DFT investigation of gas sensing characteristics of Au-doped vanadium dioxide

Abstract

Vanadium dioxide compounds are affordable and effective materials with large potential in gas sensing applications. However, it is still very challenging for available experiments to provide an in-depth understanding of sensing mechanism of VO2-based materials. In this work, density functional theory and molecular dynamics are applied to explore adsorption and diffusion of H2, CO2, CO and CH4 gases molecules in Au-VO2. Based on calculated adsorption energy, change transfer, charge density difference and density of state, a strong sensing characteristics of Au-VO2 toward CH4 gas is concluded, which is consistent with experimental conclusions. It is also inferred that H2, CO and CO2 relate physical adsorption, and CH4 corresponds to a chemical adsorption. The diffusion of CH4 in Au-VO2 is more difficult than the other gases due to the chemical adsorption of CH4.