Theoretical calculation of investigating γ-CoV2O6-PdO and γ-CoV2O6 as highly hydrogen sensor

Abstract

The incorporation of PdO is an effective way to enhance the sensitivity of γ-CoV2O6 gas sensors, while the interaction mechanism between gas and γ-CoV2O6-PdO even γ-CoV2O6 systems are still not clear. In this study, the interaction work between H2, NO, H2S, acetone and γ-CoV2O6 as well as γ-CoV2O6-PdO are investigated systematically through density functional theory (DFT) as well as molecular dynamics simulations. According to the obtained adsorption energy, band gap and charge transfers, γ-CoV2O6 and γ-CoV2O6-PdO exhibits much superior sensitivity towards H2 gas than other three gases. The mechanism of sensing behavior of H2 on γ-CoV2O6 is the elongated H-H bond in H2 and forms a bond with an oxygen atom on the substrate to form H-O-H molecule group. In addition, the adsorption of H2 on γ-CoV2O6 causes a peak near the Fermi level, and the band gap reduces as well, therefore, the conductivity of γ-CoV2O6 is changed and makes the sensing feasible. For H2 adsorption, the band gap change rates are 93.8% and 70.8%, which are much higher than other gas molecules. The further comparative research on gases diffusion characteristics indicates that both γ-CoV2O6 and γ-CoV2O6-PdO H2 has fast response toward H2 molecules. Our results present γ-CoV2O6 system can detect H2 effectively, and when it was decorated by PdO, the sensing behavior of γ-CoV2O6 toward H2 is improved, indicating it is a promising sensing material of H2 gas.