中国科技大学陈维团队报道了破坏铁单个原子局部电荷对称性用于高效电催化硝酸盐还原氨。相关研究成果发在2023年7月22日出版的《德国应用化学》。

硝酸盐污染物电化学转化为增值氨是实现人工氮循环的可行途径。然而，高过电位和低法拉第效率阻碍了电催化硝酸盐对氨还原反应（NO₃-RR）的发展。

该文中，研究人员开发了一种在空心碳多面体（表示为Fe-N/P-C）上与氮和磷配位的铁单原子催化剂作为NO₃-RR催化剂电极。由于磷原子对打破单Fe原子催化剂局部电荷对称性的调节作用，它促进了NO₃-RR过程中硝酸根离子的吸附和一些关键反应中间体的富集。Fe-N/P-C催化剂表现出90.3%的氨法拉第效率，产率为17980μg h^-1 mgcat^-1，大大优于已报道的铁基催化剂。

此外，操作SR-FTIR光谱测量揭示了基于在不同施加电势和反应持续时间下观察到的关键中间体的反应途径。密度泛函理论计算表明，NO₃-RR中间体的最佳自由能归因于不对称原子界面构型，从而实现了最佳的电子密度分布。

该项工作证明了单原子上杂原子掺杂对NO₃-RR的增强作用，并为提高单原子催化剂在不同电化学反应中的催化性能提供了一种有效的策略。

附：英文原文

Title: Breaking Local Charge Symmetry of Iron Single Atoms for Efficient Electrocatalytic Nitrate Reduction to Ammonia

Author: Jingwen Xu, Shengbo Zhang, Hengjie Liu, Shuang Liu, Yuan Yuan, Yahan Meng, Mingming Wang, Chunyue Shen, Qia Peng, Jinghao Chen, Xiaoyang Wang, Li Song, Ke Li, Wei Chen

Issue&Volume: 2023-07-22

Abstract: The electrochemical conversion of nitrate pollutants into value-added ammonia is a feasible way to achieve artificial nitrogen cycle. However, the development of electrocatalytic nitrate-to-ammonia reduction reaction (NO3-RR) has been hampered by high overpotential and low Faradaic efficiency. Here we develop an iron single-atom catalyst coordinated with nitrogen and phosphorus on hollow carbon polyhedron (denoted as Fe-N/P-C) as a NO3-RR catalyst electrode. Owing to the tuning effect of phosphorus atoms on breaking local charge symmetry of the single-Fe-atom catalyst, it facilitates the adsorption of nitrate ions and enrichment of some key reaction intermediates during the NO3-RR process. The Fe-N/P-C catalyst exhibits 90.3% ammonia Faradaic efficiency with a yield rate of 17980 μg h-1 mgcat-1, greatly outperforming the reported Fe-based catalysts. Furthermore, operando SR-FTIR spectroscopy measurements reveal the reaction pathway based on key intermediates observed under different applied potentials and reaction durations. Density functional theory calculations demonstrate that the optimized free energy of NO3-RR intermediates is ascribed to the asymmetric atomic interface configuration, which achieves the optimal electron density distribution. This work demonstrates the enhanced function of heteroatom doping on single atoms for NO3-RR, and provides an effective strategy for improving the catalytic performance of single atom catalysts in different electrochemical reactions.

DOI: 10.1002/anie.202308044

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202308044