Preparation of sponge carrier supported photocatalyst by self-assembly technique for phenol photodegradation in visible light

Abstract

The up-conversion luminescence agent Er3+:YAlO3 could up-convert visible light to ultraviolet light which could then be absorbed by the synthesized photocatalyst that contained TiO2. Accordingly, we successfully prepared the visible light responsive photocatalyst Er3+:YAlO3/TiO2 hybrid composites by the sol-gel technique and hydrothermal treatment at different temperatures in the range of 90–170°C. Subsequently, a novel self-assembly technique was used to coat a thin and even layer of Er3+:YAlO3/TiO2 hybrid composites on the sponge-type carriers. The prepared composites were characterized by various techniques, such as X-ray diffraction, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectra and Fluorescence spectra. The phenol (50mgL−1) was used as the model pollutant to compare the degradation by the Er3+:YAlO3/TiO2-coated carriers with four different coating ratios (10, 20, 30 and 40gL−1). The corresponded phenol removal efficiencies were 90.2%, 97.6%, 78.4% and 58.0% in 8h, respectively, which were much higher than that for the pristine sponge (26.5%) under visible light irradiation. On the basis of these experimental results, a possible photocatalytic mechanism over the sponge carrier supported photocatalyst was suggested to explain the phenol photodegradation.