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Abstract Synthesis of intermetallic crystals by electrodeposition of Ag from alkaline aqueous electrolytes containing AgCN onto liquid metal electrodes via an electrochemical liquid‐liquid‐solid (ec‐LLS) process has been performed. X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy were performed to identify crystalline products. Ec‐LLS experiments performed with pure liquid Hg and Ga electrodes resulted in the formation of polycrystalline Ag2Ga and Ag2Hg3. Experiments performed with In‐containing liquid metals preferentially yielded Ag9In4and AgIn2products with liquid Hg0.35In0.65and Ga0.86In0.14, respectively. The product distribution with liquid Hg0.35In0.65depended on the level of Ag supersaturation during the electrodeposition. A mechanism that accounts for the aforementioned observations is presented and discussed. This work described the formation of Ag−In intermetallic phases by the isothermal electroreduction of Ag into different liquid metal solvents via ec‐LLS. Electrodeposition of Ag into a pure Ga or pure Hg liquid metal pool yielded precisely the compounds predicted from isothermal cross‐sections of the respective binary phase diagrams. These compounds were not found when using liquid Hg or Ga containing appreciable In. The smaller enthalpy of formation for AgIn2was consistent with its synthesis in Ga0.86In0.14. However, the observed product of Ag9In4in Hg‐containing liquid metals could not be rationalized solely from thermodynamic factors. Instead, this observation was consistent with a kinetic pathway based on the lability of Hg‐metal bonds and nearly identical crystal structures of Ag9In4and Ag2Hg3. Site exchange of Hg for In is consistent with our prior observations[23]of In exchange into Hg−Pd structures during Pd electrodeposition. This mechanism is not based on any direct role of electrochemistry other than aspects that dictate the operative supersaturation of the metal solute.
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Electrodeposition of Pd Intermetallics using Hg-In by the Electrochemical Liquid-Liquid-Solid Method
Electrodeposition of Pd from alkaline baths containing Pd(CN) 2 and KCN with liquid metal electrodes has been performed. Data are presented that Pd dissolved into and reacted with the liquid metal electrodes via an electrochemical liquid-liquid-solid (ec-LLS) process. HgPd crystals were obtained with liquid Hg electrodes. On solid In electrodes, In 7 Pd 3 was exclusively formed. In contrast, InPd was the primary product with Hg 1-x In x alloy electrodes. X-ray diffraction, scanning electron microscopy, and electron backscattering diffraction show that the materials were not a pure phase, as minor components of HgPd and In 7 Pd 3 were observed for various liquid Hg-In compositions. A mechanism is proposed where the InPd intermetallic forms through an intermediate phase of HgPd by the substitution of In atoms for the Hg sites of the unit cell. This study thus motivates further exploration of Hg 1-x In x as a versatile medium for intermetallic synthesis by ec-LLS.
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- Award ID(s):
- 2106315
- PAR ID:
- 10451245
- Date Published:
- Journal Name:
- Journal of The Electrochemical Society
- Volume:
- 169
- Issue:
- 11
- ISSN:
- 0013-4651
- Page Range / eLocation ID:
- 112514
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1149/1945-7111/ac9bdc
