First principles study of Rh-doped SnO2 for highly sensitive and selective hydrogen detection

Abstract

Tin dioxide is a low-cost and efficient material with large potential in applications of hydrogen detection. Doping metals in SnO2 is a solution to further improve its electrical performance, however, atomic-scale understanding of detection mechanism of doped SnO2 is very limited. In this work, first principles and molecular dynamics method are applied to investigate adsorption properties and diffusion effects of CH4, CO2, H2, N2 on Rh-doped SnO2. By calculating adsorption energy, adsorption distance, charge density difference, density of states, it is concluded that Rh-SnO2 shows a strong sensing characteristics towards H2, which is consistent with experiment result. After adsorption of H2, the main energy bands of DOS shift to a lower level of energy, and the Fermi level move to higher level of energy. H2 shows a strong chemical adsorption effect on Rh-SnO2, while CH4, CO2 and N2 only present weak physical adsorption on Rh-SnO2. Furthermore, the diffusion of H2 in Rh-SnO2 is easier than those of other gases. Our study provides a fundamental and new perspective for designing highly sensitive hydrogen gas sensor from atomic and electronic level.