Decoration of CuO NWs Gas Sensor with ZnO NPs for Improving NO2 Sensing Characteristics.

This paper introduces a method for improving the sensitivity to NO2 gas of a p-type metal oxide semiconductor gas sensor. The gas sensor was fabricated using CuO nanowires (NWs) grown through thermal oxidation and decorated with ZnO nanoparticles (NPs) using a sol-gel method. The CuO gas sensor with a ZnO heterojunction exhibited better sensitivity to NO2 gas than the pristine CuO gas sensor. The heterojunction in CuO/ZnO gas sensors caused a decrease in the width of the hole accumulation layer (HAL) and an increase in the initial resistance. The possibility to influence the width of the HAL helped improve the NO2 sensing characteristics of the gas sensor. The growth morphology, atomic composition, and crystal structure of the gas sensors were analyzed using field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy, and X-ray diffraction, respectively.

Sensitivity Improvement of Urchin-Like ZnO Nanostructures Using Two-Dimensional Electron Gas in MgZnO/ZnO.

This paper introduces a strategy for improving the sensitivity of a gas sensor to NO2 gas. The gas sensor was fabricated using urchin-like ZnO nanostructures grown on MgO particles via vapor-phase growth and decorated with MgZnO nanoparticles via a sol-gel process. The urchin-like ZnO gas sensor decorated with MgZnO showed higher sensitivity to NO2 gas than a pristine urchin-like ZnO gas sensor. When ZnO and MgZnO form a heterojunction, a two-dimensional electron gas is generated. This improves the performance of the fabricated gas sensor. The growth morphology, atomic composition, and phase structure were confirmed through field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction, respectively.

Improved Sensitivity of α-Fe2O3 Nanoparticle-Decorated ZnO Nanowire Gas Sensor for CO.

A strategy for improving the sensitivity of a sensor for detecting CO and NH3 gases is presented herein. The gas sensor was fabricated from ZnO metal oxide semiconductor nanostructures grown via a vapor⁻liquid⁻solid process and decorated with α-Fe2O3 nanoparticles via a sol⁻gel process. The response was enhanced by the formation of an α-Fe2O3/ZnO n⁻n heterojunction and the growth of thinner wires. ZnO nanowires were grown on indium⁻tin⁻oxide glass electrodes using Sn as a catalyst for growth instead of Au. The structure and elemental composition were investigated using field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. The gas sensing results indicate that the response value to 100 ppm CO was 18.8 at the optimum operating temperature of 300 °C.