Pd-skin tuned by rare earth rich sublayer for high performance methanol resistance oxygen reduction reaction

Abstract Lanthanide contraction resulting from the increased filling of the f-shell provides a continuous strain control to tune the activities, however, the synthesis of noble-metal and rare earth (RE) alloy remains a world-class challenge. Herein, we demonstrated a class of PdRE alloy with outstanding ORR activity through hydrogen-assisted magnesiothermic reduction, and the PdEr catalyst demonstrated a record high ORR activity among the Pd-based catalysts, showing a mass activity of 1.18 A gPd -1 in acid conditions, 15.7 and 7.4 times higher than that of Pd/C and commercial Pt/C-JM. The PdEr showed remarkable methanol resistance in the electrolyte with 2 M methanol, displaying a half-wave potential of 215 mV more positive and a mass activity 4 orders higher than that of commercial Pt/C-JM. The record high ORR performance of PdRE alloys is attributed to the surface strain and electronic structure modification of the Pd skin by RE elements enriched sublayer and thus tuning the adsorption strength of key intermediates.