Density functional theory study on the mechanism of CO sensing on Cu 2O (1 1 1) surface: Influence of the pre-adsorbed oxygen atom

•The sensitivity of perfect and O pre-adsorbed Cu2O (111) to CO gas are revealed.•Both of the two kinds of surfaces have considerable sensitivity to CO gas.•The O pre-adsorbed surface is more sensitive to CO than the perfect surface.•Cu2O would be a good candidate for the detection of CO gas.