Electron Donor Gd-Evoked Pd─OH* Interaction Modulation via Alloying for Enhanced Electrocatalytic Oxygen Reduction

Excessive adsorption of oxygen-containing intermediates during oxygen reduction reactions (ORR) on palladium (Pd)-based materials is a critical factor limiting their catalytic activity. Alloying presents a powerful strategy to overcome this inherent challenge. In this study, the alloying of the low electronegativity lanthanide gadolinium (Gd) with Pd is explored. Pioneering theoretical calculations indicate that Gd, acting as an electron donor, induces charge redistribution between the metals. This process weakens the over-adsorption of OH* intermediates on the Pd surface and reduces the reaction overpotential. Subsequent experiments yield Pd 3 Gd solid-solution nano-alloys supported on conductive carbon black (Pd 3 Gd/C-600), resulting in a 30 mV enhancement in half-wave potential and a 4.5 fold increase in mass activity in an alkaline medium compared to Pd/C-600. Due to its superior performance in ORR, Zn-air batteries utilizing Pd 3 Gd/C-600 cathodes demonstrate remarkable peak power density and stability over 330 h. This study offers valuable insights into the rational design of rare earth alloys and their catalytic chemistry in ORR.