A Universal Strategy for Boosting Hydrogen Evolution Activity of Polymer Photocatalysts under Visible Light by Inserting a Narrow-Band-Gap Spacer between Donor and Acceptor

It is challenging for polymer photocatalysts to achieve high photocatalytic performance under visible light due to their weak light absorption in visible light region. Herein, a universal strategy for boosting the photocatalytic activity of donor-acceptor (D-A) conjugated polymer photocatalysts upon visible light irradiation by inserting a pi-spacer of thiophene unit between the electron donors and acceptors to form a D-pi-A molecular structure is reported. The introduction of thiophene unit with narrow band gap can enhance the conjugation degree of the polymer chains and extend the light absorption range. Meanwhile, the introduction of thiophene spacer through ternary copolymerization also enables the controllability on the chemical structure of the resulting D-pi-A polymers by altering the feed ratio between the electron donors and acceptors. The optimized D-pi-A copolymer photocatalyst shows an impressive hydrogen evolution rate (HER) of 78.4 mmol h(-1) g(-1) under visible light irradiation, and the HER could be further improved to 127.9 mmol h(-1) g(-1) under UV-vis light irradiation by loading 1 wt% Pt co-catalyst. More importantly, this strategy can also be extended to other polymeric photocatalysts with different donor and acceptor units, demonstrating the universality for enhancing the photocatalytic activity of polymeric photocatalysts.