Recent Progress and Future Outlook on Catalysts for Ammonia Electrosynthesis: Materials, Structural Design, and Reaction Efficiency

With the increasing demand for downstream ammonia products, research on ammonia fuel has received growing attention. Therefore, under the “dual carbon” context, it is crucial to develop an energy-efficient and environmentally friendly method for ammonia synthesis. Current research indicates that electrocatalytic ammonia synthesis is one of the most promising methods. This study systematically summarizes the three major factors influencing electrocatalytic nitrogen reduction reaction (eNRR) catalysts for ammonia synthesis: material optimization, structural design, and reaction engineering. In terms of materials, precious-metal-based, non-precious-metal-based, and metal-free eNRR catalysts are classified and listed. By examination of the properties and catalytic effects of various metals and non-metals in electrocatalytic ammonia synthesis, the materials with the highest catalytic activity can be further identified. To enhance catalytic efficiency, various structural strategies, such as vacancy creation, doping, interface engineering, facet engineering, and changes in the size and morphology of active sites, have been summarized. By integration of electrocatalytic reactions, including microscale nitrogen activation, proton transfer, and electron transfer, the reaction efficiency of electrocatalytic nitrogen reduction for ammonia synthesis was discussed in depth. Finally, the urgent issues that need to be addressed in the current electrocatalytic nitrogen reduction synthesis of ammonia were discussed, and unique insights for future development were provided. This review aims to provide innovative ideas for the design of eNRR catalysts to improve the rate and selectivity of electrocatalytic nitrogen reduction for ammonia synthesis and provide unique insights for the future development of catalysts.