Abstract: The photoelectrochemical reduction of CO₂ was studied at copper anode oxide film.The anodic oxide film on copper electrode consists of Cu₂O and CuO, which are p-type semiconductors.In the case of lower electric quantity (Q<0.10 C) for reduction, the higher Faradaic efficiencies for CH₄ were achieved on the film, and in the case of higher electric quantity for reduction, however, CH₃OH was the main product.The Faradaic efficiency for CH₄ as a function of the applied potential, the electric quantity for reduction and the condition of forming the anodic oxide film were determined.The preliminary mechanism of CO₂ photoelectrochemical reduction is presented.

Key words: Carbon dioxide, Copper anode oxide film, Photoelectrochemical reduction