Crystalline orientation preference for TiO2 nanotube arrays with efficient photoelectrochemical properties

Novel TiO2 nanotube arrays (TiO2 NTAs) with preferred oriented crystalline structure were firstly achieved by a facile method through anodizing Ti sheets with textured microstructure. Highly oriented crystalline structure of TiO2 NTAs, with its (004) lattice plane of anatase TiO2 paralleling to the top surface of TiO2 NTAs was identified by the results of XRD, which was further confirmed by the regular diffraction spots and lattice fringes with uniform direction in HRTEM images. In comparison with normal randomly oriented TiO2 NTAs, the quasi-single crystal structure of highly oriented TiO2 NTAs can suppress the recombination of photogenerated electron-hole pairs and enhance the transfer of photocarriers, as was proved by the photoelectrochemical measurement conducted on both normal TiO2 and oriented TiO2 NTAs. The results of this study provide a promising avenue to obtain high photoelectrochemical performance TiO2 NTAs-based hybrid nanomaterials.