Composites with transition metal oxides on aluminum and titanium and their activity in CO oxidation

Abstract

Plasma electrolytic oxidation (PEO) technique and impregnation in nitrate solutions with next air calcinations have been used to obtain the composites with binary oxides of transition metals on aluminum and titanium. The general composite formula is as follows: CuO+MxOy/PEO-layer/Ti(Al), where MxOy is oxide of transition metal (Mn, Fe, Co, Ni). Solutions of Zr(SO4)2 and of Zr(SO4)2+Ce2(SO4)3 as well as of Na2SiO3+NaOH have been used for PEO treatment of titanium, with the last one being used for aluminum treatment alone. The composites have been investigated by XRD, XSA, SEM and XPS. Catalytic tests in oxidation of CO into CO2 showed that both metal substrate and PEO layer composition impact the composites' catalytic activity. The results were compared with the catalytic test data of aluminum coatings obtained by one-stage PEO technique with precursors of transition metal oxides being added directly into forming solutions.