Dynamic Fe─F Coordination Triggered Structure‐Adaptive Fe–N–C for Efficient Oxygen Reduction Electrocatalysis
Xue Wang, Kai Li, Youze Zeng, Wei Liu, Lanlu Lu, Minhua Shao, Meiling Xiao, Changpeng Liu, Jianbing Zhu, Wei Xing
Abstract
Abstract The sustainable and widespread developments of fuel cells require material innovation toward the sluggish oxygen reduction reaction (ORR). Although iron and nitrogen co‐doped carbon material (Fe–N–C) is a promising alternative to scarce and expensive platinum‐based electrocatalysts, the linear scaling relationships among the intermediates’ adsorption energy limit maximum performance. Herein, we propose a coordination‐adaptive catalyst design to bypass the intrinsic scaling relations through incorporating quasi‐covalent Fe─F bond. Operando experiments and theoretical calculations demonstrate that the cleavage of Fe‐F bond facilitates the activation of O 2 and the formation of OOH*, while the self‐healing of Fe─F bond regulates the binding strength with O* and OH*, thus breaking the OH*‐OOH*/O* scaling relations. As a result, the well‐designed F–Fe–N–C delivers a half‐wave potential ( E 1/2 ) of 0.91 V (versus RHE), along with significantly improved stability with only 2 mV loss in E 1/2 after 80,000 voltage cycles. When applied to the cathode of anion‐exchange membrane fuel cell, F–Fe–N–C exhibits high peak power density of 813 mW cm −2 under H 2 ‐air condition and achieves extremely high current (141 mA cm −2 at 0.9 V iR‐free ) in H 2 –O 2 condition. This work not only offers a promising ORR electrocatalyst but also provides a new strategy to circumvent the fundamental constraint‐linear scaling relationships.