Simultaneous Gd₂O₃ clusters decoration and O-doping of g-C₃N₄ by solvothermal-polycondensation method for reinforced photocatalytic activity towards sulfamerazine

To improve the visible-light photocatalytic activity of graphitic carbon nitrate (g-C₃N₄) for practical application, a Gd₂O₃-cluster decorated O-doping g-C₃N₄ was fabricated via an ethanol assisted solvothermal-polycondensation method. The as-prepared photocatalysts, including bulk g-C₃N₄ (CN), O-doping g-C₃N₄ (HECN) and Gd₂O₃-cluster decorated O-doping g-C₃N₄ (HECN-xGd), were characterized and the paralleled experiments were conducted to evaluate the photocatalytic activity, mineralization capacity and mineralization mechanism, where sulfamerazine (SMR) was employed as the target pollutant. Furthermore, the quenching tests with scavengers were executed to analyze the contributions of the dominant active species, where the O₂^- was identified as a major role, and h⁺ as the minor role in the photodegradation of SMR. Results from the paralleled experiments suggested that the HECN-xGd possesses superior photocatalytic activity to HECN and CN, besides the feasible reusability through five cycles and impressive total organic carbon (TOC) removal about 60%. And the improved photocatalytic activity of HECN-xGd is ascribed mainly to the oxygen doping and Gd₂O₃ decoration. Herein, oxygen doping optimizes the structure of g-C₃N₄ and expands the light absorption range of HECN, and Gd₂O₃ facilitates the reduction of O₂ into O₂^-, and acts as the separator and transporter for the photo-induced charges.