关键词: TiO₂纳米管阵列, 还原氧化石墨烯, 光电性能

Abstract:

Decorating TiO₂ nanotube arrays with RGO to improve the photocatalytic activity of TiO₂ nanotube arrays has been reported. For the reported RGO-TiO₂ nanotube arrays, TiO₂ nanotube arrays were prepared by anodizing the high-purity Ti foil in an organic electrolyte for multiple-step treatments, while RGO were deposited on TiO₂ nanotube arrays by using cyclic voltammetry or other electrical reduction methods. To enhance the reduction degree and the coverage of RGO on the resultant RGO-TiO₂ nanotube arrays, in this work, the one-step electrochemical anodization in hydrofluoric acid was used to fabricate TiO₂ nanotube arrays with different wall thicknesses by adjusting the distance between the cathode and anode. RGO were loaded on the surface of TiO₂ nanotube arrays by pulse electroreduction deposition. When the distances between the cathode and anode were 4 and 0.5 cm, respectively, the corresponding wall thicknesses of the as-prepared TiO₂ nanotubes were 8 and 14 nm, respectively. Compared with the RGO loaded on the thin-walled TiO₂ nanotube arrays, the RGO loaded on the thick-walled TiO₂ nanotube arrays were fully reduced and the RGO coverage was greatly improved. X-ray photoelectron spectroscopy demonstrated that the reduction degree of RGO loaded on the thick-walled TiO₂ nanotube arrays was higher than that of RGO loaded on the thin-walled TiO₂ nanotube arrays with the decrease of the oxygen content. UV-vis diffuse reflectance spectroscopy showed that the band gap of RGO-TiO₂ nanotube arrays became narrower than that of TiO₂ nanotube arrays due to the loading of RGO. The photocurrent measurements displayed that the photocurrent density of the RGO loaded thick-walled TiO₂ nanotube arrays was significantly increased accordingly, showing good light absorption properties, but also lower charge transfer resistance. The method and results presented in this work would lay a good foundation for the practical photoelectrochemical catalysis application of RGO-TiO₂ nanotube arrays.

Key words: TiO₂ nanotube array, reduced graphene oxide, photoelectrochemical performance