Enhanced room-temperature NO2 response of noble metal decorated α-Fe2O3/SnO2–rGO hybrids

Reduced graphene oxide (rGO)-based materials are deemed as promising candidates for fabrication of room-temperature gas sensors, while a tougher challenge is to develop an effective strategy for improving gas responses. Here, a noble metal decoration strategy is developed to enhance NO2 responses of α-Fe2O3/SnO2–rGO hybrids. Noble metal decorated α-Fe2O3/SnO2–rGO hybrids were prepared by depositing noble metals onto α-Fe2O3/SnO2–rGO hybrids through reduction of noble metal ions by NaBH4. Most importantly, Pt modified α-Fe2O3/SnO2–rGO hybrids (designated as Pt-FSR) exhibit the highest response value of 21.3 toward 5 ppm NO2, which is much higher than that of α-Fe2O3/SnO2–rGO (8.8). Combined characterization studies indicate that the enhanced NO2 response of Pt-FSR is attributed to the narrow band gap of Pt-FSR, small particle size and excellent catalytic activity of Pt. The NO2 sensing mechanism is also investigated by FT-IR spectroscopy. The findings proposed in this work not only broaden the study of room-temperature gas sensors, but also provide suggestions for discovering the gas sensing mechanism.