DFT study of CO2 catalytic conversion by H2 over Ni13 cluster

Abstract

Understanding the mechanism and selectivity of CO2 catalytic conversion by H2 on a specific catalyst is of great significance in the context of renewable energy storage from a societal and technological point of view. In this paper, based on the density functional theory calculations, the possible reaction networks of CO2 hydrogenation on the Ni13 cluster are studied systematically. The adsorption energies of the reaction intermediates at various possible adsorption sites, the reaction energies and the activation energies of each elementary reaction are calculated. The results suggest that the adsorption properties of the CO2 and the intermediates on the Ni13 cluster are different from the specific crystal plane such as Ni(111) surface, and the intermediates are highly activated on the Ni13 surface. The most advantageous pathways for the production of HCOOH, CH3OH, and CH4 are determined, and the activation barrier of the corresponding rate-determining step is 1.63 eV, 1.55 eV, and 1.55 eV, respectively. This indicates that the Ni13 cluster has higher activity towards CO2 catalytic conversion compared with other catalysts such as Cu(111), Ni(111), and Pt/Ni(111) surface. Furthermore, the H3CO* hydrogenation or the dissociation is demonstrated to be the crucial step in determining the selectivity for CH3OH and CH4. The mechanism of CO2 hydrogenation on Ni13 cluster was determined by density functional theory calculation.