Effect of Multi-walled carbon nanotube incorporation on the photocatalytic activity of TiO2 nanotubes

Arrays of titanium dioxide (TiO 2 ) nanotubes were prepared on commercially pure titanium (Cp-Ti) foils by anodic oxidation in 0.5 M HF-based electrolyte with multi-walled carbon nanotubes (MWCNTs) addition up to 0.035 g/L. The samples were annealed at 450 °C for 1 h after the anodic oxidation to form a crystalline anatase structure. The effect of the MWCNTs addition on morphology and photocatalytic activity of the nanostructures was characterized by scanning electron microscopy (SEM), Raman spectroscopy, UV-Vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, and methylene blue (MB) degradation tests. The results showed that MWCNTs were successfully incorporated into the TiO 2 nanotube structure, and significantly affected its photocatalytic activity. The best photocatalytic performance was achieved with the use of 0.025 g/L MWCNTs in the electrolyte composition. However, when the MWCNTs content in the electrolyte increased, the electron-hole recombination rate and photon absorption ability of the structure deteriorate, resulting in a decreased photocatalytic activity.