A novel rGO-decorated ZnO/BiVO4 heterojunction for the enhancement of NO2 sensing properties

Abstract

A ZnO/BiVO₄ heterojunction has been first prepared by the co-precipitation and hydrothermal methods; then, rGO nanosheets are decorated onto the heterojunction by simple hydrazine hydrate reduction to construct a novel ZnO/BiVO₄/rGO composite-based NO₂ sensor. The structure, morphology and gas sensing performance of the composite were characterized and measured using various spectroscopies and gas sensing tests. Compared to the same kinds of gas sensors reported previously, this sensor exhibits competitive sensing performance with a maximum response of 126.64 to 1 ppm NO₂ at an operating temperature of 95 °C, which is 5.7 times and 2.4 times higher than those of the ZnO and ZnO/BiVO₄ junctions, respectively. Also, the sensor shows a rapid response and long-term stability to NO₂ compared with pure ZnO. The good sensing properties are ascribed to the formation of the n–n heterojunction between ZnO and BiVO₄ and the decoration with rGO.