Photoelectrochemical reduction of carbon dioxide at Si(111) electrode modified by viologen molecular layer with metal complex

Photoelectrochemical carbon dioxide reduction was carried out at a p-type Si(111) electrode modified with a viologen molecular layer and [AuCl ₄] ^- or [PdCl ₄] ^2-. It was proven that the reduction reaction was mediated by viologen moiety and while CO ₂ reduction was dominant at the Si(111) electrode modified with [PdCl ₄] ^2- in the potential region where viologen moiety was in the first reduced state, it became dominant at the electrode modified with [AuCl4] ^- when viologen moiety became the second reduced state. FT-IR measurement confirmed the formation of formic acid/formate ion at the [PdCl ₄] ^2-/viologenmodified Si electrode.