Research progress on structural regulation of nitrogen-fixing photocatalysts.

Photocatalytic nitrogen fixation is a forward-looking technology for zero-carbon nitrogen fixation, which is crucial for alleviating the energy crisis and achieving carbon neutrality. Based on research into the structural regulation of nitrogen-fixing photocatalysts, this review summarizes the latest progress and challenges in photocatalytic ammonia synthesis from three dimensions: active sites, crystal structures, and composite structures. In terms of active site construction, common types of active sites, including metal sites, non-metal sites, vacancies, and single atoms, are discussed. Their characteristics and methods for improving photocatalytic nitrogen fixation performance are analyzed. Furthermore, starting from the mechanism of nitrogen activation, a general strategy for active sites to promote the electron exchange process and thereby enhance nitrogen activation efficiency is explored. In terms of crystal structure construction, the design of nitrogen-fixing photocatalysts is described from three perspectives: crystal form, crystal facet, and morphology control. In terms of composite structure construction, this review discusses the key role of structures such as semiconductor-metal composites and semiconductor-semiconductor composites in promoting carrier separation. It is hoped that this review can provide new insights for the design and preparation of efficient nitrogen-fixing photocatalysts and inspire practical applications of photocatalytic nitrogen fixation.