Recent advances in electrocatalytic reduction of nitrate-to-ammonia: current challenges, resolving strategies, and future perspectives

Abstract

Generating ammonia (NH3) through electrocatalytic nitrate reduction reaction (NO3−RR) holds great significance for the development and progress of modern society since it avoids the high-energy-consumption matterof the Haber-Bosch (H-B) processfor NH3 synthesis while eliminatingthe over-enriched nitrate in the environment and promoting the natural nitrogen cycle. Recently, the efficient synthesis of NH3 via NO3−RR as emerged as a hot research topic. Up to now, the electrocatalytic mechanism and the reaction design in NO3−RR are widely researched, yet there is still a lack of in-depth understanding of the correlation among them, hindering the realization and promotion of stable and efficient NO3−RR. Hence, this review firstly provides an in-depth investigation of the theoretical mechanism of electrocatalytic nitrate reduction, aiming to reveal the origin of the difficulties faced during the reaction from the theoretical level. The review then summarizes the solving thoughts for a number of practical problems, deepening the correlation between theories and applications, and laying a solid theoretical foundation for the following solution strategies discussion. Finally, this review systematically outlines the various measures and considerations for efficient electrochemical ammonia production, as well as further prospects for the development of NH3 synthesis. Overall, this review aims to elucidate the logic of NO3−RR processes, clarify the developing lineage from theoretical mechanism to actual reaction to further improve the research system, thereby providing a systematic guidance for the subsequent advanced electrocatalytic nitrate-to-ammonia.