Abstract: TiO2 treated in hydrogen atmosphere showed enhanced photocatalytic act ivity in degrading the sulfosalicylic acid (SSal).The results of the electrochem ical impedance spectroscopy (EIS) investigation showed that the diameters of the capacitive arcs for the HTiO2 were much smaller than those of bare TiO2 and t hermally treated TiO2 in air,indicating that the charge transfer of the HTiO2 occurs more rapidly,thus inviting a higher photocatalytic activity.When an exter nal bias was applied on the HTiO2,the arc of the EIS Nyquist plot decreased ob viously than without the bias,suggesting more efficient separation of the photo generated carriers.

Key words: Photocatalysis, Titanium dioxide, Electrochemical impedance spectro scopy