As-prepared Film Electrodes Research Articles

(I2)n-encapsulated and C-encapsulated TiO2 films: Enhanced photoelectrochemical and visible-light photoelectrocatalytic properties

Visible-light absorbing (I2)n-encapsulated TiO2 film (I2-TiO2 film) and C-encapsulated TiO2 film (C-TiO2 film) were fabricated and studied as film electrodes for their photoelectrochemical and photoelectrocatalytic (PEC) properties. The as-prepared film electrodes were characterized by scanning electronic microscopy, energy-dispersive X-ray spectroscopy and UV–visible diffuse reflectance spectroscopy. The photoelectrochemical properties were evaluated by the incident photo-to-current conversion efficiency, electrochemical impedance spectroscopy and Mott–Schottky analysis data. The results showed that I2-TiO2 and C-TiO2 films exhibited stronger absorption in the 400–550nm range, lower electron transfer resistance and more negative flat band potentials comparing with pure TiO2 film. Moreover, the photoelectrochemical ability of I2-TiO2 film is superior to that of C-TiO2 film. At a bias potential of 0.5 vs (Ag/AgCl)/V, the visible-light-induced PEC degradation ratios of rhodamine B and tetracycline on I2-TiO2 film or C-TiO2 film electrodes exceeded that on pure TiO2 electrode, with the improvement by a factor of about 5 or 3. The higher PEC activity of I2-TiO2 film and C-TiO2 film could be attributed to the enhancement of separation of electron-hole pair at the external electric field and the extension of the light response range of TiO2 to the visible light with a red shift in the band gap transition.