Porphyrin Conjugated Polymer with Periodic Type II-Like Heterojunctions and Single-Atom Catalytic Sites for Broadband-Responsive Hydrogen Evolution

A novel heterometallic Zn-/Co-porphyrin conjugated polymer (ZnCoP-F CP) with its Co-porphyrin bridging unit bearing two perfluorophenyls is synthesized via a Sonogashira coupling reaction. The resulting ZnCoP-F CP without the Pt cocatalyst exhibits broadband (UV-vis-NIR) light-driven hydrogen evolution activity of 83 mu mol h(-1), which is more than twice that (39 mu mol h(-1)) of its counterpart (ZnCoP CP) with the Co-porphyrin unit bearing two phenyls. Furthermore, an apparent quantum yield of 6.92%, 5.50%, 5.78%, 3.17%, and 0.73% is achieved from the ZnCoP-F CP illuminated at 400, 500, 550, 700, and 850 nm monochromatic light, respectively. The enhanced performance of ZnCoP-F CP can be attributed to the high electron-withdrawing capacity of its perfluorophenyls and the highly dispersed Co centers in Co-porphyrin bridging units serving as single-atom catalytic sites (CoN4), which facilitate the formation of periodic type II-like heterojunctions and the fast charge transfer from Zn-porphyrin to Co-porphyrin units for hydrogen evolution reaction. The broadband-responsive feature is due to the large pi-conjugated system through the whole 2D internal framework of the porphyrin polymer. This work opens a new path to fabricate porphyrin-based polymer with an efficient and broadband-responsive hydrogen evolution system.

Automated summary

A novel heterometallic Zn-/Co-porphyrin conjugated polymer (ZnCoP-F CP) with a Co-porphyrin bridging unit bearing two perfluorophenyls is synthesized via a Sonogashira coupling reaction. The enhanced performance of ZnCoP-F CP is attributed to the high electron-withdrawing capacity of its perfluorophenyls and the highly dispersed Co centers in Co-porphyrin bridging units. Broadband-responsive feature of ZnCoP-F CP is due to the large pi-conjugated system throughout the 2D internal framework of the porphyrin polymer.