Facile synthesis of structurally ordered low-Pt-loading Pd–Pt–Fe nanoalloys with enhanced electrocatalytic performance for oxygen reduction reaction

Abstract

Developing electrocatalysts with high-Pt-utilization efficiency and appropriate surface oxygen affinity through a facile and scalable route is urgently needed for proton exchange membrane fuel cells. Here, SPD-annealing strategy is demonstrated to prepare ordered low-Pt-loading Pd–Pt–Fe nanoalloys with an average particle size of less than 5 nm and excellent electrocatalytic performance. Furthermore, the ORR performances of Pd–Pt–Fe/C nanoalloy catalysts are rationally modified by means of both precise composition control and structural transformation. With an optimal component proportion, the prepared Pd0.75Pt0.25Fe/C catalyst exhibits the most excellent intrinsic activity due to the synergistic interaction of lattice strain and ligand effect. Benefiting from the compressive strain effect induced by the relatively tight arrangement of the ordered structure, the adsorption energy of the intermediate oxygen-containing species is effectively weakened, enabling the Pd0.75Pt0.25Fe/C to obtain enhanced ORR catalytic performance in acidic condition. Notably, compared with the disordered Pd0.75Pt0.25Fe/C, the ordered Pd0.75Pt0.25Fe/C shows an extremely superior stability of 98.5% mass activity retention after 10 000 cycles. This work could provide a facile and versatile approach to constructing the ordered low-platinum electrocatalysts with enhanced ORR properties.