Main group metal elements for ambient-condition electrochemical nitrogen reduction

Electrocatalytic N-2 reduction under ambient-condition is considered to be the most appealing strategy to the conventional Haber-Bosch process for synthetic ammonia to alleviate greenhouse emissions and reduce environmental pollution, mainly powered by renewable energy. Recent years, rapid advances have been gained in this attractive research field, and numerous electrocatalysts have been exploited. However, its conversion efficiency is still far behind the requirement of industrial applications owing to the breakage of the N equivalent to N triple bond, which is an energetically challenging kinetically complex multistep reaction and the strong competing reaction of hydrogen evolution reaction. Recently, main group metal-based catalysts have been demonstrated promising application prospect for ammonia production, significantly boosting their further application in this field. However, a comprehensive review of main group metal-based catalysts towards electrochemical ammonia production applications is still lacking. In this review, the fundamentals of N-2 reduction, such as the reaction pathways, the reaction potential and the challenges of N-2 reduction have been comprehensively discussed. And then, the role, mechanism, and effect of each main group element-based catalysts used for N-2 reduction (Li, K, Al, Ga, Sn, Sb, Bi, and their compounds) are systematically summarized. Finally, several state-of-the-art strategies to promote their NRR catalytic performance, as well as the existing problems and prospects are put forward. This review is expected to guide the design and establishment of more efficient electrocatalytic N-2 reduction systems based on main group metal elements in the future. (C) 2021 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

Electrocatalytic N-2 reduction has the potential to reduce greenhouse gas emissions and environmental pollution, but faces challenges in conversion efficiency. Main group metal-based catalysts show promising prospects for ammonia production, but a comprehensive review of their applications in electrochemical ammonia production is still lacking.