Toward visible-light-assisted photocatalytic nitrogen fixation: A titanium metal organic framework with functionalized ligands

The fixation of atmospheric dinitrogen to ammonia is one of the most essential processes for sustaining life. Since the N N bond in dinitrogen is one of the strongest bonds in chemistry, it remains a grand challenge to develop efficient catalysts for fixation of N 2 under ambient conditions. Herein we report for the first time on visible-light-assisted photocatalytic nitrogen fixation by metal organic framework material at room temperature and pressure. The Ti 3+ species induced by electron transfer from ligand-to-metal charge transfer process provide active sites for N 2 reduction. Furthermore, visible-light-assisted photocatalytic N 2 fixation is achieved by ligands functionalization which extend the light harvesting of the MOF to visible region. The integration of Ti sites and amine-functionalized linkers in NH 2 -MIL-125 (Ti) shows the highest visible light photocatalysis efficiency at a rate of 12.3 μmol g −1  h −1 . This Ti MOF system therefore shows a potential as a new design of combining light-harvesting and catalytic components in a single solid platform for green NH 3 production.