Alleviating O-Intermediates Adsorption Strength over PdRhCu Ternary Metallene via Ligand Effect for Enhanced Oxygen Reduction in Practical PEMFCs

Expediting the torpid kinetics of the acidic oxygen reduction reaction (ORR) is a crucial yet formidable challenge toward advancing proton exchange membrane fuel cells (PEMFCs) for commercialization. The cutting-edge Pd-based nanomaterials for acidic ORR are hindered by their low intrinsic activities and significant CO poisoning, stemming from the challenge of simultaneously optimizing surface adsorption toward various adsorbates. Herein, we introduce an ultrathin PdRhCu ternary metallene (PdRhCu metallene) for boosting acidic ORR in PEMFC. Mechanistic studies have identified that the incorporation of Cu into the PdRh configuration could downshift the d-band center on Pd to promote weakened the adsorption of key intermediates, ensuring efficient electron transfer between the PdRhCu ternary metal sites and the adsorbates, thereby lowering the energy barriers of the rate-determining step in ORR. As a proof-of-concept, the optimized PdRhCu metallene demonstrates impressive ORR performance with a high half-wave potential (0.93 V_RHE), negligible activity decay after 10 000 cycles, and superior anti-CO-poisoning capacity compared to counterparts and commercial Pt/C catalysts. Intriguingly, the PdRhCu metallene-assembled PEMFC achieves an impressive maximum power density of 820 mW cm^-2 with high electrocatalytic stability under the H₂/air conditions, paving avenues for further advancements in metallene electrocatalyst engineering toward the practical implementation of PEMFCs.