锂介导的电化学氮还原：提升性能的机理见解
Lithium-mediated electrochemical nitrogen reduction: Mechanistic insights to enhance performance.
作者信息
Cai Xiyang, Fu Cehuang, Iriawan Haldrian, Yang Fan, Wu Aiming, Luo Liuxuan, Shen Shuiyun, Wei Guanghua, Shao-Horn Yang, Zhang Junliang
机构信息
Institute of Fuel Cells, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
出版信息
iScience. 2021 Sep 9;24(10):103105. doi: 10.1016/j.isci.2021.103105. eCollection 2021 Oct 22.
Green synthesis of ammonia by electrochemical nitrogen reduction reaction (NRR) shows great potential as an alternative to the Haber-Bosch process but is hampered by sluggish production rate and low Faradaic efficiency. Recently, lithium-mediated electrochemical NRR has received renewed attention due to its reproducibility. However, further improvement of the system is restricted by limited recognition of its mechanism. Herein, we demonstrate that lithium-mediated NRR began with electrochemical deposition of lithium, followed by two chemical processes of dinitrogen splitting and protonation to ammonia. Furthermore, we quantified the extent to which the freshly deposited active lithium lost its activity toward NRR due to a parasitic reaction between lithium and electrolyte. A high ammonia yield of 0.410 ± 0.038 μg s cm geo and Faradaic efficiency of 39.5 ± 1.7% were achieved at 20 mA cm geo and 10 mA cm geo, respectively, which can be attributed to fresher lithium obtained at high current density.
通过电化学氮还原反应（NRR）绿色合成氨作为哈伯-博施工艺的替代方法显示出巨大潜力，但受到产率低和法拉第效率低的阻碍。最近，锂介导的电化学NRR因其可重复性而重新受到关注。然而，该体系的进一步改进受到对其机理认识有限的限制。在此，我们证明锂介导的NRR始于锂的电化学沉积，随后是两个化学过程，即氮分子分裂和质子化生成氨。此外，我们量化了由于锂与电解质之间的寄生反应，新沉积的活性锂对NRR失去活性的程度。在20 mA cmgeo和10 mA cmgeo时，分别实现了0.410±0.038 μg s cmgeo的高氨产率和39.5±1.7%的法拉第效率，这可归因于在高电流密度下获得的更新鲜的锂。
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