DFT study of CO42- and CO52- relevant to oxygen reduction with the presence of molten carbonate in solid oxide fuel cells

► Geometric and electronic structure of CO42- and CO52- are analyzed using DFT. ► Molten carbonate enhances the adsorption of oxygen in the cathode of SOFCs. ► The intermediate of CO42- is vital in the process of oxygen reduction of MCFCs. ► Oxygen reduction through CO42- with the presence of carbonate is favored.