Variable dimensional structure and interface design of In2O3/rGO nanocomposites with oxygen vacancy for enhancing NO2 sensing performance

Abstract

Rational interface design is an efficient strategy to enhance gas sensing performance. Herein, the large-scale heterogeneous interfaces consisting of porous In2O3 sheets with reduced graphene oxide (rGO) modification were constructed by convenient face-to-face contacts. Heterogeneous In2O3 nanorods were employed as a counterpart to explore the role of the interface between rGO and In2O3. The morphology, surface area, chemical surface state, adsorption heat, activation energy, etc., were investigated comprehensively. The results indicated that 0.5% rGO/h-In2O3-sheet and 0.5% rGO/hc-In2O3-rod enhanced 3.88-fold and 1.66-fold in the response than corresponding pristine ones, respectively. 0.5% rGO/h-In2O3-sheet with extensive interface achieved superior sensing performance. Simultaneously, the response and recovery times of hybrids were shortened significantly, owing to the low activation energy. Moreover, 0.5% rGO/h-In2O3-sheet exhibited an ultra-high sensor response of 1397 to 1 ppm NO2 with a detection limit as low as 5 ppb at 62.5 ℃. It also possessed excellent selectivity, repeatability and long-term stability. The decoration of rGO on the In2O3 sheets dramatically manipulated the oxygen vacancy, band-gap, and Fermi level and enhanced the efficiency of gas and carriers exchange and transportation, eventually boosting the sensing performance.