The Synthesis of a Core-Shell Photocatalyst Material YF(3):Ho(3+)@TiO(2) and Investigation of Its Photocatalytic Properties

In this paper, YF(3):Ho(3+)@TiO(2) core-shell nanomaterials were prepared by hydrolysis of tetra-n-butyl titanate (TBOT) using polyvinylpyrrolidone K-30 (PVP) as the coupling agent. Characterization methods including X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) under TEM, X-ray photoelectron spectroscopy (XPS), fluorescence spectrometry, ultraviolet-visible diffuse reflectance spectroscopy, and electron spin resonance (ESR) were used to characterize the properties and working mechanism of the prepared photocatalyst material. They indicated that the core phase YF(3) nanoparticles were successfully coated with a TiO(2) shell and the length of the composite was roughly 100 nm. The Ho(3+) single-doped YF(3):Ho(3+)@TiO(2) displayed strong visible absorption peaks with wavelengths of 450, 537, and 644 nm, respectively. By selecting these three peaks as excitation wavelengths, we could observe 288 nm ((5)D(4)→(5)I(8)) ultraviolet emission, which confirmed that there was indeed an energy transfer from YF(3):Ho(3+) to anatase TiO(2). In addition, this paper investigated the influences of different TBOT dosages on photocatalysis performance of the as-prepared photocatalyst material. Results showed that the YF(3):Ho(3+)@TiO(2) core-shell nanomaterial was an advanced visible-light-driven catalyst, which decomposed approximately 67% of rhodamine b (RhB) and 34.6% of phenol after 10 h of photocatalysis reaction. Compared with the blank experiment, the photocatalysis efficiency was significantly improved. Finally, the visible-light-responsive photocatalytic mechanism of YF(3):Ho(3+)@TiO(2) core-shell materials and the influencing factors of photocatalytic degradation were investigated to study the apparent kinetics, which provides a theoretical basis for improving the structural design and functions of this new type of catalytic material.