Beschreibung:
Fundamental understanding about carbon steam gasification at atomic scale plays a significant role in industry. The reaction mechanism of graphene sheets in a steam-rich environment is simulated at the atomic scale using molecular dynamics with reactive force field. The speed segmentation phenomenon of graphene steam gasification at low temperature, that is, fast first and then slowdown, is revealed, and the activation energy of each stage of the reaction is obtained by kinetic fitting. Mono-vacancy defect promotes the initiation of the reaction at low temperatures. By visualizing the reaction process, it was found that the slowing down of the reaction rate was attributed to the CO desorption step after the surface-active sites were saturated. Focusing on the local structure, the wrack mechanism of two types of edges (armchair and zigzag), as well as single-vacancy and double-vacancy defects on the basal surface were revealed. Stable intermediate structures were discovered, and the vital role of high oxygen coverage in the surface destruction process was determined