<p class="MDPI12titleori1">Non-Idealities in Mott–Schottky Analysis of CdSe-Coated Ti and TiO₂ (Photo)electrodes

CdSe-coated electrodes, formed by electrodeposition of CdSe barrier layers on metallic Ti or porous TiO2 substrates were characterized by electrochemical impedance spectroscopy in a (photo)cell with aqueous redox electrolytes based on the sulfide/polysulfide and ferro/ferricyanide couples. Common to the metallic and oxide substrate electrodes, the shape and features of Mott–Schottky plots were found to be influenced by the electrode material properties, the electrolyte contact, and measurement conditions (illumination, frequency, potential-scan speed). The information obtained from capacitance measurements are evaluated on the basis of the ideal Schottky-diode model and photocurrent voltammetry data. The rationale behind the observed non-idealities is inquired, and peculiarities of the measuring procedure connected to the non-stationary character of the interface are discussed.