The value of the 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 \[E_{\text{pzc}}=E- E_{\sigma =0}\] where the potential at the point of zero charge is that for the given electrode in the absence of specific adsorption (other than that of the solvent).