A thin film electrode involving a nanostructured catalytic material deposited onto a surface of a conducting substrate and method of making is described. The nanostructured catalytic material contains cobalt oxide nanoflowers having a central core and nanopetals extending from the central core. The method of making the thin film electrode involves contacting the conducting substrate with an aerosol containing a cobalt complex and a solvent. A method of using the thin film electrode in an electrochemical cell for water splitting is also provided.