In this paper, the adsorption mechanism, density of states, charge population analysis and electrical conductance at room temperature are investigated for the detection of hydrogen sulfide (H2S) gas by pure, and Cu- and CuO-decorated graphene sheets (GS). All calculations are done using density functional theory. Results demonstrate that a CuO-GS structure has higher binding energy with H2S than Cu-GS, and GS. Moreover, the investigated density of states show that orbital hybridization is obviously different between the H2S and Cu-GS, and the H2S and CuO-GS, while there is no evidence for hybridization between the H2S gas and the GS. Furthermore, to find the best nanosensor, electrical conductance of all the possible configurations before and after H2S adsorption at room temperature is computationally investigated. The obtained results illustrate that electrical conductance of the CuO-GS is significantly changed by H2S gas adsorption. So, in normal conditions and at room temperature, the CuO-GS system has more favorable features in the detection of H2S than the GS, and Cu-GS structures
