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)63–/Fe(CN)64– 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.