Coupling Atomically Dispersed Fe–N<sub>5</sub> Sites with Defective N‐Doped Carbon Boosts CO<sub>2</sub> Electroreduction
Li Zhao, Jinxia Jiang, Ximeng Liu, Zhaozhao Zhu, Junjie Wang, Qian He, Qingquan Kong, Xiaobin Niu, Jun Song Chen, John Wang, Rui Wu, John Wang, Rui Wu
Abstract
Abstract Atomically dispersed iron immobilized on nitrogen‐doped carbon catalyst has attracted enormous attention for CO 2 electroreduction, but still suffers from low current density and poor selectivity. Herein, atomically dispersed FeN 5 active sites supported on defective N‐doped carbon successfully formed by a multistep thermal treatment strategy with the aid of dicyandiamide are reported. This dual‐functional strategy can not only construct intrinsic carbon defects by selectively etching pyridinic‐N and pyrrolic‐N, but also introduces an additional N from the neighboring carbon layer coordinating to the commonly observed FeN 4 , thus creating an FeN 5 active site supported on defective porous carbon nanofibers (FeN 5 /DPCF) with a local 3D configuration. The optimized FeN 5 /DPCF achieves a high CO Faradaic efficiency (>90%) over a wide potential range of −0.4 to −0.6 V versus RHE with a maximal FE CO of 93.1%, a high CO partial current density of 9.4 mA cm −2 at the low overpotential of 490 mV, and a remarkable turnover frequency of 2965 h −1 . Density functional theory calculations reveal that the synergistic effect between the FeN 5 sites and carbon defects can enhance electronic localization, thus reducing the energy barrier for the CO 2 reduction reaction and suppressing the hydrogen evolution reaction, giving rise to the superior activity and selectivity.