Solvent-Free Photoreduction of CO2 to CO Catalyzed by Fe-MOFs with Superior Selectivity

It is deemed as a desired approach to utilize solar energy for the conversion of CO2 into valuable products, and the majority of the MOFs-based photocatalytic reductions of CO2 have focused on formic acid (HCOOH) production with an organic solvent as the reaction medium. Herein, we report a solvent-free reaction route for the photoreduction of CO2 catalyzed by Fe-MOFs, namely, NH2-MIL-53­(Fe) [(Fe­(OH)­(NH2–BDC)]•G, NH2-MIL-88B­(Fe) [Fe3O­(H2O)3(NH2–BDC)3]­Cl•G, and NH2-MIL-101­(Fe) [Fe3O­(H2O)3(NH2–BDC)3]­Cl•G (NH2–BDC = 2-aminoterephthalic acid; G = guest and/or solvent molecules). Compared with the orthodox reaction route, the present out-of-the-way photocatalytic reduction of CO2 with superior selectivity to CO occurs at the gas–solid interface. The reaction procedure is environmentally friendly and provides a possibility to address the CO2 emission problem. Importantly, NH2-MIL-101­(Fe) shows the highest photocatalytic activity among these Fe-MOFs due to its efficient charge separation and electron transfer.