Abstract: A method of synthesizing bimetallic oxide nanocomposites includes the steps of: providing a first metal salt solution; adding an oxidizing agent to the first metal salt solution while degassing the solution with an inert gas; heating the first metal salt solution; adding a second metal salt solution to the heated first metal salt solution to form a reaction mixture; adding a solution comprising a poly (ionic liquid) into the reaction mixture; adding a first base into the reaction mixture; adding a second base while stirring and maintaining a temperature ranging from about 40° C. to about 65° C. to provide a solution including a bimetallic oxide nanocomposite precipitate. The first metallic salt solution can include FeCl3 dissolved in water. The second metallic salt solution can include CuCl2 dissolved in water. The bimetallic oxide nanocomposites can be combined with epoxy resin to coat a steel stubstrate.