Achieving >99.9% Faradaic Efficiency for Complete Ethanol Electrooxidation over a Co-PdZn Heterointerface.

Developing electrocatalysts with exclusive selectivity for the complete ethanol oxidation reaction (EOR) is crucial for advancing direct ethanol fuel cells (DEFCs). Herein, we report a carbon-supported Co-PdZn catalyst (Co-PdZn/NC) featuring an intimately coupled Co-PdZn nanoparticle heterointerface, which exhibits outstanding alkaline EOR performance. The catalyst delivers a high mass activity of 13.29 A mgPd-1 and achieves >99.9% Faradaic efficiency toward the C1 pathway over a wide low-to-mid potential range (0.3-0.7 V). Density functional theory (DFT) calculations reveal that strong interfacial covalent coupling between PdZn and Co drives electron transfer across the interface, creating electron-rich PdZn sites and an electron-deficient Co side. This interfacial region serves as the primary active zone, which not only enhances the adsorption of key reactants (*CH3CH2OH and *OH) but also accelerates the oxidation of strongly adsorbed intermediates (*CH3 and *CO), thereby conferring exclusive C1 pathway selectivity. This work demonstrates that well-designed heterointerfaces can precisely steer reaction pathways in complex multistep electrocatalysis, offering a general strategy for developing advanced catalysts for diverse energy-conversion reactions.