Morphological effects of Au13 clusters on the adsorption of CO2 over anatase TiO2(101)

Abstract

Density functional theory was employed to investigate the interaction between CO2 and anatase TiO2(101) surface in the presence of Au13 clusters. Two Au13 clusters (icosahedral and cuboctahedral) were used to identify correlations among activity, structural stability, and morphology of supported Au13 clusters on the TiO2(101) surface. The effects of oxygen vacancy were also studied. A strong morphological effect of Au13 clusters on the adsorption and activation of CO2 over anatase TiO2 (101) has been identified. The structural dynamic fluxionality of Au13 clusters, i.e., its adaptability toward the adsorbed CO2, plays an important role in the bonding and activation of CO2. The flexibility of the icosahedral Au13 cluster allows it to readjust so as to enable the maximum orbital overlap between the Au13 clusters and CO2, making the stabilization of CO2 feasible. In contrast, the cuboctahedral Au13 cluster tends to maintain its own structure even after CO2 adsorption, resulting in weaker CO2 binding strength. The presence of oxygen vacancy was found to introduce additional adsorption sites, and CO2 adsorption on defective TiO2(101) surface can be substantially modified by the presence of the cuboctahedral Au13 cluster. In addition, we find that the interfacial site is the preferred adsorption site for CO2 adsorption and activation on the Au13/TiO2(101) surface. These findings shed light on the importance of cluster dynamics during catalytic reaction and provide key guidelines for engineering more efficient metal–oxide interfaces in catalysis.