DFT insight into the effect of Cu atoms on adsorption and dissociation of CO over a Pd/ TiO(101) surface.

In order to improve the photocatalytic activity of a bimetallic cocatalyst, understanding its mechanism is very important for the development of a CO photocatalyst. In this study, density functional theory (DFT) calculations were performed to investigate CO adsorption and dissociation over Pd-Cu bimetallic clusters loaded on a TiO(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 CO: (1) it provides the positive polarization charge center to enhance CO adsorption, and (2) it up-shifts the d-band center of the Cu atom to improve the activation of CO. Thus, the activity of the PdCu/TiO(101) surface, as compared with that of the Pd/TiO(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 CO photocatalysts but also crucial to understand the basic mechanism of bimetallic catalysis.