Phenomenological description of the thermal reduction kinetics in graphene oxide films

Abstract

This study introduces a straightforward and cost-effective route to elaborate a thermally reduced graphene oxide film (R-GOF) at 350 °C under ambient atmosphere, followed by the investigation of the kinetic triplet of the related thermal reduction mechanism by a model-free approach. The structural, the morphological, and the electrical properties of the as-prepared films are scrutinized via a series of characterization techniques. The results demonstrate the successful reduction of the graphene oxide film (GOF), leading to a prominent electrical conductivity (3275 S m−1). Moreover, a model-free approach is applied to a differential scanning calorimetry (DSC) data to evaluate the kinetic triplet of the reduction mechanism. The activation energy (Ea) is assessed according to the most accurate isoconversional methods including Friedman (FRI), Vyazovkin (VYA), convincingly suggesting that the thermal reduction process of GOF can be treated as a one step process, giving values of 88 ± 8 and 79 ± 6 kJ mol−1, respectively. The pre-exponential factor and the kinetic model of the reaction are determined by the combination of isoconversional model with a compensation effect. Conclusively, the estimated activation energy values indicate that the graphene oxide structure, morphology and reduction conditions are the main factors to be considered when modeling and predicting its thermal reduction mechanism.