Boron- and europium-co-doped g-C3N4 nanosheets: Enhanced photocatalytic activity and reaction mechanism for tetracycline degradation

Elemental doping is an effective approach for boosting the light absorption performance, oxidation capacity, and photoinduced carrier separation ability of photocatalysts. Hence, a series of B-doped g-C3N4 (B–CN), Eu-doped g-C3N4 (Eu-CN), and B/Eu-co-doped g-C3N4 (B/Eu-CN) have been prepared through a thermal polymerization synthesis. The B/Eu-CN photocatalyst exhibited optimized photocatalytic performance for tetracycline (TC) degradation, and it possessed a modified lattice structure, enlarged specific surface area, and narrowed band gap, which could enhance light adsorption capacity, provide more active sites to promote the photocatalytic reaction, and accelerate the separation rate of photoinduced charge carriers. Furthermore, the narrower band gap and more rapid separation rate are likely attributed to the formation of the B 1s impurity energy level and E 3d energy level. These properties provided dual channels to generate ·O 2 − and further reacted with H + to produce ·OH, which could accelerate the degradation of TC. The TC degradation rate of B/Eu-CN was 90.8%, which was nearly 2.1 times that of pure CN under visible-light irradiation. This work provided a simple approach for modifying the energy band structure of photocatalysts and proved the reliability of doping methods for degrading antibiotics.