Platinum single atom anchoring on nano-MOF/tubular carbon nitride enabled nitrogen activation and multiple electron transfer for photocatalytic nitrogen fixation.

Photocatalytic nitrogen fixation offers a sustainable pathway for green ammonia synthesis under mild conditions, yet its practical application is hindered by the inefficient charge separation and insufficient active sites of conventional photocatalysts. Herein, we present a rationally engineered heterostructure comprising Pt single atoms (PtSAs) on nano metal-organic frameworks (MOF-74)/hollow double-shelled tubular CN (TCN), which addresses these limitations through synergistic effects. The Z-scheme heterojunction formed between MOF-74 and TCN establishes a built-in electric field, facilitating directional electron transfer from MOF-74 to PtSAs-modified TCN. PtSAs anchored through PtN coordination on TCN act as efficient electron traps, effectively suppressing charge carrier recombination. Furthermore, the nanoscale MOF-74 (<20 nm) enhances N adsorption by quantum confinement effects, thereby addressing the challenge of limited active sites. The photocatalytic ammonia generation rate of optimized Pt@MOF/TCN composite achieved a high ammonia production rate of 544.91 μmol g h under visible light illumination, which surpasses most reported photocatalysts. This study provides novel insights into the fundamental design principles of high-efficiency photocatalysts through atomic-level engineering and heterostucture construction.