Mediated electrochemical reduction of oxygen to hydrogen peroxide via a surface-confined naphthoquinone reagent and the mediated electrochemical reduction of a naphthoquinone redox reagent anchored to high surface area oxides

摘要: Derivatives of 1,4-naphthoquinone, 2-chloro-3-((2-(dimethylpropylammonio)ethyl)amino)-1,4-naphthoquinone bromide, Ia, and 2-chloro-3-((2-(dimethyl(3-(trimethoxysilyl)propyl)ammonio)ethyl)amino)-1,4-naphthoquinone Ib, have been synthesized used as solution surface-bound catalysts, respectively, for the electrochemical photoelectrochemical reduction O/sub 2/ to H/sub 2/O/sub 2/. The surface derivatizing reagent Ib having -Si(OCH/sub 3/)/sub 3/ functionality can be functionalize a variety surfaces including electrode materials high area oxides. reagent, (Q/QH/sub 2/)/sub surf/, has same E/sup 0/' Ia in solution, approx. -0.4 V vs. SCE at pH 7. (QH/sub surf/ reacts with aqueous electrolyte 7 rate constant > 10/sup 5/ M/sup -1/s/sup -1/ form (Q)/sub surf/. High oxides functionalized yield (M/sub x/O/sub y/)-(Q) that electrochemically reduced y/)-(QH/sub 2/) via mediation by low concentration solution. isolated from filtration reacted 2//H/sub 2/O up 0.1 M free electrolyte. Study rotating-W-disk electrodes derivatized shows redox equilibrationmore » quinone is rapid. Reduction or visible light illuminated p-WS/sub effected an potential 0.8 more positive than metallic electode. overall energetics are such effect uphill formation quinone-mediated onset 0.6 0/'(O/sub 2/). sustained photoassisted demonstrated. 15 references, 8 figures, 2 tables.« less