In Situ Grown AgI/Bi12O17Cl2 Heterojunction Photocatalysts for Visible Light Degradation of Sulfamethazine: Efficiency, Pathway, and Mechanism

Visible-light-driven photocatalysts attract great interest because they can utilize more sunlight for reactions than conventional photocatalysts. A novel visible-light-driven photocatalyst AgI/Bismuth oxychloride (Bi12O17Cl2) hybrid was synthesized by a hydrothermal-precipitation method. Several characterization tools, such as X-ray powder diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and UV–vis diffuse reflectance spectroscopy (DRS) were employed to study the phase structures, morphologies, and optical properties of the fabricated photocatalysts. These characterizations indicated that AgI nanoparticles were evenly distributed on the surface of Bi12O17Cl2, and heterostructures were formed. The photochemical characterizations demonstrated that the promoted separation of carrier transfer in the AgI/Bi12O17Cl2 heterojunction was achieved. The degradation rate of sulfamethazine (SMZ) by AgI/Bi12O17Cl2 was about 7.8 times and 35.2 times higher than that of pristine Bi12O17Cl2 and BiOCl under visible-light-driven photocatalysts, respectively. It was also found that the amount of AgI in the AgI/Bi12O17Cl2 composites played an important role in photocatalytic activity, and the optimized ratio was 25%. The AgI/Bi12O17Cl2 shows good catalytic stability and maintains similar reactivity after four cycles. Furthermore, the degradation intermediates of SMZ were identified by HPLC-MS, and the photocatalytic mechanism was proposed. These findings highlight the role of Bi12O17Cl2 on contaminant elimination and open avenues for the rational design of highly efficient photocatalysts.