Effect of Ag doping on SnO2 sensing for detecting H2S: A first-principles study

Abstract

First-principles calculations were performed to investigate the effect of Ag doping on SnO2 sensing of H2S with oxygen vacancy formation and oxygen species preadsorption. Ag preferentially substituted for Sn5c atoms, and Ag atoms were favorable for the generation of oxygen vacancies at O2c sites on the SnO2 (110) surface. The adsorbed O2 molecules dissociated on the Ag-doped SnO2 surface more easily because of the dopant catalysis, and the resistance of the Oads-preadsorbed Ag-doped SnO2 surface increased because of increased electron transfer from the surface to the Oads species. When exposed to H2S, H2S released more electrons back to the Oads-preadsorbed Ag-doped SnO2 surface, thereby increasing surface conductance. Therefore, Ag doping enhanced SnO2-semiconductors sensing. This study can provide an improved understanding of Ag-enhanced SnO2 sensing, which is helpful for designing SnO2 sensors with high sensitivity and sensing response.