Highly efficient and durable H2-etched Ni@C for alkaline polymer electrolyte fuel cells application

Abstract

Completely precious metal-free alkaline polymer electrolyte fuel cells (APEFCs) are hindered by the lack of active non-precious metal hydrogen oxidation reaction (HOR) catalysts. Up to now, few studies have focused on the APEFC performance of non-precious metal HOR catalysts. Herein, upon simply adjusting the H2/Ar ratio during calcination, we synthesized a Ni-core carbon-shell (Ni@C) catalyst that exhibits an electrochemical surface area (ECSA)-normalized exchange current density of 0.090 mA cm−2, the highest among reported Ni-based HOR catalysts. More importantly, APEFC with the optimized catalyst, Ni-1% H2/Ar as anode catalyst, has achieved a peak power density of 670 mW cm−2 (H2–O2) and 546 mW cm−2 (H2-Air CO2-free), higher than the state-of-the-art APEFC with Ni-based HOR catalysts, and can to stably work for 100 h at 200 mA cm−2. Characterization results show that H2 is able to affect the particle size and etch the carbon shell of the catalysts during synthesis, which can boost the apparent HOR catalytic activity. Further experiments reveal that proper H2 concentration during synthesis can lower the hydrogen binding energy (HBE), resulting in the enhanced intrinsic HOR catalytic activity of Ni-1% H2/Ar.