Electrochemical oxidation of ordered mesoporous carbons and the influence of graphitization

Abstract

Ordered mesoporous carbon materials (OMC), obtained by the template carbonization pathway from silica templates (sacrificial method), exhibit promising features for many applications mainly due to their large surface area. Graphitization is a common approach to improve the electrical conductivity and degradation resistance. We have investigated the graphitization of two different OMC at 1500 °C and the electrochemical oxidation by potential holding at 1.4 V vs. reversible hydrogen electrode (RHE) in acidic electrolyte. Graphitization conducts to a significant reduction of the electrooxidation associated charge, between 50 and 90% depending on the carbon properties, together with a decrease of surface area of 35–48%. The materials still exhibit a large electrochemical surface area, according to electrochemical impedance and cyclic voltammetry experiments. Upon electrooxidation, the relative amount of oxygen increases according to a comparative analysis of X-ray photoelectron spectroscopy test of the electrodes before and after potential holding. The results are of interest to define strategies towards the amelioration of carbon degradation by electrooxidation in electrochemical devices.