Structure evolution of thiophene-containing conjugated polymer photocatalysts for high-efficiency photocatalytic hydrogen production

Conjugated polymer photocatalysts have received extensive attention in the field of photocatalytic hydrogen evolution owing to their tunable molecular structures and electronic properties. Herein, we developed three donor-acceptor (D-A) type thiophene-containing narrow-band-gap conjugated polymers with pyrene as a donor and different fused-thiophene derivatives as acceptors via direct C-H arylation coupling polymerization. It was found that the band gap of the polymers can be tuned by adjusting the number of the fused-thiophene rings. The visible light absorption range can be extended by increasing the number of the thiophene rings, the planar molecular structure for both donor and acceptor units facilitates the charge transmission along the polymer skeleton, and the D-A type polymer structure promotes the dissociation of photo-induced electrons and holes. As a result, a high photocatalytic hydrogen evolution rate of 33.07 mmolh−1 g−1 was obtained by PyTP-2 with an optimized molecular structure under visible light irradiation (λ > 420 nm) without the aid of Pt co-catalyst. In addition, PyTP-2 also shows a photocatalytic activity for oxygen evolution with an average oxygen evolution rate of 58.37 µmolh−1 g−1.