| Description |
Transparent conducting indium tin oxide (ITO), aluminum-doped zinc oxide (AZO), tin-doped zinc oxide (TZO) nanoparticles were synthesized by plasma-assisted chemical vapor synthesis. The injected precursors were vaporized in the plasma flame followed by vapor-phase reaction and subsequent quenching of the vaporized precursors produced nanosized powders. The electrical and optical properties of TCO films synthesized by spin coating a dispersion of nanoparticles vary as a function of dopant. Effects of plasma torch power and plasma-gas flow rate on product phases and grain size were investigated for ITO nanoparticles. The grain size increased with increasing plasma torch power and decreased with an increase in flow rate of plasma gas. The ITO gas sensor was exposed to different concentrations of H2 gas and temperatures to evaluate its gas sensitivity. The optimum operating temperature and gas concentration of H2 showing the highest sensitivity was determined to be 350 °C and 400 ppm, respectively. The linear relation between sensitivity and concentration up to 400 ppm of H2 can benefit the actuator to detect the concentration of H2, and thus making it suitable for high-performance hydrogen gas sensing applications. Synthesized TZO1 (3 atm % Sn) nanoparticles exhibited superior photocatalytic activity compared with ZnO and the improvement was ascribed to increase in specific surface area and enhanced oxygen vacancies as revealed from the XPS O 1s and PL spectra. Hall effect measurements showed that the minimum resistivity of 1.4 х 10-3 Ωcm was obtained for TZO1 film, and all the films exhibited an average transmission of 80 %, indicating their suitability in optoelectronic applications. Optical constants of the films were determined, which varied with doping amount. The photo-current properties of ZnO and TZO films were investigated, and only TZO1 film showed photo response property when irradiated with UV lamp. XRD results of AZO nanoparticles indicate the presence of wurtzite structure without any alumina peaks and SEM micrographs revealed spherical particles. The nanosized AZO would make an excellent material for use as photocatalyst due to high surface to volume ratio. The photocatalytic property of AZO was investigated using the degradation of methylene blue under ultraviolet irradiation. The effects of various parameters, such as catalyst amount, the presence of oxidant, temperature, bubbling of O2 gas, pH, specific surface area, oxygen vacancies, and initial concentration, were studied. The optical study showed that doping leads to a red-shift in band gap. Kinetic analyses indicated that the photodegradation of methylene blue followed pseudo-first order kinetic model using Langmuir-Hinshelwood (L-H) mechanism. |
