Nanomaterials

14 pages, 11822 KiB

Open AccessArticle

Direct Z-Scheme Heterojunction Catalysts Constructed by Graphitic-C₃N₄ and Photosensitive Metal-Organic Cages for Efficient Photocatalytic Hydrogen Evolution

by Chuying Lv, Su Qin, Yang Lei, Xinao Li, Jianfeng Huang and Junmin Liu

Nanomaterials 2022, 12(5), 890; https://doi.org/10.3390/nano12050890 - 7 Mar 2022

Cited by 4 | Viewed by 2969

Abstract

The demand for improving the activity, durability, and recyclability of metal-organic cages (MOCs) that work as photocatalytic molecular devices in a homogeneous system has promoted research to combine them with other solid materials. An M₂L₄ type photosensitive metal-organic cage MOC-Q2 [...] Read more.

The demand for improving the activity, durability, and recyclability of metal-organic cages (MOCs) that work as photocatalytic molecular devices in a homogeneous system has promoted research to combine them with other solid materials. An M₂L₄ type photosensitive metal-organic cage MOC-Q2 with light-harvesting ligands and catalytic Pd²⁺ centers has been synthesized and further heterogenized with graphitic carbon nitride to prepare a robust direct Z-scheme heterojunction photocatalyst for visible-light-driven hydrogen generation. The optimized g-C₃N₄/MOC-Q2 (0.7 wt%) sample exhibits a high H₂ evolution activity of 6423 μmol g⁻¹ h⁻¹ in 5 h, and a total turnover number of 39,695 after 10 h, significantly superior to the bare MOC-Q2 used in the homogeneous solution and the comparison sample Pd/g-C₃N₄/L-4. The enhanced performances of g-C₃N₄/MOC-Q2 can be ascribed to its direct Z-scheme heterostructure, which effectively improves the charge separation and transfer efficiency. This work presents a rational approach of designing a binary photocatalytic system through combing micromolecular MOCs with heterogeneous semiconductors for water splitting. Full article

(This article belongs to the Special Issue Design and Development of Hybrid Nanostructures for Energy Storage Application)

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10 pages, 4089 KiB

Open AccessArticle

4-Levels Vertically Stacked SiGe Channel Nanowires Gate-All-Around Transistor with Novel Channel Releasing and Source and Drain Silicide Process

by Xiaohong Cheng, Yongliang Li, Fei Zhao, Anlan Chen, Haoyan Liu, Chun Li, Qingzhu Zhang, Huaxiang Yin, Jun Luo and Wenwu Wang

Nanomaterials 2022, 12(5), 889; https://doi.org/10.3390/nano12050889 - 7 Mar 2022

Cited by 10 | Viewed by 4930

Abstract

In this paper, the fabrication and electrical performance optimization of a four-levels vertically stacked Si_0.7Ge_0.3 channel nanowires gate-all-around transistor are explored in detail. First, a high crystalline quality and uniform stacked Si_0.7Ge_0.3/Si film is achieved by [...] Read more.

In this paper, the fabrication and electrical performance optimization of a four-levels vertically stacked Si_0.7Ge_0.3 channel nanowires gate-all-around transistor are explored in detail. First, a high crystalline quality and uniform stacked Si_0.7Ge_0.3/Si film is achieved by optimizing the epitaxial growth process and a vertical profile of stacked Si_0.7Ge_0.3/Si fin is attained by further optimizing the etching process under the HBr/He/O₂ plasma. Moreover, a novel ACT@SG-201 solution without any dilution at the temperature of 40 °C is chosen as the optimal etching solution for the release process of Si_0.7Ge_0.3 channel. As a result, the selectivity of Si to Si_0.7Ge_0.3 can reach 32.84 with a signature of “rectangular” Si_0.7Ge_0.3 extremities after channel release. Based on these newly developed processes, a 4-levels vertically stacked Si_0.7Ge_0.3 nanowires gate-all-around device is prepared successfully. An excellent subthreshold slope of 77 mV/dec, drain induced barrier-lowering of 19 mV/V, I_on/I_off ratio of 9 × 10⁵ and maximum of transconductance of ~83.35 μS/μm are demonstrated. However, its driven current is only ~38.6 μA/μm under V_DS = V_GS = −0.8 V due to its large resistance of source and drain (9.2 × 10⁵ Ω). Therefore, a source and drain silicide process is implemented and its driven current can increase to 258.6 μA/μm (about 6.7 times) due to the decrease of resistance of source and drain to 6.4 × 10⁴ Ω. Meanwhile, it is found that a slight increase of leakage after the silicide process online results in a slight deterioration of the subthreshold slope and I_on/I_off ratio. Its leakage performance needs to be further improved through the co-optimization of source and drain implantation and silicide process in the future. Full article

(This article belongs to the Special Issue Semiconductor Nanowires: Fabrication, Characterization, and Applications)

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27 pages, 20111 KiB

Open AccessArticle

Magnetic Field Effects Induced in Electrical Devices Based on Cotton Fiber Composites, Carbonyl Iron Microparticles and Barium Titanate Nanoparticles

by Gabriel Pascu, Octavian Madalin Bunoiu and Ioan Bica

Nanomaterials 2022, 12(5), 888; https://doi.org/10.3390/nano12050888 - 7 Mar 2022

Cited by 6 | Viewed by 1845

Abstract

This work consists in the process of preparing magnetic active composite materials based on cotton fibers, iron carbonyl microparticles and barium titanate nanoparticles, and the electrical devices manufactured with them. For different compositions of the aforementioned ingredients, three such composites are manufactured and [...] Read more.

This work consists in the process of preparing magnetic active composite materials based on cotton fibers, iron carbonyl microparticles and barium titanate nanoparticles, and the electrical devices manufactured with them. For different compositions of the aforementioned ingredients, three such composites are manufactured and compacted at constant pressure between two electrodes. In the absence and in the presence of a magnetic field, using an RLC bridge, magnetocapacitive, magnetoresistive and magnetopiezoelectric effects are highlighted in the custom fabricated devices. It is shown that these effects are significantly influenced by the composition of the materials. Based on the model elaborated in this paper, the mechanisms that contribute to the observed effects are described and the theoretical predictions are shown to agree with the experimental data. The obtained results can be used in the assembly of hybrid magnetic active composites, which are low cost, ecological and have other useful physical characteristics for applications. Full article

(This article belongs to the Special Issue Composite Materials Based on Polymeric Fibers Doped with Magnetic Nanoparticles: Synthesis, Properties and Applications)

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19 pages, 2599 KiB

Open AccessArticle

Ferric Ion Diffusion for MOF-Polymer Composite with Internal Boundary Sinks

by Kirsten I. Louw, Bronwyn H. Bradshaw-Hajek and James M. Hill

Nanomaterials 2022, 12(5), 887; https://doi.org/10.3390/nano12050887 - 7 Mar 2022

Cited by 1 | Viewed by 1661

Abstract

Simple and economical ferric ion detection is necessary in many industries. An europium-based metal organic framework has selective sensing properties for solutions containing ferric ions and shows promise as a key component in a new sensor. We study an idealised sensor that consists [...] Read more.

Simple and economical ferric ion detection is necessary in many industries. An europium-based metal organic framework has selective sensing properties for solutions containing ferric ions and shows promise as a key component in a new sensor. We study an idealised sensor that consists of metal organic framework (MOF) crystals placed on a polymer surface. A two-dimensional diffusion model is used to predict the movement of ferric ions through the solution and polymer, and the ferric ion association to a MOF crystal at the boundary between the different media. A simplified one-dimensional model identifies the choice of appropriate values for the dimensionless parameters required to optimise the time for a MOF crystal to reach steady state. The model predicts that a large non-dimensional diffusion coefficient and an effective association with a small effective flux will reduce the time to steady-state. The effective dissociation is the most significant parameter to aid the estimation of the ferric ion concentration. This paper provides some theoretical insight for material scientists to optimise the design of a new ferric ion sensor. Full article

(This article belongs to the Special Issue Multifunctional Nanomaterials for Energy Applications)

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12 pages, 2130 KiB

Open AccessArticle

Carbon Nanotube-Modified Nickel Hydroxide as Cathode Materials for High-Performance Li-S Batteries

by Qianwen Jin, Yajing Yan, Chenchen Hu, Yongguang Zhang, Xi Wang and Chunyong Liang

Nanomaterials 2022, 12(5), 886; https://doi.org/10.3390/nano12050886 - 7 Mar 2022

Cited by 4 | Viewed by 2516

Abstract

The advantages of high energy density and low cost make lithium–sulfur batteries one of the most promising candidates for next-generation energy storage systems. However, the electrical insulativity of sulfur and the serious shuttle effect of lithium polysulfides (LiPSs) still impedes its further development. [...] Read more.

The advantages of high energy density and low cost make lithium–sulfur batteries one of the most promising candidates for next-generation energy storage systems. However, the electrical insulativity of sulfur and the serious shuttle effect of lithium polysulfides (LiPSs) still impedes its further development. In this regard, a uniform hollow mesoporous Ni(OH)₂@CNT microsphere was developed to address these issues. The SEM images show the Ni(OH)₂ delivers an average size of about 5 μm, which is composed of nanosheets. The designed Ni(OH)₂@CNT contains transition metal cations and interlayer anions, featuring the unique 3D spheroidal flower structure, decent porosity, and large surface area, which is highly conducive to conversion systems and electrochemical energy storage. As a result, the as-fabricated Li-S battery delivers the reversible capacity of 652 mAh g⁻¹ after 400 cycles, demonstrating excellent capacity retention with a low average capacity loss of only 0.081% per cycle at 1 C. This work has shown that the Ni(OH)₂@CNT sulfur host prepared by hydrothermal embraces delivers strong physical absorption as well as chemical affinity. Full article

(This article belongs to the Special Issue Nanomaterials: Electrochemistry and Electro-Analytical Application)

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11 pages, 3270 KiB

Open AccessEditor’s ChoiceArticle

Physicochemical Characterization and Antibacterial Properties of Carbon Dots from Two Mediterranean Olive Solid Waste Cultivars

by Giuseppe Nocito, Emanuele Luigi Sciuto, Domenico Franco, Francesco Nastasi, Luca Pulvirenti, Salvatore Petralia, Corrado Spinella, Giovanna Calabrese, Salvatore Guglielmino and Sabrina Conoci

Nanomaterials 2022, 12(5), 885; https://doi.org/10.3390/nano12050885 - 7 Mar 2022

Cited by 18 | Viewed by 2523

Abstract

Carbon nanomaterials have shown great potential in several fields, including biosensing, bioimaging, drug delivery, energy, catalysis, diagnostics, and nanomedicine. Recently, a new class of carbon nanomaterials, carbon dots (CDs), have attracted much attention due to their easy and inexpensive synthesis from a wide [...] Read more.

Carbon nanomaterials have shown great potential in several fields, including biosensing, bioimaging, drug delivery, energy, catalysis, diagnostics, and nanomedicine. Recently, a new class of carbon nanomaterials, carbon dots (CDs), have attracted much attention due to their easy and inexpensive synthesis from a wide range of precursors and fascinating physical, chemical, and biological properties. In this work we have developed CDs derived from olive solid wastes of two Mediterranean regions, Puglia (CDs_P) and Calabria (CDs_C) and evaluated them in terms of their physicochemical properties and antibacterial activity against Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa). Results show the nanosystems have a quasi-spherical shape of 12–18 nm in size for CDs_P and 15–20 nm in size for CDs_C. UV–Vis characterization indicates a broad absorption band with two main peaks at about 270 nm and 300 nm, respectively, attributed to the π-π* and n-π* transitions of the CDs, respectively. Both samples show photoluminescence (PL) spectra excitation-dependent with a maximum at λ_em = 420 nm (λ_exc = 300 nm) for CDs_P and a red-shifted at λ_em = 445 nm (λ_exc = 300 nm) for CDs_C. Band gaps values of ≈ 1.48 eV for CDs_P and ≈ 1.53 eV for CDs_C are in agreement with semiconductor behaviour. ζ potential measures show very negative values for CDs_C compared to CDs_P (three times higher, −38 mV vs. −18 mV at pH = 7). The evaluation of the antibacterial properties highlights that both CDs have higher antibacterial activity towards Gram-positive than to Gram-negative bacteria. In addition, CDs_C exhibit bactericidal behaviour at concentrations of 360, 240, and 120 µg/mL, while lesser activity was found for CDs_P (bacterial cell reduction of only 30% at the highest concentration of 360 µg/mL). This finding was correlated to the higher surface charge of CDs_C compared to CDs_P. Further investigations are in progress to confirm this hypothesis and to gain insight on the antibacterial mechanism of both cultivars. Full article

(This article belongs to the Topic Advances and Applications of Carbon Nanotubes)

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10 pages, 3767 KiB

Open AccessArticle

Pixelated Vacuum Flat Panel Detector Using ZnS Photoconductor and ZnO Nanowires Cold Cathode

by Delin Hu, Xingpeng Bai, Chengyun Wang, Zhipeng Zhang, Xiaojie Li, Guofu Zhang, Shaozhi Deng and Jun Chen

Nanomaterials 2022, 12(5), 884; https://doi.org/10.3390/nano12050884 - 7 Mar 2022

Viewed by 2060

Abstract

Vacuum flat panel detectors (VFPDs) using cold cathode have important applications in large-area photoelectric detection. Based on the electron-bombardment-induced photoconductivity (EBIPC) mechanism, the photoconductor-type VFPDs achieved high detection sensitivity. However, pixelated imaging devices have not yet been developed. In this paper, we fabricate [...] Read more.

Vacuum flat panel detectors (VFPDs) using cold cathode have important applications in large-area photoelectric detection. Based on the electron-bombardment-induced photoconductivity (EBIPC) mechanism, the photoconductor-type VFPDs achieved high detection sensitivity. However, pixelated imaging devices have not yet been developed. In this paper, we fabricate a 4 × 7 pixel vacuum flat panel detector array made of ZnS photoconductor and ZnO nanowires cold cathode for an imaging application. The responsivity of the device and the pixel current uniformity are studied, and imaging of the patterned objects is achieved. Our results verify the feasibility of VFPDs for imaging. Full article

(This article belongs to the Special Issue The Research Related to Nanomaterial Cold Cathode)

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8 pages, 4104 KiB

Open AccessArticle

A Quantitative Chemical Method for Determining the Surface Concentration of Stone–Wales Defects for 1D and 2D Carbon Nanomaterials

by Alexander Voznyakovskii, Anna Neverovskaya, Aleksei Vozniakovskii and Sergey Kidalov

Nanomaterials 2022, 12(5), 883; https://doi.org/10.3390/nano12050883 - 7 Mar 2022

Cited by 14 | Viewed by 1718

Abstract

A quantitative method is proposed to determine Stone–Wales defects for 1D and 2D carbon nanostructures. The technique is based on the diene synthesis reaction (Diels–Alder reaction). The proposed method was used to determine Stone–Wales defects in the few-layer graphene (FLG) nanostructures synthesized by [...] Read more.

A quantitative method is proposed to determine Stone–Wales defects for 1D and 2D carbon nanostructures. The technique is based on the diene synthesis reaction (Diels–Alder reaction). The proposed method was used to determine Stone–Wales defects in the few-layer graphene (FLG) nanostructures synthesized by the self-propagating high-temperature synthesis (SHS) process in reduced graphene oxide (rGO) synthesized based on the method of Hammers and in the single-walled carbon nanotubes (SWCNT) TUBAL trademark, Russia. Our research has shown that the structure of FLG is free of Stone–Wales defects, while the surface concentration of Stone–Wales defects in TUBAL carbon nanotubes is 1.1 × 10⁻⁵ mol/m² and 3.6 × 10⁻⁵ mol/m² for rGO. Full article

(This article belongs to the Special Issue Synthesis Methods of Graphene Nanoplatelets and Their Applications in Metal and Polymer (Epoxy) Based Nanocomposites)

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11 pages, 7641 KiB

Open AccessArticle

Reconfigurable, Stretchable Strain Sensor with the Localized Controlling of Substrate Modulus by Two-Phase Liquid Metal Cells

by Linna Mao, Taisong Pan, Junxiong Guo, Yizhen Ke, Jia Zhu, Huanyu Cheng and Yuan Lin

Nanomaterials 2022, 12(5), 882; https://doi.org/10.3390/nano12050882 - 7 Mar 2022

Cited by 13 | Viewed by 2656

Abstract

Strain modulation based on the heterogeneous design of soft substrates is an effective method to improve the sensitivity of stretchable resistive strain sensors. In this study, a novel design for reconfigurable strain modulation in the soft substrate with two-phase liquid cells is proposed. [...] Read more.

Strain modulation based on the heterogeneous design of soft substrates is an effective method to improve the sensitivity of stretchable resistive strain sensors. In this study, a novel design for reconfigurable strain modulation in the soft substrate with two-phase liquid cells is proposed. The modulatory strain distribution induced by the reversible phase transition of the liquid metal provides reconfigurable strain sensing capabilities with multiple combinations of operating range and sensitivity. The effectiveness of our strategy is validated by theoretical simulations and experiments on a hybrid carbonous film-based resistive strain sensor. The strain sensor can be gradually switched between a highly sensitive one and a wide-range one by selectively controlling the phases of liquid metal in the cell array with a external heating source. The relative change of sensitivity and operating range reaches a maximum of 59% and 44%, respectively. This reversible heterogeneous design shows great potential to facilitate the fabrication of strain sensors and might play a promising role in the future applications of stretchable strain sensors. Full article

(This article belongs to the Special Issue Laser-Matter Interaction for Nanostructuration and Characterization: From Fundamentals to Sensing and Energy Applications)

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15 pages, 4670 KiB

Open AccessArticle

Synthesis of Magnetic Fe₃O₄ Nano Hollow Spheres for Industrial TNT Wastewater Treatment

by Shafi Ur Rehman, Sana Javaid, Muhammad Shahid, Mutawara Mahmood Baig, Badar Rashid, Caroline R. Szczepanski and Sabrina J. Curley

Nanomaterials 2022, 12(5), 881; https://doi.org/10.3390/nano12050881 - 7 Mar 2022

Cited by 7 | Viewed by 3377

Abstract

The aim of the present work was to synthesize magnetite (Fe₃O₄) nano hollow spheres (NHS) via simple, one-pot, template-free, hydrothermal method. The structural, morphological, and surface analysis of Fe₃O₄ NHS were studied by scanning electron microscopy [...] Read more.

The aim of the present work was to synthesize magnetite (Fe₃O₄) nano hollow spheres (NHS) via simple, one-pot, template-free, hydrothermal method. The structural, morphological, and surface analysis of Fe₃O₄ NHS were studied by scanning electron microscopy (SEM), x-ray diffraction technique (XRD), Fourier transform infrared spectroscopy FTIR and burner-Emmett-teller (BET). The as obtained magnetic (Fe₃O₄) NHS were used as an adsorbent for treating industrial trinitrotoluene (TNT) wastewater to reduce its Chemical Oxygen Demand (COD) values. Adsorption capacity (Qe) of the NHS obtained is 70 mg/g, confirming the attractive forces present between adsorbent (Fe₃O₄ NHS) and adsorbate (TNT wastewater). COD value of TNT wastewater was reduced to >92% in 2 h at room temperature. The adsorption capacity of Fe₃O₄ NHS was observed as a function of time, initial concentration, pH, and temperature. The applied Fe₃O₄ NHS was recovered for reuse by simply manipulating its magnetic properties with slight shift in pH of the solution. A modest decrease in Qe (5.0–15.1%) was observed after each cycle. The novel Fe₃O₄ NHS could be an excellent candidate for treating wastewater generated by the intermediate processes during cyclonite, cyclotetramethylene-tetranitramine (HMX), nitroglycerin (NG) production and other various environmental pollutants/species. Full article

(This article belongs to the Special Issue Development of Nanocomposite Coatings)

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18 pages, 8449 KiB

Open AccessArticle

High-Speed Erosion Behavior of Hydrophobic Micro/Nanostructured Titanium Surfaces

by Yong Chen and Jiguo Zhang

Nanomaterials 2022, 12(5), 880; https://doi.org/10.3390/nano12050880 - 7 Mar 2022

Cited by 7 | Viewed by 2415

Abstract

Ice accretion on aircrafts or their engines can cause serious problems and even accidents. Traditional anti-icing and de-icing systems reduce engine efficiency, which can be improved by the use of hydrophobic/icephobic coatings or surfaces that reduce the amount of bleed air or electric [...] Read more.

Ice accretion on aircrafts or their engines can cause serious problems and even accidents. Traditional anti-icing and de-icing systems reduce engine efficiency, which can be improved by the use of hydrophobic/icephobic coatings or surfaces that reduce the amount of bleed air or electric power needed. These hydrophobic/icephobic coatings or surfaces are eroded by high-speed air flow, water droplets, ice crystals, sand, and volcanic ash, resulting in the degradation, material loss, or deterioration of the coating’s waterproof and anti-icing properties. Thus, the durability of hydrophobic micro/nanostructured surfaces is a major concern in aircraft applications. However, the mechanism responsible for material loss in hydrophobic micro/nanostructured surfaces resulting from high-speed erosion remains unclear. In this paper, hydrophobic titanium alloy surfaces with cubic pit arrays are fabricated by photoetching and tested using a high-speed sand erosion rig. Under the same impact conditions, the erosion rates of the micro/nanostructured titanium surfaces were similar to those of smooth titanium alloy, implying that the hydrophobic surface fabricated on the bulk material had erosion-resistant capabilities. The material loss mechanisms of the micro/nanostructures under different impact angles were compared, providing useful information for the future optimization of micro/nanostructures with the goal of improved erosion resistance. Full article

(This article belongs to the Topic Materials and Surface Treatment Processes Used for Engineering Applications)

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15 pages, 2502 KiB

Open AccessArticle

Foam Synthesis of Nickel/Nickel (II) Hydroxide Nanoflakes Using Double Templates of Surfactant Liquid Crystal and Hydrogen Bubbles: A High-Performance Catalyst for Methanol Electrooxidation in Alkaline Solution

by Amani M. Bamuqaddam, Saba A. Aladeemy, Mohamed A. Ghanem, Abdullah M. Al-Mayouf, Nouf H. Alotaibi and Frank Marken

Nanomaterials 2022, 12(5), 879; https://doi.org/10.3390/nano12050879 - 7 Mar 2022

Cited by 8 | Viewed by 2507

Abstract

This work demonstrates the chemical synthesis of two-dimensional nanoflakes of mesoporous nickel/nickel (II) hydroxide (Ni/Ni(OH)₂-NFs) using double templates of surfactant self-assembled thin-film and foam of hydrogen bubbles produced by sodium borohydride reducing agent. Physicochemical characterizations show the formation of amorphous mesoporous [...] Read more.

This work demonstrates the chemical synthesis of two-dimensional nanoflakes of mesoporous nickel/nickel (II) hydroxide (Ni/Ni(OH)₂-NFs) using double templates of surfactant self-assembled thin-film and foam of hydrogen bubbles produced by sodium borohydride reducing agent. Physicochemical characterizations show the formation of amorphous mesoporous 2D nanoflakes with a Ni/Ni(OH)₂ structure and a high specific surface area (165 m²/g). Electrochemical studies show that the electrocatalytic activity of Ni/Ni(OH)₂ nanoflakes towards methanol oxidation in alkaline solution is significantly enhanced in comparison with that of parent bare-Ni(OH)₂ deposited from surfactant-free solution. Cyclic voltammetry shows that the methanol oxidation mass activity of Ni/Ni(OH)₂-NFs reaches 545 A/cm² g_cat at 0.6 V vs. Ag/AgCl, which is more than five times higher than that of bare-Ni(OH)₂. Moreover, Ni/Ni(OH)₂-NFs reveal less charge transfer resistance (10.4 Ω), stable oxidation current density (625 A/cm² g_cat at 0.7 V vs. Ag/AgCl), and resistance to the adsorption of reaction intermediates and products during three hours of constant-potential methanol oxidation electrolysis in alkaline solution. The high-performance electrocatalytic activity of Ni/Ni(OH)₂ nanoflakes is mainly derived from efficient charge transfer due to the high specific surface area of the 2D mesoporous architecture of the nanoflakes, as well as the mass transport of methanol to Ni²⁺/Ni³⁺ active sites throughout the catalyst layer. Full article

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

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36 pages, 5208 KiB

Open AccessArticle

Quantitative Features Analysis of Water Carrying Nanoparticles of Alumina over a Uniform Surface

by Abdul Hamid Ganie, Fazlullah Fazal, Carlos Andrés Tavera Romero and Muhammad Sulaiman

Nanomaterials 2022, 12(5), 878; https://doi.org/10.3390/nano12050878 - 6 Mar 2022

Cited by 4 | Viewed by 2196

Abstract

Little is known about the rising impacts of Coriolis force and volume fraction of nanoparticles in industrial, mechanical, and biological domains, with an emphasis on water conveying 47 nm nanoparticles of alumina nanoparticles. We explored the impact of the volume fraction and rotation [...] Read more.

Little is known about the rising impacts of Coriolis force and volume fraction of nanoparticles in industrial, mechanical, and biological domains, with an emphasis on water conveying 47 nm nanoparticles of alumina nanoparticles. We explored the impact of the volume fraction and rotation parameter on water conveying 47 nm of alumina nanoparticles across a uniform surface in this study. The Levenberg–Marquardt backpropagated neural network (LMB-NN) architecture was used to examine the transport phenomena of 47 nm conveying nanoparticles. The partial differential equations (PDEs) are converted into a system of Ordinary Differential Equations (ODEs). To assess our soft-computing process, we used the RK4 method to acquire reference solutions. The problem is investigated using two situations, each with three sub-cases for the change of the rotation parameter K and the volume fraction

ϕ

. Our simulation results are compared to the reference solutions. It has been proven that our technique is superior to the current state-of-the-art. For further explanation, error histograms, regression graphs, and fitness values are graphically displayed. Full article

(This article belongs to the Special Issue Computational Study of Nanomaterials)

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15 pages, 6622 KiB

Open AccessFeature PaperArticle

An Operational DNA Strand Displacement Encryption Approach

by Enqiang Zhu, Xianhang Luo, Chanjuan Liu and Congzhou Chen

Nanomaterials 2022, 12(5), 877; https://doi.org/10.3390/nano12050877 - 6 Mar 2022

Cited by 16 | Viewed by 2638

Abstract

DeoxyriboNucleic Acid (DNA) encryption is a new encryption method that appeared along with the research of DNA nanotechnology in recent years. Due to the complexity of biology in DNA nanotechnology, DNA encryption brings in an additional difficulty in deciphering and, thus, can enhance [...] Read more.

DeoxyriboNucleic Acid (DNA) encryption is a new encryption method that appeared along with the research of DNA nanotechnology in recent years. Due to the complexity of biology in DNA nanotechnology, DNA encryption brings in an additional difficulty in deciphering and, thus, can enhance information security. As a new approach in DNA nanotechnology, DNA strand displacement has particular advantages such as being enzyme free and self-assembly. However, the existing research on DNA-strand-displacement-based encryption has mostly stayed at a theoretical or simulation stage. To this end, this paper proposes a new DNA-strand-displacement-based encryption framework. This encryption framework involves three main strategies. The first strategy was a tri-phase conversion from plaintext to DNA sequences according to a Huffman-coding-based transformation rule, which enhances the concealment of the information. The second strategy was the development of DNA strand displacement molecular modules, which produce the initial key for information encryption. The third strategy was a cyclic-shift-based operation to extend the initial key long enough, and thus increase the deciphering difficulty. The results of simulation and biological experiments demonstrated the feasibility of our scheme for encryption. The approach was further validated in terms of the key sensitivity, key space, and statistic characteristic. Our encryption framework provides a potential way to realize DNA-strand-displacement-based encryption via biological experiments and promotes the research on DNA-strand-displacement-based encryption. Full article

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17 pages, 1906 KiB

Open AccessArticle

Numerical Simulation of a Time-Dependent Electroviscous and Hybrid Nanofluid with Darcy-Forchheimer Effect between Squeezing Plates

by Muhammad Sohail Khan, Sun Mei, Shabnam, Unai Fernandez-Gamiz, Samad Noeiaghdam and Aamir Khan

Nanomaterials 2022, 12(5), 876; https://doi.org/10.3390/nano12050876 - 6 Mar 2022

Cited by 25 | Viewed by 2055

Abstract

In this article, the behavior of transient electroviscous fluid flow is investigated through squeezing plates containing hybrid nanoparticles. A hybrid nanofluid

{MoS}_{2} + Au

/

C_{2} H_{6} O_{2} - H_{2} O

was formulated by dissolving the components of [...] Read more.

In this article, the behavior of transient electroviscous fluid flow is investigated through squeezing plates containing hybrid nanoparticles. A hybrid nanofluid

{MoS}_{2} + Au

/

C_{2} H_{6} O_{2} - H_{2} O

was formulated by dissolving the components of an inorganic substance such as molybdenum disulfide

({MoS}_{2})

and gold (Au) in a base fluid of ethylene glycol/water. This hybrid non-liquid flow was modeled by various nonlinear mathematical fluid flow models and subsequently solved by numerical as well as analytical methods. For the numerical solution of nonlinear ODEs, a built-in function BVP4C was used in MATLAB, and the same problem was solved in MATHEMATICA by HAM. The result of the present problem related to the results obtained from the existing literature under certain conditions. The outcomes revealed that the concentration profiles were more sensitive to homogeneity diversity parameters. The simulation of the various physical parameters of the model indicated that the heat transfer through a mixture of hybrid nanofluids was greater than a simple nanofluid. In addition, the phenomenon of mixed convection was considered to improve the velocity of simple nanofluids and hybrid nanofluids, when both cases have low permeability. A rise in the volume fraction of the nanomaterials,

Φ

, was associated with an increase in the heat transfer rate. It was observed that the heat transfer rate of the hybrid nanofluids

{MoS}_{2} + {Au / C}_{2} H_{6} O_{2} - H_{2} O

was higher than that of the single nanofluids

{MoS}_{2} / C_{2} H_{6} O_{2} - H_{2} O

. Full article

(This article belongs to the Special Issue Research of Carbon Nanomaterials and Nanocomposites)

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16 pages, 3509 KiB

Open AccessEditor’s ChoiceArticle

Tunable Electronic Properties of Few-Layer Tellurene under In-Plane and Out-of-Plane Uniaxial Strain

by Genwang Wang, Ye Ding, Yanchao Guan, Yang Wang and Lijun Yang

Nanomaterials 2022, 12(5), 875; https://doi.org/10.3390/nano12050875 - 6 Mar 2022

Cited by 5 | Viewed by 2563

Abstract

Strain engineering is a promising and fascinating approach to tailoring the electrical and optical properties of 2D materials, which is of great importance for fabricating excellent nano-devices. Although previous theoretical works have proved that the monolayer tellurene has desirable mechanical properties with the [...] Read more.

Strain engineering is a promising and fascinating approach to tailoring the electrical and optical properties of 2D materials, which is of great importance for fabricating excellent nano-devices. Although previous theoretical works have proved that the monolayer tellurene has desirable mechanical properties with the capability of withstanding large deformation and the tunable band gap and mobility conductance induced by in-plane strain, the effects of in-plane and out-of-plane strains on the properties of few-layer tellurene in different phases should be explored deeply. In this paper, calculations based on first-principles density functional theory were performed to predict the variation in crystal structures and electronic properties of few-layer tellurene, including the α and β phases. The analyses of mechanical properties show that few-layer α-Te can be more easily deformed in the armchair direction than β-Te owing to its lower Young’s modulus and Poisson’s ratio. The α-Te can be converted to β-Te by in-plane compressive strain. The variations in band structures indicate that the uniaxial strain can tune the band structures and even induce the semiconductor-to-metal transition in both few-layer α-Te and β-Te. Moreover, the compressive strain in the zigzag direction is the most feasible scheme due to the lower transition strain. In addition, few-layer β-Te is more easily converted to metal especially for the thicker flakes considering its smaller band gap. Hence, the strain-induced tunable electronic properties and semiconductor-to-metal transition of tellurene provide a theoretical foundation for fabricating metal–semiconductor junctions and corresponding nano-devices. Full article

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13 pages, 9599 KiB

Open AccessArticle

Switching Field Distribution in BN/FePtCAg/MgTiON and FePtCAg/MgTiOBN Films

by Jai-Lin Tsai, Chun-Yu Sun, Jun-Kai Lin, Gaun-Jhen Huang, Kuan-Cheng Liu and He-Ting Tsai

Nanomaterials 2022, 12(5), 874; https://doi.org/10.3390/nano12050874 - 6 Mar 2022

Cited by 1 | Viewed by 1766

Abstract

BN is the currently required segregant for perpendicular FePt media. We found that BN can be diffused from the MgTiOBN intermediate layer during a high temperature process. The FePtCAg film sputtered on MgTiOBN layers illustrates higher perpendicular magnetocrystalline anisotropy (K_u) (1.43 [...] Read more.

BN is the currently required segregant for perpendicular FePt media. We found that BN can be diffused from the MgTiOBN intermediate layer during a high temperature process. The FePtCAg film sputtered on MgTiOBN layers illustrates higher perpendicular magnetocrystalline anisotropy (K_u) (1.43 × 10⁷ erg/cm³) and coercivity (normal to film surface) (17 kOe) at 350 K compared to BN/FePtCAg/MgTiON film. From the microstructure, the FePtCAg film shows the granular structure on the MgTiOBN intermediate layer, but parts of the irregular FePt grains are agglomerated and partially separated in the matrix, with grains size being, on average, 26.7 nm. Cross-sectional imaging showed that the FePt grains have a truncated pyramid shape with a lower wetting angle, which is influenced by the surface energy of MgTiOBN. BN segregation at FePt grains or boundaries is still not clear. Using the electron energy loss spectrum (EELS), we found that part of the BN atoms were clearly observed in the FePt lattice and iron-boride oxide was indexed in the x-ray photoelectron spectroscopy (XPS) spectra. To determine the effects of BN segregant (from capping layer or intermediate layer) on the magnetic switching behavior of FePtCAg film, the intrinsic-(ΔH_int = 6.17 kOe, 6.54 kOe) and extrinsic- (ΔH_ext = 0.80 kOe, 0.39 kOe) switching field distribution (SFD) were measured by plotting saturated major- and unsaturated minor- hysteresis loops to evaluate the crystal orientation and microstructure (grains volume and distribution) for BN/FePtCAg/MgTiON and FePtCAg/MgTiOBN films, respectively. The main contribution of intrinsic SFD is the c-axis misalignment for the BN/FePt/MgTiON sample; however, the dispersed magnetic anisotropy has a higher input to intrinsic SFD for FePtCAg/MgTiOBN/CrRu film. Full article

(This article belongs to the Section Nanocomposite Materials)

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15 pages, 5163 KiB

Open AccessArticle

Ag Decoration and SnO₂ Coupling Modified Anatase/Rutile Mixed Crystal TiO₂ Composite Photocatalyst for Enhancement of Photocatalytic Degradation towards Tetracycline Hydrochloride

by Mao Tang, Yangwen Xia, Daixiong Yang, Shiji Lu, Xiaodong Zhu, Renyong Tang and Wanming Zhang

Nanomaterials 2022, 12(5), 873; https://doi.org/10.3390/nano12050873 - 6 Mar 2022

Cited by 10 | Viewed by 2544

Abstract

The anatase/rutile mixed crystal TiO₂ was prepared and modified with Ag decoration and SnO₂ coupling to construct a Ag@SnO₂/anatase/rutile composite photocatalytic material. The crystal structure, morphology, element valence, optical properties and surface area were characterized, and the effects of [...] Read more.

The anatase/rutile mixed crystal TiO₂ was prepared and modified with Ag decoration and SnO₂ coupling to construct a Ag@SnO₂/anatase/rutile composite photocatalytic material. The crystal structure, morphology, element valence, optical properties and surface area were characterized, and the effects of Ag decoration and SnO₂ coupling on the structure and photocatalytic properties of TiO₂ were studied. Ag decoration and SnO₂ coupling are beneficial to reduce the recombination of photogenerated electrons and holes. When the two modification are combined, a synergistic effect is produced in suppressing the photogenerated charge recombination, making Ag@SnO₂/TiO₂ exhibits the highest quantum utilization. After 30 min of illumination, the degradation degree of tetracycline hydrochloride (TC) by pure TiO₂ increased from 63.3% to 83.1% with Ag@SnO₂/TiO₂. Full article

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13 pages, 2326 KiB

Open AccessEditor’s ChoiceArticle

Merging Porphyrins with Gold Nanorods: Self Assembly Construct to High Fluorescent Polyelectrolyte Microcapsules

by Vanda Vaz Serra, Sofia G. Serra, Mariana C. S. Vallejo, Pedro M. R. Paulo, Nuno M. M. Moura, David Botequim, Maria Graça P. M. S. Neves and Sílvia M. B. Costa

Nanomaterials 2022, 12(5), 872; https://doi.org/10.3390/nano12050872 - 5 Mar 2022

Cited by 4 | Viewed by 2875

Abstract

Dual probe porphyrin-gold nanorod polyelectrolyte microcapsules were developed to explore the enhancing effects of a plasmonic interface of self-assembled gold nanoparticles in the fluorescence emission from porphyrins loaded into the capsules’ core. An analysis of fluorescence lifetime imaging microscopy (FLIM) data reports a [...] Read more.

Dual probe porphyrin-gold nanorod polyelectrolyte microcapsules were developed to explore the enhancing effects of a plasmonic interface of self-assembled gold nanoparticles in the fluorescence emission from porphyrins loaded into the capsules’ core. An analysis of fluorescence lifetime imaging microscopy (FLIM) data reports a notable 10⁵–10⁶-fold increase in the maximum detected photon rates from diffraction-limited spots and an overall six-fold increase in fluorescence as averaged over the whole microcapsule area. Large emission enhancements were correlated with decreases in fluorescence lifetimes. The microcapsule’s design proved effective in achieving high fluorescent hybrids and may shed light on new possibilities for advanced materials imaging applications. Full article

(This article belongs to the Topic Synthesis, Properties and Applications of Fluorescent Nanomaterials)

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10 pages, 3688 KiB

Open AccessArticle

PDMS-Encapsulated MXene@Polyester Fabric Strain Sensor for Multifunctional Sensing Applications

by Wengang Lu, Beenish Mustafa, Zhiyuan Wang, Fuzhuo Lian and Geliang Yu

Nanomaterials 2022, 12(5), 871; https://doi.org/10.3390/nano12050871 - 5 Mar 2022

Cited by 16 | Viewed by 3523

Abstract

Flexible strain sensors based on 2D materials have been proven effective for wearable health monitoring devices, human motion detection, and fitness applications. These sensors are flexible, light, and user-friendly, but their sensitivity and detection range need to be enhanced. Among many 2D materials, [...] Read more.

Flexible strain sensors based on 2D materials have been proven effective for wearable health monitoring devices, human motion detection, and fitness applications. These sensors are flexible, light, and user-friendly, but their sensitivity and detection range need to be enhanced. Among many 2D materials, MXene attracts much interest due to its remarkable properties, such as high electrical conductivity, excellent mechanical properties, flexibility, and good hydrophilicity. However, it is a challenge to fabricate strain sensors with extreme sensitivity and a wide sensing range. In this work, a multifunctional, cost-effective, and highly sensitive PDMS-encapsulated MXene@polyester fabric strain sensor was fabricated. Firstly, complete adsorption of MXene within the fabric formed conductive networks, and then PDMS was used to endow superhydrophobicity and corrosion resistance. The strain sensor demonstrated multifunctional applications and outstanding performance, such as long-term stability (over 500 cycles) and a wide sensing range (8%). The proposed sensor has promising potential for wearable electronic devices such as health monitoring systems and physiological sensing applications. Full article

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

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13 pages, 3988 KiB

Open AccessArticle

Optimizing Performance of Coaxis Planar-Gated ZnO Nanowire Field-Emitter Arrays by Tuning Pixel Density

by Songyou Zhang, Xiuqing Cao, Guofu Zhang, Shaozhi Deng and Jun Chen

Nanomaterials 2022, 12(5), 870; https://doi.org/10.3390/nano12050870 - 5 Mar 2022

Cited by 2 | Viewed by 1789

Abstract

Gated ZnO nanowire field emitter arrays (FEAs) have important applications in large-area vacuum microelectronic devices such as flat panel X-ray sources and photodetectors. As the application requires high-pixel-density FEAs, how the pixel density affects the emission performance of the gated ZnO nanowire FEAs [...] Read more.

Gated ZnO nanowire field emitter arrays (FEAs) have important applications in large-area vacuum microelectronic devices such as flat panel X-ray sources and photodetectors. As the application requires high-pixel-density FEAs, how the pixel density affects the emission performance of the gated ZnO nanowire FEAs needs investigating. In this paper, the performance of coaxis planar -gated ZnO nanowire FEAs was simulated under different pixel sizes while keeping the lateral geometric parameter in proportion. The variations in emission current and gate modulation with pixel size were obtained. Using the obtained device parameters, the coaxis planar-gated ZnO nanowire FEAs were prepared. Field emission measurement results showed that a current density of 3.2 mA/cm² was achieved from the fabricated ZnO nanowire FEAs when the gate voltage was 140 V. A transconductance of 253 nS was obtained, indicating effective gate control. The improved performance is attributed to optimized gate modulation. Full article

(This article belongs to the Section Nanoelectronics, Nanosensors and Devices)

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14 pages, 4486 KiB

Open AccessArticle

Computational Screening of Metal-Organic Frameworks for Ethylene Purification from Ethane/Ethylene/Acetylene Mixture

by Yageng Zhou, Xiang Zhang, Teng Zhou and Kai Sundmacher

Nanomaterials 2022, 12(5), 869; https://doi.org/10.3390/nano12050869 - 4 Mar 2022

Cited by 5 | Viewed by 2836

Abstract

Identification of high-performing sorbent materials is the key step in developing energy-efficient adsorptive separation processes for ethylene production. In this work, a computational screening of metal-organic frameworks (MOFs) for the purification of ethylene from the ternary ethane/ethylene/acetylene mixture under thermodynamic equilibrium conditions is [...] Read more.

Identification of high-performing sorbent materials is the key step in developing energy-efficient adsorptive separation processes for ethylene production. In this work, a computational screening of metal-organic frameworks (MOFs) for the purification of ethylene from the ternary ethane/ethylene/acetylene mixture under thermodynamic equilibrium conditions is conducted. Modified evaluation metrics are proposed for an efficient description of the performance of MOFs for the ternary mixture separation. Two different separation schemes are proposed and potential MOF adsorbents are identified accordingly. Finally, the relationships between the MOF structural characteristics and its adsorption properties are discussed, which can provide valuable information for optimal MOF design. Full article

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

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12 pages, 4543 KiB

Open AccessFeature PaperArticle

Impact of the Nanocarbon on Magnetic and Electrodynamic Properties of the Ferrite/Polymer Composites

by Alex V. Trukhanov, Daria I. Tishkevich, Svetlana V. Podgornaya, Egor Kaniukov, Moustafa A. Darwish, Tatiana I. Zubar, Andrey V. Timofeev, Ekaterina L. Trukhanova, Vladimir G. Kostishin and Sergei V. Trukhanov

Nanomaterials 2022, 12(5), 868; https://doi.org/10.3390/nano12050868 - 4 Mar 2022

Cited by 101 | Viewed by 2831

Abstract

Binary and ternary composites (CM) based on M-type hexaferrite (HF), polymer matrix (PVDF) and carbon nanomaterials (quasi-one-dimensional carbon nanotubes—CNT and quasi-two-dimensional carbon nanoflakes—CNF) were prepared and investigated for establishing the impact of the different nanosized carbon on magnetic and electrodynamic properties. The ratio [...] Read more.

Binary and ternary composites (CM) based on M-type hexaferrite (HF), polymer matrix (PVDF) and carbon nanomaterials (quasi-one-dimensional carbon nanotubes—CNT and quasi-two-dimensional carbon nanoflakes—CNF) were prepared and investigated for establishing the impact of the different nanosized carbon on magnetic and electrodynamic properties. The ratio between HF and PVDF in HF + PVDF composite was fixed (85 wt% HF and 15 wt% PVDF). The concentration of CNT and CNF in CM was fixed (5 wt% from total HF + PVDF weight). The phase composition and microstructural features were investigated using XRD and SEM, respectively. It was observed that CM contains single-phase HF, γ- and β-PVDF and carbon nanomaterials. Thus, we produced composites that consist of mixed different phases (organic insulator matrix—PDVF; functional magnetic fillers—HF and highly electroconductive additives—CNT/CNF) in the required ratio. VSM data demonstrate that the main contribution in main magnetic characteristics belongs to magnetic fillers (HF). The principal difference in magnetic and electrodynamic properties was shown for CNT- and CNF-based composites. That confirms that the shape of nanosized carbon nanomaterials impact on physical properties of the ternary composited-based magnetic fillers in polymer dielectric matrix. Full article

(This article belongs to the Special Issue Actual Problems of Solid State Physics: Nanomaterials and Nanotechnologies)

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14 pages, 2482 KiB

Open AccessArticle

Electrochemical and X-ray Photoelectron Spectroscopy Surface Characterization of Interchain-Driven Self-Assembled Monolayer (SAM) Reorganization

by Angelo Tricase, Anna Imbriano, Nicoletta Ditaranto, Eleonora Macchia, Rosaria Anna Picca, Davide Blasi, Luisa Torsi and Paolo Bollella

Nanomaterials 2022, 12(5), 867; https://doi.org/10.3390/nano12050867 - 4 Mar 2022

Cited by 4 | Viewed by 2400

Abstract

Herein, we report a combined strategy encompassing electrochemical and X-ray photoelectron spectroscopy (XPS) experiments to investigate self-assembled monolayer (SAM) conformational reorganization onto an electrode surface due to the application of an electrical field. In particular, 3-mercaptopriopionic acid SAM (3MPA SAM) modified gold electrodes [...] Read more.

Herein, we report a combined strategy encompassing electrochemical and X-ray photoelectron spectroscopy (XPS) experiments to investigate self-assembled monolayer (SAM) conformational reorganization onto an electrode surface due to the application of an electrical field. In particular, 3-mercaptopriopionic acid SAM (3MPA SAM) modified gold electrodes are activated with a 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysulfosuccinimide (NHSS) (EDC-NHSS) mixture by shortening the activation time, from 2 h to 15/20 min, labelled as Protocol-A, -B and -C, respectively. This step, later followed by a deactivation process with ethanolamine (EA), plays a key role in the reaction yields (formation of N-(2-hydroxyethyl)-3-mercaptopropanamide, NMPA) but also in the conformational rearrangement observed during the application of the electrical field. This study aims at explaining the high performance (i.e., single-molecule detection at a large electrode interface) of bioelectronic devices, where the 3MPA-based SAM structure is pivotal in achieving extremely high sensing performance levels due to its interchain interaction. Cyclic voltammetry (CV) experiments performed in K₄Fe(CN)₆:K₃Fe(CN)₆ for 3MPA SAMs that are activated/deactivated show similar trends of anodic peak current (I_A) over time, mainly related to the presence of interchain hydrogen bonds, driving the conformational rearrangements (tightening of SAMs structure) while applying an electrical field. In addition, XPS analysis allows correlation of the deactivation yield with electrochemical data (conformational rearrangements), identifying the best protocol in terms of high reaction yield, mainly related to the shorter reaction time, and not triggering any side reactions. Finally, Protocol-C’s SAM surface coverage, determined by CV in H₂SO₄ and differential pulse voltammetry (DPV) in NaOH, was 1.29 * 10¹³ molecules cm⁻², being similar to the bioreceptor surface coverage in single-molecule detection at a large electrode interface. Full article

(This article belongs to the Special Issue Nanomaterials for Electrochemical Applications)

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17 pages, 4618 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Facile Synthesis of Sustainable Biomass-Derived Porous Biochars as Promising Electrode Materials for High-Performance Supercapacitor Applications

by Ravi Moreno Araujo Pinheiro Lima, Glaydson Simões dos Reis, Mikael Thyrel, Jose Jarib Alcaraz-Espinoza, Sylvia H. Larsson and Helinando Pequeno de Oliveira

Nanomaterials 2022, 12(5), 866; https://doi.org/10.3390/nano12050866 - 4 Mar 2022

Cited by 20 | Viewed by 3542

Abstract

Preparing sustainable and highly efficient biochars as electrodes remains a challenge for building green energy storage devices. In this study, efficient carbon electrodes for supercapacitors were prepared via a facile and sustainable single-step pyrolysis method using spruce bark as a biomass precursor. Herein, [...] Read more.

Preparing sustainable and highly efficient biochars as electrodes remains a challenge for building green energy storage devices. In this study, efficient carbon electrodes for supercapacitors were prepared via a facile and sustainable single-step pyrolysis method using spruce bark as a biomass precursor. Herein, biochars activated by KOH and ZnCl₂ are explored as templates to be applied to prepare electrodes for supercapacitors. The physical and chemical properties of biochars for application as supercapacitors electrodes were strongly affected by factors such as the nature of the activators and the meso/microporosity, which is a critical condition that affects the internal resistance and diffusive conditions for the charge accumulation process in a real supercapacitor. Results confirmed a lower internal resistance and higher phase angle for devices prepared with ZnCl₂ in association with a higher mesoporosity degree and distribution of Zn residues into the matrix. The ZnCl₂-activated biochar electrodes’ areal capacitance reached values of 342 mF cm⁻² due to the interaction of electrical double-layer capacitance/pseudocapacitance mechanisms in a matrix that favors hydrophilic interactions and the permeation of electrolytes into the pores. The results obtained in this work strongly suggest that the spruce bark can be considered a high-efficiency precursor for biobased electrode preparation to be employed in SCs. Full article

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18 pages, 3228 KiB

Open AccessArticle

Swelling-Resistant, Crosslinked Polyvinyl Alcohol Membranes with High ZIF-8 Nanofiller Loadings as Effective Solid Electrolytes for Alkaline Fuel Cells

by Po-Ya Hsu, Ting-Yu Hu, Selvaraj Rajesh Kumar, Kevin C.-W. Wu and Shingjiang Jessie Lue

Nanomaterials 2022, 12(5), 865; https://doi.org/10.3390/nano12050865 - 4 Mar 2022

Cited by 8 | Viewed by 2445

Abstract

The present work investigates the direct mixing of aqueous zeolitic imidazolate framework-8 (ZIF-8) suspension into a polyvinyl alcohol (PVA) and crosslinked with glutaraldehyde (GA) to form swelling-resistant, mechanically robust and conductivity retentive composite membranes. This drying-free nanofiller incorporation method enhances the homogeneous ZIF-8 [...] Read more.

The present work investigates the direct mixing of aqueous zeolitic imidazolate framework-8 (ZIF-8) suspension into a polyvinyl alcohol (PVA) and crosslinked with glutaraldehyde (GA) to form swelling-resistant, mechanically robust and conductivity retentive composite membranes. This drying-free nanofiller incorporation method enhances the homogeneous ZIF-8 distributions in the PVA/ZIF-8/GA composites to overcome the nanofiller aggregation problem in the mixed matrix membranes. Various ZIF-8 concentrations (25.4, 40.5 and 45.4 wt.%) are used to study the suitability of the resulting GA-crosslinked composites for direct alkaline methanol fuel cell (DAMFC). Surface morphological analysis confirmed homogeneous ZIF-8 particle distribution in the GA-crosslinked composites with a defect- and crack-free structure. The increased ionic conductivity (21% higher than the ZIF-free base material) and suppressed alcohol permeability (94% lower from the base material) of PVA/40.5%ZIF-8/GA resulted in the highest selectivity among the prepared composites. In addition, the GA-crosslinked composites’ selectivity increased to 1.5–2 times that of those without crosslink. Moreover, the ZIF-8 nanofillers improved the mechanical strength and alkaline stability of the composites. This was due to the negligible volume swelling ratio (<1.4%) of high (>40%) ZIF-8-loaded composites. After 168 h of alkaline treatment, the PVA/40.5%ZIF-8/GA composite had almost negligible ionic conductivity loss (0.19%) compared with the initial material. The maximum power density (P_max) of PVA/40.5%ZIF-8/GA composite was 190.5 mW cm⁻² at 60 °C, an increase of 181% from the PVA/GA membrane. Moreover, the P_max of PVA/40.5%ZIF-8/GA was 10% higher than that without GA crosslinking. These swelling-resistant and stable solid electrolytes are promising in alkaline fuel cell applications. Full article

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13 pages, 2552 KiB

Open AccessArticle

Influence of Copper Oxide Nanoparticles on Gene Expression of Birch Clones In Vitro under Stress Caused by Phytopathogens

by Tatiana A. Grodetskaya, Peter M. Evlakov, Olga A. Fedorova, Vyacheslav I. Mikhin, Olga V. Zakharova, Evgeny A. Kolesnikov, Nadezhda A. Evtushenko and Alexander A. Gusev

Nanomaterials 2022, 12(5), 864; https://doi.org/10.3390/nano12050864 - 4 Mar 2022

Cited by 8 | Viewed by 3092

Abstract

Recently, metal oxide nanoparticles (NPs) have attracted attention as promising components for the protection and stimulation of plant microclones in tissue culture in vitro. However, the effect of NPs on the genetic mechanisms underlying plant adaptive responses remains poorly understood. We studied the [...] Read more.

Recently, metal oxide nanoparticles (NPs) have attracted attention as promising components for the protection and stimulation of plant microclones in tissue culture in vitro. However, the effect of NPs on the genetic mechanisms underlying plant adaptive responses remains poorly understood. We studied the effect of column-shaped CuO NPs 50 nm in diameter and 70–100 nm in length at a concentration of 0.1–10 mg/L on the development of phytopathogenic fungi Alternaria alternata, Fusarium oxysporum, and Fusarium avenaceum in culture, as well as on the infection of downy birch micro-clones with phytopathogens and the level of genes expression associated with the formation of plant responses to stress induced by microorganisms. CuO NPs effectively suppressed the development of colonies of phytopathogenic fungi A. alternata and F. avenaceum (up to 68.42% inhibition at 10 mg/L CuO NPs) but not the development of a colony of F. oxysporum. Exposure to the NPs caused multidirectional responses at the level of plant genes transcription: 5 mg/L CuO NPs significantly increased the expression level of the LEA8 and MYB46 genes and decreased the expression of DREB2 and PAL. Infection with A. alternata significantly increased the level of MYB46, LEA8, PAL, PR-1, and PR-10 transcripts in birch micro-clones; however, upon exposure to a medium with NPs and simultaneous exposure to a phytopathogen, the expression of the MYB46, PR-1, and PR-10 genes decreased by 5.4 times, which is associated with a decrease in the pathogenic load caused by the effect of NPs and the simultaneous stimulation of clones in vitro. The results obtained can be used in the development of preparations based on copper oxide NPs for disinfection and stimulation of plant phytoimmunity during clonal micropropagation of tree crops. Full article

(This article belongs to the Special Issue Metal-Based Nanomaterials for Biomedical, Agricultural, and Environmental Applications: Prospects and Uncertainties)

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14 pages, 6434 KiB

Open AccessArticle

High Purity Single Wall Carbon Nanotube by Oxygen-Containing Functional Group of Ferrocene-Derived Catalyst Precursor by Floating Catalyst Chemical Vapor Deposition

by Sook Young Moon, Seung-Yeol Jeon, Sung-Hyun Lee, Anna Lee and Seung Min Kim

Nanomaterials 2022, 12(5), 863; https://doi.org/10.3390/nano12050863 - 4 Mar 2022

Cited by 3 | Viewed by 2750

Abstract

Single wall carbon nanotubes (SWCNTs) were synthesized using oxygen-containing ferrocene derived catalysts. The mechanism of synthesizing carbon nanotubes was clarified by the catalyst’s exothermic or endothermic decomposition processes. By monitoring the decomposition process of ferrocene-derived catalyst precursors with and without sulfur, we found [...] Read more.

Single wall carbon nanotubes (SWCNTs) were synthesized using oxygen-containing ferrocene derived catalysts. The mechanism of synthesizing carbon nanotubes was clarified by the catalyst’s exothermic or endothermic decomposition processes. By monitoring the decomposition process of ferrocene-derived catalyst precursors with and without sulfur, we found that the types of oxygen function groups closely influence catalyst formation and nanotube growth. The ferrocene-derived catalyst precursors have a different oxygen containing groups, which are hydroxyl (–OH, ferrocenenemethanol) and carbonyl (C=O, acetylferrocene, and 1,1′-diacetylferrocene). The sulfur chemical state (S 2p) on synthesized catalyst particles using acetylferrocene and 1,1′-diacetylferrocene has more sulfate (

{SO}_{4}^{2 -}

) than others, and there also is a carbon state (C-S-C). The catalyst particle using ferrocenemethanol predominant formed metal–sulfur bonds (such as S²⁻ and

S_{n}^{2 -}

). The hydroxyl group (–OH) of ferrocenemethanol enhanced the etching effect to remove amorphous carbon and prevented oxidation on the catalyst particle surfaces; however, the carbonyl group (C=O) of acetylferrocene reacted with the catalyst particles to cause partial oxidation and carbon dissociation on the surface of the catalyst particles. The partial oxidation and carbon contamination on catalyst particles controlled the activity of the catalyst. The DFT study revealed that the ferrocene-derived catalyst precursor was dissociated according to following process: the functional groups (such as CH₃CO and COH) => first Cp ligands => second Cp ligands. The pyrolysis and release of Fe ions were delayed by the functional groups of ferrocene-derived precursors compared to ferrocene. The thermal-decomposition temperature of the catalyst precursor was high, the decomposition time was be delayed, affecting the formation of catalyst particles and thus making smaller catalyst particles. The size and composition of catalyst particles not only affect the nucleation of CNTs, but also affect physical properties. Therefore, the I_G/I_D ratio of the CNTs changed from 74 to 18 for acetylferrocene and ferrocene, respectively. The purity also increased from 79 to 90% using ferrocene-derived precursors. Full article

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10 pages, 2512 KiB

Open AccessArticle

Magnetic Field Sensing Based on Whispering Gallery Mode with Nanostructured Magnetic Fluid-Infiltrated Photonic Crystal Fiber

by Chencheng Zhang, Shengli Pu, Zijian Hao, Boyu Wang, Min Yuan and Yuxiu Zhang

Nanomaterials 2022, 12(5), 862; https://doi.org/10.3390/nano12050862 - 3 Mar 2022

Cited by 41 | Viewed by 3500

Abstract

A kind of novel and compact magnetic field sensor has been proposed and investigated experimentally. The proposed sensor consists of a tapered single mode fiber coupled with a nanostructured magnetic fluid-infiltrated photonic crystal fiber, which is easy to be fabricated. The response of [...] Read more.

A kind of novel and compact magnetic field sensor has been proposed and investigated experimentally. The proposed sensor consists of a tapered single mode fiber coupled with a nanostructured magnetic fluid-infiltrated photonic crystal fiber, which is easy to be fabricated. The response of magnetic fluid to magnetic field is used to measure the intensity of magnetic field via whispering gallery mode. The magnetic field-dependent shift in resonance wavelength is observed. The maximum magnetic field intensity sensitivity is 53 pm/mT. The sensor sensitivity is inversely proportional to the thickness of the photonic crystal fiber cladding. Full article

(This article belongs to the Special Issue Advanced Nanocomposites for Photonics and Optoelectronics and Mechanics)

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16 pages, 7730 KiB

Open AccessArticle

Molecular Dynamics Simulation Study of the Self-Assembly of Phenylalanine Peptide Nanotubes

by Vladimir Bystrov, Ilya Likhachev, Alla Sidorova, Sergey Filippov, Aleksey Lutsenko, Denis Shpigun and Ekaterina Belova

Nanomaterials 2022, 12(5), 861; https://doi.org/10.3390/nano12050861 - 3 Mar 2022

Cited by 5 | Viewed by 2713

Abstract

In this paper, we propose and use a new approach for a relatively simple technique for conducting MD simulation (MDS) of various molecular nanostructures, determining the trajectory of the MD run and forming the final structure using external force actions. A molecular dynamics [...] Read more.

In this paper, we propose and use a new approach for a relatively simple technique for conducting MD simulation (MDS) of various molecular nanostructures, determining the trajectory of the MD run and forming the final structure using external force actions. A molecular dynamics manipulator (MD manipulator) is a controlled MDS type. As an example, the applicability of the developed algorithm for assembling peptide nanotubes (PNT) from linear phenylalanine (F or Phe) chains of different chirality is presented. The most adequate regimes for the formation of nanotubes of right chirality D from the initial L-F and nanotubes of left chirality L of their initial dipeptides D-F modes were determined. We use the method of a mixed (vector–scalar) product of the vectors of the sequence of dipole moments of phenylalanine molecules located along the nanotube helix to calculate the magnitude and sign of chirality of self-assembled helical phenylalanine nanotubes, which shows the validity of the proposed approach. As result, all data obtained correspond to the regularity of the chirality sign change of the molecular structures with a hierarchical complication of their organization. Full article

(This article belongs to the Special Issue Nanomaterials Investigation by Molecular Dynamics Simulation)

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