Molecular engineering of donor-acceptor structured g-C3N4 for superior photocatalytic oxytetracycline degradation

The inherent structural defects of graphitic carbon nitride (g-C3N4), especially low separation efficiency of photogenerated carriers, have greatly limits its photocatalytic degradation ability towards pollutants. Conjugated g-C3N4 (CN) with tailored donor–acceptor units have recently attracted great attention because of the controlled optical bandgap and favorable separation of charge carriers. Here, a novel 5-bromo-2-thiophenecarboxaldehyde (BTC) grafted CN photocatalyst (TCN) was prepared. The results have showed that this new material has significant performance advantages. Up to 2.43-fold apparent rate constant improvement in photocatalytic OTC degradation was realized using TCN-5 compared to CN, and the efficiency for OTC degradation was as high as 93%. And at the end of the reaction (at 60 min), the removal efficiency of TOC was 38%, which should be due to the accelerated the intramolecular charge separation and controllable electron migration. This work unravels intramolecular charge transfer in donor–acceptor structured CN for oxytetracycline photocatalytic degradation, which is expected to bring a promising approach for the photocatalytic degradation of antibiotics.