Solvent‐in‐Gas System for Promoted Photocatalytic Ammonia Synthesis on Porous Framework Materials

Photocatalytic nitrogen reduction reaction (PNRR) is emerging as a sustainable ammonia synthesis approach to meet global carbon neutrality. Porous framework materials with well‐designed structures have great opportunities in PNRR; however, they suffer from unsatisfactory activity in the conventional gas‐in‐solvent system (GIS), owing to the hindrance of nitrogen utilization and strong competing hydrogen evolution caused by overwhelming solvent. In this study, porous framework materials are combined with a novel “solvent‐in‐gas” system, which can bring their superiority into full play. This system enables photocatalysts to directly operate in a gas‐dominated environment with a limited proton source uniformly suspended in it, achieving the accumulation of high‐concentrated nitrogen within porous framework while efficiently restricting the solvent‐photocatalyst contact. An over eightfold increase in ammonia production rate (1820.7 µmol g−1 h−1) compared with the conventional GIS and an apparent quantum efficiency as high as ≈0.5% at 400 nm are achieved. This system‐level strategy further finds applicability in photocatalytic CO2 reduction, featuring it as a staple for photosynthetic methodology. Conventional gas‐in‐solvent reaction systems for photocatalytic nitrogen reduction suffer from unsatisfactory activity, since the overwhelming protic solvent severely hinders the nitrogen transfer and causes strong competing hydrogen evolution. In this work, a novel “solvent‐in‐gas” system, which enables direct operation of photocatalyst under a nitrogen gas‐dominated environment with limited proton source, is designed to fundamentally solve the above problem.