Progress of solar photo-thermo-catalysis for ammonia synthesis and decomposition under mild conditions

With the advantages of high hydrogen storage capacity and easy liquefaction, ammonia has emerged as a hydrogen carrier to solve the bottlenecks in hydrogen storage and transportation, providing support for the construction of a green ammonia-hydrogen industrial chain featuring “clean ammonia synthesis→safe and low-cost ammonia storage and transportation→carbon-free ammonia-hydrogen utilization”. Traditional thermocatalytic ammonia synthesis and decomposition are limited by high energy consumption and harsh reaction conditions, while photocatalysis struggles to meet industrial demands due to low solar-to-chemical conversion efficiency. Solar photo-thermo-catalysis offers a breakthrough solution for efficient ammonia synthesis and decomposition under mild conditions. This technology couples the photothermal effect of long-wave photons with the photoelectric effect of short-wave photons, fundamentally changing the reaction pathway and mechanism of solar light-thermal-chemical conversion. It achieves a “1+1>2” synergistic effect, jointly enhancing catalytic activity from both reaction kinetics and thermodynamics, effectively reducing reaction temperature, improving solar energy utilization, and ensuring the efficient and economical conversion of solar energy into chemical energy. This review focuses on four mechanisms: photo-assisted thermocatalysis (PATC), photo-driven thermocatalysis (PDTC), Thermo-assisted photocatalysis (TAPC), and photo-thermal co-catalysis (PTCC), systematically analyzing the corresponding synergy principles, catalyst design strategies, and performance enhancement laws in ammonia synthesis and decomposition. It also discusses key challenges in current research and future development trends, providing theoretical foundations for the application of photo-thermo-catalytic technology in the field of ammonia-hydrogen energy.