Vapor-phase hydrothermal synthesis of rutile TiO_2 nanostructured film with exposed pyramid-shaped (111) surface and superiorly photoelectrocatalytic performance

摘要

Rutile TiO_2 nanostructured film with exposed pyramid-shaped (111) surface was successfully fabricated using metal titanium foil as substrate through a facile vapor-phase hydrothermal method. The fabricated rutile TiO_2 film was composed of vertically aligned rod-like structures with diameters ranged from 400 to 700 nm and thickness of ca. 2.0 lm. The obtained rutile TiO_2 film as photoanode exhibited excellent photoelectrocatalytic activity toward water oxidation and rhodamine B decolorization under UV illumination, which was more than 3.5 and 1.2 times of that obtained by highly ordered anatase TiO_2 nanotube array film photoanode under the same experimental conditions, respectively. The excellent photoelectrocatalytic performance of the rutile TiO_2 film photoanode could be due to the superior photoelectron transfer property and the high oxidative capability of {111} crystal facets. The superior photoelectron transfer capability of the photoanodes was manifested by the inherent resistance (R_0) of the photoanodes using a simple photoelectrochemical method. The calculated R_0 values were 50.5 and 86.2 Ω for the rutile TiO_2 nanostructured film and anatase TiO_2 nanotube array film, respectively. Lower R0 value of the rutile TiO_2 photoanode indicated a superior photoelectron transfer capability owing to good single crystal property of the rod-like rutile nanostructure. Almost identical valence band level(1.94 eV) of the rutile TiO_2 nanostructured film and anatase TiO_2 nanotube array film (meaning a similar oxidation capability) further confirmed the significant role of photoelectron transfer capability and exposed high-energy {111} crystal facets for improved photoelectrocatalytic performance of the rutile TiO_2 nanostructured film photoanode.