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A Highly Efficient Metal‐Free Electrocatalyst of F‐Doped Porous Carbon toward N 2 Electroreduction
Author(s) -
Liu Yan,
Li Qiuyao,
Guo Xu,
Kong Xiangdong,
Ke Jingwen,
Chi Mingfang,
Li Qunxiang,
Geng Zhigang,
Zeng Jie
Publication year - 2020
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201907690
Subject(s) - electrocatalyst , electronegativity , reversible hydrogen electrode , catalysis , inorganic chemistry , materials science , metal , carbon fibers , lewis acids and bases , electrochemistry , chemistry , electrode , working electrode , organic chemistry , metallurgy , composite material , composite number
N 2 electroreduction into NH 3 represents an attractive prospect for N 2 utilization. Nevertheless, this process suffers from low Faraday efficiency (FE) and yield rate for NH 3 . In this work, a highly efficient metal‐free catalyst is developed by introducing F atoms into a 3D porous carbon framework (F‐doped carbon) toward N 2 electroreduction. At −0.2 V versus reversible hydrogen electrode (RHE), the F‐doped carbon achieves the highest FE of 54.8% for NH 3 , which is 3.0 times as high as that (18.3%) of pristine carbon frameworks. Notably, at −0.3 V versus RHE, the yield rate of F‐doped carbon for NH 3 reaches 197.7 µg NH3 mg −1 cat. h −1 . Such a value is more than one order of magnitude higher than those of other metal‐free electrocatalysts under the near‐ambient conditions for NH 3 product to date. Mechanistic studies reveal that the improved performance in N 2 electroreduction for F‐doped carbon originates from the enhanced binding strength of N 2 and the facilitated dissociation of N 2 into *N 2 H. F bonding to C atom creates a Lewis acid site due to the different electronegativity between the F and C atoms. As such, the repulsive interaction between the Lewis acid site and proton H suppresses the activity of H 2 evolution reaction, thus enhancing the selectivity of N 2 electroreduction into NH 3 .