Polypyrrole reinforced ZIF-67 with modulated facet exposure and billion-fold electrical conductivity enhancement towards robust photocatalytic CO2 reduction

The implementation of metal organic frameworks (MOFs) as the co-catalysts in hybrid photocatalytic systems puts requirements on both their charge-carrying capability and solvent stability. In the current study, in order to simultaneously promote the electrical conductivity and water stability of ZIF-67, an in situ monomer trapping strategy is deployed to synthesize polypyrrole (PPy)-reinforced ZIF-67 ensembles. Through coordination modulation, the incremental addition of pyrrole monomers enables to alter the crystal morphology of ZIF-67 from rhombic dodecahedra to truncated rhombic dodecahedra, and further to cubes. Upon polymerization, the resulted composite, in comparison to ZIF-67, demonstrates a billion fold conductivity enhancement, much improved chemical stability in pronated solvents, as well as largely retained specific surface area and porosity, enabling it functioning as an outstanding co-catalyst for catalyzing robust photocatalytic CO2 reduction. Furthermore, a PPy-mediated electron harvest and relay mechanism is proposed for rationalizing the enhanced photocatalytic performance. (C) 2021 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.