Photocatalytic conversion of nitrite in aqueous solution over nanocomposite photocatalyst Er3+:Y3Al5O12/BiPO4 using different photosources

Three crystal phases of BiPO 4 (HBIP, nMBIP and mMBIP), corresponding photocatalysts (Er 3+ :Y 3 Al 5 O 12 /HBIP, Er 3+ :Y 3 Al 5 O 12 /nMBIP and Er 3+ :Y 3 Al 5 O 12 /mMBIP) and their nanocomposite photocatalyst (Er 3+ :Y 3 Al 5 O 12 /(H-nM-mM)BIP) were prepared by hydrothermal, ultrasonic dispersion and liquid boiling methods. The prepared photocatalysts were characterized by X-ray diffractometer (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and UV–vis diffuse reflectance spectra (DRS). The catalytic activity of prepared photocatalysts was evaluated via photocatalytic conversion rate of nitrite under ultraviolet-light, visible-light and simulated solar-light irradiations. These three photocatalysts all exhibited excellent performance under simulated solar-light irradiation and reached 85.36%, 84.42% and 78.53% conversion rates, respectively, for Er 3+ :Y 3 Al 5 O 12 /mMBIP, Er 3+ :Y 3 Al 5 O 12 /nMBIP and Er 3+ :Y 3 Al 5 O 12 /HBIP. Particularly, Er 3+ :Y 3 Al 5 O 12 /(H-nM-mM)BIP was also found to play a high catalytic activity, resulting in 78.68%, 70.04% and 82.57% conversion rates, respectively, under ultraviolet-light, visible-light and simulated solar-light irradiation. In addition, the study of used times showed that the prepared photocatalysts can be effectively recycled without an apparent inactivation on the photocatalytic activity. This research may provide a potential way for converting nitrite and other contaminants by utilizing solar energy efficiently.