Entropy-mediated ultrafine PdSnPtAgBi nanoparticles as a high-performance electrocatalyst with enhanced CO tolerance for alcohol oxidation

Pd-based electrocatalysts are regarded as highly promising candidates for improving the anodic alcohol oxidation reaction in direct alcohol fuel cells (DAFCs). However, their practical deployment is severely hindered by the facile accumulation of poisoning CO* intermediates at the active sites, and their poor CC bond cleavage ability leads to incomplete alcohol oxidation and low catalytic stability. In this study, ultrafine PdSnPtAgBi alloy nanoparticles with an average size of ∼2.63 nm were successfully synthesized via entropy-driven regulation. The higher configurational entropy effectively suppressed phase separation, promoting the formation of a single-phase structure while inhibiting crystal growth. This resulted in a highly dispersed nanostructure with abundant accessible active sites, significantly enhancing alcohol oxidation activity. Experimental and theoretical investigations reveal that Pd and Pt act as direct active centers, while the incorporation of Ag effectively mitigates the adsorption of CO*. Meanwhile, the oxophilic Sn and Bi atoms promote OH* adsorption, thereby accelerating the oxidative removal of intermediates. This synergistic interaction significantly enhances the CO tolerance and overall catalytic robustness of PdSnPtAgBi/C. Owing to the synergetic effect of constituent metals, PdSnPtAgBi/C exhibits remarkable mass activities of 15.02 and 15.40 A mg_Pd+Pt^-1 for the ethanol oxidation reaction (EOR) and ethylene glycol oxidation reaction (EGOR), respectively, in alkaline media which is 19.76- and 20.81-fold enhancements over commercial Pd/C. These findings not only highlight the efficacy of entropy-engineered multimetallic alloys in overcoming the intrinsic limitations of Pd catalysts but also provide a conceptual framework for the rational design of ultrafine Pd-based alloy electrocatalysts for efficient alcohol oxidation.