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Unveiling Synergistic Effects of Interstitial Boron in Palladium-Based Nanocatalysts for Ethanol Oxidation Electrocatalysis

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journal contribution
posted on 2020-08-05, 18:33 authored by Lizhi Sun, Hao Lv, Yaru Wang, Dongdong Xu, Ben Liu
Alloying is one of the most promising routes for tuning the physicochemical properties of noble metal-based nanocatalysts and thus improving their (electro)­catalytic performance. Despites numerous achievements, bimetallic and trimetallic nanoalloys have still been thoroughly studied for the past two decades. In this study, metalloid boron (B) was alloyed within palladium (Pd)-based nanocatalysts to promote the electrochemical ethanol oxidation reaction (EOR) in alkaline media. The optimum PdCuB nanocatalyst exhibited remarkable electrochemical EOR activity (5.83 A mgPd–1) and good operation stability (both cycling and chronoamperometric studies). Mechanistic studies in both pure KOH and a KOH/ethanol mixture attributed superior EOR performance to positive synergistic effects of B in Pd-based nanocatalysts that kinetically accelerated the removal of poisoning ethoxy intermediates (the rate-determining step of EOR). They included (i) an electronic effect that changed the electronic structure of Pd and thus weakened the adsorption of poisoning ethoxy intermediates, (ii) a bifunctional effect that facilitated the adsorption of OHads and thus kinetically accelerated the further oxidation of poisoning intermediates, and (iii) a structural effect in which smaller B interstitially inserted into Pd-based nanocrystals and thus suppressed the physical Ostwald ripening processes.

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