2D Benzodithiophene based conjugated polymer/g-C3N4 heterostructures with enhanced photocatalytic activity: Synergistic effect of antibacterial carbazole side chain and main chain copolymerization

Constructing polymer heterojunction (PHJ) has emerged as an alternative to pursue excellent photocatalytic sterilization and contaminant degradation performance. Herein, the antibacterial carbazole unit is employed as the side chain of benzodithiophene. Besides, the main chain copolymerization strategy is adopted to tune the light absorption and exciton dissociation of these 2D donor−acceptor (D−A) conjugated polymer/g-C3N4 PHJ by introducing different A units. Specifically, copolymerizing diketopyrrolopyrrole into P4 drastically bathochromic-shifts the light absorption of the PHJ. By contrast, introducing fluorinated benzotriazole into P9 contributes to achieve the most efficient charge separation. Surprisingly, the P7/g-C3N4 with benzodithiophene-4,8-dione as the A unit reaches the balance between light absorption, charge separation efficiency, and water wettability. Consequently, the P7/g-C3N4 shows the highest photocatalytic activity with over 99.7% antibacterial rates for E. coli and S. aureus and 97.6% degradation rate for Rhodamine B under irradiation for 45 and 90 min, respectively. [Display omitted] •Four 2D benzodithiophene based conjugated polymers are synthesized.•The antibacterial carbazole unit is employed as the side chain of benzodithiophene.•The main chain copolymerization strategy is adopted to broaden the light absorption.•These Px/g-C3N4 are among the most effective PHJs in enhancing the light absorption.•The P7/g-C3N4 with BDD as the acceptor unit possess the best photocatalytic activity.