TiO₂(B)/anatase heterostructure nanofibers decorated with anatase nanoparticles as efficient photocatalysts for methanol oxidation

TiO₂(B) nanofibres, TiO₂(B)/anatase heterostructure nanofibres, TiO₂(B)/anatase heterostructure nanofibres decorated with anatase nanoparticles, and thermally highly stable anatase TiO₂ nanorods have been prepared by hydrothermal treatment of TiO₂ P25 in aqueous NaOH solution followed by controlled ion-exchange and thermal annealing processes. The obtained TiO₂ nanomaterials were characterized by x-ray diffraction, scanning electron microscopy, transmission electron microscopy, diffuse reflectance spectroscopy, electrochemical impedance spectroscopy, and nitrogen adsorption. The photocatalytic activities of the prepared materials were quantified by measuring the photocatalytic methanol oxidation under UV–vis illumination. The results indicated that TiO₂(B)/anatase heterostructure nanofibres decorated with anatase nanoparticles (84% anatase and 16% TiO₂(B)) exhibit 3.5-fold higher photocatalytic activity towards methanol oxidation than TiO₂(B) nanofibres and anatase TiO₂ nanorods. These nanofibres even showed higher photocatalytic activity than TiO₂ P25. This is explained by a better separation of the photogenerated charge carriers and, most likely, by the facile interfacial charge transfer between TiO₂(B) and anatase structures as confirmed by impedance spectroscopy measurements.