Encapsulation of Single Iron Sites in a Metal-Porphyrin Framework for High-Performance Photocatalytic CO2 Reduction

Efficient CO2 reduction with earth-abundant photocatalysts is a highly attractive but very challenging process for chemists. Herein, we synthesized an indium-porphyrin framework, In(H2TCPP)((1-n))[Fe(TCPP)(H2O)]((1-n))[DEA]((1-n))(In-FenTCPP-MOF; H2TCPP = tetrakis(4-benzoic acid)porphyrine; DEA = diethylamine), with a porphyrin ring supporting the single-site iron for the high-performance visible-light-driven conversion of CO2 to CO. A high CO yield of 3469 mu mol g(-1) can be achieved by a 24 h photocatalytic reaction with a high CO selectivity (ca. 99.5%). This activity was much higher than that of its cobalt analogues or the Fefree indium-based metal-organic framework (MOF). Systematic experimental and theoretical studies indicate that the porphyrin-supported iron centers in the MOF matrix serve as efficient active sites, which can accept electrons from the photoexcited MOFs in order to mediate CO2 reduction.