DFT insight into the effect of Cu atoms on adsorption and dissociation of CO₂ over a Pd₈/ TiO₂(101) surface

Abstract

In order to improve the photocatalytic activity of a bimetallic cocatalyst, understanding its mechanism is very important for the development of a CO₂ photocatalyst. In this study, density functional theory (DFT) calculations were performed to investigate CO₂ adsorption and dissociation over Pd-Cu bimetallic clusters loaded on a TiO₂(101) surface, aiming at understanding the origin of the effect caused by the presence of Cu. The results demonstrated that the introduction of a Cu atom has a dual effect on the adsorption and dissociation of CO₂: (1) it provides the positive polarization charge center to enhance CO₂ adsorption, and (2) it up-shifts the d-band center of the Cu atom to improve the activation of CO₂. Thus, the activity of the Pd₇Cu₁/TiO₂(101) surface, as compared with that of the Pd₈/TiO₂(101) surface, can be significantly improved, and the active center is the introduced Cu atom. This result is not only helpful for the development of effective CO₂ photocatalysts but also crucial to understand the basic mechanism of bimetallic catalysis.