Insights into ethanol electro-oxidation over solvated Pt(1 0 0): Origin of selectivity and kinetics revealed by DFT

The use of ethanol fuel in direct ethanol fuel cells has been hindered by the slow kinetics of anodic ethanol electro-oxidation reactions over Pt catalysts. We employ ab initio molecular dynamics simulations and thermodynamic integrations on the solvated Pt(1 0 0) model electrode surface with explicit water molecules, to systematically investigate the ethanol electrocatalytic oxidation mechanisms including partial oxidation to acetic acid and complete oxidation to CO2. We find that the ethanol decomposition rate does not limit the overall efficiency of the ethanol electro-oxidation reaction. However, the slow oxidation kinetics of surface intermediates to final products, due to the bonding between intermediates and the Pt surface being too strong, is the main obstacle. We suggest that weakening the surface affinity towards adsorption of the intermediates such as CO, for example by engineering the surface structures (e.g. via alloying), could improve the overall catalytic effeciency for ethanol electro-oxidation reaction.