Density functional theory study the mechanism of two CO* forming *OC-CO on different size of Cun (n = 3 to 20) clusters supported on TiO2

Abstract

Cun@TiO2 nanocatalytic materials are widely used in experiments to catalyze the reduction of CO2 to hydrocarbon fuels and oxygenated alcohols. However, due to the complexity of the coupling reaction of the Cun@TiO2 catalyst to form key CC bonds to C2 products, it is unclear. In this paper, the density functional theory (DFT) is employed to systematically study the influence of the size of Cun clusters on the CC bond formation with the Cun cluster supporting on the TiO2 surface. It was discovered that the adsorption of Cu metal clusters of different sizes on TiO2 was primarily determined by the bonding of TiO2 oxygen atoms. Subsequently, in the CO*+CO* → COOC* coupling reaction on each different Cun cluster size, we found that the active site was the interface position, when the Cun cluster showed a three-dimensional configuration, with the increase of the Cu cluster, that is, the coordination number increased, the activation energy barrier gradually decreased, and when the coordination of Cu cluster reached saturation, the coupling energy barrier size also stabilized. This work provides new sight of the size of co-catalyst in the CO2 reduction reaction and may guide to synthesis higher efficiency co-catalyst.