Photoelectrocatalytic reduction of 4-Chlorobiphenyl Using Anion radicals and Visible Light

Article abstract of DOI:10.1021/j100261a039

Excitation of electrochemically generated anion readicals of anthracene and 9,10-diphenylanthracene with visible light (>740 nm) gave greater than 10-fold increases in the rates of reductive dechlorination of 4-chlorobiphenyl.Peak shapes and potentials of cyclic voltammograms of the hydrocarbon catalysts alone with the light on indicated an increase in the rate of mass transport to the glassy carbon electrode caused by convective thermal gradients.However, less than 4percent of the light-assisted increase in electrocatalytic rate constant could be explained by a localized increase in temperature of the reaction layer near the electrode.Good agreement of current-potential data from illuminated electrodes with a model for a two-electron electrocatalytic dark reaction allowed computation of a conditional rate constant by nonlinear regression analysis of the voltammetric data, even in the presence of an exponantially increasing background current.Kinetic results suggested the establishment of a fast, light-assisted reduction pathway, featuring either a photoexcited anion radical of the catalyst or an electron ejected from the excited anion radical as a powerful reducing agent.