Electrochemical measurements on metal oxide electrodes—II. Impedance measurements on Nb-doped single crystal TiO2

Mott—Schottky plots were measured on single crystal Nb-doped TiO₂ in aqueous buffer solutions and KCl electrolytes of concentration between 1 M and 10^?4 M KCl. The influence of surface pretreatment, nature of the dopant and solution conductivity on the Mott—Schottky plots was examined. The surface pretreatment was found to affect the frequency dispersion of the Mott—Schottky plots. Analyses of published data and results from the present study suggest that the point of zero charge of differently doped TiO₂ samples influences the flatband potential. The impedance measurements in KCl electrolytes showed that the flatband potential of single crystal Nb-doped TiO₂ could be determined in low conductivity electrolytes such as 10^?3 M KCl.