Synthesis of ZnO@In2O3 heterojunction with unique hexagonal three-dimensional structure for ultra sensitive ethanol detection

Abstract

The unique interface barrier characteristics of heterojunction have a significant impact on the gas sensing properties of composites. In this work, we report the successful synthesis of ZnO@In2O3 heterojunction nanocomposites with ultra sensitive response to ethanol by simple hydrothermal method and subsequent annealing treatment. SEM, TEM, XRD and other morphological characterization methods were used to detect the composites. Through the analysis of the characterization results, it can be found that the special structure of heterojunction is a three-dimensional structure which composed of ZnO hexagonal nanosheets and surface attached In2O3 nanoparticles, with a specific surface area of 63.27 m2/g. Measurements show that diameter of the nanosheets is 200–300 nm, the thickness is 40–60 nm, and the particle size of In2O3 nanoparticle is 30–60 nm. Due to the unique hexagonal three-dimensional structure, large specific surface area and rich mesoporous structure, gas sensing test results of the sensor prepared through ZnO@In2O3 heterojunction present that response value to 100 ppm ethanol at 160 °C is 28.6, which is much higher than pure ZnO and In2O3; It also presents the ability of rapid ethanol detection (response and recovery time are 8 s and 17 s); The synthesis of unique heterojunction structure greatly improves the sensitivity to ethanol, lower operating temperature significantly reduces energy consumption, and the repeatability and stability of sensors also perform excellent. Above advantages confirm that ZnO@In2O3 heterojunction nanocomposite is one of the ideal materials for rapid ethanol detection.