Highly efficient photocatalytic degradation of methylene blue by PoPD/TiO2 nanocomposite

The poly-o-phenylenediamine (PoPD)/TiO 2 nanocomposite was successfully synthesized via ‘in situ’ oxidative polymerization method. The modified photocatalysts were characterized by BET, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrarad spectra (FT-IR), thermogravimrtic analysis (TGA), X-ray photoelectron spectroscopy (XPS), Ultraviolet-visible diffuse reflectance spectrum (UV-Vis DRS) and Photocurrent Test. The results showed that the PoPD exists on the surface of TiO 2 , the presence of PoPD does not impact on the lattice structure and grain size of TiO 2 , and the presence of PoPD enhances the visible response and photoelectric property. The photocatalytic degradation of methylene blue (MB) was chosen as a model reaction to evaluate the photocatalytic activities of TiO 2 and PoPD/TiO 2 . The optimal preparation condition was the molar ratio of oPD to TiO 2 = 3:1, HCl concentration = 1.2 mol/L, the molar ratio of APS to oPD = 1:1. The apparent first-order rate constant k app of PoPD/TiO 2 nanocomposite was 0.0098 min -1 , which is 6 times higher than TiO 2 (0.0016 min -1 ). Meanwhile, the PoPD/TiO 2 nanocomposites showed excellent photocatalytic stability, and the photocatalytic stability was depended on the stability of structure. At last, the photocatalytic mechanism of POPD/TiO 2 nanocomposites was also proposed based on the synergetic effect between TiO 2 and PoPD.