Electrochemical and gas-phase photocatalytic performance of nanostructured TiO2(B) prepared by novel synthetic route

Nanostructured phase pure TiO₂(B) with microfibrous morphology was synthesized by newly developed protocol employing amorphous TiO₂ as a precursor. Compared to traditional syntheses from K₂Ti₄O₉, the new product exhibited better electrochemical performance and stability. Cyclic voltammetry of Li-insertion into the TiO₂(B) evidences a pseudocapacitive faradaic process of Li accommodation which is basically different from the diffusion-controlled lithium storage in anatase or rutile. The presence of two pairs of peaks in cyclic voltammogram with formal potentials of ca. 1.5 and 1.6 V is specific for TiO₂(B). This enables to use cyclic voltammetry for identification of this phase in a broad palette of TiO₂ materials of various origin.

The photocatalytic activity of TiO₂(B) in a gas phase was evaluated using the total oxidation of propane with oxygen and the photocatalytic reduction of NO to N₂ in an oxygen rich gas mixture. For the total oxidation of propane in the gas mixture containing 300 ppm propane and 20% oxygen, the reaction rates per 1 m²/g of the BET surface area of the catalyst for TiO₂(B) prepared by our protocol and Hombifine N (anatase, S_BET = 300 m²/g) are comparable. For the photocatalytic NO reduction to N₂ in an atmosphere containing 20% oxygen the ratio of quantum yields for TiO₂(B) and Hombifine N was found to be 0.08, which is roughly equivalent to the ratio of their BET surface areas (0.09), despite different phase composition of both materials. In comparison with the standard catalyst our material exhibited higher selectivity in the reduction of NO to N₂.