Enhanced Visible-Light Photocatalytic Activity and Mechanism of Ag@AgCl-Decorated TiO2 Nanotubes

This paper describes the excellent photocatalytic and photoelectrochemical performance of Ag@AgCl/TiO2 nanotubes (Ag@AgCl/TNTs) that were successfully prepared by a simple multistep reaction route. Using AgNO3 as Ag source and HCl as Cl source, AgCl was loaded onto synthetic TNTs by a coprecipitation method, and some of the Ag+ on the nanotubes was reduced to Ag0 by a photoreduction method. The crystal structure, morphology, and properties of the materials were characterized by x-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) measurements, x-ray photoelectron spectroscopy (XPS), ultraviolet–visible (UV–Vis) spectrophotometry, and photoluminescence (PL) techniques. The effects of using different ratios of Ag@AgCl on the photocatalytic performance of the composites were investigated via degradation of o-nitrobenzoic acid (o-NBA). The results showed that the optimum doping ratio of Ag@AgCl was 40%, and the removal rate of o-NBA by 40%Ag@AgCl/TNTs (40%AC/T) was 3.68 and 5.76 times higher compared with TNTs under visible light, respectively. When Ag@AgCl was loaded on TiO2 nanotubes, the mechanism of activity enhancement of the prepared material can be regarded as the surface plasmon resonance (SPR) effect of Ag0, which enhanced the response of the material to visible light, effectively achieving separation of photogenerated electrons and holes.