Enhanced Visible-Light Photocatalytic Activity and Mechanism of Ag@AgCl-Decorated TiO 2 Nanotubes
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https://doi.org/10.1007/s11664-020-08552-6 Ó 2020 The Minerals, Metals & Materials Society
Enhanced Visible-Light Photocatalytic Activity and Mechanism of Ag@AgCl-Decorated TiO2 Nanotubes ZHENG ZHANG,1 CHANGSHENG FENG,1 CAIYUN JIANG,2 and YUPING WANG1,3 1.—School of Chemistry and Material Science, Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, Nanjing Normal University, Nanjing 210023, China. 2.—Department of Engineering and Technology, Jiangsu Institute of Commerce, Nanjing 211168, China. 3.—e-mail: [email protected]
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. Key words: Ag@AgCl, TiO2 nanotubes, heterojunction, nitrobenzoic acid, photocatalysis
INTRODUCTION Photocatalytic oxidation has been demonstrated to be prominently superior for decomposition of pollutants that are toxic and difficult to treat using general biochemical methods.1 Titanium dioxide (TiO2), as one of the semiconductor materials with photocatalytic properties, had attracted widespread attention from researchers due to its advantages
(Received July 2, 2020; accepted October 7, 2020) Zheng Zhang and Changsheng Feng contributed equally to this work.
such as a suitable energy band potential, nontoxic and harmless nature, low cost, ready availability, good photoelectric conversion efficiency, and chemical stability.2–4 However, titanium oxide can only be activated by light in the ultraviolet region, which accounts for only 3% to 5% of solar energy. In addition, photogenerated electrons and holes with slow transfer rates result in a low quantum efficiency for TiO2. Compared with particles, titanium dioxide nanocrystalline spheres, titanium dioxide nanorods, and tita
