Electrical double layer on the Cd–Ga liquid alloy in solutions of surface-inactive electrolytes in water, methanol and propylene carbonate

A novel electrode, liquid Cd (0.3 at.%)–Ga eutectic alloy, was fabricated and studied. Its electrical double layer characteristics were shown to differ markedly from those of a Ga electrode; they are practically identical to those of the Cd electrode. It was found that, in the absence of a metal–solvent chemisorption interaction, the electron capacitance of the Cd–Ga electrode approaches the electron capacitance of the Ga, In–Ga and Tl–Ga electrodes, but differs from that of the Hg electrode. The Cd–Ga electrode resembles the In–Ga electrode in its lyophilic nature. The value of the chemisorption potential drop of solvents (water, propylene carbonate and methanol), obtained with the Cd–Ga electrode, follows the rule characteristic of the Ga, In–Ga and Tl–Ga electrodes, namely, the chemisorption potential drop of a solvent correlates with the metal work function (in vacuo). Mercury does not fall into this pattern, which was explained by the longer distance of the solvent dipoles to the ionic lattice in this metal. The chemisorption interaction of the solvents with the Cd–Ga electrode, like Ga and In–Ga electrodes, is shown to increase with the solvent donor number.