differential capacitance

https://doi.org/10.1351/goldbook.D01702
Differential capacitance (per unit area of interphase or electrode; SI unit \(\text{F m}^{-2}\)) is given by \[C=(\frac{\partial Q}{\partial E})_{T,p,\mu _{i},...}\] where \(E\) is the potential of the electrode with respect to a reference electrode, \(\mu _{i}\) is a set of chemical potentials which are held constant, \(T\) is the thermodynamic temperature, \(Q\) is the electric charge (per unit area of interphase or electrode), and \(p\) is the pressure.
Sources:
PAC, 1974, 37, 499. (Electrochemical nomenclature) on page 509 [Terms] [Paper]
PAC, 1983, 55, 1251. (Interphases in systems of conducting phases (Provisional)) on page 1261 [Terms] [Paper]