Determination of coordination form of tungsten ion in molten alkali chloride by electrochemical method

et al. 2022

J. Phys. Chem. C

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The macroscopic properties of reactions are closely tied not only to the thermodynamics and dynamics of the reactions but also to the microstructure of the ionic complexes. We herein report the analysis of the reduction process of tungsten ions in molten salt by combining the electrochemical, thermodynamic, dynamic, and configuration parameters. The thermodynamic and dynamic properties, including the apparent electrode potential, Gibbs free energy, and diffusion coefficient, of the tungsten ions were calculated by square-wave voltammetry and were found to be in good agreement with the simulation results. In addition, the concomitant changes of the diffusion coefficient and coordination number are elucidated. In all cases, the change of coordination number of the tungsten ion complexes led to the change of electrochemical, thermodynamic, and dynamic parameters. These findings propose a new dimension for regulating the structure of metal ion complexes and analyzing the reaction properties. The combination of simulation and experiment provides a basis for the mechanism analysis of the reduction and synthesis of metal materials.

Section: Results and Discussionmentioning

confidence: 99%

“…The radial distribution function (RDF) was analyzed by the trajectory files of Forcite. More simulation details have been shown in our previous work …”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Tungsten Ion Complexes in a Cationic/Anionic Molten Salt System: Thermodynamic/Dynamic/Simulation Investigation Reveals Configuration-Induced Changes in Reaction

et al. 2022

J. Phys. Chem. C

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“…In previous studies, tungsten ions dissolved in salt have been formed using tungsten carbide (WC) as a sacrificial anode. [5][6][7][8][9] The electrochemical reduction of tungsten ions proceeded in two steps with two and four exchanged electrons. Although nano-tungsten powders could be extracted by this method, several problems still require to be explored.…”

Section: Introductionmentioning

confidence: 99%

Valence and coordination form transition of tungsten ions in molten alkali chlorides

Phys. Chem. Chem. Phys.

et al. 2022

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“…Electrochemical in situ techniques have a wide range of applications moving from lab-scale use to industrial production processes. − The electrochemical methods have been successfully applied to the in situ detection of the valence transition process of tungsten ions in various molten salt systems. , With the increase of the alkali cation radius of molten salt, the tungsten ion in molten salt changes from a two-step electron-transfer process, W(VI) → W(IV) → W(0), to a one-step electron-transfer process, W(II) → W(0), after electrolysis of WC. Similar trends are observable in the molten salt with various [Cl – ]/[F – ] ratios.…”

mentioning

confidence: 99%

In Situ Spectroscopic Identification and DFT-Assisted Prediction of the Valence and Structure of Tungsten Ions in a Cationic/Anionic Molten Salt System

et al. 2023

J. Phys. Chem. C

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Understanding the reduction mechanism and coordination of tungsten ions in molten salt is one of the key factors to improve the electrolysis efficiency of tungsten carbide. In situ spectroscopy combined with simulation calculation is a strong analytical technique for characterizing chemical species and their behaviors in molten salts. The tungsten ion group was investigated by in situ high-temperature and room-temperature spectroscopy combined with density functional theory (DFT) calculations. For the described in situ spectroscopic studies, a new setup was used, which allowed the registration of UV−vis spectra of tungsten ions in cationic and anionic molten salt systems. The DFT calculation results proved useful for estimating the trend of experimental spectra. Through experimental and theoretical studies, the tungsten ion groups in various molten salt systems were identified, and the effect of cations and anions in molten salt systems onto tungsten ion group formation could be elucidated.