ANODIC ELECTROCHEMICAL PRETREATMENT TIME AND POTENTIAL AFFECT THE ELECTROCHEMICAL CHARACTERISTICS OF MODERATELY BORON-DOPED DIAMOND ELECTRODE

摘要

Boron-doped diamond (BDD) electrodes, both as-prepared and electrochemically oxidized were studied. The relation between the anodic oxidation treatment time, anodic potential and electrochemical characteristics has been discussed. Electron transfer processes in all BDD electrode surface were studied by cyclic voltammetry. The ferric/ferrous sulfate and ferri/ ferrocyanide redox systems were chosen respectively to act as the probe of one-electron transfer processes. The relation between ΔE and ψ, the dimensionless parameter, was obtained with a correlation coefficient greater than 0.9987 by mathematics fitting function. The rate constants of the electron transfer reaction, k~0, were evaluated using the ΔE_p values. The k~0 values for all BDD electrodes ranged from 3.33 x 10~(-5) to 4.72 x 10~(-5) cm s~(-1) in 0.1 m FeSO4/ 0.1 m H2SO4 and from 1.01 x 10~(-4) to 2.49 x 10~(-4) cm s~(-1) in 0.1 m K4[Fe(CN)6]/0.1 m H2SO4 system, which were in the standard range for a quasi-reversible system, respectively. The electrochemical properties of the BDD electrodes changed as a function of the surface anodic treatment time and potential. The anodic oxidation at low potential stripped mainly the impurities of BDD surface, sp~2-carbon, and had little effect on the modification of the surface. While increasing the anodic potential up to +2.0 V, the anodic oxidation stripped the impurities of the BDD surface at first and carried out the modification of the BDD surface from hydrogen-terminated hydrophobic to oxygen-terminated hydrophilic surface with increasing anodic treatment time.