The Effect of Chemical Etching by HF Solution on the Photocatalytic Activity of Visible Light-responsive TiO2 Thin Films for Solar Water Splitting

Abstract

The effect of chemical etching by HF solution on the photoelectrochemical performance and photocatalytic activity of visible light-responsive TiO 2 (Vis-TiO 2 ) thin films prepared by a radio-frequency magnetron sputtering method has been investigated. It was found that VisTiO 2 thin films treated with HF solution (HF-Vis-TiO 2 ) exhibit a remarkable enhancement of the photoelectrochemical performance not only under UV but also visible light irradiation as compared to untreated Vis-TiO 2 . The incident photon to current conversion efficiencies reached 66 and 9.4% under UV (k = 360 nm) and visible light (k = 420 nm), respectively. The HF-Vis-TiO 2 thin films have a larger surface area and higher donor density than Vis-TiO 2 , indicating that the remarkable increase in the photocurrent may be due to the short diffusion length of the photoformed holes in reaching the solid-liquid interface as well as to the high conductivity. Moreover, the HF-Vis-TiO 2 thin films were found to act as efficient photocatalysts for the decomposition of water with the separate evolution of H 2 and O 2 from H 2 O under visible or sunlight irradiation.

Uniaxial Freezing, Freeze‐Drying, and Anodization for Aligned Pore Structure in Dye‐Sensitized Solar Cells

“…Also, Kitano et al 18 have showed that hydrofluoric acid etching of TiO 2 increases the photoelectrochemical performance not only under UV but also visible light irradiation, with the HF‐treated thin films having a larger surface area and higher donor density than nontreated films.…”

Effect of Surface Treatment on the Selective Photocatalytic Oxidation of Benzyl Alcohol into Benzaldehyde by O2 on TiO2 Under Visible Light

“…Titanium dioxides (TiO 2 ) are a promising nano-sized material for such photochemical applications [1][2][3][4] as H 2 production by water splitting, the degradation of volatile organic compounds (VOC), organic synthesis, dye-sensitized solar cells, and super-hydrophilic materials. Since the band gap of TiO 2 with an anatase structure is ca.…”

Semiconductor photocatalytic systems for the production of hydrogen by the action of visible light

“…The oxidation of a titanium plate in the presence of water vapor and NaF gave thin films of fluorine-doped titanium dioxide on which the photoelectrochemical splitting of water was realized by the action of visible light [222]. After etching in a solution of HF nanocrystalline films of TiO 2 have photocatalytic properties in the total decomposition of water by the action of visible light [223]; this is obviously due to the formation of titanium oxyfluorides in the surface layer of the films. In addition to the complex systems described above, in which conditions for the spatial separation of the cathodic and anodic processes in the decomposition of water are created, substances capable of realizing both these processes simultaneously under the influence of visible light are also being developed.…”