Fabrication of boron-doped TiO₂ nanotube array electrode and investigation of its photoelectrochemical capability

Boron-doped TiO₂ nanotube arrays were produced by forming a nanotube-like TiO₂ film in an anodization process on a Ti sheet, followed by chemical vapor deposition treatment using trimethyl borate as the boron source with N₂ as the carrier gas, and were characterized by ESEM, XPS, XRD, and UV-vis methods. The highly ordered vertically oriented nanotube arrays were obtained, and the nanotubes were open at the top end with an average diameter of approximately 80 nm. Analysis by XPS indicated that the introduced boron was probably incorporated into TiO₂ and that the chemical environmental surrounding boron might be Ti-B-O. The boron-doped sample with a mixture of anatase and rutile was identified by X-ray diffraction. A shift of the absorption edge to a lower energy in the spectrum of the UV-vis absorption was observed. Under both UV and 400-620 nm visible light irradiation, the B-doped TiO₂ nanotube array electrode exhibited a higher photoconversion efficiency than the non-doped one, a notable photoconversion efficiency of 31.5% was achieved under high-pressure mercury lamp irradiation, and a photoconversion efficiency of 15.1% on the B-doped electrode was obtained under λ > 290 nm light irradiation. The photoelectrocatalytic activity of the prepared electrode was evaluated using pentachlorophenol as a test substance under UV and visible light irradiation. © 2007 American Chemical Society.