Gas-sensing properties and mechanisms of Cu-doped SnO2 spheres towards H2S

We report on the synthesis of pristine and Cu-doped SnO2 spheres using a facile hydrothermal method and investigate their microstructures and gas-sensing response. We focus on how Cu doping can have an impact on gas-sensing behavior of SnO2-based sensors toward H2S. We find that Cu doping can enhance significantly the gas response of SnO2 toward H2S, the origin of which can be clarified with a proposed adsorption model. First-principles calculations reveal that adsorption energy of H2S on Cu-doped surface is lower than that on undoped one and the interaction between adsorbed H2S and Cu-doped surface is stronger than that between adsorbed H2S and pure surface, which consequently improves gas-sensing performances of SnO2 toward H2S. Such a combined experimental and calculational study offers an explanation on how Cu doping affects gas-sensing performances of SnO2.