Tin Oxide Nanowires Research Articles

Optimization of Contact Pad Design for Silver Nanowire-Based Transparent Heater to Improve Heating Characteristics.

Transparent heaters are gaining significant attention for applications such as antifog glass, smart windows, and smart farm greenhouses. A transparent heater basically consists of transparent conducting materials that serve as a heating area and contact pad electrode to apply power. To fabricate a transparent heater, materials with excellent light transmittance and low sheet resistance are required. Among various transparent conducting materials, such as Indium Tin Oxide (ITO), carbon nanotube (CNT), graphene, and silver nanowires (AgNWs), AgNWs are particularly favored due to their good electrical, optical, and mechanical properties. However, in order to improve the heating characteristics of transparent heaters, research is essential not only on improving the properties of transparent conducting materials but also on the design of contact pad electrodes that can uniformly improve current distribution. Here, we explore various shapes of contact pad electrodes for AgNW-based transparent heaters to improve current distribution. Shapes such as line, spot, twisted, and parallel-type contact pad electrodes are designed and investigated to optimize overall heating characteristics. We analyze the heating properties of these transparent heaters with various contact pad electrodes, demonstrating how their specific shape and size affect heating characteristics and uniformity. We also investigate the optimal shape of the contact pad electrode to minimize transmission loss through UV-VIS spectroscopy. As a result, we confirm that the shape of the contact pad electrode was important for simultaneously achieving high heating characteristics of 120 °C, good heating uniformity, and over 80% transparency in an AgNW-based transparent heater.

Surface modification of tin oxide nanowires through hydroxyl group anchoring

Surface modification of tin oxide nanowires through hydroxyl group anchoring

N-doped MoS2@indium tin oxide (ITO) core–shell nanowires for high-performance ammonium ion micro-supercapacitor

Ammonium (NH4+) ion aqueous supercapacitors have gained significant attention due to their notable cost-effectiveness, safety profile, and environmental benefits. Despite this, the optimization of the capacitive performance of electrode materials for NH4+ ion storage remains inadequate. To tackle these challenges, we present a composite electrode depend upon molybdenum disulfide (MoS2) and indium tin oxide nanowires (MoS2@ITO NWs) as the primary host for (NH4+) ions. Additionally, we introduce a straightforward radio frequency nitrogen (N) plasma technique to incorporate nitrogen doping into the MoS2 film, thereby enhancing its performance. The introduction of N plasma doping into two-dimensional MoS2 results in an expansion of the interlayer distance and an improvement in electronic conductivity. This, in turn, facilitates the facile and highly reversible insertion and extraction of NH4+ ions during cycling. Consequently, the N plasma doping significantly enhances the device areal capacitance of MoS2@ITO NWs, increasing it from 78.6 to 161.8 mF cm−2 at 1 mA cm−2, with an exceptional capacity retention (>89.2% after 10 000 cycles) and superior rate capability up to 10 mA cm−2. The integration N of atoms within the straightforward hierarchical core–shell design strategy exhibits promising prospects for bolstering the performance of metal sulfide electrodes and other high-capacity electrode materials aimed at energy storage applications.

Micrometric thermal electronic nose able to detect and quantify individual gases in a mixture

Recent urbanization and environmental problems urge for networks of sensors that can monitor air quality. Small, inexpensive, and smart sensors are one of the key components enabling the realization of such networks. Chemoresistive sensors are the ideal candidate, but they greatly lack selectivity, and for this reason, they are usually combined in arrays to create electronic noses, whose dimensions, however, make them not miniaturizable and cannot be integrated into portable devices. To overcome this inconvenience, we present a thermal electronic nose consisting of identical resistive sensors working at different temperatures so that the whole device is simple to make and tiny. The device contains two sensor arrays based on tin oxide nanowires decorated with Ag and Pt nanoparticles, respectively. The five sensors in each array are identical, but their response is differentiated by different temperatures locally generated by an on-chip integrated heater. This innovative approach allows the tiny array of five sensors together with the integrated heater to occupy only approximately 50 × 200 μm2 and consume only 120 μW. The tiny and portable device can estimate the concentration of H2 and NH3 in a mixture with a root mean square error of 6.1 ppm and 13.3 ppm, respectively, and it still works well after two months. The performance analysis of the double partial least squares regression used for concentration estimation also allows for feedback on which sensors are the most sensitive to which gas so that the electronic nose can be engineered for specific applications using the most suitable sensors. The size of the thermal electronic nose allows it to be integrated into portable and wearable devices, and its performance makes it suitable for any gas detection application. For example, a smartphone with an integrated sensor could carry out breath analysis and act as medical pre-screening or be used to evaluate the freshness of agri-food products in a rapid and non-invasive way.

Defect Location in Laterally Aligned Tin Oxide Nanowires: The Role of Growth Direction, Interface Dimensionality, and Catalyst

Laterally aligned SnO2 nanowires, which exhibit planar growth along crystallographically defined directions of a sapphire substrate surface, are superior for bio- and gas-sensing applications. Little is known about their cross-sectional geometry and the defect distribution within the nanowire cross section, although this substantially determines the electronic properties of the nanowires. In this study, SnO2 nanowires were grown on r-plane sapphire substrates. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) reveal the highly oriented growth of the SnO2 nanowires toward the substrate edges. High-resolution transmission electron microscopy (HRTEM) of the NW cross section and strain mapping allowed for analyzing the crystallographic alignment of the SnO2 NW to the sapphire substrate and the defect distribution within the SnO2 nanowire cross section. These techniques revealed a defect-free SnO2–Al2O3 interface and a high alignment of the SnO2 NW lattice toward the sapphire substrate along the NW width. The determined high defect density close to the nanowire surface will be discussed in comparison to freestanding SnO2 nanowires and SnO2 thin films on sapphire substrates considering the differences in the growth direction and the interface dimensionality.

Sequential coating of Sb-doped SnO2 nanowire for photoelectrochemical cells of panchromatic light absorption and low thermalization loss

A photoelectrochemical (PEC) cell is a device of enormous potential in producing hydrogen via water splitting using solar energy. However, the low charge collection efficiency and thermalization loss of a photoelectrode limit the performance of the PEC cell. In this study, these problems are addressed by sequentially coating CdS and CdSe along the longitudinal direction of antimony-doped tin oxide and tin oxide nanowire (NW) arrays. Because of the vertical alignment of CdS and CdSe, larger band gap material (CdS) and smaller band gap material (CdSe) absorb blue and red light, respectively. Such selective absorption reduces the thermalization loss and increases the photocurrent density. In addition, antimony-doped tin oxide NWs increase the collection efficiency of photogenerated carriers and decrease the onset voltage by increasing the electric conductivity and decreasing the mismatch in the Fermi energy level. The photocurrent of the vertically aligned CdS and CdSe on antimony-doped tin oxide NWs is 17.6 mA cm−2, which is 50% higher than that of the traditional cascade-type CdSe/CdS photoelectrode.

Formation of sub-100-nm suspended nanowires with various materials using thermally adjusted electrospun nanofibers as templates

The air suspension and location specification properties of nanowires are crucial factors for optimizing nanowires in electronic devices and suppressing undesirable interactions with substrates. Although various strategies have been proposed to fabricate suspended nanowires, placing a nanowire in desired microstructures without material constraints or high-temperature processes remains a challenge. In this study, suspended nanowires were formed using a thermally aggregated electrospun polymer as a template. An elaborately designed microstructure enables an electrospun fiber template to be formed at the desired location during thermal treatment. Moreover, the desired thickness of the nanowires is easily controlled with the electrospun fiber templates, resulting in the parallel formation of suspended nanowires that are less than 100 nm thick. Furthermore, this approach facilitates the formation of suspended nanowires with various materials. This is accomplished by evaporating various materials onto the electrospun fiber template and by removing the template. Palladium, copper, tungsten oxide (WO3), and tin oxide nanowires are formed as examples to demonstrate the advantage of this approach in terms of nanowire material selection. Hydrogen (H2) and nitrogen dioxide (NO2) gas sensors comprising palladium and tungsten oxide, respectively, are demonstrated as exemplary devices of the proposed method.

Metal oxide semiconductor nanowires enabled air-stable ultraviolet-driven synaptic transistors for artificial vision

The multi-terminal transistor can provide reliable platform to construct artificial synapses with various benefits. In particular, synaptic transistors based on wide-bandgap metal oxide semiconductors (MOSs) offer opportunities to realize ultraviolet (UV) artificial vision. In this work, via a low-cost electrospinning technique, we have fabricated bio-inspired synaptic transistors based on zinc tin oxide (ZnSnO) nanowires, which can be effectively tuned by UV laser to achieve air-stable synaptic characteristics, such as excitatory post-synaptic current, paired-pulse facilitation, and learning-forgetting process based on long-term potentiation. The adsorption/desorption of oxygen molecules governs the generation of free charge carriers in the ZnSnO nanowires. Via the combination of transmission electron microscopy and X-ray diffraction measurements, we found that the revealed SnO2/ZnO heterostructures can effectively mitigate the recombination of UV-induced free carriers in the ZnSnO nanowires. Furthermore, based on the synaptic characteristics obtained from ZnSnO nanowires, we present several applications relevant to the UV artificial vision. We believe this study can provide insights into importance of heterostructures in synaptic transistors based on low-dimension MOSs with superior environmental stability and various applications.

Long-memory retention and self-powered ultraviolet artificial synapses realized by multi-cation metal oxide semiconductors

We fabricated synaptic transistors based on IZTO-6 nanowires, which can achieve long-memory retention of long-term potentiation. Meanwhile, Al/IZTO-6/Ni devices indicate that MOS based synapses have self-powered capability.

Promoting CO2 reduction to formate selectivity on indium-doped tin oxide nanowires

Electrochemical reduction of CO2 to various chemicals is a promising approach to dealing with excessive CO2 accumulation in the atmosphere. Even though numerous electrocatalysts have been extensively utilized for the reaction, several challenges remain such as high overpotential, poor stability, and low selectivity followed by the domination of hydrogen formation. To overcome these problems, multi-component materials have been proposed due to their advanced catalytic activity compared to single-component materials. Herein, we present preparation of the indium-doped tin oxide nanowires (In-SnO2 NWs) as an efficient electrocatalyst to promote CO2 reduction into formate. The unique 1D structure of SnO2 NWs with simultaneously doped-In (5.4at% In) can enhance the selectivity toward formate by up to ∼82 % compared to bare SnO2 NWs (∼58.9 %) at −1.04 V (vs RHE). The modified SnO2 surface driven by In-doping induces electron delocalization in between, and the surface defects provide more active sites. Thus, the intermediate could be stably adsorbed to produce more formate ions.

Chemical vapor deposition growth of tin oxide nanowires for electrochemical sensor development

AbstractThis paper reports a growth of tin oxide nanowires on gold patterns by chemical vapor deposition. A 90 nm gold layer was deposited on a silicon wafer using a sputtering system and pre‐pattern by lift‐off techniques. Tin oxide nanowires were selectively grown on the gold pattern by chemical vapor deposition technique with 750°C and 5 × 10‐2 torr. High resolution transmission electron microscopy measurements showed that nanowire possessed a single crystal nature with tetragonal crystal system and the calculated lattice constants (a = 0.474 nm; c = 0.318 nm) were closed to those of standard pattern of SnO2. The ready SnO2 nanowire grown on the gold patterns were investigated for electrochemical sensor development.

High-performance Zn microbattteries based on a NiCo-LDH@ITO nanowire/carbon cloth composite

Following the fast growth of micro-energy storage devices, there is an urgent need to develop miniaturized electronic devices with excellent performance that are both green and safe. Planar interdigitated rechargeable Zn microbatteries (MBs) have gained widespread attention in recent years due to their ease of series-parallel integration, mechanical flexibility and no need of traditional separators. We prepared a patterned cathode of NiCo layered double hydroxide (LDH)@indium tin oxide (ITO) nanowires (NWs) @carbon cloth (CC) by the chemical vapor deposition of ITO NWs on the carbon fibers of CC, laser patterning, and finally the electrodeposition of NiCo-LDH to coat the ITO NW@CC. The cathode was combined with a patterned Zn foil anode to form a planar MB. Because of the highly conductive ITO NWs@CC current collector, the interdigitated MB had a satisfactory performance with a high specific capacity of 453.5 mAh g−1 (corresponding to 0.56 mAh cm−2) in an alkaline water-based electrolyte at 1 mA cm−2. After 4 000 cycles the capacity increased to 216% of the initial value due to gradual penetration of electrolyte into the three-dimensional NiCo-LDH@ITO NW@CC network. It also had excellent energy (798.4 μWh cm−2, corresponding to 649.9 Wh kg−1) and power density (4.1 mW cm−2, corresponding to 3 282.7 mW kg−1). Furthermore, MBs connected in series-parallel in lighting tests illustrate the excellent performance of the device. Therefore, this fast and simple fabrication of Zn MBs with an in-plane interdigital structure provides a reference for next-generation high-performance, environmentally-friendly, and scalable planar micro-energy storage systems.

Nanosensor Based on Thermal Gradient and Machine Learning for the Detection of Methanol Adulteration in Alcoholic Beverages and Methanol Poisoning.

Methanol, naturally present in small quantities in the distillation of alcoholic beverages, can lead to serious health problems. When it exceeds a certain concentration, it causes blindness, organ failure, and even death if not recognized in time. Analytical techniques such as chromatography are used to detect dangerous concentrations of methanol, which are very accurate but also expensive, cumbersome, and time-consuming. Therefore, a gas sensor that is inexpensive and portable and capable of distinguishing methanol from ethanol would be very useful. Here, we present a resistive gas sensor, based on tin oxide nanowires, that works in a thermal gradient. By combining responses at various temperatures and using machine learning algorithms (PCA, SVM, LDA), the device can distinguish methanol from ethanol in a wide range of concentrations (1–100 ppm) in both dry air and under different humidity conditions (25–75% RH). The proposed sensor, which is small and inexpensive, demonstrates the ability to distinguish methanol from ethanol at different concentrations and could be developed both to detect the adulteration of alcoholic beverages and to quickly recognize methanol poisoning.

INVESTIGATION OF I-V CHARACTERISTICS OF CARBON NANOTUBES AND TIN OXIDE NANOWIRES HETEROJUNCTION FOR GAS SENSING APPLICATIONS

In this study, heterojunctions of carbon nanotubes (CNTs) and tin oxide nanowires (SnO2) were investigated to determine their electrical performance for gas sensing applications. The I–V characteristics of the heterojunction were measured in air and H2S gas. The electrical parameters such as barrier height ϕB, ideality factor n, series resistance Rs, and reverse saturation current Io were extracted from the I-V plots. In H2S gas, the barrier height ϕB and series resistance Rs are lower compared to air, whereas the ideality factor n and saturation current Io are higher. These findings are essential for promoting technologies aimed at forming high-quality heterojunctions for gas sensing applications.

Fabrication and Photocatalytic Properties of Zinc Tin Oxide Nanowires Decorated with Silver Nanoparticles.

With the continuous advancement of high-tech industries, how to properly handle pollutants has become urgent. Photocatalysis is a solution that may effectively degrade pollutants into harmless molecules. In this study, we synthesized single crystalline Zn2SnO4 (ZTO) nanowires through chemical vapor deposition and selective etching. The chemical bath redox method was used to modify the ZTO nanowires with Ag nanoparticles to explore the photocatalytic properties of the nanoheterostructures. The combination of the materials here is rare. Optical measurements by photoluminescence (PL) and UV–Vis show that the PL spectrum of ZTO nanowires was mainly in the visible light region and attributed to oxygen vacancies. The luminescence intensity of the nanowires was significantly reduced after modification, demonstrating that the heterojunction could effectively reduce the electron-hole pair recombination. The reduction increased with the increase in Ag decoration. The conversion from the UV–Vis absorption spectrum to the Tauc Plot shows that the band gap of the nanowire was 4.05 eV. With 10 ppm methylene blue (MB) as the degradation solution, ZTO nanowires exhibit excellent photodegradation efficiency. Reusability and stability in photodegradation of the nanowires were demonstrated. Photocatalytic efficiency increases with the number of Ag nanoparticles. The main reaction mechanism was confirmed by photocatalytic inhibitors. This study enriches our understanding of ZTO-based nanostructures and facilitates their applications in water splitting, sewage treatment and air purification.

Preparation of Indium Tin Oxide Nanowires by Using physical-vapor-transport method

This paper presents a physical-vapor-transport method for the growth of Indium Tin Oxide (ITO) nanowires. ITO nanowires were successfully fabricated by physical vapor transport method using gold nanoparticles as catalyst prepared by two methods. The effects of holding temperature and catalyst on the growth of ITO nanowires were investigated. The experimental results show that the longer ITO nanowires can be grown by increasing the holding temperature at 850 °C, increasing the proportion of carbon powder, and using gold nanoparticles catalyst with smaller particle size. The longest ITO nanowire we fabricated is as long as 45 μm. Our experiments show that the density and diameter of ITO nanowires can be controlled by controlling the density and diameter of gold nanoparticle catalysts. The smaller the nanoparticle diameter is, the easier it is to grow long ITO nanowires.

Properties of High Efficiency Nanostructured Copper Indium Gallium Selenide Thin Film Solar Cells

Nowadays it is widely acknowledged that solar photovoltaic energy is one of the preferred options for sustainable management of the future energy needs of the world. For this, new technological processes, known as second and third generations, based on the use of thin films and nanomaterials, have recently been developed in order to reduce the cost of solar cells. Over the past few years, the yield of second-generation Cu(In, Ga)Se2 thin-film cells has exceeded 22 %. It was found that as nanostructured materials such as nanowire arrays often have a higher light absorption rate than thin films, they can therefore be used. This article aims to design and model nanostructured CIGS thin film solar cells based on indium tin oxide (ITO) nanowires. Modelling provides information on the operation of CIGS solar cells, as well as on the mechanisms of absorption and electric charge transport. The purpose of this work is to evaluate the electrical and optical characteristics (ISC, VOC, FF, η) of a ZnO/CdS/CIGS heterojunction thin film structure. Thus, an optimum efficiency of 17.57 % and a form factor of 76.56 % were achieved. Afterwards, the Mo film rear contact was replaced with ITO nanowires which were introduced into the CIGS-based solar cell. The results indicated that the solar cells under study exhibited very good photovoltaic performance, with an efficiency of 21.26 %. It is worth noting that this performance is higher than that of the corresponding CIGS thin film cells. In addition, the large active surface area of the ITO nanowire electrode and the short distance that the charge must travel helped to improve charge collection in the nanostructure. This would certainly increase the short circuit current ISC, and consequently the electrical efficiency. The simulation was based on the low-field mobility model, and on Shockley-Read-Hall (SRH) and Auger carrier transport and recombination models which may be activated in ATLAS-SILVACO (2D).

Synthesis and Characterization of Indium Tin Oxide Nanowires with Surface Modification of Silver Nanoparticles by Electrochemical Method.

In this study, indium tin oxide nanowires (ITO NWs) with high density and crystallinity were synthesized by chemical vapor deposition (CVD) via a vapor–liquid–solid (VLS) route; the NWs were decorated with 1 at% and 3 at% silver nanoparticles on the surface by a unique electrochemical method. The ITO NWs possessed great morphologies with lengths of 5~10 μm and an average diameter of 58.1 nm. Characterization was conducted through transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscope (XPS) to identify the structure and composition of the ITO NWs. The room temperature photoluminescence (PL) studies show that the ITO NWs were of visible light-emitting properties, and there were a large number of oxygen vacancies on the surface. The successful modification of Ag was confirmed by TEM, XRD and XPS. PL analysis reveals that there was an extra Ag signal at around 1.895 eV, indicating the potential application of Ag-ITO NWs as nanoscale optical materials. Electrical measurements show that more Ag nanoparticles on the surface of ITO NWs contributed to higher resistivity, demonstrating the change in the electron transmission channel of the Ag-ITO NWs. ITO NWs and Ag-ITO NWs are expected to enhance the performance of electronic and optoelectronic devices.

Indium Tin Oxide Nanowire Arrays as a Saturable Absorber for Mid-Infrared Er:Ca0.8Sr0.2F2 Laser.

We demonstrated a passively Q-switched Er:Ca0.8Sr0.2F2 laser with indium tin oxide nanowire arrays as an optical modulator in the mid-infrared region. In the Q-switched regime, the maximum output power of 58 mW with a slope efficiency of 18.3% was acquired. Meanwhile, the minimum pulse duration and highest repetition rate of the stable pulse trains were 490 ns and 17.09 kHz, corresponding to single pulse energy of 3.4 μJ and peak power of 6.93 W, respectively. To the best of our knowledge it was the first time that indium tin oxide nanowire arrays were employed as a saturable absorber to make pulse lasers carried out at 2.8 μm. The experimental data show that indium tin oxide nanowire arrays can be employed as a competitive candidate for saturable absorber in the field of mid-infrared solid-state lasers.

Investigation of the influence of calcination temperature on morphology and structure of electrospun 1D SnO2 nanostructures

The aim of the study was to manufacture the SnO2 one-dimensional nanostructures via the sol-gel technique and electrospinning methods from a solution of polyvinylpyrrolidone (PVP), tin chloride pentahydrate (SnCl4-5H2O), N, N-dimethylformamide (DMF) and ethanol (EtOH). The as obtained fibrous mats consisting of polymer and precursors particles were subjected to the heat treatment in air in the following temperatures 500, 600 °C to obtain pristine tin oxide nanowires. The scanning electron microscope (SEM) was used to determine the effect of calcination temperature on the morphology and structure of produced 1D SnO2. The energy dispersive spectrometry (EDX) and Fourier-Transform Infrared spectroscopy (FTIR) were performed to investigate the chemical composition and structure of manufactured nanomaterials, respectively.