Effect of oxygen nonstoichiometry on photo-electrochemical properties of TiO2−x

Polycrystalline TiO2−x pellets were equilibrated at 1220–1420 K in a flow of Ar + 7 vol.% H2 gas mixture. The resulting deviation x from stoichiometric composition of titanium dioxide was determined gravimetrically. X-ray diffractometry revealed coexistence of rutile with TinO2n−1 Magnéli phases. Optical reflectance and photocurrent spectroscopies served as experimental methods of the band gap determination. Polycrystalline TiO2−x were used as photoanodes in a photoelectrochemical cell. The photocurrent response to the applied voltage was studied. It was found that TiO2−x with x ca. 0.006 exhibited the best photoelectrochemical performance.