Journal of the American Chemical Society· 2026Q1
Redox Buffering and Corrosion in Molten Chloride Salts Dictated by Chlorobasicity
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- Q1SCImago
- 2026year
Short summary
Molten salt chlorobasicity dictates redox buffer speciation and corrosion thermodynamics, demonstrated by a 0.49 V shift in the Eu(III)/Eu(II) potential and altered chromium dissolution in KCl-MgCl2 vs. LiCl-KCl melts.
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Key points
- Chlorobasicity of molten salts directly influences redox buffer speciation and alloy corrosion.
- Increasing MgCl2 content in LiCl-KCl and KCl-MgCl2 melts shifted the Eu(III)/Eu(II) apparent potential by +0.49 V.
- In situ XANES showed progressive Eu(III) reduction in KCl-MgCl2, while Eu(III) remained stable in LiCl-KCl.
- Chromium dissolution from Ni-20Cr alloys occurred concurrently with Eu(III) to Eu(II) conversion, identifying Eu(III) as the oxidizing species.
AI-generated from the title and abstract; the full text is not read.
Abstract
Abstract This study establishes an in situ synchrotron approach to directly link molten-salt chemistry, redox-buffer speciation, and alloy corrosion in chloride melts. Using a first-of-its-kind corrosion cell coupled to simultaneous X-ray absorption spectroscopy (XAS) and X-ray fluorescence (XRF), we monitor europium redox-buffer speciation and chromium dissolution during corrosion of Ni-20Cr in molten LiCl-KCl and KCl-MgCl2 salts. To build a mechanistic framework, we combine UV–vis optical basicity measurements, in situ electrochemistry, and molecular dynamics simulations to quantify how salt chlorobasicity reshapes europium solvation and shifts the Eu(III)/Eu(II) apparent potential. Increasing MgCl2 content drives the apparent potential of the Eu(III)/Eu(II) couple +0.49 V relative to LiCl-KCl and stabilizes Eu(II)-compatible solvation environments. In situ, time-resolved Eu L3-edge XANES reveals progressive Eu(III) reduction in KCl-MgCl2 melts, while Eu(III) remains predominantly stable in LiCl-KCl. This behavior is consistent with a chlorobasicity-activated reaction with boron nitride (BN) cell components. In less chlorobasic melts, salt redox chemistry enables BN chlorination, allowing BN to act as a sacrificial reductant and chlorinating agent that promotes Eu(III) to Eu(II) conversion, whereas this pathway is not thermodynamically favored in LiCl-KCl. During active corrosion of Ni-20Cr, coupled Eu XANES and Cr XRF measurements show concurrent Eu(III) to Eu(II) conversion and Cr dissolution, confirming that Eu(III) is the oxidizing species driving chromium oxidation. Together, these results demonstrate that chlorobasicity is a central control variable for redox-buffer speciation and corrosion thermodynamics, and more broadly that chlorobasicity can enable or suppress reactive pathways with structural materials in high-temperature molten salts.
The authors' abstract, as published at the source. Journal of the American Chemical Society, 2026 · DOI ↗
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Fluid Flow and Transfer ProcessesChemical Engineering