Titanium-supported Ce-, Zr-containing oxide coatings modified by platinum or nickel and copper oxides and their catalytic activity in CO oxidation

A combination of plasma electrolytic oxidation (PEO) and impregnation techniques followed by annealing in air has been used to obtain composites Pt/nZrO2 + pTiO2/Ti, Pt/nZrO2 + pTiO2 + zCeOx/Ti, NiO + CuO/nZrO2 + pTiO2/Ti, NiO + CuO/nZrO2 + pTiO2 + zCeOx/Ti with different zirconium and titanium contents and ZrO2/TiO2 phase ratio. The composites have been investigated by means of XRD, XPS and SEM/XSA methods. According to the XPS data, the platinum content on the coating surface is ~ 0.4 at.%, whereas the XSA measurements have shown that the nickel and copper contents in coatings attain 16 and 8 at.%, respectively, depending on the initial oxide coatings composition. Nickel and copper oxides form either extended islets or solid layers (“crusts”) on the coating surface. Both the composites promoted with platinum and those with the “crust” built from nickel and copper oxides are active in CO oxidation at the temperatures above 200 °C and 300 °C, respectively.