Cathodic Electrodeposition of Mixed Molybdenum Tungsten Oxides from Peroxo-polymolybdotungstate Solutions

摘要

Mixed molybdenum tungsten trioxide films of varying stoichiometry (Mo_xW_(1-x)O_,0 < x < 1) were prepared by cathodic electrodeposition on indium tin oxide (ITO)-coated glass substrates from aqueous peroxo-polymolybdotungstate solutions.Electrochemical quartz crystal microbalance (EQCM),cyclic voltammetry,and chronocoulometry were used to gain insight into the electrodeposition mechanism.The compositional and structural properties were characterized for Mo_xW_(1-x)O_3 films deposited at intermediate potentials (-0.35 V vs Ag/AgCl) and sintered at 250 deg C using energy-dispersive spectroscopy,X-ray diffraction,and Raman spectroscopy.These studies reveal that films consist of homogeneously mixed Mo_xW_(1-x)O_3,with an enriched Mo content ranging in composition from 0.4 < x < 0.7 depending upon the mol % Mo present in the deposition solution.Chronoamperometry and spectroelectrochemical measurements were conducted to estimate lithium ion diffusion coefficients and coloration efficiencies for the mixed metal oxide films in 1 M LiClOVpropylene carbonate.The subtle interplay between structural and compositional properties due to the uniform mixing of Mo and W oxide components shows that electrochromic and lithium ion transport properties are moderately enhanced relative to those of single-component WO3 and M0O3 and demonstrate improved structural stability over pure MoO_3 polymorphs during electrochemical cycling.