Boosting Photocatalytic Hydrogen Production of Porphyrinic MOFs: The Metal Location in Metalloporphyrin Matters

Fucheng Leng, Hang Liu, Meili Ding, Qipu Lin, Hai-Long Jiang

Index: 10.1021/acscatal.8b00764

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Abstract

Metal-organic frameworks (MOFs) have demonstrated great potentials toward catalysis, particularly in the establishment of structure-property relationship. Herein, an unusual OOP (out-of-plane) porphyrin based MOF, synthesized by controlling the metal ion release with unprecedented In(OH)3 precursor, possesses high stability and exhibits unexpectedly high photocatalytic hydrogen production activity, far surpassing the isostructural in-plane porphyrin-based MOF counterparts. In the MOF structure, indium ions not only form indium-oxo chains but also metalate the porphyrin rings in situ, locating above the porphyrin plane instead of fitting coplanar into the cavity and affording unusual OOP porphyrin. Control experiments demonstrate that the OOP In(III) ions readily detach from the porphyrin rings under light excitation, avoiding the fast back electron transfer and thus greatly improving electron-hole separation efficiency and photocatalytic performance. To our knowledge, this is an unprecedented report on boosting MOF photocatalysis based on the special metalloporphyrin behavior.