Dramatically Enhanced Ambient Ammonia Electrosynthesis Performance by In‐Operando Created Li–S Interactions on MoS 2 Electrocatalyst

• Published in: Advanced energy materials 2019-04, Vol.9 (14)
• Main Authors: Liu, Yanyan, Han, Miaomiao, Xiong, Qizhong, Zhang, Shengbo, Zhao, Cuijiao, Gong, Wanbing, Wang, Guozhong, Zhang, Haimin, Zhao, Huijun
• Format: Article
• Language: English
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.201803935

The Haber‐Bosch process can be replaced by the ambient electrocatalytic N 2 reduction reaction (NRR) to produce NH 3 if suitable electrocatalysts can be developed. However, to develop high performance N 2 fixation electrocatalysts, a key issue to be resolved is to achieve efficient hydrogenation of N 2 without interference by the thermodynamically favored hydrogen evolution reaction (HER). Herein, in‐operando created strong Li–S interactions are reported to empower the S‐rich MoS 2 nanosheets with superior NRR catalytic activity and HER suppression ability. The Li + interactions with S‐edge sites of MoS 2 can effectively suppress hydrogen evolution reaction by reducing H* adsorption free energy from 0.03 to 0.47 eV, facilitate N 2 adsorption by increasing N 2 adsorption free energy from –0.32 to –0.70 eV and enhance electrocatalytic N 2 reduction activity by decreasing the activation energy barrier of the reaction control step (*N 2 → *N 2 H) from 0.84 to 0.42 eV. A NH 3 yield rate of 43.4 μg h −1 mg −1 MoS 2 with a faradaic efficiency (FE) of 9.81% can be achieved in presence of strong Li–S interactions, more than 8 and 18 times by the same electrocatalyst in the absence of Li–S interactions. This report opens a new way to design and develop catalysts and catalysis systems.