Template-free, microscale dimple patterning of pure titanium surface through anodic dissolution using non-aqueous ethylene glycol-TiCl₄ electrolytes

We report a single-step anodic dissolution route for the template-free patterning of pure titanium (Ti) surfaces into a microscale, dimpled topography using non-aqueous ethylene glycol-TiCl₄ electrolytes. Anodic dissolution of Ti metal (i.e. 0.04 M Ti⁴⁺) into a 40 EG: 1 TiCl₄ electrolyte was found to induce a predominant change in the anodic dissolution reaction of Ti metal, converting its surface morphology from a slightly-pitted, bright finish into a dimple-patterned surface. The dimple pattern, ca. 4.5 µm in size and 1 µm in cusp height, was found self-organised with no apparent relation to underlying metal grain structure and independent of the applied potential within the anodic current plateau. The origin of the dimple patterning is surmised to arise from a dynamic self-organisation of the double layer, templated via tracery anodic reaction products – Ti-glycolate-derived, stacked-nanolayers (SNLs).