Unveiling the Molecular Planarity of Donors in Organic Conjugated Polymers for Efficient Photocatalytic H ₂ O ₂ Production under Visible Light

Conjugated polymers with donor–acceptor structures represent potential catalysts for H2O2 photosynthesis because of their intrinsic charge separation ability, which is mainly dependent on the structural characteristics of the building blocks. However, apart from charge separation ability, charge transfer ability also significantly affects the photocatalytic activity. Herein, the biphenyl (BPH) donor and the 1,4-diphenylbutadiyne (DPB) donor were copolymerized with the dibenzo[b,d]thiophene-S,S-dioxide (BTDO) acceptor, respectively, to synthesize two donor–acceptor polymers. The comparative study uncovered that the molecular planarity of donors significantly affects the photocatalytic activity of polymers. Compared to the BPH donor with a twisted molecular structure, the DPB donor with extended π-conjugation shows higher molecular planarity, which promotes the charge transfer in DPB-BTDO. Thus, DPB-BTDO with a DPB donor shows a much higher H2O2 generation rate of 4.79 mmol h–1 g–1 than BPH-BTDO (0.80 mmol h–1 g–1) with the BPH donor in pure water without sacrificial agents, demonstrating the significant influence of the molecular planarity of donors on photocatalytic H2O2 production.