Fabrication Of TiO₂ Nanotubes Electrode And Application In Photoelectrocatalytic Degradation Of Pentachlorophenol

TiO₂ nanotubes electrode is fabricated by anodic oxidation method. SEM images indicat that the top-opened TiO₂ nanotubes are well aligned and organized into high-density uniform arrays, with diameter ranging in size from 30 to 70 nm. The XRD patterns show that the sample fabricated by anodic oxidation is amorphous without being annealed. As the 500°C annealed sample crystallized in the anatase phase, which is in good photocatalytic activity. The initial absorbance edge is blue-shift and the energy band gap is 3.32eV.In quartz glass reactor, the photoelectrocatalytic degradation of PCP in aqueous solutions as well as the effect factors such as bias potential, the initial pH value in solution, concentration of Na₂SO₄, light intensity and the area of the TiO₂ nanotubes electrode was investigated. The PCP degradation first-order kinetic constant and photo-conversion efficiency using TiO₂ nanotubes electrode are compared to that of using TiO₂ film electrode (prepared by anodic oxidation) in the same conditions. The stability of TiO₂ nanotubes electrode is also evaluated. The interim-products are also deduced. The result indicates that the photocatalysis and the electrochemical process have a significant synergic effect on the degradation of PCP. The photoelectrocatalysis of PCP is enhanced when increasing bias potential, Na₂SO₄ concentration and in acidic solution. This result indicated that the kinetic constant of PEC degradation of PCP and photo-conversion efficiency on TiO₂ nanotubes electrode is 1.4,1.3higher than that of TiO₂ film electrode in the same condition respectively. The results of the 10 repeated experiments for photoelectrocatalytic degradation of PCP in 2h show that the degradation efficiencies are rather stable with the deviation only 3.3%. Little tetrachlorophenol (TetraCP), quinone and some other simple inorganic acids are the course products.Zn²+, Fe³+ and Cu²+ are doped on TiO₂ nanotubes electrode using dipping method. Both SEM and XRD results show doped TiO₂ nanotubes electrode remain tube-like structure and anatase. However, DRS displays doped TiO₂ nanotubes electrodes' initial absorbance edges shift in different degree. Energy band gaps are 3.37eV,3.14eV, 2.86eV respectively.