ENHANCING THE ELECTROCHEMICAL REVERSIBILITY OF QUINONES ON PLATINUM SURFACES IN ORDER TO IMPROVE THE CHARACTERISTICS OF PHOTOBIOELECTRODES WITH PHOTOSYNTHETIC REACTION SITES

Electrochemical aspects of exogenic quinones functioning as the electr on transfer mediators required in the development of photobioelectrode s with photosynthetic reaction sites were studied. New methods for the modification of Pt and Pt amalgam electrodes with monolayers of napht hoquinones were suggested. The immobilized quinone monolayers were fou nd to be electrochemically reversible. It was shown, moreover, that an enhanced electrochemical reversibility of ubiquinone solubilized in t he aqueous medium can be attained when the Pt surface is modified by c ysteamine or, particularly so, by amalgamation. Monolayer adsorption o f the reaction sites on the electrode surface has almost no influence on the electrochemical properties of the monolayer of immobilized naph thoquinone, but appreciably restricts the electrochemical process invo lving solubilized ubiquinone. The photoelectric activity of bacterial reaction sites adsorbed on the different electrode substrates was inve stigated, and found to strongly depend on the type of monolayer presen t. The results obtained were discussed in relation to the electrochemi cal properties of quinones.