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

Generating ammonia (NH3) through the electrocatalytic nitrate reduction reaction (NO3-RR) holds great significance for the development and progress of modern society since it avoids the high energy consumption and emission for industrial NH3 synthesis while eliminating nitrate pollution in the environment. Recently, the process routes for NH3 synthesis by NO3-RR that align with the concept of green and sustainable development have been widely reported. As a result, a rich variety of technological advances have been accumulated in both the basic research and practical application fields of NO3-RR. However, these individual technological advances often lack systematic summarization, which hinders their dissemination and application in NO3-RR systems. Hence, this review first 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 at the theoretical level. The review then summarizes the theoretical solution 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 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 developmental lineage from theoretical mechanism to actual reaction to further improve the research system, and thereby provide systematic guidance for subsequent advanced electrocatalytic nitrate-to-ammonia conversion.