Spectroelectrochemistry of Highly Doped Nanostructured Tin Dioxide Electrodes

A new, highly doped nanostructured SnO 2:Sb electrode has been prepared. This electrode possesses characteristics markedly different from undoped nanostructured semiconductor electrodes. Cyclic voltammetry and spectroelectrochemical experiments reveal that the whole of the nanostructured SnO 2:Sb electrode is electronically addressed in a potential range extending from negative to significantly positive of the flatband potential. The flatband potential of nanostructured SnO 2:Sb, obtained from the Mott−Schottky analysis, shows Nernstian dependence on pH and is given by +0.10 − (0.06)(pH) (V vs Ag/AgCl). The extinction coefficient for conduction band electrons is determined to be 2400 M -1 cm -1 at 700 nm. A theoretical model, based on expressions derived for spherical semiconductor particles, fully accounts for the observed capacity−potential relation.