Advances in catalysts and reaction systems for electro/photocatalytic ammonia production

Ammonia is a vital component in the fertilizer and chemical industries, as well as serving as a significant carrier of renewable hydrogen energy. Compared with the industry’s principal technique, the Haber-Bosch method, for ammonia synthesis, electro/photocatalytic ammonia synthesis is increasingly recognized as a viable and ecofriendly alternative. This method enables distributed small-scale deployment and can be powered by sustainable renewable energy sources. However, the efficiency of electro/photocatalytic nitrogen reduction reaction is hindered by the challenges in activating the N≡N bond and nitrogen’s low solubility, thereby limiting its large-scale industrial applications. In this review, recent advancements in electro/photocatalytic nitrogen reduction are summarized, encompassing the complex reaction mechanisms, as well as the effective strategies for developing electro/photocatalytic catalysts and advanced reaction systems. Furthermore, the energy efficiency and economic analysis of electro/photocatalytic nitrogen fixation are deeply discussed. Finally, some unsolved challenges and potential opportunities are discussed for the future development of electro/photocatalytic ammonia synthesis.