An In2O3 nanorod-decorated reduced graphene oxide composite as a high-response NOx gas sensor at room temperature

Abstract

A novel composite room temperature gas sensor based on an In₂O₃ nanorod-decorated reduced graphene oxide composite (In₂O₃ NR/rGO composite) was successfully synthesized via a facile reflux method. In this synthesis, In³⁺ and urea were adsorbed on GO through electrostatic interactions in a water solution. The subsequent reflux treatment led to the transformation of the In(OH)₃ nanorods coated on GO and also to the reduction of graphene oxide. We demonstrate that the composite can detect NO_x gas with a response of 1.45, a fast response time of 25.0 s for 97.0 ppm NO_x and a low detection limit of 970 ppb at room temperature. Compared with the pure In₂O₃ NRs, the composite has a faster response within 30.0 s over the whole range of NO_x concentration. The enhanced sensing properties are attributed to the synergy of the superior conductivity of rGO and the nanostructure of the In₂O₃ NR/rGO composite. The present strategy for combining various hydroxide and nanoscale building blocks into integrated 3D structures will open new opportunities for designing and synthesizing multifunctional composites.