engleski

Evaluation of surface potential from single crystal electrode potential, Adsorption

The new method of evaluation of the point of zero potential for the metal oxide exhibiting a saddle-like surface potential function Ψ0(pH), as obtained by acid base potentiometric titration using Single Crystal Electrode, was proposed. The electrode potential of sapphire single crystal electrode (A crystal plane, 11¯20) was measured, point of zero potential and surface potentials were evaluated, and the results were analyzed using the Surface Complexation Model. The electroneutrality point corresponding to the point of zero potential was found to be at pHpzp = 7.0. Thermodynamic protonation equilibrium constants for the first and the second step of protonation were obtained as lgK◦1 = 12.7 ; lgK◦2 = 1.2.

single crystal electrode; sapphire; surface potential; electrical interfacial layer; sSurface complexation; equilibrium parameters; surface charging

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