Preparation of NaYF4:Yb,Tm/TiO2/RGO composite and photocatalytic degradation of nitenpyram

A ternary photocatalytic composite NaYF4:Yb,Tm/TiO2/RGO was synthesized by hydrothermal method, and it was characterized by scanning electron microscopy, X-ray diffraction, UV-Vis dif-fuse reflectance spectroscopy, Fourier-transform infrared spectroscopy and photoluminescence spectroscopy. The effect of pH, dosage of catalyst, and initial concentration of nitenpyram on degradation efficiency were tested. The best results were occurred on pH 9, and dosage 1.0 g/L. Higher concentration of nitenpyram was not favorable for photocatalysis due to the inhibition of UV penetration. The obtained ternary composite exhibited a significant enhancement in pho-tocatalytic efficiency, and about 76.08% of nitenpyram was degraded within 60 min under UV irradiation. Furthermore, NaYF4:Yb,Tm/TiO2/RGO can be reused for 6 times without significant catalysis loss. During nitenpyram photocatalytic degradation, photo-induced holes and hydroxyl radicals may be the two main active species according to trapping experiments. The possible intermediate product was put forwarded.