Photoelectrocatalytic oxidation of phenol on TiO2 nanotubes under oxygen pressure

The photoelectrocatalytic oxidation of phenol on an electrochemically synthesized array of titania nanotubes used as a photoanode under UV irradiation was studied. The physicochemical properties of the array of titania nanotubes were studied by electron microscopy, X-ray diffraction, electron spectroscopy in the UV and visible regions, and Raman spectroscopy. The electrochemically synthesized film consisted of an array of vertically oriented nanotubes of titania with a pore diameter of ~100–150 nm, wall thickness of ~10 nm, and length of ~6 µm. The photoelectrocatalytic oxidation of phenol on the array of TiO2 nanotubes by irradiation with UV light and without irradiation under oxygen pressure was studied by voltammetry. The oxygen pressure intensified the photoelectrocatalytic oxidation of phenol. An increase in the oxygen pressure from 0.1 to 0.6 MPa led to an increase in the maximum current of phenol oxidation by a factor of 1.25. The rate constant and initial rate of the photoelectrocatalytic oxidation of phenol at different oxygen pressures were calculated. The mechanism of the photoelectrocatalytic oxidation of phenol was studied by UV spectroscopy and high-performance liquid chromatography; the intermediates formed in the oxidation were determined.