Thermally Stimulated Transformation of the Surface Nanoarchitecture of Ni-and Cu-Doped Oxide Coatings on Titanium

Abstract

It has been shown that triangular nanocrystals with a thickness of ~ 50 nm and a height of ~ 500 nm, mainly containing copper oxides, are formed on the surface of Ni-and Cu-doped plasma electrolytic oxide (PEO) coatings on titanium during air annealing at 500-700 °C. Upon the annealing at 750-850 °C, rectangular nanoand micro-sized crystals presumably consisting of nickel tungstate cover the coating surface. At annealing temperatures above 850 °C, the brushes of Ni5TiO7whiskers having a diameter of tens to 200 nm and a length up to 10 μm are formed on the surface. The thermally stimulated change in the surface nanoarchitecture and the composition of nanoformations explains the change in the catalytic activity of the formed composites in oxidation of CO into CO2.