Effect of anodization parameters on the structural morphology of titanium in fluoride containing electrolytes

In the present work, formation of titania nanopores on titanium substrate was investigated in aqueous (sulphuric acid) and neutral organic (glycerol) electrolytes containing different concentrations of HF (0.1–0.2 M). The surface morphology, topography and phase structures were analyzed using scanning electron microscopy, atomic force microscopy and X‐ray diffraction techniques, respectively. Under optimized electrolyte conditions, titania nanopore is obtained with the average pore diameter of 64 nm and 84 nm for aqueous and organic electrolytes, respectively. Atomic force microscope investigation shows that the porous layer forms under a competition of titania formation and oxide dissolution up to a limiting thickness of ~ 75 nm and 100 nm respectively for aqueous and organic electrolytes. The porous structure was observed at 0.15 M HF concentration. It was found that depending on the electrolytes the pore diameter alters and also its concentration effected the porous structures formation. Compared to aqueous electrolytes, organic electrolytes showed larger diameter pores. From the X‐ray diffraction measurement it is evident that the as prepared titania nanopores are amorphous in nature, whereas the anodized heat treated titania nanopores are in anatase phase.

► Aqueous and organic electrolytes were used to synthesize nanoporous titania.
► The surface morphology varies with various concentrations of HF.
► Nanopores were formed at optimum HF concentration of 0.15 M.
► Nanopore diameter was found to be affected by the electrolyte used.