First-Principles Calculations on Resistance and Electronic Properties of H2 Adsorption on CoO-SnO2 Heterojunction Surface

Compared with pure metal oxides, heterojunction greatly changes the response to gas by the synergistic effect of interface. In this work, density functional theory was used to reveal the adsorption performance of H2 on heterojunction under oxygen conditions. Firstly, 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) makes the adsorption of H2 more stable. The DOS results show that the resistance of heterojunction increases with H2 adsorption, in the same trend as that of CoO(110) with H2 adsorption, but that of the heterojunction increases more. The electron density and electron density difference indicate that heterojunction improves the reaction between H2 and oxygen ions on CoO(110). However, the resistance of CoO(110)(II)/SnO2(100)(II) increases after H2 adsorption, contrary to the resistance change of SnO2(100). Besides, the bonding energy between H2 and the adsorption site becomes worse. The above results demonstrate that the presence of heterojunction can indeed change the response trend and the adsorption behavior of H2. Interestingly, the adsorption sites and effects of H2 are different when the same two metal oxides are used as the substrates of the heterojunctions, respectively.