Room-temperature hydrogen sensor based on grain-boundary controlled Pt decorated In2O3 nanocubes

New, highly sensitive room temperature (RT) hydrogen gas sensors were fabricated by coating Pt-decorated-cube-like-In2O3 on Au electrodes. In2O3, with diameters between 200 and 300 nm, was obtained by a hydrothermal method and coated with Pt by a simple solution based on chemical technique. The morphological and elemental studies of the material were carried out using SEM, TEM and EDAX analysis. The loading of the Pt nanoparticles (NPs) enhanced the catalytic dissociation of oxygen molecules, adsorbed a substantial quantity of hydrogen, and the sensor exhibited a dramatic decrease in working temperatures to 25 °C. Responding to 1.5 vol% hydrogen, the sensor achieved response and recovery times of approximately 33 s and 66 s, respectively. The sensor also achieved excellent stability and high sensitivity to hydrogen at RT. In addition, it also showed a slow response to CO. The gas response to 1.5 vol% CO was 10 times lower than that to hydrogen. For other organic compounds in the gaseous state, such as ethanol, acetone and isopropanol, the response could be neglected. Such a large discrepancy reveals the sensor's outstanding selectivity to H2. Grain boundary theory and spillover theory are applied to explain the gas sensing effect of the Pt-coated In2O3 nanocubes sensor.