Papers by Keyword: In₂O₃

Abstract: Formaldehyde is an indoor pollutant that poses a risk to human health, and prolonged exposure may lead to various diseases. Therefore, highly sensitive and selective detection technologies are needed to accurately monitor formaldehyde concentrations. In₂O₃ is a commonly-used semiconductor material in gas sensing. However, the gas sensing performance of pure In₂O₃ sensors falls far from expectation and the construction of heterojunctions is an effective strategy to resolve such issue. In this study, indium oxide-based composites (Co₃O₄/In₂O₃) with a typical p-n heterojunction were synthesized via a simple template-free hydrothermal method for high-performance formaldehyde sensing. XRD, SEM, TEM, and XPS confirmed the p-n heterojunction formation and its positive impact on enhancing surface reactivity. Gas-sensing tests demonstrated that the 3 wt% Co₃O₄/In₂O₃ sensor exhibited optimal performance. The 3 wt% Co₃O₄/In₂O₃ sensor exhibited a response value of 11.1 to 100 ppm formaldehyde at 300°C that was threefold higher than that of pure In₂O₃ (3.77); its recovery time was 41 seconds quicker than that of In₂O₃ (73 s vs. 114 s). The sensor also showed excellent selectivity, reproducibility, and stability. This research presents a scalable, heterojunction-driven design concept for the next generation of gas sensors.

Abstract: Group III–V compound semiconductors are attracting attention as new channel materials that have higher carrier mobility than Si. However, defects easily occur at the interface between the semiconductor and insulator film, which degrades performance. In an earlier study, we demonstrated that the interfacial properties of InP are degraded by the growth of In₂O₃ and that In₂O₃ grows better in water than in air. Therefore, it is necessary to suppress the growth of In₂O₃ to improve the interfacial properties of InP. In this work, we focused on functional water, which can be controlled by adjusting the water conditions, and investigated the growth behavior of In₂O₃ in functional water. As a result, we found that the growth is suppressed in the low-pH range and in hydrogen water. It is important that H⁺ ions reduce OH⁻ ions, which contributes to the reaction with InP.

Abstract: In this report it is being discussed approaches for designing the SnO₂ and In₂O₃ ozone sensors based on the film parameters optimization. It was considered the influence of the conditions of the SnO₂ and In₂O₃ films deposition by spray pyrolysis method and the parameters of those films on operating characteristics of ozone sensors. Main factors, controlling operating characteristics of thin film ozone sensors were determined. Recommendations to process of the SnO₂ and In₂O₃ films deposition, promoting an attainment of optimal operating gas sensing properties, were formulated.

Abstract: Fabrication of high sphericity, monodispersed microspheres (100~600 nm) of various oxides (SiO₂, TiO₂, ZnO, In₂O₃, SnO₂) via sol-gel process and polystyrene (PS) microspheres (200~400 nm) via emulsion polymerization is presented. A high colloidal stability suspension was obtained by adjusting the zeta potential of such spheres and pH of the colloid. The 3-D photonic crystal (PhC) templates of opaline structure on ITO-coated glasses and silicon wafers were easily formed under electrophoretic self-assembly (EPSA) of microspheres under the influence of exerting electrical forces. Different setups of counter-electrode were attempted to establish an electrical field. The lattice constant of an ordered opal structure by EPSA can also be tuned by the electrical field gradient. Interestingly various self-assembled 3-D structures of silica microspheres in either symmetrical curvilinear profile or triangular ridges can be produced through EPSA route using specific counter-electrode setups. The measured optic properties of such 3-D PhC templates manifest photonic bandgap (PBG) based on planar-wave expansion (PWE) simulation to verify the existence of real PBG in PhC samples with tunable nanostructures. The PS PhC templates are currently used to easily transform into inverse opal structure (IOS) by infiltrating sol of other oxides with high dielectric constant (e.g. ZnO or TiO₂) and filled with metallic nanoparticles (Ni or Cu) by electrochemical deposition or chemical bath deposition (CBD).

Abstract: The La-doped porous In₂O₃ nanospheres were prepared by a simple hydrothermal method, and La³⁺ accounted for 3 mol% of the In³⁺. The La exists and has been doped in the lattice of In₂O₃ characterized respectively by the means of energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD), the morphology of the samples with uniform nanospheres observed by field-emission scanning electron microscopy (FESEM). Moreover, the sensor exhibits higher response properties compared with pure porous In₂O₃ nanospheres towards different acetone concentration at operating temperature 300 °C. The response and recovery times is about 13 s and 8 s to 50 ppm acetone.

Abstract: In this review different aspects of material and structural engineering of metal oxides aimed for application in conductometric gas sensors (chemiresistors) were analyzed. Results, mainly obtained for SnO₂ and In₂O₃–based sensors during surface functionalizing by noble metals have been used for showing an opportunity of material and structural engineering of metal oxides to optimize gas sensing characteristics.

Abstract: Hollow nanofiber In₂O₃ is synthesized by electrospinning. The as-synthesized materials are characterized by scanning electron microscope (SEM) and X-ray power diffraction (XRD). The formaldehyde sensing properties of the devices using In₂O₃ films are investigated at different operating temperatures. The results reveal that the response of hollow nanofiber In₂O₃ sensor is about 2.5 to 1 ppm formaldehyde at the optimum operating temperature of 270°C. The response and recovery time is about 3 s and 19 s, respectively. Moreover, sensor possesses a good selectivity to some common gas.

Abstract: Fe-doped In₂O₃ nanowires were synthesized on an Si substrate with the deposited Au layer by a CVD method and characterized by XRD, SEM, TEM , the PL measurement was performed using HeCd laser excitation at 325 nm. Fe-doped In₂O₃ nanowires preferentially grow along the [10 direction The PL spectra of the Fe-doped In₂O₃ nanowires show an ultraviolet (UV) emission and a blue emission. The property of PL of the Fe-doped In₂O₃ nanowires are discussed.

Abstract: This study explored the decolorization of C.I. Reactive Red 2 (RR2) by the ultraviolet (UV)/TiO₂, UV/TiO₂ + In₂O₃, and UV/TiO₂-In₂O₃ systems. The TiO₂-In₂O₃ was generated by the sol-gel method and TiO₂ + In₂O₃ was created by mixing TiO₂ and In₂O₃ powders. The surface properties of TiO₂, In₂O₃, and TiO₂-In₂O₃ were analyzed by X-ray diffraction, a specific surface area analyzer, UV-vis spectroscopy, and scanning electron microscopy. The specific surface area of TiO₂, In₂O₃, and TiO₂-In₂O₃ was 29.5, 44.6, and 35.7 m²/g, respectively; additionally, the band gap of TiO₂, In₂O₃, and TiO₂-In₂O₃ was 2.95, 2.64, and 2.91 eV; respectively. The decolorization rate constant fit pseudo-first-order kinetics and that of the UV/TiO₂, UV/TiO₂ + In₂O₃, and UV/TiO₂-In₂O₃ systems was 0.0023, 0.0031, and 0.0072 min^-1; respectively.

Abstract: In₂O₃ nanotowers have been fabricated on Au item-shaped parallel electrodes using thermal evaporation of the mixed powders of In₂O₃ and graphite with Au catalysts. The morphology and structure of the prepared nanorods are determined on the basis of field-emission scanning electron microscopy (FESEM) and x-ray diffraction (XRD). The self-assembly grown sensors of In₂O₃ nanotowers have excellent performance in sensor response to hydrogen concentration of 1000 ppm under operated temperature of 300°C.