Electrocatalytic Reduction of Dioxygen on 9,10-Anthraquinones-Incorporated Clay-Modified Glassy Carbon Electrodes

摘要

The preparation and electrochemical characterization of 9,10-anthraquinones adsorbed clay-modified and anthra-quinones-clay composite-modified glassy carbon electrodes(GCEs)were investigated.The influence of the pH on the electrochemical behavior and stability of the clay-modified electrodes(CMEs)were studied by cyclic voltammetry in acidic and neutral aqueous media.For the dioxygen reduction,anthraquinones adsorbed clay-modified electrodes possess good electrocatalytic abilities with overpotential ranging from 174 to 452 mV,lower than the bare GCE in the pH range 4.0-7.0;also,anthraquinones-clay composite-modified electrodes exhibited potent catalytic activities with an overpotential of about 128-21 mV lower than at a bare GCE at pH 7.0-8.0.The diffusion coefficients of mediators in clay films were evaluated by chronoamperometric techniques.Chronocoulometric studies showed the involvement of two electrons in the reduction of anthraquinones and four electrons in dioxygen reduction at the optimum pH.In addition,hydrodynamic voltammetric studies were performed to determine the mass-specific activity of the anthraquinones used,the heterogeneous rate constants for the reduction of O_2 at the surface of modified electrodes and the apparent diffusion coefficient of O_2 in aqueous O_2-saturated buffer solutions.