Promoting the ORR catalysis of Pt-Fe intermetallic catalysts by increasing atomic utilization and electronic regulation

Abstract

Development of efficient and low cost oxygen reduction reaction (ORR) catalysts through a scalable production method plays a key role in promoting the wide application of fuel cells for electronic vehicles but remains a grand challenge. Here a practicable strategy is proposed for the synthesis of small particle size multimetallic Pt-based intermetallic nanoparticles (NPs) for enhancing ORR catalysis. Benefiting from the specific intermetallic architecture, small particle sizes (less than 5 nm), as well as the tuned electronic structure, the as-prepared supported Mo–PtFe NPs manifest distinct improvement in catalytic activity for ORR than commercial JM Pt/C catalyst in acid medium. The optimized Mo–PtFe/C–H delivers a remarkably increased mass activity of 0.78 A/mgPt, displaying outstanding ORR catalysis among the recently reported PtFe-based intermetallic catalysts. Furthermore, the intermetallic Mo–PtFe/C–H exhibits enhanced catalytic stability with 94.07% retention of initial mass activity and integrity of intermetallic structure after 5000 cycles. A series of comparative experiments show that origin for the exceptional ORR catalysis of Mo–PtFe/C–H originates from the increased amount of catalytically active sites of the small-sized intermetallic NPs and the optimally weakened oxygen binding energy tuned by Mo. This work highlights the universal and scalable synthetic strategy for preparation of small particle size Pt-based intermetallic catalysts for effectively catalyzing ORR in fuel cells.