Search for: All records

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 Hg_0.35In_0.65and Ga_0.86In_0.14, respectively. The product distribution with liquid Hg_0.35In_0.65depended 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 Ga_0.86In_0.14. 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.