RGO modified α-Fe2O3–ZnFe2O4 heterojunction for improving sensing performance of α-Fe2O3 to triethylamine

Abstract

In order to develop a sensitive, stable and cheap gas sensor for detection of triethylamine (TEA), the bimetal oxide of ZnFe2O4 with α-Fe2O3 heterojunctions with different proportions were synthesized and reduced graphene oxide (rGO) modified on heterojunctions by hydrothermal and chemical precipitation methods. The gas-sensing tests to TEA showed that the 6α-Fe2O3/ZnFe2O4-rGO (0.8 wt%) composite has highest response reaches 10.48–20 ppm TEA with a rapid response time of 29 s, an impressively low detection limit of 0.145 ppm and reliable stability within 32 days at operating temperature of 143 °C. Compared with reported before, it has higher response at lower operating temperature and lower concentration of test gas. The enhancing mechanism is attributed to the formation of semiconductor heterojunction, which makes the resistance of composite in air further increase and further decrease in TEA compared with α-Fe2O3 due to generating an additional electron depletion layer in the heterojunction interface, while rGO accelerates the electron transfer and provides more active sites for gas adsorption.