P(3MT-co-F)/modified g-C3N4 Z-scheme heterojunction with improved planarity and charge separation for enhanced visible-light photocatalytic H2 production

Modified graphitic carbon nitride (MCN) was synthesized via calcinating β-alanine introduced melamine supramolecular precursors and poly(3-methylthiophene-co-fluorene) (P(3MT-co-F)) with improved planarity was prepared by polymerization of 3-methylthiophene (3MT) and fluorene (F) monomers. P(3MT-co-F)/MCN heterojunction was constructed by electrostatic self-assembly and the optimal 3P(3MT 1 -co-F 1 )/MCN exhibits excellent H 2 production performance of 11108 μmol h −1  g −1 under visible light, 150 times higher than MCN. The enhancement is attributed to the following aspects: First, F monomer as a rigid unit can regulate the main-chain torsion of P(3MT-co-F), enhancing planarity and facilitating intramolecular charge transport within copolymer. Second, N⋯S interactions and π-π stacking interactions at heterojunction interface improve the charge transfer and separation. Third, the incorporation of P(3MT-co-F) with narrow band gap into MCN not only broadens visible light absorption range and enhances visible light response, but also forms a Z-scheme heterojunction with MCN, further enhancing the charge separation and retaining the electrons with strong reducibility.