Differential-capacitance studies of silane-modified SnO₂ electrodes at low modulation frequencies

Differential-capacitance studies, at low modulation frequencies, were conducted on a variety of silane-modified SnO₂ electrodes. Silanes with amine functionality, when added to the SnO₂ surface, perturb the ionic population of the gel-like surface layer. This phenomenon and the nonideal capacitance behavior observed for SnO₂ electrodes at low modulation frequencies can be explained by the presence of a surface-state capacitance term in parallel with the normal space-charge capacitance.