Origin of Catalytic Effect in the Reduction of CO2 at Nanostructured TiO2 Films

Electrocatalytic activity of nanostructured TiO2 films toward the reduction of CO, is probed by depositing a nanostructured film on a glassy carbon electrode. The one-electron reduction of CO, in acetonitrile seen at an onset potential of -0.95 V (vs NHE) is significantly lower than the one observed with a glassy carbon electrode. The electrocatalytic role of TiO2 is elucidated through spectroelectrochemistry and product analysis. Ti species formed when the TiO2 film is subjected to negative potentials have been identified as active reduction sites. Binding of CO, to catalytically active Ti-3+ followed by the electron transfer facilitates the initial one-electron reduction process. Methanol was the primary product when the reduction was carried out in wet