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

Effect of Different sp2 Bond Contents on the Reactivity and Mechanical Properties of Coke Carbon: A ReaxFF Molecular Dynamics Study

“…Nonperiodic boundaries were set in the Z direction, allowing the gas molecules to penetrate and react downward from the upper part of the coke model. The ReaxFF parameter was originally used in Plimpton’s study, and it has been validated for its feasibility in computing reaction paths, kinetics, transition states, and process energies. ,, Moreover, this set of ReaxFF parameters was consistent with Li’s research, which has been proved to better simulate the relevant gasification reaction of the carbon-containing models. ,, In the process of the reaction, simulations of the coke model and gas molecules were performed in the NPT ensemble for 20 ps, which served to eliminate the unstable dangling bonds in the model and minimize the energy of the model. After that, the whole system was heated to 3500 K and was performed in the NVT ensemble for 1000 ps at 3500 K, allowing the coke model to fully react with gas molecules.…”

“…However, these methods cannot provide the microstructure evolution process of coke to explain its reaction mechanism. In order to gain a deeper understanding of the structural changes of carbon-containing materials during the reaction process, simulation methods using reactive force field (ReaxFF) and molecular dynamics (MD) have been widely used. – These methods have been proven to be effective in studying the microstructural changes of carbon-containing materials under high-temperature conditions. Tian et al used ReaxFF-MD to build a large coke molecular structure containing more than 60,000 atoms .…”

Degradation of Graphene in High- and Low-Humidity Air, and Vacuum Conditions at 300–500 K

“…On the other hand, at 450 and 500 K, graphene was volatilized in vacuo, while oxygen gas was reacted/chemisorbed on the graphene under non-vacuum conditions, creating defects (increased intensity of the D band), and graphene was destroyed via a continuous oxidation reaction with CO 2 and CO production for long-time heating in high- and low-humidity conditions at 500 K. Although defect creation on graphene could be caused by oxidation gas in the low- and high-humidity air, more change in low-humidity air indicated that the oxidation reaction was inhibited by water vapor. This was caused by the quick oxidation of graphene with water vapor [ 46 ]. Water chemisorption and oxidation mainly occurred on graphene edges and, thus, competed with each other, and an oxidation reaction via oxygen gas, in which water vapor chemisorbs on graphene, was prevented.…”

Interactions of graphene with oxidants in a mixed atmosphere: synergistic effects of O2/H2O and O2/CO2 on gasification reactivity and kinetics

“…[40][41][42][43] The ReaxFF simulation of graphene gasification process in C-H-O system has obtained the apparent activation energy which is consistent with the experimental results (190-270 kJ mol À1 ). [27][28][29]44 A scaling relationship is generally established between the theoretical and experimental results for developing systematic correlations.…”

“…26 In recent years, our group has carried out extensive MD computer simulations using the ReaxFF method to investigate the thermal behavior, reaction kinetics, and mechanisms of graphene oxidation under O 2 , CO 2 , and H 2 O environments. [27][28][29] The reactive force field (ReaxFF), based on quantum mechanical (QM) structure and energy data, is being used increasingly for accurately describing bond breakage/ formation reactions while significantly reducing computational requirements. 30 While a fundamental understanding has been achieved regarding the oxidation behavior and mechanisms associated with individual oxidants, there is very limited atomic-level information on the oxidation behavior in a mixed oxidant environment.…”