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

• Published in: Journal of energy chemistry 2021-09, Vol.60, p.202-208
• Main Authors: Yuan, Xuzhou, Mu, Qiaoqiao, Xue, Songlin, Su, Yanhui, Zhu, Yanlei, Sun, Hao, Deng, Zhao, Peng, Yang
• Format: Article
• Language: English
• Subjects: Coordination modulation; Electrical conductivity; Photocatalytic CO2 RR; Polypyrrole; ZIF-67
• ISSN: 2095-4956
• DOI: 10.1016/j.jechem.2020.12.025

A novel strategy is deployed to synthesize the ZIF-67 reinforced with polypyrrole (ZIF-67@PPy) where pyrrole monomer modulates the crystal morphology of ZIF-67. The ZIF-67@PPy demonstrated improved catalytic activity and stability for photocatalytic CO2 reduction. [Display omitted] 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.