Impact of oxidants O2, H2O, and CO2 on graphene oxidation: A critical comparison of reaction kinetics and gasification behavior

Journal article (2022)
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2022

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English

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Abstract

Fundamental understanding of the oxidation behavior of O
2, H
2O, and CO
2 in the process of oxyfuel combustion is of great significance. Extensive MD simulations with reactive force-field (ReaxFF) were performed to compare the gasification behavior under the individual influence of three oxidant molecules on a pristine and a mono-vacant graphene sheet. Distinct differences were observed in almost every aspect including initial kinetics, rate changes, complete/incomplete combustion, gasified regions, and the role of vacancy defects. In the case of O
2, the nucleation stage is harder while the later stages contained no limiting behavior; The gasification kinetics is highest for H
2O during initial periods, but the oxidative behavior changes as higher gas consumption levels are reached; CO
2 has the highest thermodynamic stability and the formation of stable intermediate structures troubles the gasification. Significant out-of-plane activity is observed in the case of H
2O oxidant. Results suggest that there may be little overlap in the oxidation sites for CO
2 and H
2O. In-depth atomic level investigations consistent with the experimental phenomenon will have implications for future design, process optimization, and their commercial application.