Low-Coordination Trimetallic PtFeCo Nanosaws for Practical Fuel Cells.

Abstract

Developing high-performance catalysts for fuel cell catalysis is the most critical and challenging step for the commercialization of fuel cell technology. Here 1D trimetallic platinum-iron-cobalt nanosaws (Pt₃ FeCo NSs) with low-coordination features are designed as efficient bifunctional electrocatalysts for practical fuel cell catalysis. The oxygen reduction reaction (ORR) activity of Pt₃ FeCo NSs (10.62 mA cm^-2 and 4.66 A mg^-1 _Pt at 0.90 V) is more than 25-folds higher than that of the commercial Pt/C, even after 30 000 voltage cycles. Density functional theory calculations reveal that the strong inter-d-orbital electron transfer minimizes the ORR barrier with higher selectivity at robust valence states. The volcano correlation between the intrinsic structure featured with low-coordination Pt-sites and corresponding electronic activities is discovered, which guarantees high ORR activities. The Pt₃ FeCo NSs located in the membrane electrode assembly (MEA) also achieve very high peak power density (1800.6 mW cm^-2 ) and competitive specific/mass activities (1.79 mA cm^-2 and 0.79 A mg^-1 _Pt at 0.90 V_iR-free cell voltage) as well as a long-term lifetime in specific H₂ O₂ medium for proton-exchange-membrane fuel cells, ranking top electrocatalysts reported to date for MEA. This work represents a class of multimetallic Pt-based nanocatalysts for practical fuel cells and beyond.