Mixed-metal MIL-101(Fe/Cr) MOF photocatalyst: Efficient photocatalytic nitrogen fixation by promoting ligand-metal charge transfer

Achieving efficient ligand-metal charge transfer remains a significant challenge for constructing high-performance N 2 -fixing MOF photocatalysts. Herein, we successfully fabricated mixed-metal MIL-101(Fe/Cr) materials to achieve ligand-metal charge transfer, leading to significantly improved N 2 fixation performance. Performance test under visible light demonstrated that MIL-101(Fe/Cr) achieved nitrogen fixation activity of 125.19 μmol h −1  g −1 , which is 1.7 times greater than that of pure MIL-101(Fe). The experimental confirm that the incorporation of Cr metal enables the more favorable accumulation of photogenerated electrons at the Fe catalytic centers, attributed to increased electronic interactions and enhanced charge transfer efficiency, thus facilitating the activation process of N 2 , and consequently enhancing ammonia (NH 3 ) production. This work provides new insights into strategies for improving the ligand-metal charge transfer efficiency of MOF-based photocatalytic nitrogen fixation materials.