Structure Dynamics of Carbon-Supported Platinum-Neodymium Nanoalloys during the Oxygen Reduction Reaction

Platinum-rare earth nanoalloys have been predicted tobe promisingproton exchange membrane fuel cell (PEMFC) electrocatalysts for thecathodic oxygen reduction reaction (ORR). However, their implementationin PEMFCs is limited by the challenge of their preparation as carbon-supportednanostructures. Consequently, the practical structure-activity-stabilitytrends for this class of nanoalloys remain largely unexplored. Herein,carbon-supported Pt-Nd nanoalloys as ORR electrocatalysts aredescribed. The physical chemistry of selected electrocatalysts wasextensively investigated by means of combined ex situ and operando techniques, which reveal the uniquestructural dynamics of Pt-Nd nanoalloys in a simulated PEMFCcathode environment. The experimental observations, supported by theoreticalcalculations, indicate that after initial significant structural modificationin the early stage of operation, the ORR activity is mediated in thelonger term by surface compressive strain rather than charge transferbetween Pt and Nd. Such key operando structure-activity-stabilityrelations underpin further optimization of carbon-supported Pt-rareearth nanoalloys as fuel cell cathode catalysts.