Polypyrrole reinforced ZIF-67 with modulated facet exposure and billion-fold electrical conductivity enhancement towards robust photocatalytic CO_(2) 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 insitu 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 billionfold 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 CO_(2) reduction. Furthermore, a PPy-mediated electron harvest and relay mechanism is proposed for rationalizing the enhanced photocatalytic performance.

Synthesis and Electrochemistry of Aryl-Substituted Tripyrrinone Copper Complexes. Comparison of Redox Properties to Structurally Related Porphyrins and Corroles

Four awl-substituted tripyrrinone copper（II） complexes were synthesized and characterized as to their electro- chemical and spectroelectrochemical properties. The examined compounds are represented as （YPh）3TPO2Cu, where TPO2 is a dianion of the tripyrrinone and Y is a CH3O, CH3, H or CI substituent on the para-position of each phenyl ring of the compound. The neutral compounds are ESR active and show a typical d9 Cu（II） signal in frozen CH2C12 solution. Each Cu（II） compound undergoes three reductions between -0.61 and -1.90 V and two oxidations between 1.00 and 1.24 V in CH2Cl2 containing 0.1 mol/L tetra-n-butylammonium perchlorate. The potentials for oxidation are similar to those of copper tetraarylporphyrins but the reduction potentials are positively shifted as compared to the corresponding tetraarylporphyrins. Thus, the potential difference between the first one-electron oxidation and first one-electron reduction （the HOMO-LUMO gap） of （YPh）3TPO2Cu, which ranges from 1.68 to 1.75 V, is similar to that of copper corroles （1.73-1.85 V）, but smaller than the separation of 2.30-2.37 V for the copper tetraarylporphyrins under the same solution conditions.