A modified Z-scheme Er3+:YAlO3@(PdS/BiPO4)/(Au/rGO)/CdS photocatalyst for enhanced solar-light photocatalytic conversion of nitrite

Z-scheme structure is an effectively construction to improve the photocatalytic activity due to the excellent photo-generated electron-hole pairs separation efficiency. In this paper, the Er3+:YAlO3@(PdS/BiPO4)/ (Au/rGO), (Au/rGO)/CdS and modified Z-scheme Er3+:YAlO3@(PdS/BiPO4)/(Au/rGO)/CdS photocatalysts were prepared by hydrothermal, ultrasonic dispersion, deposition-precipitation and ultrasonic-assisted methods. The prepared samples were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectra (DRS), fourier transform infrared spectra (FT-IR), raman spectra and photoluminescence (PL) spectra. The photocatalytic activity of prepared samples were evaluated via photocatalytic conversion rate of nitrite under ultraviolet-light and simulated solar-light irradiations. Due to the enhanced separation efficiency of electron-hole pairs, the Er3+:YAlO3@(PdS/BiPO4)/(Au/rGO)/CdS exhibited excellent performance under both ultraviolet-light and simulated solar-light irradiation, reaching 94.59% and 91.25% conversion rates, respectively. Meanwhile, the effects of simulated solar-light irradiation time and corresponding reaction kinetics on photocatalytic conversion of nitrite were studied. Subsequently, the effects of electron and hole scavengers were investigated to further elaborate the possible mechanism. In addition, the study of used times showed that the prepared modified Z-scheme Er3+:YAlO3@(PdS/BiPO4)/(Au/rGO)/CdS nanocomposites can be effectively recycled without an apparent inactivation on photocatalytic activity. This research may provide a potential way by utilizing solar energy efficiently for converting nitrite and other contaminants released into the environment. (C) 2017 Elsevier B.V. All rights reserved.