CO2 chemisorption and dissociation on flat and stepped transition metal surfaces

Abstract

As a promising and practical way to decrease CO2 emissions, the conversion of CO2 to value-added chemicals has received significant recent attention. The activation of CO2 on catalyst surfaces might proceed via a chemisorption state with a bent CO2 configuration, in which substrate electrons are transferred into the antibonding orbital of the CO2 adsorbate. Based on density functional theory calculations, we present an extensive survey of CO2 chemisorption and dissociation on flat and stepped surfaces of several transition metals. The binding energy of chemisorbed CO2 is closely correlated with the extent of electron transfer from the metal to CO2, as evidenced by a linear relationship found between the CO2 adsorption energy and its Bader charge. Transition state scaling (TSS) correlations between binding energies of transition states and binding energies of either initial or final states are found to exist for the dissociation of the chemisorbed CO2 on flat and stepped surfaces, which can be used to predict the efficacies of the catalysts. Our results show that defect sites at stepped surfaces have a strong influence on CO2 chemical activation and dissociation.