To enhance photocatalytic activity spectra area of the TiO₂ based photocatalyst, and to separate and recycle photocatalyst easily, magnetic photocatalyst was prepared with β-NaYF₄:Yb³⁺,Tm³⁺, TiO₂, Fe₃O₄ as carriers, and tetraethyl orthosilicate as precursor. The magnetic infrared responsive photocatalysts were thoroughly characterized by field emission scanning electron microscopy, X-ray diffraction, a fluorescence spectrometer and UV–Vis–NIR diffuse reflectance spectroscopy. They showed that the composite of β-NaYF₄:Yb³⁺,Tm³⁺/TiO₂/Fe₃O₄@SiO₂ (UCTFS) emits visible luminescence upon 980 nm excitation, and energy transfer from β-NaYF₄:Yb³⁺,Tm³⁺ to TiO₂ was verified. The photocatalytic activities of the UCTFS were studied by orthogonal experiments for photodegradating methylene blue (MB). The degradation rate of MB can reach 86.69% under the optimal conditions. After the four recycles, the degradation rate remained 52.72%. It also showed that 50.27% of the degradation efficiency of phenol can be obtained under the same experimental parameters. These results suggest that magnetic UCTFS composite is stable and a magnetic NIR-driven photocatalyst for degradation of organic pollutants. Moreover, the NIR driven photocatalytic mechanism of this reported composite was proposed. The strategy suggested here may be indicated for the effective fabrication of magnetic NIR-driven photocatalyst for application in the water purification by full spectra of solar energy.

FESEM images of β-NaYF₄:Yb³⁺,Tm³⁺, TiO₂, Fe₃O₄ and β-NaYF₄:Yb³⁺,Tm³⁺/TiO₂/Fe₃O₄@SiO₂ (a UC, b TiO2, c FO, d UCTFS20)