Sulfur-doped graphene for efficient electrocatalytic N2-to-NH3 fixation

• Published in: Chemical communications (Cambridge, England) Vol. 55; no. 23; pp. 3371 - 3374
• Main Authors: Li, Xia, Yang, Jiajia, Wang, Huanbo, Zhao, Runbo, Chen, Hongyu, Fang, Weihai, Asiri, Abdullah M, Xie, Fengyu, Cui, Ganglong, Sun, Xuping
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 2019
• Subjects: active sites; Ammonia; Carbon; Catalysis; chemical reactions; Chemical reduction; Density functional theory; electrodes; energy; Energy consumption; Fixation; Graphene; hydrochloric acid; hydrogen; nitrogen; Sulfur
• DOI: 10.1039/c9cc00602h
• ISSN: 1359-7345; 1364-548X

Industrial NH3 synthesis mainly relies on the carbon-emitting Haber–Bosch process operating under severe conditions. Electrocatalytic N2-to-NH3 fixation under ambient conditions is an attractive approach to reduce energy consumption and avoid direct carbon emission. In this communication, sulfur-doped graphene (S-G) is proposed as an efficient and stable electrocatalyst to drive the nitrogen reduction reaction (NRR) under ambient conditions. In 0.1 M HCl, this S-G attains a remarkably large NH3 yield of 27.3 μg h−1 mgcat.−1 and a high Faradaic efficiency of 11.5% at −0.6 and −0.5 V vs. a reversible hydrogen electrode, respectively, much higher than those of undoped G (6.25 μg h−1 mgcat.−1; 0.52%). Density functional theory calculations reveal that carbon atoms close to substituted sulfur atoms are the underlying catalytic active sites for the NRR on S-G, and the related NRR mechanism is also explored.