Limiting the Uncoordinated N Species in M–Nx Single‐Atom Catalysts toward Electrocatalytic CO2 Reduction in Broad Voltage Range

• Published in: Advanced materials (Weinheim) 2022-06, Vol.34 (25), p.e2104090-n/a
• Main Authors: Xi, Dawei, Li, Jiayi, Low, Jingxiang, Mao, Keke, Long, Ran, Li, Jiawei, Dai, Zehui, Shao, Tianyi, Zhong, Yuan, Li, Yu, Li, Zibiao, Loh, Xian Jun, Song, Li, Ye, Enyi, Xiong, Yujie
• Format: Article
• Language: English
• Subjects: Carbon; Carbon dioxide; Chemical reduction; CO 2 reduction; Dopants; Electric potential; electrocatalysis; joule heating; Materials science; N species; Nitrogen; Ohmic dissipation; Resistance heating; Selectivity; single atom; Single atom catalysts; Voltage
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202104090

Carbon‐supported single‐atom catalysts (SACs) are extensively studied because of their outstanding activity and selectivity toward a wide range of catalytic reactions. Amidst its development, excess dopants (e.g., nitrogen) are always required to ensure the high loading content of SACs on the carbon support. However, the use of excess dopants is accompanied by formation of miscellaneous structures (particularly the uncoordinated N species) on catalysts, leading to adverse effects on their performance. Herein, the synthesis of carbon‐supported Ni SACs with precisely controlled single‐atom structure via joule heating strategy, showing the coordination of 80% of N dopants with metal elements, is reported. The preclusion of the unfavorable N species is confirmed to be the main reason for the superior performance of optimized Ni SACs in electrocatalytic carbon dioxide reduction reaction, which demonstrates unprecedented activity, selectivity, and stability under an exceptionally broad voltage range (>92% CO selectivity in the range of −0.7 to −1.9 V reversible hydrogen electrode). Such a synthetic strategy is further applicable for the design of SACs with various metals. This work demonstrates a facile method for preclusion of unfavorable dopants in the SACs and its importance in catalytic application. Single‐atom catalysts (SACs) supported on nitrogen‐doped carbon may contain miscellaneous structures on the support, leading to misinterpretations of catalytic behavior. Here the Ni–Nx SACs in which 80% of N dopants are coordinated with Ni atoms are synthesized via joule heating to demonstrate unprecedented activity, selectivity, and stability toward electrocatalytic CO2 reduction in a broad voltage range.