Study of electrodeposited tungsten trioxide thin films

Abstract

WO₃ films have been electrodeposited in a solution containing dissolved tungsten and alcohol. The deposition conditions and the deposition efficiency on various substrates were studied. The properties of the electrodeposited WO₃ film were characterised by electrochemical, surface analytical and in situ optical techniques. The results indicated that the electrodeposited WO₃ films have similar electrochromic behaviour to that of anodically grown WO₃ films. A Nernst type response for H⁺ concentration has been demonstrated on reduced films, with a slope of 64 mV (pH)^–1. The electrodeposited films have selective permeability to different ions and molecules. Since the zero-charge potential of the electrodeposited film is much more anodic, anions such as Fe(CN)₆^3–/Fe(CN)₆^4– cannot enter the n-type film at potentials more negative than its zero-charge potential. However, some cations can diffuse in and out of the electrodeposited WO₃ film reversibly.