Nanomaterials

Fuel cells have already demonstrated their potential for green energy generation. However, the low reaction performance becomes an obstacle in terms of large-scale commercial manufacturing. Accordingly, this work focuses on a new unique fabrication of three-dimensional pore hierarchy TiO₂-graphene aerogel (TiO₂-GA) supporting PtRu catalyst for anodic catalyst direct methanol fuel cell, which is facile, ecologically benign, and economical. In this work, a hydrothermal technique was used, followed by a freeze-drying technique and a microwave-assisted ethylene reduction technique. The structural properties of the studied materials were confirmed by UV/visible spectroscopy, XRD, Raman spectrum, FESEM TEM, and XPS. Based on existing structural advantages, the performance of PtRu/TiO₂-GA has been investigated on DMFC anode catalysts. Furthermore, electrocatalytic stability performance with the same loading (~20%) was compared to commercial PtRu/C. Experimental outcomes show that the TiO₂-GA support offered a significantly high surface area value of 68.44 m²g⁻¹, mass activity/specific activity (608.17 mAmg⁻¹/0.45 mA/cm²_PtRu) that is higher than commercial PtRu/C (79.11 mAmg⁻¹/0.19 mA/cm²_PtRu). In passive DMFC mode, PtRu/TiO₂-GA showed a maximum power density of 3.1 mW cm⁻², which is 2.6 times higher than that of the PtRu/C commercial electrocatalyst. This suggests that PtRu/TiO₂-GA has a promising possibility for methanol oxidation and may be used as an anodic element in DMFC. Full article

A microstructure determines macro functionality. A controlled periodic structure gives the surface specific functions such as controlled structural color, wettability, anti-icing/frosting, friction reduction, and hardness enhancement. Currently, there are a variety of controllable periodic structures that can be produced. Laser interference lithography (LIL) is a technique that allows for the simple, flexible, and rapid fabrication of high-resolution periodic structures over large areas without the use of masks. Different interference conditions can produce a wide range of light fields. When an LIL system is used to expose the substrate, a variety of periodic textured structures, such as periodic nanoparticles, dot arrays, hole arrays, and stripes, can be produced. The LIL technique can be used not only on flat substrates, but also on curved or partially curved substrates, taking advantage of the large depth of focus. This paper reviews the principles of LIL and discusses how the parameters, such as spatial angle, angle of incidence, wavelength, and polarization state, affect the interference light field. Applications of LIL for functional surface fabrication, such as anti-reflection, controlled structural color, surface-enhanced Raman scattering (SERS), friction reduction, superhydrophobicity, and biocellular modulation, are also presented. Finally, we present some of the challenges and problems in LIL and its applications. Full article

WTe₂, a low−symmetry transition metal dichalcogenide, has broad prospects in functional device applications due to its excellent physical properties. When WTe₂ flake is integrated into practical device structures, its anisotropic thermal transport could be affected greatly by the substrate, which matters a lot to the energy efficiency and functional performance of the device. To investigate the effect of SiO₂/Si substrate, we carried out a comparative Raman thermometry study on a 50 nm−thick supported WTe₂ flake (with κ_zigzag = 62.17 W·m⁻¹·K⁻¹ and κ_armchair = 32.93 W·m⁻¹·K⁻¹), and a suspended WTe₂ flake of similar thickness (with κ_zigzag = 4.45 W·m⁻¹·K⁻¹, κ_armchair = 4.10 W·m⁻¹·K⁻¹). The results show that the thermal anisotropy ratio of supported WTe₂ flake (κ_zigzag/κ_armchair ≈ 1.89) is about 1.7 times that of suspended WTe₂ flake (κ_zigzag/κ_armchair ≈ 1.09). Based on the low symmetry nature of the WTe₂ structure, it is speculated that the factors contributing to thermal conductivity (mechanical properties and anisotropic low−frequency phonons) may have affected the thermal conductivity of WTe₂ flake in an uneven manner when supported on a substrate. Our findings could contribute to the 2D anisotropy physics and thermal transport study of functional devices based on WTe₂ and other low-symmetry materials, which helps solve the heat dissipation problem and optimize thermal/thermoelectric performance for practical electronic devices. Full article

This work analyzes the magnetic configurations of cylindrical nanowires with a bulk Dzyaloshinskii–Moriya interaction and easy-plane anisotropy. We show that this system allows the nucleation of a metastable toron chain even when no out-of-plane anisotropy exists in the nanowire’s top and bottom surfaces, as usually required. The number of nucleated torons depends on the nanowire length and the strength of an external magnetic field applied to the system. The size of each toron depends on the fundamental magnetic interactions and can be controlled by external stimuli, allowing the use of these magnetic textures as information carriers or nano-oscillator elements. Our results evidence that the topology and structure of the torons yield a wide variety of behaviors, revealing the complex nature of these topological textures, which should present an exciting interaction dynamic, depending on the initial conditions. Full article

We have demonstrated a two-step wet chemical approach for synthesizing ternary Ag/Ag₂S/CdS heterostructures for efficient photocatalytic hydrogen evolution. The CdS precursor concentrations and reaction temperatures are crucial in determining the efficiency of photocatalytic water splitting under visible light excitation. In addition, the effect of operational parameters (such as the pH value, sacrificial reagents, reusability, water bases, and light sources) on the photocatalytic hydrogen production of Ag/Ag₂S/CdS heterostructures was investigated. As a result, Ag/Ag₂S/CdS heterostructures exhibited a 3.1-fold enhancement in photocatalytic activities compared to bare CdS nanoparticles. Furthermore, the combination of Ag, Ag₂S, and CdS can significantly enhance light absorption and facilitate the separation and transport of photogenerated carriers through the surface plasma resonance (SPR) effect. Furthermore, the Ag/Ag₂S/CdS heterostructures in seawater exhibited a pH value approximately 2.09 times higher than in de-ionized water without an adjusted pH value under visible light excitation. The ternary Ag/Ag₂S/CdS heterostructures provide new potential for designing efficient and stable photocatalysts for photocatalytic hydrogen evolution. Full article

Non-isothermal crystallization kinetics of montmorillonite (MMT)/polyamide 610 (PA610) composites were readily prepared by in situ melt polymerization followed by a full investigation in terms of their microstructure, performance, and crystallization kinetics. The kinetic models of Jeziorny, Ozawa, and Mo were used in turn to fit the experimental data, in all of which Mo’s analytical method was found to be the best model for the kinetic data. Differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) studies were used to investigate the isothermal crystallization behavior and MMT dispersion levels in the MMT/PA610 composites. The experiment results revealed that low MMT content can promote the PA610 crystallization, whilst high MMT content result in MMT agglomeration, and reduce the PA610 crystallization rate. Full article

Elastic strain sensor nanocomposites are emerging materials of high scientific and commercial interest. This study analyzes the major factors influencing the electrical behavior of elastic strain sensor nanocomposites. The sensor mechanisms were described for nanocomposites with conductive nanofillers, either dispersed inside the polymer matrix or coated onto the polymer surface. The purely geometrical contributions to the change in resistance were also assessed. The theoretical predictions indicated that maximum Gauge values are achieved for mixture composites with filler fractions slightly above the electrical percolation threshold, especially for nanocomposites with a very rapid conductivity increase around the threshold. PDMS/CB and PDMS/CNT mixture nanocomposites with 0–5.5 vol.% fillers were therefore manufactured and analyzed with resistivity measurements. In agreement with the predictions, the PDMS/CB with 2.0 vol.% CB gave very high Gauge values of around 20,000. The findings in this study will thus facilitate the development of highly optimized conductive polymer composites for strain sensor applications. Full article

Transfersomes are deformable vesicles that can transport drugs across difficult-to-permeate barriers in human tissues. In this work, nano-transfersomes were produced for the first time by a supercritical CO₂ assisted process. Operating at 100 bar and 40 °C, different amounts of phosphatidylcholine (2000 and 3000 mg), kinds of edge activators (Span^® 80 and Tween^® 80), and phosphatidylcholine to edge activator weight ratio (95:5, 90:10, 80:20) were tested. Formulations prepared using Span^® 80 and phosphatidylcholine at an 80:20 weight ratio produced stable transfersomes (−30.4 ± 2.4 mV ζ-potential) that were characterized by a mean diameter of 138 ± 55 nm. A prolonged ascorbic acid release of up to 5 h was recorded when the largest amount of phosphatidylcholine (3000 mg) was used. Moreover, a 96% ascorbic acid encapsulation efficiency and a quasi-100% DPPH radical scavenging activity of transfersomes were measured after supercritical processing. Full article

This study aims to design and test different formulations composed of dextran-coated iron oxide nanoparticles (IONPs) loaded with 5-Fluorouracil (5-FU) with varying nanoparticle:drug ratios on colorectal cancer cells. The stable suspension of IONPs s was synthesized by the adapted co-precipitation method. The stable suspension of IONPs was mixed with a solution of dextran and 5-FU solubilized in a saline solution. The final suspensions with optimized ratios of IONP:5-FU in the final suspension were 0.5:1, 1:1, and 1.5:1. The information on the morphology and size distribution of the IONPs suspension and IONP loads with 5-FU was obtained using scanning electron microscopy (SEM). The presence of 5-FU and dextran on the surface of the IONPs was highlighted by energy-dispersive X-ray spectroscopy (EDS) studies. The determination of the surface charge of the nanoparticles in the final suspensions of IONP:5-FU was achieved by measuring the zeta potential (ζ). The hydrodynamic diameter of the resulting suspensions of IONP:5-FU was determined by dynamic light scattering (DLS). A cytocompatibility analysis was performed using Caco-2 (human epithelial colorectal adenocarcinoma) cells. In this research, our goal was to find a relationship between the formulation ratio of nanoparticles and drug, and the cellular response after exposure, as a strategy to increase the efficacy of this drug-delivery system. The nanoparticle uptake and antitumor activity, including modulation of oxidative stress, apoptosis, and proliferation biomarkers, were analyzed. The present study showed that the nanoformulation with the ratio IONP:5-FU 1.5:1 had the highest anti-tumor efficiency. Moreover, decreased MCM-2 expression in Caco-2 cells exposed to dextran-coated iron oxide nanoparticles loaded with 5-FU was demonstrated for the first time. Full article

The capability of tailoring the resonance wavelength of metasurfaces is important as it can alleviate the manufacturing precision required to produce the exact structure according to the design of the nanoresonators. Tuning of Fano resonances by applying heat has been theoretically predicted in the case of silicon metasurfaces. Here, we experimentally demonstrate the permanent tailoring of quasi-bound states in the continuum (quasi-BIC) resonance wavelength in an a-Si:H metasurface and quantitatively analyze the modification in the Q-factor with gradual heating. A gradual increment in temperature leads to a spectral shift in the resonance wavelength. With the support of ellipsometry measurements, the spectral shift resulting from the short-duration (ten minutes) heating is identified to be due to refractive index variations in the material rather than a geometric effect or amorphous/polycrystalline phase transition. In the case of quasi-BIC modes in the near-infrared, resonance wavelength could be adjusted from T = 350 °C to T = 550 °C without affecting the Q-factor considerably. Apart from the temperature-induced resonance trimming, large Q-factors can be attained at the highest analyzed temperature (T = 700 °C) in the near-infrared quasi-BIC modes. Resonance tailoring is just one of the possible applications of our results. We expect that our study is also insightful in the design of a-Si:H metasurfaces where large Q-factors are required at high temperatures. Full article

The transport characteristics of a gate-all-around Si multiple-quantum-dot (QD) transistor were studied by means of experimental parametrization using theoretical models. The device was fabricated by using the e-beam lithographically patterned Si nanowire channel, in which the ultrasmall QDs were self-created along the Si nanowire due to its volumetric undulation. Owing to the large quantum-level spacings of the self-formed ultrasmall QDs, the device clearly exhibited both Coulomb blockade oscillation (CBO) and negative differential conductance (NDC) characteristics at room temperature. Furthermore, it was also observed that both CBO and NDC could evolve along the extended blockade region within wide gate and drain bias voltage ranges. By analyzing the experimental device parameters using the simple theoretical single-hole-tunneling models, the fabricated QD transistor was confirmed as comprising the double-dot system. Consequently, based on the analytical energy-band diagram, we found that the formation of ultrasmall QDs with imbalanced energetic natures (i.e., imbalanced quantum energy states and their imbalanced capacitive-coupling strengths between the two dots) could lead to effective CBO/NDC evolution in wide bias voltage ranges. Full article

A nonlinear MEMS multimass sensor is numerically investigated, designed as a single input-single output (SISO) system consisting of an array of nonlinear microcantilevers clamped to a shuttle mass which, in turn, is constrained by a linear spring and a dashpot. The microcantilevers are made of a nanostructured material, a polymeric hosting matrix reinforced by aligned carbon nanotubes (CNT). The linear as well as the nonlinear detection capabilities of the device are explored by computing the shifts of the frequency response peaks caused by the mass deposition onto one or more microcantilever tips. The frequency response curves of the device are obtained by a pathfollowing algorithm applied to the reduced-order model of the system. The microcantilevers are described by a nonlinear Euler-Bernoulli inextensible beam theory, which is enriched by a meso-scale constitutive law of the nanocomposite. In particular, the microcantilever constitutive law depends on the CNT volume fraction suitably used for each cantilever to tune the frequency bandwidth of the whole device. Through an extensive numerical campaign, the mass sensor sensitivity estimated in the linear and nonlinear dynamic range shows that, for relatively large displacements, the accuracy of the added mass detectability can be improved due to the larger nonlinear frequency shifts at resonance (up to 12%). Full article

Rapid urban industrialization and agricultural production have led to the discharge of excessive phosphate into aquatic systems, resulting in a rise in water pollution. Therefore, there is an urgent need to explore efficient phosphate removal technologies. Herein, a novel phosphate capture nanocomposite (PEI−[email protected]) with mild preparation conditions, environmental friendliness, recyclability, and high efficiency has been developed by modifying aminated nanowood with a zirconium (Zr) component. The Zr component imparts the ability to capture phosphate to the PEI−[email protected], while the porous structure provides a mass transfer channel, resulting in excellent adsorption efficiency. Additionally, the nanocomposite maintains more than 80% phosphate adsorption efficiency even after ten adsorption–desorption cycles, indicating its recyclability and potential for repeated use. This compressible nanocomposite provides novel insights into the design of efficient phosphate removal cleaners and offers potential approaches for the functionalization of biomass−based composites. Full article

1T-TaS₂ has attracted much attention recently due to its abundant charge density wave phases. In this work, high-quality two-dimensional 1T-TaS₂ crystals were successfully synthesized by a chemical vapor deposition method with controllable layer numbers, confirmed by the structural characterization. Based on the as-grown samples, their thickness-dependency nearly commensurate charge density wave/commensurate charge density wave phase transitions was revealed by the combination of the temperature-dependent resistance measurements and Raman spectra. The phase transition temperature increased with increasing thickness, but no apparent phase transition was found on the 2~3 nm thick crystals from temperature-dependent Raman spectra. The transition hysteresis loops due to temperature-dependent resistance changes of 1T-TaS₂ can be used for memory devices and oscillators, making 1T-TaS₂ a promising material for various electronic applications. Full article

In this study, we investigated the use of porous silicon (PSi) fabricated using metal-assisted chemical etching (MACE) as a substrate for the deposition of Au nanoparticles (NPs) for the reduction of nitroaromatic compounds. PSi provides a high surface area for the deposition of Au NPs, and MACE allows for the fabrication of a well-defined porous structure in a single step. We used the reduction of p-nitroaniline as a model reaction to evaluate the catalytic activity of Au NPs on PSi. The results indicate that the Au NPs on the PSi exhibited excellent catalytic activity, which was affected by the etching time. Overall, our results highlighted the potential of PSi fabricated using MACE as a substrate for the deposition of metal NPs for catalytic applications. Full article

3D printing technology has been used to directly produce various actual products, ranging from engines and medicines to toys, especially due to its advantage in producing items of complicated, porous structures, which are inherently difficult to clean. Here, we apply micro-/nano-bubble technology to the removal of oil contaminants from 3D-printed polymeric products. Micro-/nano-bubbles show promise in the enhancement of cleaning performance with or without ultrasound, which is attributed to their large specific surface area enhancing the adhesion sites of contaminants, and their high Zeta potential which attracts contaminant particles. Additionally, bubbles produce tiny jets and shock waves at their rupture, driven by coupled ultrasound, which can remove sticky contaminants from 3D-printed products. As an effective, efficient, and environmentally friendly cleaning method, micro-/nano-bubbles can be used in a range of applications. Full article

Nanomaterials are currently used for different applications in several fields. Bringing the measurements of a material down to nanoscale size makes vital contributions to the improvement of the characteristics of materials. The polymer composites acquire various properties when added to nanoparticles, increasing characteristics such as bonding strength, physical property, fire retardance, energy storage capacity, etc. The objective of this review was to validate the major functionality of the carbon and cellulose-based nanoparticle-filled polymer nanocomposites (PNC), which include fabricating procedures, fundamental structural properties, characterization, morphological properties, and their applications. Subsequently, this review includes arrangement of nanoparticles, their influence, and the factors necessary to attain the required size, shape, and properties of the PNCs. Full article

α-Al₂O₃ nanoparticles can enter a micro-arc oxidation coating and participate in the coating-formation process through chemical reaction or physical–mechanical combination in the electrolyte. The prepared coating has high strength, good toughness and excellent wear and corrosion resistance. In this paper, 0, 1, 3 and 5 g/L of α-Al₂O₃ nanoparticles were added to a Na₂SiO₃-Na(PO₄)₆ electrolyte to study the effect on the microstructure and properties of a Ti6Al4V alloy micro-arc oxidation coating. The thickness, microscopic morphology, phase composition, roughness, microhardness, friction and wear properties and corrosion resistance were characterized using a thickness meter, scanning electron microscope, X-ray diffractometer, laser confocal microscope, microhardness tester and electrochemical workstation. The results show that surface quality, thickness, microhardness, friction and wear properties and corrosion resistance of the Ti6Al4V alloy micro-arc oxidation coating were improved by adding α-Al₂O₃ nanoparticles to the electrolyte. The nanoparticles enter the coatings by physical embedding and chemical reaction. The coatings’ phase composition mainly includes Rutile-TiO₂, Anatase-TiO₂, α-Al₂O₃, Al₂TiO₅ and amorphous phase SiO₂. Due to the filling effect of α-Al₂O₃, the thickness and hardness of the micro-arc oxidation coating increase, and the surface micropore aperture size decreases. The roughness decreases with the increase of α-Al₂O₃ additive concentration, while the friction wear performance and corrosion resistance are improved. Full article

The catalytic conversion of CO₂ into valuable commodities has the potential to balance ongoing energy and environmental issues. To this end, the reverse water–gas shift (RWGS) reaction is a key process that converts CO₂ into CO for various industrial processes. However, the competitive CO₂ methanation reaction severely limits the CO production yield; therefore, a highly CO-selective catalyst is needed. To address this issue, we have developed a bimetallic nanocatalyst comprising Pd nanoparticles on the cobalt oxide support (denoted as CoPd) via a wet chemical reduction method. Furthermore, the as-prepared CoPd nanocatalyst was exposed to sub-millisecond laser irradiation with per-pulse energies of 1 mJ (denoted as CoPd-1) and 10 mJ (denoted as CoPd-10) for a fixed duration of 10 s to optimize the catalytic activity and selectivity. For the optimum case, the CoPd-10 nanocatalyst exhibited the highest CO production yield of ∼1667 μmol g⁻¹_catalyst, with a CO selectivity of ∼88% at a temperature of 573 K, which is a 41% improvement over pristine CoPd (~976 μmol g⁻¹_catalyst). The in-depth analysis of structural characterizations along with gas chromatography (GC) and electrochemical analysis suggested that such a high catalytic activity and selectivity of the CoPd-10 nanocatalyst originated from the sub-millisecond laser-irradiation-assisted facile surface restructure of cobalt oxide supported Pd nanoparticles, where atomic CoOx species were observed in the defect sites of the Pd nanoparticles. Such an atomic manipulation led to the formation of heteroatomic reaction sites, where atomic CoOx species and adjacent Pd domains, respectively, promoted the CO₂ activation and H₂ splitting steps. In addition, the cobalt oxide support helped to donate electrons to Pd, thereby enhancing its ability of H₂ splitting. These results provide a strong foundation to use sub-millisecond laser irradiation for catalytic applications. Full article