The effect of adsorbed monolayers on the reduction of oxygen and hydrogen peroxide at the dme has been investigated. The monolayers studied were I-and dZ-a-palmitoyl lecithin, lysolecithin, quatemized poly4vinylpyridine, polylysine and cytochrome C. The monolayers inhibited the reduction of 0. and of H,O, to various extents, shifting the corresponding polarographic halfwave potentials to more negative potentials. The cytochrome-C monolayer formed an exception, exhibiting a catalytic influence on the reduction of H,O,.
The effect of the adsorbed monolayer on the different steps of the reduction mechanism is discussed. The inhibition of the reduction process by the monolayers is believed to be caused by blocking of the transport of the negatively charged intermediates and their accumulation near the electrode surface.
R&sum&
-On a examind l'effet des couches monomol&ulaire adsorb&s sur la rbduction d'oxygkne et d'eau oxygenke B l'&ctrode de mercure gouttante. Les couches monomoleculaire que l'on a Ctudih etait I-et dl-a-palmitoyl lecithin, lysolecithm, poly4vinyipyridine quatern& polylysine, et cytochrome C. Les couches monoatomiques inhibitent la rkduction d'O* et d'HPOI & des degr&s differents, en dCplacent le potential de demi-vague polarographique correspondant aux plus negatifs. La couche monomolCculaire de cytochrome C fait exception, montrant qu'i 1p otentiels influence catalytique sur la reduction d'H,O,. ya a vue On discut les elTets de la couche monomoltculaire adsorb& sur les &apes differentes de la m&&anism de rkduction. On pense que l'inhibition du processus de rCduction par les couches monomol&ulaires est 2 cause de l'arr& de transport des intermkdiares chang&s negativement et leur accumulation tous prts de la surface de l'tlectrode. Zusammenfassung-Der Eintluss adsorbierter Monoschichten auf die Reduktion von Sauerstoff und von Wasserstoffperoxyd an einer Quecksilber-Tropfelektrode wurde untersucht .