Medium-Entropy Amorphous Alloyed Single-Atom Pd Catalysts for Direct Ethylene Glycol Fuel Cells.

Abstract

Precise regulation of the d-band center of palladium (Pd) for targeted electrocatalysis held tremendous scientific and technological potential, yet achieving this via rational structural design remained challenging. Herein, we present medium-entropy amorphous alloyed single-atom (MEAASA) Pd nanosheets (NSs), wherein the d-band center of Pd was delicately modulated to an optimal value via the synergistic effect of medium-entropy alloying, single-atom coordination, and oxyphilic Cr/Mo/W modification. The as-synthesized PdCrMoW MEAASA NSs exhibited exceptional mass activities of 2.15 and 15.19 A mg^- ¹ for the oxygen reduction reaction (ORR) and ethylene glycol oxidation reaction (EGOR), respectively, which were 15.4 and 4.4 times higher than those of commercial Pt/C. Experimental results suggested that the optimized d-band center not only balanced the adsorption and activation of key intermediates but also suppressed CO formation via a non-CO dominated pathway, enabling a 4 e^- ORR process and a nearly complete 10 e^- EGOR process with 91.5% C1 selectivity. In practical direct ethylene glycol fuel cells (DEGFCs), the PdCrMoW MEAASA NSs delivered a peak power density of 117 mW·cm^- ², markedly outperforming the state-of-the-art commercial Pt/C catalyst.