Effect of the Morphology of TiO2/Ti Electrodes on Photoactivity in the Electrochemical Reduction of Carbon Dioxide

A study was carried out on the photoelectrochemical reduction of CO2 using TiO2/Ti photoelectrodes, whose activity increases in going from samples obtained by dip-coating method to films formed by electrochemical anodization of titanium and further increases in going from disordered structures (spongy structure) to ordered nanotube structure. The introduction of electron donors into the anode chamber of the photoelectrochemical cell considerably enhances the photoactivity of the system. In the series of electron donors studied, this photoactivity increases in the series (CH3)2CHCH2OH = C3H7OH < C2H5OH < CH3CH(OH)CH3 < CH3OH. The major product of the reduction of CO2 is oxalic acid obtained in 61% yield.