Recent advances of structure-performance relationship and improvement methods of catalysts for photochemical and electrochemical reduction of nitrogen to green ammonia

As zero-carbon artificial ammonia synthesis technologies for nitrogen fixation, eNRR (electrocatalytic nitrogen reduction reaction) and pNRR (photocatalytic nitrogen reduction reaction) are receiving more and more attention, in which NRR catalysts play a crucial role with significant potential. Herein, The NRR mechanism including nitrogen adsorption, activation, electron migration, and hydrogenation, eNRR & pNRR experiment system, and the basic properties, structure-performance relationship and advanced improvement design of NRR catalysts are reviewed. Metal-based catalysts including Fe, Mo, Bi, Ti, Ru, Au, Ag, Ce, Zn, Sn and so on, have an advantage in nitrogen adsorption, nitrogen activation and ammonia selectivity. In addition to being catalyst support, non-metallic materials can also have certain NRR activity, such as g-C3N4 and graphene, especially with vacancy design and modification. Besides, the photoelectric and catalytic performance can be further improved by synthesize composite catalysts to produce heterojunction structure. This review aims to assist academia to understand the research progress of NRR technology and catalyst and provide ideas for innovating more promising and high-performance NRR catalysts.