The Effect of Surface Site Ensembles on the Activity and Selectivity of Ethanol Electrooxidation by Octahedral PtNiRh Nanoparticles

Direct ethanol fuel cells are attractive power sources based on a biorenewable, high energy‐density fuel. Their efficiency is limited by the lack of active anode materials which catalyze the breaking of the C−C bond coupled to the 12‐electron oxidation to CO2. We report shape‐controlled PtNiRh octahedral ethanol oxidation electrocatalysts with excellent activity and previously unachieved low onset potentials as low as 0.1 V vs. RHE, while being highly selective to complete oxidation to CO2. Our comprehensive characterization and in situ electrochemical ATR studies suggest that the formation of a ternary surface site ensemble around the octahedral Pt3Ni1Rhx nanoparticles plays a crucial mechanistic role for this behavior. It's the shape, that matters: The efficient and complete electrooxidation of ethanol at low overpotentials has been a prime research target for a long time. The unique combination of a ternary Pt‐Ni‐Rh ensemble on defined octahedral {111} facets now shows promising activity coupled with good selectivity in this transformation.