Pyrene- and 1,3,5-triazine-based D–A two-dimensional polymers for sunlight-driven hydrogen evolution: the influence of the linking pattern?

Polymer Chemistry Pub Date: 2022-09-22 DOI: 10.1039/D2PY00807F

Abstract

Conjugated microporous polymers (CMPs) have been widely used as photocatalysts for water splitting to produce hydrogen. Appropriate design of the CMP structure is a key factor for enhancing the efficiency of photocatalytic hydrogen evolution. Herein, we report two pyrene and 2,4,6-triphenyl-1,3,5-triazine-based conjugated microporous polymers (CMPs), TzSPy and TzPy, which were synthesized via Pd-catalyzed Suzuki–Miyaura polymerization. The integration of pyrene with triazine resulted in continuous electron donor–acceptor systems with high photocatalytic hydrogen evolution activity. Although the 1,6-linked TzSPy skeleton possesses a larger torsional angle compared to the 2,7-linked TzPy, it has a higher degree of conjugation and, consequently, can absorb visible light across a broader wavelength range. TzSPy and TzPy exhibited surprising hydrogen evolution rates (HER) of 10.3 mmol g?1 h?1 and 6.93 mmol g?1 h?1, respectively, under simulated sunlight (AM1.5G). DFT calculations and the experimental results of additional four groups of pyrene-based CMPs supported our conclusions that the 1,6-substituted pyrene-based CMPs possess a greater degree of conjugation compared to 2,7-substituted pyrene-based CMPs and thus demonstrate a higher photocatalytic activity.

Graphical abstract: Pyrene- and 1,3,5-triazine-based D–A two-dimensional polymers for sunlight-driven hydrogen evolution: the influence of the linking pattern
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