Synergetic Effects of Random Copolymerization/Backbone Fluorination and Heterojunction of Terpolymer/g‐C₃N₄ Enhance Photocatalytic Hydrogen Evolution

In the field of photocatalytic hydrogen evolution, most polymer heterojunctions (PHJs) exhibit an unsatisfactory hydrogen evolution rate due to the decay of undissociated excitons, charge recombination, and weak light capture capacity. Herein, the design and synthesis of a series of D–A₁–D–A₂‐type random conjugated terpolymers (DIn, n = 1, 2, 3) are reported by copolymerizing fluorinated 2,2′‐bithiophene with different proportions of diketopyrrolopyrrole (DPP) and isoindigo (IID) for efficient vis‐light‐driven hydrogen evolution. Notably, the ternary copolymerization and fluorination strategy in the polymer backbone would enhance the intramolecular interactions and rebuild the extended π‐network over the polymeric heterojunction, which achieve broad and strong absorption ranging from 350 to 900 nm and a better effective photoexcitation separation, thus leading to a significantly increased hydrogen evolution reaction (HER) of 16.01 mmol h⁻¹ g⁻¹, via simply tuning the composition of DPP and IID units in the backbone of random terpolymers. The HER performance is almost 20 times higher than that of the typical g‐C₃N₄. This work offers a new strategy to develop efficient visible‐light‐driven photocatalysts via ternary copolymerization and backbone fluorination strategy of terpolymer/g‐C₃N₄ PHJs for broadband solar photon harvesting.