Facile synthesis of Br-doped g-C3N4 nanosheets via one-step exfoliation using ammonium bromide for photodegradation of oxytetracycline antibiotics

Graphitic carbon nitride (g-C3N4) was suggested since it enables the oxidation process under visible light irradiation. To enhance the photocatalytic activity of g-C3N4 (BCN) it is essential to exfoliate bulk g-C3N4 to the nanosheets form via a one-step exfoliation method, which was used to prepare g-C3N4 nanosheets with Br (CNN-Br) or Cl (CNN-Cl) doping by using melamine and ammonium salts. The final production yield reached 52% and the specific volume of CNN-Br was eight times compared to BCN. The Cl and Br doping of g-C3N4 was changed to increase the light absorbance in the visible-light region and to slightly decrease the bandgap energy of the samples. Additionally, the photocurrent densities of the CNN samples were enhanced compared with that of BCN. We evaluated the photocatalytic performance of the resultant nanosheets for the photodegradation of oxytetracycline under visible-light irradiation. The results showed that the Br or Cl doping of g-C3N4 and the nanosheet structure had synergetic effects, namely enhancing the absorbance in the visible-light region, the efficiency of photoinduced charge carriers, and the charge-separation capability. These improvements are useful for the photocatalytic degradation of antibiotics.