Impact of oxidants O-2, H2O, and CO2 on graphene oxidation: A critical comparison of reaction kinetics and gasification behavior

Z Liang and R Khanna and KJ Li and F Guo and Y Ma and H Zhang and YS Bu and ZS Bi and JL Zhang, CHEMICAL ENGINEERING JOURNAL, 450, 138045 (2022).

DOI: 10.1016/j.cej.2022.138045

Fundamental understanding of the oxidation behavior of O2, H2O, and CO2 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 monovacant 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 O2, the nucleation stage is harder while the later stages contained no limiting behavior; The gasification kinetics is highest for H2O during initial periods, but the oxidative behavior changes as higher gas consumption levels are reached; CO2 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 H2O oxidant. Results suggest that there may be little overlap in the oxidation sites for CO2 and H2O. In-depth atomic level investigations consistent with the experimental phenomenon will have implications for future design, process optimization, and their commercial application.

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