https://doi.org/10.1351/goldbook.P04775
The value of the where the potential at the point of zero charge is that for the given electrode in the absence of
electric potential
of an electrode at which one of the charges defined is zero. The reference electrode
against which this is measured should always be clearly stated. The potential difference with respect to the potential of zero charge is defined by specific adsorption
(other than that of the solvent).