Figure ) Internal energy calculation as a function of applied electric field fit to eq. ) internal energy of reaction response to an applied electric field where filled lines represent the fit to eq. 11, (g-i) Fermi energy response to an applied electric field, where solid line represents the fit to eq. 12 and 13, and experimental shift in electrostatic surface potential as a function of overpotential relationship at the Sm 0.2 Ce 0.8 O 1.9 -gas interface in (j) 0.35mbar 1:8:4 H 2 : H 2 O : Ar (blue circles), (k) 0.36mbar 2:25 CO : CO 2 (magenta triangles), 9 and (l) La 0.8 Sr 0.2 FeO 3 in 1.3mbar O 2 (purple squares). The solid and dashed lines represents the linear fit to the experimental data and simulated results, respectively.