Unveiling graphite anodic expansion: Insights from electrochemical techniques, mass spectrometry, and kinetic modelling

Abstract

Anodic expansion of graphite at different pH has been studied by coupling a mass spectrometer to an electrochemical cell. The mass spectrometry technique permits to follow the electrochemical gasification of graphite as well as the reaction products formed from the electrolyte. The current and mass spectrometry signals suggest that the neutral medium is the least aggressive for expansion. In addition, chronoamperometric expansion of graphite at different potentials has been carried out using the neutral medium. This experimental approach permits to get detailed information about the reaction mechanism that produces graphene-oxide based materials. The effect of potential and electrolyte concentration have been studied, and it has been observed that the degree of oxidation of the graphene oxide material obtained can be controlled. In addition, a kinetic model based on a phase-moving boundary has been used to describe the chronoamperometric experiments. Two types of graphene oxide materials have been obtained with the anodic synthesis and have been classified as few-layer graphene oxides (FLGOs) and graphene oxide quantum dots (GOQDs). The physicochemical and electrochemical properties of both products have been studied.