Enhanced CO sensor based on In2O3 nanocubes with decoration of Au under high humidity: Experimental combined with theoretical study

Au-modified In2O3 nanocubes with varying Au content (0.7, 1, 2, 3, 10 mol%) were prepared via a simple hydrothermal method and in-situ reduction. The morphology of Au-modified In2O3 was consistent with pure In2O3, both exhibiting cubic structures composed of ∼31 nm particles. Gas sensing tests revealed that compared to pure In2O3, 1 mol% Au-modified In2O3 nanocubes exhibited a 40 °C lower optimal operating temperature (OOT), and a higher response value of 4.88 to 100 ppm CO. Additionally, Au/In2O3 sensors showed significantly less influence from humidity (75 %, 85 %) than pure In2O3 sensors and maintained CO sensing ability under high humidity conditions. First-principles calculations of the adsorption energies of CO molecules on In2O3 and Au/In2O3 surfaces were further performed to investigate the gas sensing mechanism. The results indicated that the improved CO sensing performance of Au/In2O3 sensors can be attributed to the chemical sensitization effects of Au.