Nano-lamellar/nano-tubular hierarchical porous structure produced by selective dissolution and anodization of lamellar Ti-40 at.% Al alloy

• A novel nano-laminated porous/tubular structure was fabricated by two step methods.
• The fabrication process consists of selective dissolution and anodizaton of lamellar Ti-Al alloy.
• The structure has various potentials of applications because of its very high specific surface area.

A novel hierarchical nano-porous structure with laminated and tubular pores was fabricated by two step method in which selective dissolution of lamellar Ti-40 at.% Al alloy was followed by anodization. In the first step, grating structure consisting of α2-Ti3Al lamellae and crevasses was produced by selective dissolution of γ lamellae from the lamellar alloy. The spacing of gratings was controlled close to visible light wavelength. In the second step, the gratings were anodized and hierarchical porous structure consisting of nano-laminated crevasse and nano pores was formed. The XPS result indicates that the porous structure consists of oxide and hydroxide containing Ti and Al with a molar proportion of 1.5:1. The self-organized pores were homogeneous with a diameter of approximately 20 nm, the depth of pores is 100~200 nm. The dimensions of gratings and pores can be tuned with the combination of alloy composition and conditions of heat treatment, selective dissolution, and anodization.