Density Functional Theory Study of CO2 Adsorption and Reduction on Stoichiometric and Doped Ceria

Abstract

Periodic density functional theory (DFT) calculations were performed to estimate the adsorption energies of the reactant, product and intermediates for CO2 reduction to methanol on stoichiometric and doped CeO2 (110) surface. A planar structure of CO2 was considered to adsorb on stoichiometric ceria surface with a binding energy of -23.4 kJ/mol. The planar structure is likely to participate in CO2 hydrogenation reactions via the formation of formate (HCOO) or carboxyl (COOH) intermediate. Between the two intermediates, the carboxyl mediated route shows all the way exothermic steps and is likely to produce methanol. Ceria based materials have been suggested to possess high catalytic and electrocatalytic activity for CO2 reduction which can be further improved by aliovalent metal dopants. Surface of ceria was doped with aliovalent dopants such as Gd, Pr and Sm. The calculated adsorption energies of CO2 on doped ceria were comparable to stoichiometric ceria. Electronic structure calculations plotted in the form of projected density of states showed reduced band gaps for Gd doped ceria as compared to bulk ceria, suggesting towards higher electronic conductivities of the doped ceria materials.