Theoretical Insights into Synergistic Effects at Cu/TiC Interfaces for Promoting CO Activation.

The adsorption behaviors of CO at the Cu /TiC(001) interfaces ( = 1-8) have been investigated using the density functional theory method. Our results reveal that the introduction of copper clusters on a TiC surface can significantly improve the thermodynamic stability of CO chemisorption. However, the most stable adsorption site is sensitive to the size and morphology of Cu particles. The interfacial configuration is the most stable structure for copper clusters with small ( ≤ 2) and large ( ≥ 8) sizes, in which both Cu particles and TiC support are involved in CO activation. In such a case, the synergistic behavior is associated with the ligand effect introduced by directly forming adsorption bonds with CO. For those Cu clusters with a medium size ( = 3-7), the configuration where CO adsorbs solely on the exposed hollow site constructed by Cu atoms at the interface shows the best stability, and the charger transfer becomes the primary origin of the synergistic effect in promoting CO activation. Since the most obvious deformation of CO is observed for the TiC(001)-surface-supported Cu and Cu particles, copper clusters with specific sizes of = 4 and 7 exhibit the best ability for CO activation. Furthermore, the kinetic barriers for CO dissociation on Cu- and Cu-supported TiC surfaces are determined. The findings obtained in this work provide useful insights into optimizing the Cu/TiC interface with high catalytic activation of CO by precisely controlling the size and dispersion of copper particles.