Progress in electrocatalytic nitrate reduction for green energy: Catalyst engineering, mechanisms, and techno-economic feasibility

Ammonia (NH3) is an irreplaceable chemical that has been widely demanded to keep the sustainable development of modern society. However, its industrial production consumes a huge amount of energy and releases extraordinary greenhouse gases (GHG’s), leading to various environmental issues. To achieve the green production of ammonia is a great challenge that has been extensively pursued recently. In the review, the most promising strategy, electrochemical nitrate reduction reaction (e-NO3RR), is comprehensively investigated to give a complete understanding of its development and mechanism and provide guidance for future directions. However, owing to the complex reactions and limited selectivity, a good understanding of the mechanisms is crucial to further development and commercialization. Moreover, NO3−RR is a promising strategy for water treatment and NH3 production. A detailed overview of the recent progress in NO3−RR for NH3 production with non-transition and transition metal electrocatalysts is summarized. In addition, critical advanced techniques, future challenges, and prospects are discussed to guide future research on transition metal catalysts for commercial NH3 synthesis by NO3− reduction.