Effect of Applied Potential on C-C Bond Cleavage in Electrocatalytic Ethanol Oxidation

Direct ethanol fuel cells are a promising venue for efficient energy utilization due to their high energy density, fuel renewability, and low toxicity. Understanding C–C bond activation in the ethanol oxidation reaction (EOR) is critical for the design of effective electrocatalyst. In density functional theory (DFT) studies of electrocatalytic activities in EOR, the computational hydrogen electrode model is commonly used, where the applied potential does not impact non-redox C-C bond activation. In this work, we employed a constant electrode model in DFT calculations to investigate C–C bond cleavage in CH2CO and CHCO species on the Ir(100) surface under applied potentials ranging from 0.45 to 3.73 V (vs SHE). Our results show that activation energy barriers for both reactions are potential-dependent, although the extent of this dependence varies by reaction. Under fuel cell conditions, the C-C bond activation barriers on Ir(100) increase than in the gas phase or aqueous solution. Density of states analysis reveals the varying impact of applied potential on different reactions.