Branch-Regulated Palladium-Antimony Nanoparticles Boost Ethanol Electro-oxidation to Acetate

Tuning the composition and morphology of bimetallic nanoparticles (NPs) offers an effective strategy to improve their electrocatalytic performance. In this work, we present a facile wet-chemistry procedure to engineer PdSb NPs with controlled morphology. Spherical or branched NPs are produced by tuning the heterogeneous nucleation of Sb on Pd seeds. Compared with pure Pd NPs, the incorporation of Sb not only decreases the amount of Pd used but also results in a significant increase of activity and stability for the electrocatalytic ethanol oxidation reaction (EOR). Best performances are obtained with highly branched PdSb NPs, which deliver a specific activity of 109 mA cm^-2 and a mass activity of up to 2.42 A mg_Pd^-1, well above that of a commercial Pd/C catalyst and branched Pd NPs. Moreover, PdSb displays significant stability enhancement of over 10 h for the EOR measurements. Density functional theory calculations reveal that the improved performance of PdSb NPs is related to the role played by Sb in reducing the energy barrier of the EOR rate-limiting step. Interestingly, as a side and value-added product of the EOR, acetate is obtained with 100% selectivity on PdSb catalysts.