Optical and photo catalytic characteristics of Ag2S/TiO2 nanocomposite films prepared by electrochemical anodizing and SILAR approach

Abstract

Ag2S decorated titanium oxide nanotubes (Ag2S/NTs) were prepared by electrochemical anodizing and successive ionic layer adsorption and reaction (SILAR) approach. The prepared samples were characterized by X-ray diffraction, field emission scanning electron microscopy coupled with energy dispersive X-ray analysis and diffuse reflectance spectroscopy. SEM results indicate titanium oxide nanotubes (NTs) with 90–220 nm in diameter and 15–30 nm in wall thickness were prepared by one-step anodizing method on the surface of titanium foils. Characterization of the Ag2S/NTs samples indicated that the number of SILAR cycles influenced the morphology of fabricated films. The degradation of rhodamine B was used as a model reaction to evaluate the photo catalytic activity of the obtained samples. Results showed that the photo catalytic activity of Ag2S/NTs nanocomposite samples is higher than that with bare NTs sample. The incorporation of Ag2S on NTs improves the photo catalytic activity due to the synergetic effect. Ag2S/NTs nanocomposite sample prepared by SILAR deposition with 2 cycles gives the highest degrading rate, which can be attributed to appropriate Ag2S content and high surface area of this sample. Ag2S/NTs nanocomposites are easy to be recycled and have good stability for repeated use. With the improved visible light degradation performance, Ag2S/NTs samples would be expected to be used in water purification. Since these prepared electrodes can be easily removed and replaced after the photo catalytic reaction, avoiding the filtration step after photoreaction or the immobilizing process required for photo catalyst particles, the operation in the photo-reactor becomes much easier from an engineering point of view.