Abstract: The photoelectrochemical reduction of carbon dioxide on P⁺/P-silicon electrode in aqueous solution was reported. The effects of cathodic polarization potential, electrolysis time and electrolyte pH, were studied by means of electrochemical voltammetry and prolonged electrolysis. The cathodic reduction products were formic acid and a small amount of formaldehyde. A power energy conversion efficiency of 4.0% of carbon dioxide reduction was achieved. Also the photoelectrochemical reduction process of carbon dioxide was discussed.

Key words: Reduction of carbon dioxide, P⁺/P-Si Photocathode, Solar energy conversion