## 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]