. IAST selectivities between the three binary mixtures show a finely tuned and difficult to predict interplay of pore window size with (critical) adsorptive size and possibly a role of electrostatics through functional groups such as NH₂. Full article

(This article belongs to the Special Issue Advanced Porous Nanomaterials: Synthesis, Properties, and Application)

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10 pages, 2196 KiB

Open AccessEditor’s ChoiceArticle

A Versatile Route for Synthesis of Metal Nanoalloys by Discharges at the Interface of Two Immiscible Liquids

by Ahmad Hamdan and Luc Stafford

Nanomaterials 2022, 12(20), 3603; https://doi.org/10.3390/nano12203603 - 14 Oct 2022

Cited by 6 | Viewed by 1561

Abstract

Discharge in liquid is a promising technique to produce nanomaterials by electrode erosion. Although its feasibility was demonstrated in many conditions, the production of nanoalloys by in-liquid discharges remains a challenge. Here, we show that spark discharge in liquid cyclohexane that is in [...] Read more.

Discharge in liquid is a promising technique to produce nanomaterials by electrode erosion. Although its feasibility was demonstrated in many conditions, the production of nanoalloys by in-liquid discharges remains a challenge. Here, we show that spark discharge in liquid cyclohexane that is in contact with conductive solution, made of a combination of Ni-nitrate and/or Fe-nitrate and/or Co-nitrate, is suitable to produce nanoalloys (<10 nm) of Ni-Fe, Ni-Co, Co-Fe, and Ni-Co-Fe. The nanoparticles are synthesized by the reduction of metal ions during discharge, and they are individually embedded in C-matrix; this latter originates from the decomposition of cyclohexane. The results open novel ways to produce a wide spectrum of nanoalloys; they are needed for many applications, such as in catalysis, plasmonic, and energy conversion. Full article

(This article belongs to the Special Issue Morphological Design and Synthesis of Nanoparticles)

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15 pages, 3648 KiB

Open AccessEditor’s ChoiceArticle

Surface-Enhanced Raman Spectroscopy Chips Based on Silver Coated Gold Nanostars

by Miriam Parmigiani, Benedetta Albini, Giovanni Pellegrini, Marco Genovesi, Lorenzo De Vita, Piersandro Pallavicini, Giacomo Dacarro, Pietro Galinetto and Angelo Taglietti

Nanomaterials 2022, 12(20), 3609; https://doi.org/10.3390/nano12203609 - 14 Oct 2022

Cited by 14 | Viewed by 4606

Abstract

Surface-enhanced Raman scattering (SERS) is becoming widely used as an analytical tool, and the search for stable and highly responsive SERS substrates able to give ultralow detection of pollutants is a current challenge. In this paper we boosted the SERS response of Gold [...] Read more.

Surface-enhanced Raman scattering (SERS) is becoming widely used as an analytical tool, and the search for stable and highly responsive SERS substrates able to give ultralow detection of pollutants is a current challenge. In this paper we boosted the SERS response of Gold nanostars (GNS) demonstrating that their coating with a layer of silver having a proper thickness produces a 7-fold increase in SERS signals. Glass supported monolayers of these GNS@Ag were then prepared using simple alcoxyliane chemistry, yielding efficient and reproducible SERS chips, which were tested for the detection of molecules representative of different classes of pollutants. Among them, norfloxacin was detected down to 3 ppb, which is one of the lowest limits of detection obtained with this technique for the analyte. Full article

(This article belongs to the Special Issue SERS/SERRS-Active Nanostructures and Nanocomposites)

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20 pages, 3275 KiB

Open AccessEditor’s ChoiceArticle

Multifunctional Loblolly Pine-Derived Superactivated Hydrochar: Effect of Hydrothermal Carbonization on Hydrogen and Electron Storage with Carbon Dioxide and Dye Removal

by Al Ibtida Sultana, Cadianne Chambers, Muzammil M. N. Ahmed, Pavithra Pathirathna and Toufiq Reza

Nanomaterials 2022, 12(20), 3575; https://doi.org/10.3390/nano12203575 - 12 Oct 2022

Cited by 12 | Viewed by 2658

Abstract

Pore modulation via hydrothermal carbonization (HTC) needs investigation due to its crucial effect on surface that influences its multirole utilization of such ultraporous sorbents in applications of energy storage- hydrogen and capacitive- as well as for pollutant abatement- carbon capture and dye removal. [...] Read more.

Pore modulation via hydrothermal carbonization (HTC) needs investigation due to its crucial effect on surface that influences its multirole utilization of such ultraporous sorbents in applications of energy storage- hydrogen and capacitive- as well as for pollutant abatement- carbon capture and dye removal. Hence, loblolly pine was hydrothermally carbonized followed by KOH activation to synthesize superactivated hydrochars (SAH). The resulting SAHs had specific surface area (SSA) 1462–1703 m²/g, total pore (TPV) and micropore volume (MPV) of 0.62–0.78 cm³/g and 0.33–0.49 cm³/g, respectively. The SAHs exhibit excellent multifunctional performance with remarkably high atmospheric CO₂ capture of 145.2 mg/g and high pressure cryogenic H₂ storage of 54.9 mg/g. The fabricated supercapacitor displayed substantial specific capacitance value of maximum 47.2 Fg⁻¹ at 1 A g⁻¹ in 6 M KOH and highest MB dye removal of 719.4 mg/g. Higher HTC temperature resulted in increased surface porosity as higher SSA, TPV benefitted H₂ storage and MB dye removal while superior MPV favored CO₂ capture. Moderate HTC temperature ensured higher mesopore-to-macropore volume ratio favoring electrochemical performance. Isotherm modelling of the adsorbates was compared using models: Langmuir, Freundlich, Langmuir- Freundlich and Temkin. Full article

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

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13 pages, 2208 KiB

Open AccessEditor’s ChoiceArticle

Elucidation of Strain-Dependent, Zinc Oxide Nanorod Response for Nanorod-Guided Fluorescence Intensity

by Johnson Truong, Andrew Stoner, Marion Ryan C. Sytu, T Rizana Tatlock, David H. Cho and Jong-in Hahm

Nanomaterials 2022, 12(20), 3558; https://doi.org/10.3390/nano12203558 - 11 Oct 2022

Cited by 3 | Viewed by 1876

Abstract

In this work, we examine how strain exerted on individual ZnO nanorods (NRs) can influence the fluorescence signals that are emitted from fluorophore molecules and subsequently coupled into and guided along the NR. We elucidate the relationships between the incremental levels of compressive [...] Read more.

In this work, we examine how strain exerted on individual ZnO nanorods (NRs) can influence the fluorescence signals that are emitted from fluorophore molecules and subsequently coupled into and guided along the NR. We elucidate the relationships between the incremental levels of compressive and tensile strain on the NRs and measured fluorescence intensity of a model fluorophore, rhodamine 6G (R6G), as a function of the position on the NRs. We reveal that compressive strain on the NRs leads to a decrease in the guided fluorescence signal, while tensile strain leads to an increase in the fluorescence intensity. Compared to an unstrained state, approximately 35% decrease (increase) in R6G fluorescence intensity was observed from ZnO NRs when they were under compressive strain of −14% (tensile strain of +10%). Further, our systematic acquisition of the incremental addition of uniaxial strain result in a linear relationship of the coupled fluorescence signal and the amount of applied strain. The degree of fluorescence intensification on nanorod ends (DoF), which is a quantitative indicator for the amount of R6G signals coupled into and waveguided to the NR ends compared to those on the main body, also exhibits a linear relationship with strain. These outcomes, in turn, demonstrate that strain alters the waveguiding capabilities of ZnO NRs in a predictable manner, which can be exploited to modulate and optimize fluorescence and other light signals emitted by a nearby source. Considering the wide utility of ZnO NRs in photonics, optoelectronics, and sensors, insights from our study may be highly valuable to effectively controlling and enhancing optical signals from chemical and biological analytes through strain. Full article

(This article belongs to the Special Issue One-Dimensional Nanostructures: Synthesis, Characterization and Applications)

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