Facile preparation of Au-loaded mesoporous In₂O₃ nanoparticles with improved ethanol sensing performance

The in situ monitoring of toxic volatile organic compound gases using metal oxide-based gas sensors is still challenging. Herein, mesoporous In₂O₃ nanoparticles, assembled using smaller nanoparticles, were synthesized via a facile solvothermal method and used to load Au nanoparticles to prepare mesoporous Au/In₂O₃ for ethanol detection. The obtained In₂O₃ and Au/In₂O₃ were meticulously analysed by XRD, SEM, BET, TEM and XPS techniques. It was revealed that Au nanoparticles were uniformly distributed on mesoporous In₂O₃ nanoparticles. Notably, the obtained mesoporous 1% Au/In₂O₃ is highly sensitive to ethanol gas at an optimal working temperature of 180 °C, showing a response of 55 to 50 ppm of ethanol, which is considerably higher compared to that of In₂O₃ nanoparticles. The significantly enhanced sensitivity results from the electronic and chemical sensitization effects of Au nanoparticles. Moreover, the mesoporous Au/In₂O₃ nanoparticles also showed eminent selectivity, short response/recovery time, low detection limit, good linear relationship, superb repeatability, and wonderful long-term stability, suggesting that Au/In₂O₃ nanoparticles have great potential application for in situ monitoring of ethanol gas.