Iron atom-cluster interactions increase activity and improve durability in Fe-N-C fuel cells.

Wan, Xin; Liu, Qingtao; Liu, Jieyuan; Liu, Shiyuan; Liu, Xiaofang; Zheng, Lirong; Shang, Jiaxiang; Yu, Ronghai et al. · Nat Commun · 2022

basic_science · Level V

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Abstract

Simultaneously increasing the activity and stability of the single-atom active sites of M-N-C catalysts is critical but remains a great challenge. Here, we report an Fe-N-C catalyst with nitrogen-coordinated iron clusters and closely surrounding Fe-N<sub>4</sub> active sites for oxygen reduction reaction in acidic fuel cells. A strong electronic interaction is built between iron clusters and satellite Fe-N<sub>4</sub> due to unblocked electron transfer pathways and very short interacting distances. The iron clusters optimize the adsorption strength of oxygen reduction intermediates on Fe-N<sub>4</sub> and also shorten the bond amplitude of Fe-N<sub>4</sub> with incoherent vibrations. As a result, both the activity and stability of Fe-N<sub>4</sub> sites are increased by about 60% in terms of turnover frequency and demetalation resistance. This work shows the great potential of strong electronic interactions between multiphase metal species for improvements of single-atom catalysts.