Emerging metal−organic framework-based materials for photocatalytic and electrocatalytic NH3 synthesis: Design principles, structure-activity correlation, and mechanistic insights

Sustainable ammonia (NH3) synthesis through artificial nitrogen fixation has gained significant attention as a promising alternative to the energy-intensive Haber-Bosch process, offering a greener pathway for NH3 production. In particular, to optimize the economic sustainability pathway of NH3 synthesis technology, it is paramount to engineer novel catalysts. Emerging MOFs are a type of lightweight porous network materials with tunable channels, high surface areas, and designable components, which offer intriguing functionalities in photo- and electro-driven N2 reduction reaction (NRR) by lowering reaction potentials and accelerating reaction rates. Although some progress has been achieved in this area, fundamental issues remain to be addressed to better understand the relationship between the structures, properties, catalytic activity, and potential applications of MOF-based catalysts. Herein, based on the comprehensive design concept, the latest advancements in MOF-based material design principle, structural modulation mechanism, and reaction engineering are systematically summarized to elucidate the structure-activity correlations in NRR. It begins with the MOF-based material design principles, which encompass synthesis strategies, material properties, and the transition from laboratory to large-scale continuous production progress. Following that, in terms of structural modulation mechanism, particular emphasis is placed on the analysis of crystal structure, atomic configuration, and electronic properties, aiming to gain a deeper understanding of the transport and reaction processes of charge carriers. Furthermore, the structure-activity correlations and reaction engineering are elaborated for NRR. Finally, a comprehensive analysis of the prospects and challenges associated with MOF-based catalysts in NRR is presented, along with detailed solutions.