| In biosystems the molecules organize themselves into complex functional entities with cooperating components of molecular dimensions. In the photosynthetic reaction center, solar energy harvested by antenna pigments is funneled to the special pair, where multistep electron transfer reactions proceed to separate an electron-hole pair across the lipid bilayer. The well organized and asymmetric molecular arrangement across the membrane plays an important role in charge separation in photosynthesis. For the design of artificial photosynthetic model systems, most researchers have employed semiconductor electrodes. It is of great interest to see how a photosynthetic model system behaves on metal electrodes, which have not been studied as extensively.; In Chapter I, enhanced carbon dioxide reduction is investigated. It appears that excitation of the plasmon in silver can enhance the production of the carbon dioxide radical and its photoelectrochemical reduction. The mechanism of plasmon enhancement is also discussed in this Chapter.; In Chapter II, the results of an electrochemical and a photoelectrochemical investigation of methyl viologen on a silver electrode in the presence of, as well as in the absence of carbon dioxide are presented. It is concluded that only the methyl viologen radical layer which is nearest to the silver electrode is photoactive. The role of neutral methyl viologen in carbon dioxide reduction is also discussed and a possible reaction mechanism is proposed. |
