The effect of vacancy size on the oxidation process of graphene by CO2: A ReaxFF molecular dynamics study

Abstract

The gasification process of graphene has been studied extensively, but the kinetic behavior of its surface vacancies under CO2 atmosphere is not clear enough. Correctly understanding its behavior can help people to better understand the evolution of carbon structure during gasification from a microscopic perspective. In this study, ReaxFF-MD was used to investigate the entire gasification process of the defective graphene in the CO2 atmosphere, including the generation of some gases. When the vacancy existed, the stable structure of the surface would be destroyed, resulting in the formation of the 5-member ring and 7-member ring vacancies. Meanwhile, the carbon bond near these vacancies would extend or break, which was used to capture the O atom of CO2 molecule and generate CO gas molecule. With the increase of the aperture of the vacancy, the number of active sites on the defective surface increased, which not only improved the CO2 adsorption reaction rate but also promoted the expansion of the vacancy size. Our study will have important implications for clarifying the gasification process of CO2 gas molecules on the carbon structure of vacancies of different sizes, deepening the understanding of the gasification mechanism from the atomic scale. By revealing the interaction mechanism between the defective graphene and CO2, it provides a theoretical basis for the industrial graphene application process.