First principles investigations of the carbon dioxide reduction to ethylene over the M10@TiO2 catalysts

Cu metal clusters loading on the surface of TiO2 served as co-catalyst can catalyze the reduction of CO2 to C2 products. However, the details mechanism of this reaction is still not clear. Moreover, finding other metal clusters to replace Cu is an attractive subject. In this work, the C-C bond forming mechanism by two CO* on several metal clusters (Cu, Ga, Co, Fe, Ni, Pt, Pd, Mo, and Zr) loading on TiO2 (101) surface (M10@TiO2) were investigated by climbing image nudged elastic band (cNEB) within density functional theory (DFT). We found the energy barrier of C-C bond forming on Cu10@TiO2 and Ga10@TiO2 is low around 0.7 eV which indicates that they are efficiency co-catalyst in CO2 reduction to C2 products. For other metal clusters, the energy barrier is large around 1.5 eV, and they are exclude comparing to Cu and Ga clusters. The reaction path to C2H4 has also been calculated on Cu10@TiO2 and Ga10@TiO2. The step energy on Ga10@TiO2 is all smaller than the energy barrier of C-C bond forming which makes Ga10@TiO2 may as be good as Cu10@TiO2. This work provides useful insights into the CO2 reduction to C2 products on metal clusters loading on TiO2 catalyst.