Electrochemical Doping of Compact TiO2Thin Layers

Electrochemical n-doping of dense thin films of TiO2 (anatase) occurs upon proton insertion from acidic aqueous electrolyte solution. Details of the reaction are investigated by cyclic voltammetry and by electrochemical impedance spectroscopy. The good-quality films are ideally compact, mimicking the properties of a macroscopic single-crystal electrode. The n-doping is stable for at least weeks of electrode storage in air at room temperature. Doping manifests itself by characteristic morphological differences of the surface. Electrochemical Li+ insertion indicates that there is a competition between Li+ and H+ ions in the lattice, detectable by cyclic voltammetry.