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

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 H-2/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% H-2/Ar as anode catalyst, has achieved a peak power density of 670 mW cm(-2) (H-2-O-2) and 546 mW cm(-2) (H-2-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 H-2 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 H-2 concentration during synthesis can lower the hydrogen binding energy (HBE), resulting in the enhanced intrinsic HOR catalytic activity of Ni-1% H-2/Ar.

Automated summary

In this study, a Ni@C catalyst with high HOR catalytic activity was successfully synthesized by adjusting the H-2/Ar ratio during calcination. APEFC performance with this catalyst achieved higher peak power density and stable working time.