Highly selective and sensitive detection of NO2 using rGO-In2O3 structure on flexible substrate at low temperature

Reduced graphene oxide (rGO)-In2O3 hybrid materials were prepared by a solvothermal reaction of an In precursor containing rGO sheets, which were coated onto flexible substrates for gas sensors. The rGO-In2O3 flexible sensors showed a high and reversible response (resistance ratio = 22.3) to 500 ppb NO2 at 150 °C and negligible cross-responses to C2H5OH, CO, NH3, toluene, H2, and HCHO. The ultrahigh response and selectivity of rGO-In2O3 hybrid materials to NO2 were attributed to the chemical affinity of rGO to NO2 and the extension of the electron depletion layer in n-type In2O3 forming a p-n junction with the p-type rGO.