Construction of silver iodide/silver/bismuth tantalate Z-scheme photocatalyst for effective visible light degradation of organic pollutants.

In this work, novel Z-scheme AgI/Ag/Bi3TaO7 photocatalysts with excellent visible light responsive performance were prepared by a facile hydrothermal reaction combined with ultrasonic assisted precipitation-photoreduction process. The samples were characterized by X-ray power diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-absorption spectra, electrochemical impedance spectroscopy (EIS) and photoluminescence (PL). The photocatalytic performance of AgI/Ag/Bi3TaO7 composites was assessed by the decomposition of sulfamethoxazole (SMZ) under visible light irradiation. The experimental results revealed that AgI/Ag/BTO-2 showed the best photocatalytic activity for degradation of SMZ (the apparent rate constant was 212 times as high as that of pure Bi3TaO7). The results also showed that the as-prepared AgI/Ag/Bi3TaO7 sample exhibited high activity for the degradation of other organic pollutants (oxcarbazepine, RhB and X-3B). A probable mechanism on the enhanced photocatalytic performance was put forward based on the results of band structure, radicals trapping tests and ESR. In addition, the implanted metallic Ag acted as charge transfer bridge played an important role in the formation of a stable Z-scheme AgI/Ag/Bi3TaO7 system with powerful redox ability. This study offers a good example for the design and development of new efficient visible light responsive photocatalysts for organic pollutants degradation.