Engineering green ammonia photoproduction from nitrogen: Advances, challenges and perspectives

Green ammonia, produced by harnessing renewable solar energy to split nitrogen, plays a pivotal role in both agricultural practices and forthcoming energy configurations, driving the sustainable development of human society with zero-carbon emissions. However, nitrogen photoreduction currently faces the challenges of poor activation ability and low yield, and it is still challenging to unravel the intertwined problems in this field and provide direction for its development due to the complex reaction mechanism and multidisciplinary aspects such as photochemistry, catalysis, interface science, and technology. This review focuses on capturing the latest advances in photocatalytic nitrogen-to-ammonia conversion, delving into fundamental principles regarding the process, efficient photocatalysts for practical ammonia synthesis, and well-designed catalytic environments. Besides, this article provides insightful guidelines for analyzing complicated reaction mechanisms and identifying key bottlenecks or specific rate-determining steps, such as reactant activation, interfacial reaction engineering, and hydrogen evolution side reactions. By integrating perspectives from atomic mechanisms, nanoscale photocatalysts, microscale interfacial engineering, and macroscale reaction system design, this review advances the development of nitrogen photoreduction from proof-of-concept discoveries to viable solar-to-chemical conversion technologies, while also providing a valuable entry point for researchers into this burgeoning field.