First-principles calculations on the resistance and electronic properties of H2 adsorption on a CoO–SnO2 heterojunction surface

Abstract

Compared with pure metal oxides, heterojunctions greatly change the response to gas by the synergistic effect of the interface. In this work, density functional theory was used to reveal the adsorption performance of H₂ on the heterojunction under oxygen conditions. First, we determined the most reasonable heterojunction structure based on the adhesion work. According to the adsorption energy, the presence of SnO₂₍100)(I)/CoO(110)(II) made the adsorption of H₂ more stable. The DOS results showed that the resistance of the heterojunction increased with H₂ adsorption, following the same trend as that of CoO(110) with H₂ adsorption, although that of the heterojunction increased more. The electron density and electron density difference indicated that the heterojunction improved the reaction between H₂ and oxygen ions on CoO(110). However, the resistance of CoO(110)(II)/SnO₂(100)(II) increased after H₂ adsorption, contrary to the resistance change of SnO₂(100). Besides, the bonding energy between H₂ and the adsorption site became worse. The above results demonstrated that the presence of the heterojunction could indeed change the response trend and the adsorption behavior of H₂. Interestingly, the adsorption sites and effects of H₂ were different when two metal oxides were used as the substrate of the heterojunction, respectively.