Enhanced high-temperature CO2 electrolysis on CeO2 by inducing under-coordinated dual-atom active sites

Abstract

Stable CO2 electrolysis to CO and O2 in solid-oxide electrochemical cells (SOCs) is challenging due to the competitive carbon deposition. CeO2-based electrodes have shown advanced carbon-tolerant ability in SOCs. Here, by conducting density-functional theory calculations, we report highly selective CO2 to CO conversion catalyzed by a novel dual-atom site in CeO2 induced by substituting one Ce with two Pd (Ni or Cu). CO2 is effectively activated in the form of carbonate species (CO2*O) with oxygen strongly adsorbed by the under-coordinated dual-atom site, which then dissociates C–O bond with a 1.00 eV lower barrier compared to clean CeO2. By contrast, a 0.22 eV larger barrier is found for carbon deposition on dual-atom sites than on CeO2, leading to carbon suppression over dual-atom sites. Therefore, 2Pd (2Ni or 2Cu) dual-atom sites in CeO2 can significantly improve kinetics of CO2 reduction into CO because of the crucial role of their under-coordinated local structure in facilitating CO2 activation while preventing carbon deposition during CO2 electrolysis, which sheds light on rational design of dual-atom active sites in metal oxide catalysts.