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

Abstract

Mixed molybdenum tungsten trioxide films of varying stoichiometry (MoxW1 - xO3, 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 MoxW1 - xO3 films deposited at intermediate potentials (-0.35 V vs Ag/AgCl) and sintered at 250 degrees C using energy-dispersive spectroscopy, X-ray diffraction, and Raman spectroscopy. These studies reveal that films consist of homogeneously mixed MoxW1 - xO3, 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 LiClO4/propylene 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 MoO3 and demonstrate improved structural stability over pure MoO3 polymorphs during electrochemical cycling.

Controlled synthesis of monodisperse WO3·H2O square nanoplates and their gas sensing properties

“…Among the numerous semiconductor metal oxides, tungsten oxide is an important n-type functional semiconductor with a wide band gap of 2.6 eV with many excellent properties [8][9][10]. Recently, tungsten oxide (WO 3 ) and hydrous tungsten oxide (WO 3 ·xH 2 O) with nanostructures exhibit pronounced photochromism and that makes them to be a promising material used as gas sensors [11,12], electrochromic device [13,14], photoelectrochromic device [15], electrocatalyst [16,17], photocatalyst [18], and so forth. The morphological parameters such as size, shape and facet of tungsten oxide particles are critically important in its applications such as sensing properties [19,20].…”

Synthesis and nanostructure of [Mo(C 6 H 4 O 2 ) 3 ]·2(C 4 H 8 N 2 O) and the synthesis from 1,2-PDA to (C 4 H 8 N 2 O)

“…The [Mo(cat) 3 ] complex is distorted from octahedral geometry with approximately D 3 molecular point symmetry, of which the center Mo coordinated with three catechol ligands and formed three five-membered rings with dihedral angles 82.5(8)°, 82.5(8)° and 86.8(6)° between the three catechol planes respectively (Fig.1A). The Mo-O bond lengths range from 2.021(4) to 2.075(4) Å (table 3), which are close to the Mo-O cis (2.0 to 2.1 Å) in MoO 2 (cat) 2 [29] and MoO 3 L A L B (L A/B =cat/en) complexes [1] . M A N U S C R I P T ACCEPTED MANUSCRIPT…”

“…The experimental result exhibited a quasi-reversible curves and appeared an peak at 457 mV which corresponded to the oxidation-reduction between Mo(VI) to Mo(V) [29] . The peak of Mo(V) to Mo( IV) hasn't been observed, which might be due to its peak overlapped with the band of the reduction of hydrogen ions (Fig.4A).…”

“…The obtained powder was mono-nano-lamellas under TEM ( Figure 3D, E), which agree well with the summing-up that the quantum motifs in bulk crystals are the templates of their nano-structures. [29] Scheme 2. The major reaction pathway of (C 4 H 8 N 2 O) in complex (A) and the formation of C 4 N 2 H 9 in the reaction of the complex (B).…”

Cathodic Electrodeposition of Mixed Rhenium-Molybdenum Oxides

“…Mixed metal oxides prepared by this route are of great interest as they offer the additional opportunity to systematically tailor microstructural characteristics, electronic and ion conductivity and to influence associated electrochromic and lithium insertion properties. For example, the electrochemical deposition of Mo x W 1-x O 3 materials from a peroxo-polymolybdotungstate solution was recently published (9), and these materials demonstrated improved coloration efficiency and stability over their single component metal oxide counterparts (10). These studies also point to the possibility of improving energy storage performance by stabilizing the local structure through structural modifications by doping with different cations.…”