Fabrication of sandwich-structured g-C3N4/Au/BiOCl Z-scheme photocatalyst with enhanced photocatalytic performance under visible light irradiation

A novel sandwich-structured g-C3N4/Au/BiOCl Z-scheme heterojunction with enhanced visible-light-driven photocatalytic activity was successfully fabricated using the reactable ionic liquid (1-methyl-3-[3'-(trimethoxysilyl) propyl] imidazolium chloride) as the template by a facile photoreduction followed by in situ deposition. The samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, scanning electron microscope and ultraviolet-visible diffuse reflectance spectroscopy. The role of Au in this system was discussed during the degradation of rhodamine B and tetracycline and photocatalytic hydrogen evolution under visible light irradiation. The influence of BiOCl dosage on the photocatalytic activity was also systematically investigated. The result found that the photocatalytic activity was improved using the as-fabricated CN/Au/BiOCl Z-scheme heterojunction than g-C3N4 or BiOCl. Besides, the fast separation rate of photogenerated electron-hole pairs and the improved light absorption in visible ranges of CN/Au/BiOCl samples might be related to the fact that the construction of Z-scheme could improve the optical and conductive properties and enhance the final photocatalytic property. From the free radicals trapping experiments, it was found that the photogenerated holes of BiOCl were the predominant active species in the photocatalytic process.