Preparation Of Silicon-doped TiO₂ Nanotube Arrays And Its Photoelectrocatalytic Activity

The TiO₂ nano-material semiconductor,because of its high photocatalytic activity,had been reported widely in the photocatalytic domain.The Si doped TiO₂ nano-material system not only had high photocatalytic activity,but also possessed high thermal stability and quantum size effect.The Si doped TiO₂ nano-materials,which had been reported up to present, were almost as the powder form.When the Si doped TiO₂ nano-materials were loaded to the surface of electrode,that not only solved the recycle problem of the powder photocatalyst,but also restrained the complex of the electric charge,it could show a higher photocatalytic activity.The ordered silicon-doped TiO₂ nanotube arrays on a Ti sheet were fabricated by electrochemical anodization followed by electrodeposition or modification with Silicon tetrachloride.With these two methods,the SEM images showed that the obtained nanotube arrays were highly ordered and vertically oriented.The X-ray diffraction(XRD) analysis revealed that the introduced silicon might be incorporated into titania matrix,and hence helped to increase the thermal stability of titania,which was in favor of suppressing the formation of rutile and the growth of anatase crystallite.The Si-doped samples fabricated by electrodeposition showed significant blue shift and enhanced absorption intensities in UV light regions,its photocurrent density under UV light is 1.48 times that of the undoped TiO₂ nanotube arrays.The photoelectrocatalytic activity of the Si-doped samples fabricated by electrodeposition was evaluated with pentachlorophenol as a test substance,and the degradation kinetic constant of Si-doped electrode(1.651 h^-1) is 2.0 times that with undoped TiO₂ nanotube electrode(0.823 h^-1) under UV light irradiation.The SPS analysis revealed that the responded peak of the Si-doped TiO₂ nanotubes,which modification with Silicon tetrachloride,moved to 310-380nm range.And the degradation kinetic constant of Si-doped electrode degrading phenol(0.91 h^-1) was 1.3 times that with undoped TiO₂ nanotube electrode(0.69 h^-1) under UV light irradiation.In addition,with carbon nanotubes as a template,the silicon-doped TiO₂ nanotubes.was prepared by chemical vapor deposition(CVD).The Si-doped TiO₂ nanotubes which may containing different Si content could be prepared just changing the content of the Si source in the Ti source.The problem is that,the SiO₂/TiO₂ coated on carbon nanotubes would be separated easily from Ti sheet.Therefore,the preparation parameters of this method needed to be further improved.