Growth mechanism and gas-sensing characteristics of organic-additive-free zinc oxide of various shapes

Zinc oxide is widely used in gas sensors, solar cells, and photocatalysts because of its wide bandgap and exciton binding energy of 60 meV in various metal oxides. To use ZnO as a gas sensor, it is necessary to synthesize it with surface defects and a large specific surface area. In this study, hydrothermal synthesis without surfactants was employed to obtain organic-additive-free ZnO. For morphology control, we varied the ratio of the hydroxide ion concentration to the zinc ion concentration. To confirm the growth mechanism of ZnO, we performed X-ray diffraction, scanning electron microscopy, and transmission electron microscopy analyses. Raman spectroscopy and photoluminescence measurements were performed to analyze the surface properties. The Brunauer-Emmett-Teller method and probe stations were used to measure the specific surface area and sensitivity of the gas sensor, respectively. The results confirmed that flower-shaped ZnO is the most suitable gas-sensing material.

Automated summary

Zinc oxide is widely used in gas sensors and photocatalysts due to its unique band structure and surface properties. In this study, we successfully synthesized organic-additive-free ZnO using hydrothermal synthesis method without surfactants. By controlling the concentrations ratio, we were able to control the morphology of the ZnO. Various characterization techniques were employed to understand the growth mechanism and surface properties of the ZnO. The flower-shaped ZnO material exhibited the best performance as a gas sensor.