Hierarchically mesoporous carbon spheres coated with a single atomic Fe-N-C layer for balancing activity and mass transfer in fuel cells

Novel cost-effective fuel cells have become more attractive due to the demands for rare and expensive platinum-group metal (PGM) catalysts for mitigating the sluggish kinetics of the oxygen reduction reaction (ORR). The high-cost PGM catalyst in fuel cells can be replaced by Earth-abundant transition-metal-based catalysts, that is, an Fe-N-C catalyst, which is considered one of the most promising alternatives. However, the performance of the Fe-N-C catalyst is hindered by the low catalytic activity and poor stability, which is caused by insufficient active sites and the lack of optimization of the triple-phase interface for mass transportation. Herein, a novel Fe-N-C catalyst consisting of mono-dispersed hierarchically mesoporous carbon sphere cores and single Fe atom-dispersed functional shells are presented. The synergistic effect between highly dispersed Fe-active sites and well-organized porous structures yields the combination of high ORR activity and high mass transfer performance. The half-wave potential of the catalyst in 0.1 M H2SO4 is 0.82 V versus reversible hydrogen electrode, and the peak power density is 812 mW center dot cm(-2) in H-2-O-2 fuel cells. Furthermore, it shows superior methanol tolerance, which is almost immune to methanol poisoning and generates up to 162 mW center dot cm(-2) power density in direct methanol fuel cells.

Automated summary

The article introduces a novel Fe-N-C catalyst consisting of mono-dispersed hierarchically mesoporous carbon sphere cores and single Fe atom-dispersed functional shells. A synergistic effect between highly dispersed Fe-active sites and well-organized porous structures yields a combination of high ORR activity and high mass transfer performance.