Tuning Acceptor Length in Photocatalytic Donor-Acceptor Conjugated Polymers for Efficient Solar-to-Hydrogen Energy Conversion

Comprehensive Summary The development of conjugated polymer photocatalysts for efficient solar-to-hydrogen energy conversion is highly desirable for the sustainability of our society. Although the construction of donor-acceptor (D-A) structure in conjugated polymer photocatalysts for solar-to-hydrogen energy conversion has been well documented, less attention has been paid on how large D and how large A units combined together could achieve the best performance. Herein, a series of D-A copolymers P(BDT-DBTSOx) (x = 7, 19, 39, and 79) composed of a benzodithiophene (BDT) donor unit and an oligomeric dibenzo[b,d]thiophene sulfone (DBTSO) acceptor segment were synthesized and studied. It was found that the polymer photocatalytic stabilities under full-arc irradiation improved upon shortening the length of the acceptor segment. Under visible light irradiation and in the presence of 3 wt% Pt cocatalyst, P(BDT-DBTSO79) displayed the best performance with an optimal hydrogen evolution rate of 119.3 +/- 5.8 mmol center dot g(-1)center dot h(-1). This is 1.4-fold as that of DBTSO homopolymer and 22.5-fold as that of BDT/DBTSO alternative copolymer, highlighting the importance of acceptor length in D-A structure for achieving high photocatalytic performance.