Effect of Reduced Grapheme Oxide in Enhancing the Photocatalytic Activity of β-NaYF<sub>4</sub>:Ho<sup>3+</sup>@TiO<sub>2</sub>

Abstract

β-NaYF 4 :Ho 3+ @TiO 2 -reduced graphene oxide (NYFH@TO-rGO) ternary composites photocatalysts were prepared via a three-step method and used for cleanup of Rhodamine B (RhB) aqueous solution under visible light irradiation. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), fluorescence spectrometries, ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), electron spin resonance (ESR), and photoelectrochemical properties were used to characterize the photocatalyst. The results revealed that rGO as an excellent platform and successfully to load NYFHo@TO core-shell microcrystals. In this photocatalyst, the loading of UC microcrystals is expected to emit UV (290 nm) light after absorbing Vis (450 nm) light of the solar spectrum and the optical response of the rGO is enhanced from UV to Vis. so as to realize the visible light-driven photocatalysis of TiO 2 . It was found that add to rGO can efficient charge separation, extended light absorption range (red-shifted to 402.6 nm), enhanced adsorption performance, and improve photocatalytic activity. This novel tenary photocatalyst can reach decomposition rate of RhB as high as 87% after 10 h of irradiation by visible-light Xe lamp. Compared with the blank experiment, the efficiency was significantly improved. It is of great significance to design an effective solar light-driven photocatalysis in promoting environmental protection.