Direct photoelectrochemical characterization of photocatalytic H, N doped TiO2 powder suspensions

Abstract: The photoelectrochemical (PEC) properties of photocatalysts as powder suspensions were measured directly by an electrochemical technique that allows the action spectrum and relative activities to be measured. This technique was applied to various photocatalyst powders, such as TiO2 synthesized in various ways to produce materials claimed to be active in the visible region (e.g. so-called “black TiO2”), in the presence of a sacrificial electron donor reactants. Hydrogen-treated TiO2 does not show visible light PEC activity, whereas some ammonia-treated TiO2 powders show some visible light PEC activity up to a wavelength of 520 nm. Structural and elemental analysis of these types of modified TiO2 revealed that an amorphous layer and slight nitrogen doping on the crystalline surface provides the capability of visible light utilization for rutile TiO2. The generality of the technique with other particles (BiVO4, WO3) and its advantages over simple photodecomposition experiments is also discussed.