UV-visible and near-infrared active NaGdF4:Yb:Er/Ag/TiO2 nanocomposite for enhanced photocatalytic applications

Abstract

A near infra-red (NIR) active NaGdF₄:Yb:Er/Ag/TiO₂ nanocomposite photocatalyst was successfully synthesized by a one-pot thermal decomposition method. The composite structure, morphology and elemental mapping of the synthesized NaGdF₄:Yb:Er/Ag/TiO₂ nanocomposite were characterized by X-ray diffraction and transmission electron microscopy analysis. The energy transfer among NaGdF₄:Yb:Er, Ag, and TiO₂ was revealed by upconversion photoluminescence measurements at 980 nm. The Ag and NaGdF₄ nanoparticles enhanced the visible and NIR light absorption property of the NaGdF₄:Yb:Er/Ag/TiO₂ nanocomposite. The NIR and UV-visible light induced photocatalytic study of the NaGdF₄:Yb:Er/Ag/TiO₂ composite was examined by rhodamine B degradation. The energy transfer among NaGdF₄:Yb:Er, Ag, and TiO₂ significantly influenced the photocatalytic activity under NIR irradiation. The catalysts produced oxidative species during NIR irradiation, which are responsible for the photocatalytic degradation of rhodamine B. NaGdF₄:Yb:Er/Ag/TiO₂ showed photocatalytic activity under NIR and UV-visible radiation (full solar irradiation), which is superior to a UV or visible light active photocatalyst. The study provided a UV-visible and NIR-responsive photocatalyst and its energy transfer mechanism.