Kinetics of the electrochemical deposition and dissolution of sodium tungsten bronzes

Randin, Jean‐Paul

doi:10.1016/0013-4686(74)80018-6

Cited by 10 publications

(4 citation statements)

References 11 publications

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“…Assignment of the rate-limiting step for k TI is not as straightforward and can only be speculated. Randin noted that the reduction of WO 3 to the tetramer is not the rate-limiting step in electrolytic synthesis . Though the conditions in an electrolytic melt are quite different from those in a mixture of powders, it is reasonable to assume that charge can readily move from metallic W to an adjacent WO 3 particle, and thus reaction should similarly be rapid.…”

Section: Resultsmentioning

confidence: 99%

“…Randin noted that the reduction of WO 3 to the tetramer is not the rate-limiting step in electrolytic synthesis. 33 Though the conditions in an electrolytic melt are quite different from those in a mixture of powders, it is reasonable to assume that charge can readily move from metallic W to an adjacent WO 3 particle, and thus reaction 10 should similarly be rapid. Given the comparably high carrier mobility in metallic W, it is also reasonable to assume that some Na 2 WO 4 contacting a different part of the same W particle could be oxidized quickly, so reaction 11 should also be fairly rapid.…”

Section: S T S ( )mentioning

confidence: 99%

“…Although their preparation methods are quite different from those used here, these findings suggest that Na 2 W 2 O 7 may be an intermediate phase in Na x WO 3 synthesis. Several authors − have performed kinetic studies on the electrochemical reduction of Na 2 WO 4 :WO 3 melts. Fredlein and Damjanovic described a potential reaction mechanism for the deposition of Na x WO 3 on the cathode, which starts with the reduction of (WO 3 ) 4 tetramers and ultimately leads to Na 0.25 WO 3 deposition, which is then sodiated by the melt.…”

Section: Introductionmentioning

confidence: 99%

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Intermediate Phases and Reaction Kinetics of the Furnace-Assisted Synthesis of Sodium Tungsten Bronze Nanoparticles

et al. 2021

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The sodium tungsten bronzes are nonstoichiometric metal oxides which have recently attracted interest for their applications as plasmonic materials. Although several synthesis routes have been reported, none offer the flexibility and mass throughput of the furnace-assisted methods. Although widely used, the intermediate phases and kinetics of such methods have not previously been studied. In this work, we use in-situ neutron powder diffraction and Rietveld refinement to characterize sodium tungsten bronze synthesis, with a particular focus on preparing nanoparticles. The reaction is found to proceed much more quickly than previous ex-situ studies would suggest, as once the reagents reach the reaction temperature, phase purity is achieved within seconds. Through kinetic analysis, order-of-magnitude estimates for the Arrhenius parameters are obtained, and a two-step reaction mechanism is proposed. These findings contribute to the synthesis strategy of sodium tungsten bronze nanoparticles for plasmonic applications.

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Section: Resultsmentioning

confidence: 99%

Section: S T S ( )mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Intermediate Phases and Reaction Kinetics of the Furnace-Assisted Synthesis of Sodium Tungsten Bronze Nanoparticles

et al. 2021

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“…Moreover, a hypothesis was put forward about simultaneous bronze dissolution and sodium dissolution from the deposit [32]. Randin [33,34] believed that the electrodeposition of sodium tungsten bronzes from melts containing 10, 20 and 50 mol% WO 3 is a complex reaction controlled by at least three processes including diffusion in the electrolyte, heterogeneous reaction (adion surface diffusion), and charge transfer. Elwell et al [35] proposed a model considering the resistances of these stages and concluded that the growth rate of OTB crystals is determined by both interfacial kinetics and diffusion in the melt, since the growth rate of a single OTB crystal increases if it rotates.…”

Section: Introductionmentioning

confidence: 99%

Mechanism and Kinetics of the Phase Formation and Dissolution of NaxWO3 on a Pt Electrode in a Na2WO4–WO3 Melt

Kosov,

Grishenkova,

Semerikova

et al. 2023

Materials

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A comprehensive study concerning the phase formation mechanism and growth/dissolution kinetics of sodium tungsten bronze crystals during the electrolysis of a 0.8Na2WO4–0.2WO3 melt was carried out. The regularities of deposit formation on a Pt(111) working electrode were investigated experimentally using cyclic voltammetry, chronoamperometry, scanning electron microscopy, and X-ray diffraction analysis. Models have been developed to calculate the current response during the formation, growth and dissolution of a two-phase deposit consisting of NaxWO3 and metallic tungsten or two oxide tungsten bronzes with different sodium content. These models consider mass transfer to the electrode and nuclei; chemical and electrochemical reactions with the participation of polytungstate ions, Na+, Na0, and O2−; as well as the ohmic drop effect. The approach was proposed to describe the dissolution of an NaxWO3 crystal with a nonuniform sodium distribution. The fitting of cyclic voltammograms was performed using the Levenberg–Marquardt algorithm. The NaxWO3 formation/growth/dissolution mechanism was determined. Concentration profiles and diffusion coefficients of [WnO3n]−, reaction rate constants, number density of nuclei, and time dependencies of crystal size were calculated. The proposed approaches and models can be used in other systems for the cyclic voltammogram analysis and study of the mechanism and kinetics of electrode processes complicated by phase formation; parallel and sequential electrochemical and chemical reactions; as well as the formation of a deposit characterized by a nonuniform phase and/or chemical composition.

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Reactions at the Electrodes

Doumerc¹

1990

Inorganic Reactions and Methods

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Kinetics of the electrochemical deposition and dissolution of sodium tungsten bronzes

Cited by 10 publications

References 11 publications

Intermediate Phases and Reaction Kinetics of the Furnace-Assisted Synthesis of Sodium Tungsten Bronze Nanoparticles

Intermediate Phases and Reaction Kinetics of the Furnace-Assisted Synthesis of Sodium Tungsten Bronze Nanoparticles

Mechanism and Kinetics of the Phase Formation and Dissolution of NaxWO3 on a Pt Electrode in a Na2WO4–WO3 Melt

Reactions at the Electrodes

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