Oxide layers with Pd-containing nanoparticles on titanium

• Plasma electrolytic oxidation + template sol–gel synthesis → PdOx/SiO2 + TiO2/Ti.
• Palladium is concentrated in nanosized structures of a diameter of 25–60 nm.
• The fabricated composites catalyze oxidation of CO into CO2 at T > 170 °C.

PdOx/SiO2 + TiO2/Ti composites with different palladium contents have been fabricated by a combination of plasma electrolytic oxidation and template sol–gel synthesis on titanium substrates. The effect of multiplicity of deposition of titanium hydroxide gel with palladium nanoparticles on the composite composition and the surface morphology has been investigated. It has been established that the coatings surface is heterogeneous: it is built from alternating sites of different types with varying palladium content. Palladium is concentrated in nanosized structures of a diameter of 25–60 nm. The fabricated composites catalyze the reaction of oxidation of CO into CO2 at temperatures above 170 °C. It has been demonstrated that at the average concentration of palladium in coatings equal to 0.04 at.% the activation energy for this reaction is equal to ∼55 kJ/mol, whereas at 0.1–0.2 at.% it is equal to ∼46 kJ/mol.

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