Lithium-mediated electrochemical nitrogen reduction: Mechanistic insights to enhance performance
Xiyang Cai,
Cehuang Fu,
Haldrian Iriawan,
Fan Yang,
Aiming Wu,
Liuxuan Luo,
Shuiyun Shen,
Guanghua Wei,
Yang Shao-Horn,
Junliang Zhang
Affiliations
Xiyang Cai
Institute of Fuel Cells, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
Cehuang Fu
Institute of Fuel Cells, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
Haldrian Iriawan
Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Materials, Imperial College London, London SW7 5RB, UK
Fan Yang
Institute of Fuel Cells, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
Aiming Wu
Institute of Fuel Cells, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
Liuxuan Luo
Institute of Fuel Cells, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
Shuiyun Shen
Institute of Fuel Cells, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
Guanghua Wei
SJTU-Paris Tech Elite Institute of Technology, Shanghai Jiao Tong University, Shanghai 200240, China
Yang Shao-Horn
Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Corresponding author
Junliang Zhang
Institute of Fuel Cells, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; Corresponding author
Summary: 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−1 cm−2 geo and Faradaic efficiency of 39.5 ± 1.7% were achieved at 20 mA cm−2 geo and 10 mA cm−2 geo, respectively, which can be attributed to fresher lithium obtained at high current density.
