| Abstract
| - Carbon-doped TiO2, demonstrated as an efficient photocatalyst in visible light photooxidation of organiccompounds, was prepared with different doping concentrations and investigated via differential electrochemicalmass spectroscopy (DEMS) and capacitive surface photovoltage (SPV) measurements in the form of thinlayer electrodes. In all cases the total photocurrent as well as the surface photovoltage of the doped materialsdecreased markedly in relation to the undoped one. No detectable oxygen evolved from the doped electrodesin acidic solution under UV-light excitation. Since an oxidation of formic acid is still apparent, it is concludedthat this oxidation occurs via isolated, catalytically poorly active trap states within the forbidden energy region.The existence of these states is confirmed by capacitive SPV measurements.
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