Synthesis and Characterization of Self-Organized Oxide Nanotube Arrays via a Facile Electrochemical Anodization

Abstract

Self-organized oxide nanotube arrays have been prepared by a facile two-electrode electrochemical anodization on Ti-2Al-1.5Mn alloy in a 0.5 wt % NH4F aqueous electrolyte. The surface morphology, structure, elemental analysis, and optical and photoelectrochemical behaviors of the nanotubular films are considered. The morphology greatly depends on the applied voltage and anodization time. The as-formed nanotubes under the optimized condition, at 20 V for 3 h, are highly ordered with ∼500 nm in length and the average tube diameter is about 90 nm. The possible “oxide growth and dissolution” mechanism is also discussed. By annealing the initially amorphous films at different temperatures, the importance of the crystalline nature is confirmed. A continuously remarkable red-shift of the absorption edge has been observed with increasing annealing temperature, which is related to the increasing crystallization and the possible new energy bands formed in the TiO2 band gap. The photoelectrochemical properties are investigated and the highest photocurrent of 3.11 mA/cm2 is obtained under AM1.5 100 mW/cm2 illumination at 0.65 V (vs Ag/AgCl). Significantly, a considerable and sustained water splitting behavior has also been observed, and the present convenient synthesis technique can also be extended to other binary or ternary oxide compositions for various applications.

Role of aluminum doping on phase transformations in nanoporous titania anodic oxides

“…The principles of porous anodic oxide formation on titanium and its alloys are very well documented in the literature [7,8,10]. This process requires anodic polarization of titanium in inorganic or organic electrolytes that contains fluoride ions.…”

“…These unique properties make TiO 2 a promising material for a wide range of application fields such as photocatalysis [1e3], photovoltaic cells [4], gas sensors [5,6], solar cells [7,8], lithium-ion batteries [7], energy storage devices [7], photochromic switching [7], hydrogen generation by water photoelectrolysis [9], optical emissions [1,10,11], bioimplant applications [10], and electronic devices [1].…”

An Innovative Approach to Synthesize Highly-Ordered TiO2 Nanotubes

“…Finally, the chemical dissolution of metal and oxide will proceed due to etching by fluoride ions and substantially enhanced by the presence of H + ion. 23 Ti-O bond also becomes weak under the applied electric field which causes the field dissolution. Ti 4+ goes into the electrolyte while the free O 2− ions diffuse across the oxide layer and react with Ti metal at the oxide/metal interface.…”

Photoelectrocatalytic properties of a vertically aligned Ti-W alloy oxide nanotubes array and its applications in dye wastewater degradation

“…Recently, mixed metal oxide NTs have been prepared on Ti alloy by a simple electrochemical anodic method [20][21][22]. Compared with the conventional doping of TiO 2 NTs and the TiO 2 -based composite films, the reported mixed metal oxide NTs fabricated by Ti alloy anodization have a more uniform distribution, a larger surface area and a higher stability; thus their photoelectrocatalytic properties can be significantly enhanced.…”