A novel Z-scheme sonocatalyst system, Er3+:Y3Al5O12@Ni(Fe0.05Ga0.95)2O4-Au-BiVO4, and application in sonocatalytic degradation of sulfanilamide

Guowei Wang, Siyi Li, Xue Ma, Jing Qiao, Guanshu Li, Hongbo Zhang, Jun Wang, Youtao Song

Index: 10.1016/j.ultsonch.2018.03.010

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Abstract

A novel Z-scheme coated composite, Er3+:Y3Al5O12@Ni(Fe0.05Ga0.95)2O4-Au-BiVO4, was designed for sonocatalytic degradation of sulfanilamide and fabricated by sol-hydrothermal and calcination methods. The prepared sample was characterized by X-ray diffractometer (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), UV-vis diffuse reflectance spectra (DRS), fourier transform infrared (FT-IR) spectra, Raman spectra and photoluminescence (PL) spectra. In Er3+:Y3Al5O12@Ni(Fe0.05Ga0.95)2O4-Au-BiVO4, Ni(Fe0.05Ga0.95)2O4 and BiVO4 form a Z-scheme sonocatalytic system, Er3+:Y3Al5O12 as an up-conversion luminescence agent (from visible-light to ultraviolet-light) provids the ultraviolet-light for satisfying the energy demand of wide band-gap Ni(Fe0.05Ga0.95)2O4 and Au nanoparticles as co-catalyst forms more active sites to enrich electrons. Also, Au nanoparticles as conductive channels promotes the electrons (e–) from conduction band of BiVO4 to transfer to valence band of Ni(Fe0.05Ga0.95)2O4. Due to the characteristics of valence state diversity, the Fe3+ and V5+ constitute a redox reaction recombination system, which can also push electrons (e–) on conduction band of BiVO4 to quickly transfer to valence band of Ni(Fe0.05Ga0.95)2O4. The sonocatalytic activity of Er3+:Y3Al5O12@Ni(Fe0.05Ga0.95)2O4-Au-BiVO4 nanocomposite was detected through degradation of sulfanilamide under ultrasonic irradiation. A high sonocatalytic degradation ratio (95.64%) of sulfanilamide can be obtained when the conditions of 10.00 mg/L sulfanilamide, 1.00 g/L Er3+:Y3Al5O12@Ni(Fe0.05Ga0.95)2O4-Au-BiVO4, 300 min ultrasonic irradiation and 100 mL total volume were adopted. Some factors such as ultrasonic irradiation time and cycle number on the sonocatalytic degradation efficiency are also investigated by using TOC and UV-vis spectroscopy. Subsequently, the effects of hydroxyl radicals (•OH) and hole scavengers were investigated to elaborate the mechanism. The researches show that the prepared Z-scheme Er3+:Y3Al5O12@Ni(Fe0.05Ga0.95)2O4-Au-BiVO4 coated composite displayed an excellent sonocatalytic activity in degradation of sulfanilamide under ultrasonic irradiation. © 2017 Elsevier B.V. All rights reserved.