Highly efficient photocatalytic degradation of methylene blue by PoPD/TiO(2) 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.