Preparation of gas sensor based on Fe-doped reduced graphene/ZnSnO<sub>3</sub> nanocomposite and optimization mechanism of enhanced gas-sensing performance for formaldehyde gas

Abstract

Formaldehyde is the main indoor air pollution gas, which seriously affects people’s health. ZnSnO3 is a ternary metal oxide material with excellent gas-sensing performance. In this work, the rGO and Fe-doing are used to optimize ZnSnO3 gas-sensing properties further, and the Fe-doped reduced graphene/ZnSnO3 nanocomposite is prepared by the hydrothermal method. The technologies of X-ray diffraction, Roman, Infrared spectrum, X-ray photoelectron spectrum, scanning electron microscope, transmission electron microscope, UV-visible diffuse-reflectance spectrum, and electron spin-resonance spectroscopy are used to characterize the morphology, structure, chemical composition, defects, and energy level of the products, while the corresponding gas-sensing properties of sensitivity, response-recovery time, optimum working temperature, selectivity, stability, and humidity effects are determined using formaldehyde as a target gas. The results revealed that using the rGO improved the specific surface area and electron mobility, formed p-n heterojunction, caused a drastic change in resistance, reduced the optimum working temperature, and enhanced the gas-sensing properties of ZnSnO3. Meanwhile, the Fe-doping increased the oxygen vacancies defects and promoted the Debye electron depletion layer on the surface of ZnSnO3, which furtherly enhanced the gas-sensing performance of ZnSnO3. This work provides the technical support and theoretical basis for the optimization of ZnSnO3 gas-sensing properties.