Pyrazine‐linked Iron‐coordinated Tetrapyrrole Conjugated Organic Polymer Catalyst with Spatially Proximate Donor‐Acceptor Pairs for Oxygen Reduction in Fuel Cells
Yang Wang, Minghao Wang, Ting Chen, Weisheng Yu, Hongfei Liu, Cheng Han, Wentuan Bi, Min Zhou, Yi Xie, Changzheng Wu
Abstract
Abstract Nitrogen‐coordinated iron (Fe−N 4 ) materials represent the most promising non‐noble electrocatalysts for the cathodic oxygen reduction reaction (ORR) of fuel cells. However, molecular‐level structure design of Fe−N 4 electrocatalyst remains a great challenge. In this study, we develop a novel Fe−N 4 conjugated organic polymer (COP) electrocatalyst, which allows for precise design of the Fe−N 4 structure, leading to unprecedented ORR performance. At the molecular level, we have successfully organized spatially proximate iron‐pyrrole/pyrazine (FePr/Pz) pairs into fully conjugated polymer networks, which in turn endows FePr sites with firmly covalent‐bonded matrix, strong d‐π electron coupling and highly dense distribution. The resulting pyrazine‐linked iron‐coordinated tetrapyrrole (Pz−FeTPr) COP electrocatalyst exhibits superior performance compared to most ORR electrocatalysts, with a half‐wave potential of 0.933 V and negligible activity decay after 40,000 cycles. When used as the cathode electrocatalyst in a hydroxide exchange membrane fuel cell, the Pz−FeTPr COP achieves a peak power density of ≈210 mW cm −2 . We anticipate the COP based Fe−N 4 catalyst design could be an effective strategy to develop high‐performance catalyst for facilitating the progress of fuel cells.