Improved NO2 sensing properties at low temperature using reduced graphene oxide nanosheet–In2O3 heterojunction nanofibers

Abstract

Pure In2O3 and reduced graphene oxide (rGO)–In2O3 composite nanofibers are prepared by a facile electrospinning technique. Low-temperature gas-sensing properties to NO2 of the produced nanofibers are evaluated. Our results indicate that in comparison with pure In2O3 nanofibers, the rGO–In2O3 heterojunction nanofibers display much better sensing properties in response, selectivity and detection limit to NO2. Moreover, the weight ratios of rGO to In2O3 are used as a parameter to estimate the best gas-sensing properties of rGO–In2O3 nanofibers. Consequently, the heterojunction nanofibers with an optimized amount of rGO (2.2 wt%) exhibit the highest response of 42 to 5 ppm NO2 at the low operating temperature of 50 °C, which is 4.4 times higher than that of pristine In2O3. From our perspective, the enhanced sensing properties of the composite nanofibers can be mainly attributed to the formation of p–n heterojunctions between rGO and In2O3, and ultrahigh specific surface area as well as strong gas adsorption capacity of rGO nanosheets. These excellent gas-sensing properties make the rGO–In2O3 heterojunction nanofibers attractive to application for low-temperature NO2 gas sensors.