Indium Oxide–Graphene Composites Prepared by the Sol–Gel Process and Single-Electrode Gas Sensors on Their Base

Abstract

Indium oxide–graphene composites (containing 0–6.0 wt % graphene) were manufactured by the sol–gel process. The phase composition, microstructure, and gas-sensitive properties of the prepared materials were studied. The composites consist of isolated In2O3 and graphene phases, where graphene is predominantly adsorbed on the surfaces of indium oxide grains (the indium oxide grain sizes are 8–11 nm). The nanocomposites are distinguished by an enhanced sensitivity to both reducing gases (CH4, acetone) and oxidative gases (NO2). A far greater enhancement is in the sensory response to oxidative gases. Presumably, the major factors influencing the sensory properties of the composite are the high defectiveness of In2O3 and graphene phases, higher specific surface areas of composites compared to those of individual In2O3, and the likely formation of p–n junctions in the indium oxide and graphene contact zone. Graphene additives to indium oxide can improve the main performances (sensory response, response time, and recovery time) of single-electrode semiconductor sensors.