Fabrication and characterization of copper doped TiO2 nanotube arrays by in situ electrochemical method as efficient visible-light photocatalyst

Highly ordered copper doped TiO2 nanotube arrays (CuTiO2NTs) thin-film were prepared in an aqueous solution containing NH4F and different concentrations of copper nitrate via the electrochemical oxidation of titanium substrates. The resulting nanotubes were characterized by FE-SEM, XRD, XPS and EDX. The CuTiO2NTs showed a tube diameter of 40-90 nm and wall thickness of 20-30 nm. Diffuse reflectance spectra showed a shift toward longer wavelengths relative to pure TiO2 nanotubes (TiO2NTs). The visible light photo-catalytic activity of the CuTiO2NTs electrodes was evaluated by the removal of methylene blue (MB) dye and the production of hydrogen. The results showed that CuTiO2NTs samples exhibited better photo-catalytic activity than the TiO2NTs. This work demonstrated a feasible and simple anodization method to fabricate an effective, reproducible, and inexpensive visible-light-driven photo-catalyst for hydrogen evolution and environmental applications.