Ga-Modification Near-Surface Composition of Pt-Ga/C Catalyst Facilitates High-Efficiency Electrochemical Ethanol Oxidation through a C2 Intermediate

In electrochemical ethanol oxidation reactions (EOR)catalyzedby Pt metal nanoparticles through a C2 route, the dissociation ofthe C-C bond in the ethanol molecule can be a limiting factor.Complete EOR processes producing CO2 were always exemplifiedby the oxidative dehydrogenation of C1 intermediates, a reaction routewith less energy utilization efficiency. Here, we report a Pt3Ga/C electrocatalyst with a uniform distribution of Ga overthe nanoparticle surface for EOR that produces CO2 at mediumpotentials (>0.3 V vs SCE) efficiently through direct and sustainableoxidation of C2 intermediate species, i.e., acetaldehyde. We demonstratethe excellent performance of the Pt3Ga-200/C catalyst byusing electrochemical in situ Fourier transform infrared reflectionspectroscopy (FTIR) and an isotopic labeling method. The atomic intervalstructure between Pt and Ga makes the surface of nanoparticles nonensembled,avoiding the formation of poisonous *CH x and *CO species via bridge-type adsorption of ethanol molecules.Meanwhile, the electron redistribution from Ga to Pt diminishes the*O/*OH adsorption and CO poisoning on Pt atoms, exposing more availablesites for interaction with the C2 intermediates. Furthermore, thedissociation of H2O into *OH is facilitated by the highhydrophilicity of Ga, which is supported by DFT calculations, promotingthe deep oxidation of C2 intermediates. Our work represents an extremelyrare EOR process that produces CO2 without observing kineticlimitations under medium potential conditions.