PtNiFe nanoalloys with co-existence of energy-optimized active surfaces for synergistic catalysis of oxygen reduction and evolution†
Abstract
Platinum nanocatalysts mediated by 3d transition metals show improved activity for the oxygen reduction reaction (ORR) but poor activity for the oxygen evolution reaction (OER). Herein, we report the preparation of a Pt-partially coated PtNiFe nanoalloy electrocatalyst that shows excellent activity for the ORR and OER. For the ORR, the onset potential is +1.02 V, the half-wave potential is +0.95 V, and the mass activity is 0.91 A mgPt−1, 13 times that of commercial Pt/C. For the OER, the overpotential at 10 mA cm−2 is as low as 308 mV. All of this results in a very low ORR–OER overpotential gap of 588 mV, outperforming previously reported bifunctional catalysts in alkaline media. The remarkable bifunctional catalytic performance can be attributed to the co-existence of energy-optimized and synergistic ORR and OER active surfaces on nanoalloys caused by the Pt partially coated core–shell structure, as indicated by density functional theory calculations. This work will promote the development of platinum-based bifunctional electrocatalysts for practical applications in renewable energy storage and conversion.
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