Semiconductor Electrodes: XIV . Electrochemistry and Electroluminescence at n‐Type in Aqueous Solutions

The electrochemical behavior of single crystal n ‐ TiO 2 was investigated in aqueous solutions. Charge transfer at the semiconductor/electrolyte interface was probed with several redox couples with standard redox potentials spanning a wide range. Most reductions occurred at potentials close to V fb , the flatband potential and the current‐voltage behavior suggested involvement of surface states in the charge transfer process. Evidence for the adsorption of phosphate ion and its effect on the reduction of Fe ( CN ) 6 3 − is also presented. Electroluminescence was observed during reduction of S 2 O 8 2 − at wavelengths longer than 700 nm, suggesting the existence of intermediate levels.