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

• For the first time, atomic sensing mechanism of γ-CoV 2 O 6 -PdO and γ-CoV 2 O 6 towards H 2 gas is studied. • Predicted gases sensing behaviors of γ-CoV 2 O 6 -PdO as well as γ-CoV 2 O 6 consist with experiments results in other work. • Detection of H2 is related to formation of O–H bonds between H2 and O atom in γ-CoV 2 O 6 . • Our analysis provides a basis for designing of γ-CoV 2 O 6 -based gas sensor. The incorporation of PdO is an effective way to enhance the sensitivity of γ-CoV 2 O 6 gas sensors, while the interaction mechanism between gas and γ-CoV 2 O 6 -PdO even γ-CoV 2 O 6 systems are still not clear. In this study, the interaction work between H 2 , NO, H 2 S, acetone and γ-CoV 2 O 6 as well as γ-CoV 2 O 6 -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-CoV 2 O 6 and γ-CoV 2 O 6 -PdO exhibits much superior sensitivity towards H 2 gas than other three gases. The mechanism of sensing behavior of H 2 on γ-CoV 2 O 6 is the elongated H-H bond in H 2 and forms a bond with an oxygen atom on the substrate to form H-O-H molecule group. In addition, the adsorption of H 2 on γ-CoV 2 O 6 causes a peak near the Fermi level, and the band gap reduces as well, therefore, the conductivity of γ-CoV 2 O 6 is changed and makes the sensing feasible. For H 2 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-CoV 2 O 6 and γ-CoV 2 O 6 -PdO H 2 has fast response toward H 2 molecules. Our results present γ-CoV 2 O 6 system can detect H 2 effectively, and when it was decorated by PdO, the sensing behavior of γ-CoV 2 O 6 toward H 2 is improved, indicating it is a promising sensing material of H 2 gas.