Rational design of a donor-acceptor structured poly(3-bromothiophene) modified g-C3N4 for enhanced photocatalytic degradation of 2-mercaptobenzothiazole

Donor-acceptor (D-A) structure has gained momentous attention due to its controllable optical band gap and impressive carrier separation performance. The intramolecular charge transfer within photocatalysts could be modulated by constructing a D-A structure, thereby enhancing their performance in degrading pollutants. In our recent research, using poly(3-bromothiophene) (PTh-Br) and dicyandiamide (DCD) as precursors, a series of D-A structures (CN-PTh-Br(x)) based on polythiophene donors and carbon nitride acceptors were obtained by one-pot synthesis for first-time. The density functional theory calculations further demonstrate that PTh-Br segment (an electron donor) donates electrons to tri-s-triazine rings (an electron acceptor). The introduction of electron-rich polythiophene groups and electron-withdrawing Br atoms on carbon nitride skeleton can propel the transfer and separation of holes and electrons. Moreover, the polythiophene groups with high conjugation length can optimize the optical absorption of CN-PTh-Br(x) at 450–600 nm, thus markedly heightening the visible-light utilization efficiency of the materials. The photocatalytic performance of CN-PTh-Br(x) was assessed through the photodegradation of 2-mercaptobenzothiazole (MBT) under visible-light illumination. The photodegradation performance of CN-PTh-Br(0.5) stood out among all the samples, demonstrating a remarkable ability to remove 99.8 % of MBT within 45 min.