Nano Trends最新文献

Layered hexagonal zinc indium sulfide coupled with multiwalled carbon nanotubes (MWCNT/H-ZnIn₂S₄) nanocomposites were prepared via using the hydrothermal method and investigated its photoelectrochemical (PEC) water-splitting properties. A series of MWCNT/H-ZnIn₂S₄ nanocomposites with different concentrations of MWCNT have been synthesized. The effects of the addition of different concentrations of MWCNT on the PEC performance of H-ZnIn₂S₄ material are studied. The outcomes showed that the maximum value of photocurrent density is obtained for 20 wt% MWCNT/H-ZnIn₂S₄, which is ∼3.8 times higher as compared to the H-ZnIn₂S₄ photoanode under visible light illumination. The enhancement in the current density is because of the electron-accepting behavior of MWCNT that helps in the effective separation and transfer of charges at the interface. The ability of MWCNT to accept and transport electrons offers a better path to regulate the movement of photogenerated charge carriers, extending the lifetime of the photogenerated charges produced in the semiconductors. A plausible mechanism for observed enhanced PEC activity of MWCNT/H-ZnIn₂S₄ nanocomposites is provided, which is supported by impedance spectroscopy and Mott-Schottky results.

Textile-based supercapacitors (TSCs) are being used to meet the ever-increasing demand for mobile, safe, and convenient energy sources to power personal electronic devices. To that end, the smart textiles used in wearable technology need to be made from highly conductive yarns that are easily manufacturable. To date, synthetic- and cellulosic-based yarns have been exclusively used for the fabrication of TSCs, while other yarns have not been explored. Here, we used conductive protein-based yarns for TSCs and report on the use of wool coated with Ti₃C₂T_x MXene as a potential electrode material. To knit TSCs, wool and cotton yarns were coated with MXene flakes and their surfaces were characterized using Scanning Electron Microscopy (SEM) and X-Ray Photoelectron Spectroscopy (XPS). The electrochemical characterization was conducted to examine the performance of wool- and cotton-based MXene electrodes as substrates and determine charge storage and resistive behavior. These tests showed that wool TSCs exhibited more pseudocapacitive behavior, while cotton TSCs exhibited a wider current range. At a scan rate of 5 mV/s, cotton TSCs presented an areal capacitance of 823.9 mF/cm² while this value for the wool TSCs was 284 mF/cm². The performance of yarns was also tested under various mechanical deformation conditions and after washing in order to assess the stability of TSCs. This study indicates the potential of protein-based yarns as electrode substrates for integration of MXene to fabricate smart textile-based devices.

Nanogenerators have garnered significant attention in the field of robotics due to their high performance, ease of design and fabrication, and lightweight nature. By utilizing such sensing systems, machines can be endowed with specific sentience capabilities. Moreover, sensors that based on nanogenerators can operate continuously without requiring an external power source. The following paper presents a comprehensive review of recent developments and applications of nanogenerator-based sensors in robotics in recent years. These sensors are categorized according to their sensory functions (including tactile, hearing, smell, vision and displacement, etc.), with a focus on their working mechanisms, materials and structures. Furthermore, this review investigates the usage of these devices in flexible manipulators and human-machine interfaces. Finally, the challenges and opportunities pertaining to nanogenerator-based sensors are discussed.

A key parameter in the analysis of compounds and the study of their physical, chemical, and mechanical properties is the knowledge of the crystal size. There are two common techniques for determining this size: transmission electron microscopy (TEM) and Brunauer-Emmett-Teller theory (BET). These methods are time-consuming and expensive; thus, the calculation of this size by X-ray diffraction (XRD) is proposed. There are several methods for calculating the crystal size by X-ray diffraction, but not all peaks were considered and the errors were very large. In this study, the Modified Scherrer method is practically explained, and three important rules for obtaining crystal size values with high accuracy are introduced and applied. For better understanding, this study explains the Modified Scherrer method for iron oxide (Fe₂O₃), titanium oxide (TiO₂) and vanadium oxide (V₂O₅) powders as examples. Crystal size values were calculated using the modified Scherrer method for Fe₂O₃, TiO₂, and V₂O₅ as 30.94, 16.57, and 24.30 nm, respectively. Furthermore, the extracted crystal size values of ∼ 31, 18 and 30 nm for Fe₂O₃, TiO₂, and V₂O₅ were tandemly recorded by TEM. Moreover, the crystal size values for Fe₂O₃, TiO₂, and V₂O₅ were calculated to 32.96, 15.87 and 16.66 nm by BET tandemly. The results show that the Modified Scherrer method has high accuracy and agreement with the analyses of TEM and BET. Thus, this method is proposed for calculating each crystalline compound as it has high accuracy and XRD analysis is available and cheaper.

This study utilized molecular dynamics simulations to assess the influence of structural alterations, such as waviness and vacancy defects, on the mechanical properties of carbon nanotubes. This work utilizes the LAMMPS simulation environment to compare models of carbon nanotubes, thus enabling the observation of fracture properties at an atomistic level. A comparative analysis was conducted on pristine straight carbon nanotubes and their wavy and defective counterparts. The study was divided into two stages: the initial stage revealed that straight carbon nanotubes exhibited superior mechanical strength when subjected to tensile loading. However, introducing waviness along the axis of the carbon nanotubes resulted in a significant reduction in strength. Subsequently, in the second stage, vacancy defects were introduced to the carbon nanotube structure, which were quantified by defect densities and plotted against the tensile strength of the carbon nanotubes. This analysis allowed for a deeper understanding of the correlation between the defect density and tensile strength of carbon nanotube structure. Finally, a relationship between the strain energy and temperature variation in carbon nanotubes was established, emphasizing the importance of temperature control in the applications and manufacturing processes of carbon nanotubes. Overall, this study provides valuable insights into the factors that can affect the mechanical properties of carbon nanotubes.

This study elucidates on growth and integration of aligned carbon nanotube-based field emission cathode for electron gun-device fabrication. Particularly, it emphasises on field emission (FE) and thermal transport (TT) properties of carbon nanotube (CNT) arrays with controlled atomistic defects (AD) to design a cold cathode (CC) for electron gun. To assess the influence of AD on FE and TT, aligned undoped (pure CNT) and N-doped herringbone (doped CNT) were fabricated using droplet-assisted solvent-thermolysis to use them as CC. Results demonstrated that doped CNT with higher degree of AD exhibited a lower turn-on field in FE in comparison to pure CNT could be ascribed to N addition in carbon lattice. Ambiguously, doping-mediated AD in doped CNT helps to achieve the best FE but lowers TT with significant decrease in thermal conductivity (111 to 5.1 W/m.k at room temperature) in comparison to pure CNT. Based on the FE behavior, a doped CNT arrays-based cathode was integrated into an electron gun, which exhibited maximum emission current of 81.3 mA/cm² at a grid voltage of 2 kV.

The presence of the mecA gene and penicillin-binding protein 2a (PBP2a) plays an important role in the antibiotic resistance of methicillin-resistant S. aureus (MRSA). We have developed a method for duplex detection of transmembrane PBP2a expression and the mecA gene using the plasmonic decay properties of Surface-enhanced Raman scattering (SERS) and the unique properties of beacon molecules. The duplex SERS-based test was more specific, sensitive, and rapid than polymerase chain reaction for genetic materials or ELISA for PBP2a expression, and it has a limit of detection that can detect as little as 27 PBP2a-expressed S. aureus and 8.5 pM of mecA. The efficacy of the duplexing test was demonstrated by the observed receiver operating characteristics (ROC) with its area under the curve (AUC) of 0.92 for MRSA-spiked samples. Additionally, the sensor can be developed and integrated with a portable Raman system for on-site detections.

Quantum dots (QDs) of boron nitride, also known as white graphene, are remarkable zero-dimensional substances in the nascent stages of research. Boron nitride quantum dots (BNQDs) are biocompatible in nature and possess unique chemical, optical, electrochemical, and catalytic properties. Due to their excellent properties, these materials are finding enormous applications in fields like sensing, photocatalysis, chemotherapy, bioimaging, and the detection of metal ions. This review gives a detailed account of the recent advancements in the field of BNQDs, with a comprehensive list of references. Herein, we introduce the structural, physical, and chemical properties of BNQDs, followed by an elaborate discussion on the advancements in BNQDs synthesis methods. The review comprises a detailed discussion of the application of BNQDs in the field of sensing, including fluorescent sensors, electrochemiluminescent sensors, thermal sensors, gas sensors, bioimaging, and biosensors. Based on the attention BNQDs are gaining amongst researchers, this review gives the outlook for the synthesis and utilization of BNQDs in sensing applications in the near future.

Fabrication of iron oxide (Fe₂O₃) nanoparticles (NPs) with different spectral lights was carried out to unveil the effect of change in the wavelength of Photons. NPs were synthesized by co-precipitation technique exposed to different light regimes (dark environment, daylight, and colored lights (blue, green, yellow, and red) from light emitting diodes (LEDs) at room temperature. X-ray diffractogram (XRD) analysis revealed that the synthesized NPs were hematite (α-Fe₂ O₃) with rhombohedral structure while scanning electron microscopic (SEM) study demonstrate the spherical and nano-disk like surface morphology. An increase in the size of NPs from 20.61 nm to 28.87 nm was observed with the increase in the wavelength of light. The elemental composition and surface chemistry of NPs were studied from energy-dispersive x-ray diffractive (EDX) and Fourier transform infrared spectroscopy (FT-IR) spectra. Maximum free radical quenching activity and total antioxidant potential were found by red light synthesized NPs (13.72%, and 36.72 ± 1.06 µg AAE/mg, respectively). The dark environment synthesized NPs had the maximum reduction potential (20.20 ± 0.4 µg AAE/mg). The highest metal chelating and cation radical scavenging was observed by blue light (41.48%) and daylight (9.71%) synthesized NPs respectively. α-Fe₂O₃ NPs showed significant enzyme inhibitory effects on urease, lipase, and alpha-amylase. The NPs also exhibited intrinsic peroxidase-like activity. Green and red light synthesized α-Fe₂O₃ NPs displayed the strongest antibacterial activity (12 mm) against Methicillin-resistant Staphylococcus aureus, and Pseudomonas aeruginosa respectively. This study is considered a novel step toward the synthesis of hematite (α-Fe₂O₃) NPs under LEDs with specific physio-chemical and biological properties to be employed in biological, environmental, and agricultural fields.

Despite recent progress in 3D printing of graphene, formulation of aqueous 3D printable graphene inks with desired rheological properties for direct ink writing (DIW) of multifunctional graphene macrostructures remains a major challenge. In this work, we develop a novel 3D printable pristine graphene ink in aqueous phase using conductive nanofibrillar network formulation by controlling the interfacial interactions between graphene and PEDOT:PSS nanofibrils. The formulated inks, tailored for energy applications, provide excellent 3D printability for fabricating multilayer 3D structures (up to 30 layers) with spanning features and high aspect ratio. The 3D printed aerogels, comprising interconnected networks of graphene flakes and PEDOT:PSS nanofibrils, exhibit excellent electrical conductivity as high as ∼630 S m ^− 1 and can be converted into conductive hydrogels via swelling in water/electrolyte. The formulated graphene inks were used for fabricating 3D printed supercapacitor electrodes (power density of 11.3 kW kg⁻¹ and energy density of 7.3 Wh kg⁻¹) with excellent performance and durability.