Preparation of Ag@AgCl-doped TiO2/sepiolite and its photocatalytic mechanism under visible light

A cube-like Ag@Ag Cl-doped TiO_2/sepiolite(denoted Ag@Ag Cl–TiO_2/sepiolite) was successfully synthesized via a novel method. X-ray diffraction, scanning electron microscopy, energy dispersion X-ray fluorescence, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and diffuse reflectance ultraviolet–visible spectroscopy were performed to determine the structure and physicochemical properties of Ag@Ag Cl–TiO_2/sepiolite. SEM micrographs revealed that Ag@Ag Cl nanoparticles and TiO_2 film are well deposited on the surface of tube-like sepiolite. As a result, Ag@Ag Cl–TiO_2/sepiolite exhibits a red shift relative to TiO_2/sepiolite. Photocatalytic experiments demonstrated that the dosage of catalysts plays an important role during photocatalysis. The photoelectrochemical activities of Ag@Ag Cl–TiO_2/sepiolite and TiO_2/sepiolite were also investigated. Photocurrent responses confirmed that the ability of Ag@Ag Cl–TiO_2/sepiolite to separate photo-generated electron–hole pairs is stronger than that of TiO_2/sepiolite. Methylene Blue degradation is also improved under alkaline conditions and visible light irradiation because more UOH is produced by visible light excitation.This excellent catalytic ability is mainly attributed to the formed Ag nanoparticles and the Schottky barrier at the Ag/TiO_2 interface. Active species analysis indicated that UO2-and h+are implicated as active species in photocatalysis. Therefore, catalysts are excited to produce abundant electron–hole pairs after they absorb photons in photocatalysis.     

Ag@AgCl催化剂的制备及可见光降解三聚氰胺

在超声波辅助作用下制备了Ag@AgCl可见光催化剂,采用紫外可见分光光度计、扫描电镜(SEM)对该催化剂进行了表征,该催化剂在可见光区有较强的吸收,粒径在微米级.以三聚氰胺为模型化合物测试其可见光催化性能.研究发现,该催化剂在可见光照下,不仅可以使三聚氰胺发生脱氨基反应,而且能使其环结构破坏,但却不能催化氰脲酸降解.通过除氧实验、空穴捕获、顺磁共振等实验测试,对其可能的催化降解机理进行了探讨.