Reproducible Electrodeposition of Hydrogen Molybdenum Bronze Films and Electrochemical Reduction of Carbon Dioxide

Abstract

Electrochemical synthesis of hydrogen bronze films including molybdenum, tungsten and vanadium are useful electrocatalytic films. This paper describes reproducible hydrogen molybdenum bronze film formation on indium tin oxide and carbon paper substrates by electrodeposition. Film formation is a kinetic process dependent on concentration, time and potential. Bulk electrolysis over time determined the dependence of film thickness on time of deposition. Once the films were prepared, the films were characterized by thickness, conductivity, XPS and X-Ray Diffraction. Cyclic voltammetry in dilute sulfuric acid confirmed that these films are not electrochromic. Hydrogen bronze films on conductive carbon paper were also prepared. Carbon dioxide bubbled into 0.5 M NaHCO3 using a hydrogen bronze film as the working electrode resulted in formate quantified by ion chromatography. Cyclic voltammetry and Tafel plots using the as deposited films in 0.5 M NaHCO3 saturated with CO2 showed catalytic activity toward reduction of carbon dioxide. A Farradaic efficiency of 8% was obtained with an applied potential of -0.4 V.