Enhanced visible light photocatalytic activity of a floating photocatalyst based on B–N-codoped TiO2 grafted on expanded perlite

Abstract

Floating photocatalysts of boron–nitrogen codoped TiO₂ grafted on expanded perlite (B–N-TiO₂/EP) were prepared by a facile sol–gel method. The catalysts were characterized by thermogravimetric differential thermal analysis (TG-DTA), X-ray diffraction (XRD), N₂ adsorption–desorption (BET), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectroscopy (UV-vis-DRS). The results showed that by modifying the boron doping content in B–N-TiO₂/EP, we could effectively obtain photocatalysts with a high BET surface area and porosity. Increasing the boron doping contents would inhibit the transformation of anatase TiO₂ to the rutile phase. Compared with N-TiO₂/EP, B–N-TiO₂/EP exhibits an evident red-shift of the absorption band edge and the absorption intensity of the visible region increases obviously. The enhanced RhB photodegradation rate of B_0.57–N-TiO₂/EP could reach 94% after 3 h of visible light irradiation. Moreover, the floating photocatalyst could be easily separated and reused, showing great potential for practical applications in environmental cleanup and solar energy conversion.