Generalized Encapsulations of ZIF-Based Fe-N-C Catalysts with Controllable Nitrogen-Doped Carbon for Significantly-Improved Stability Toward Oxygen Reduction Reaction

The vigorous development of efficient platinum group metal-free catalysts is considerably important to facilitate the universal application of proton exchange membrane fuel cells. Although nitrogen-coordinated atomic iron intercalated in carbon matrix (Fe-N-C) catalysts exhibit promising catalytic activity, the performance in fuel cells, especially the short lifetime, remains an obstacle. Herein, a highly-active Fe-N-C catalyst with a power density of >1 w cm(-2) and prolonged discharge stability with a current density of 357 mA cm(-2) after 40 h of constant voltage discharge at 0.7 V in H-2-O-2 fuel cells using a controllable and efficient N-C coating strategy is developed. It is clarified that a thicker N-C coating may be more favorable to enhance the stability of Fe-N-C catalysts at the expense of their catalytic activity. The stability enhancement mechanism of the N-C coating strategy is proven to be the synergistic effect of reduced carbon corrosion and iron loss. It is believed that these findings can contribute to the development of Fe-N-C catalysts with high activity and long lifetimes.

Automated summary

The development of efficient platinum group metal-free catalysts is crucial for the widespread application of proton exchange membrane fuel cells. However, the performance and lifespan of nitrogen-coordinated atomic iron intercalated in carbon matrix (Fe-N-C) catalysts are still obstacles. In this study, a highly-active and stable Fe-N-C catalyst is developed using a controllable N-C coating strategy. The stability enhancement is achieved through reduced carbon corrosion and iron loss. These findings contribute to the development of Fe-N-C catalysts with high activity and long lifetimes.