Preparation of WO 3 Films on Titanium and Graphite Foil for Fuel Cell and Supercapacitor Applications by Electrochemical (Cathodic) Deposition Method

Numerous electrochemical and chemical methods are suitable for preparation of tungsten trioxide (WO 3 ) films. Many of these methods, however, have not been carefully studied, so information on the specific features of the WO 3 film deposition technology is lacking. This paper describes the preparation of WO 3 films by cathodic electrodeposition from the synthesized solution of peroxotungstic acid (PTA) on the surface of thermally expanded graphite (TEG) and titanium electrodes designed as foils. A stepwise pattern of reduction of tungsten oxides from PTA was revealed. The suitability of the WO 3 film electrode as a material for electrochemical power industry was experimentally demonstrated. Specifically, WO 3 /Ti was found to be applicable as a protective coating for hydrogen fuel cells, and WO 3 /TEG, as a cathode material for asymmetric supercapacitors. Based on the charge-discharge curves for the WO 3 /TEG electrode used as a cathode in the free volume of th KOH electrolyte, the specific capacitance of the supercapacitor was estimated at 630 F/g. Electrochemical analysis showed that that WO 3 films deposited on the titanium surface afford enhancement of the hydrogen overpotential and protection against pitting corrosion during potentiostatic polarization tests at the cathode potential of a fuel cell.