Electrochemical surface modification and regeneration of carbon fiber microelectrodes in deionized water

The contamination, passivation, or fouling of the detection electrodes is a serious problem undermining the analytical performance of electroanalytical devices. In this paper, a simple and effective carbon fiber microelectrodes (CFME) renewal method was proposed for the first time. CFME was pretreated with an initial potential of 1.75 V in deionized water for 26.13 min to obtain an activated electrode with a significantly increased electrochemical response to dopamine. This method can restore the electrochemical performance of the inactivated CFME. An advantage of this method is that its activation and regeneration effect on the electrode was not less than the other reported activation solutions, although deionized water does not contain any other electrolyte. Our study furthered the understanding of the activation mechanism of CFME treated electrochemically in deionized water, this was ascribed to a renewing in the surface of carbon fibers after electrochemical treatment. At the same time, it was proved that the oxygen-containing functional groups were modified on the surface of activated CFME, which led to the regeneration of an electrochemically active surface and improved CFME sensitivity. The differential pulse voltammetry (DPV) response of dopamine showed good linearity (R² = 0.9961) on the regenerated CFME in the concentration range from 1.0 × 10⁻⁷ to 1.0 × 10⁻⁴ mol/L. A limit of detection as low as 3.1 × 10^–8 mol/L was found. The regenerated CFME was quite stable and had good reproducibility. It is expected to be applied to activate and regenerate electrodes contaminated in the monitoring of a complex biological microenvironment.