Density functional theory calculations for understanding gas conversion reactions on single metal atom embedded carbon-based nanocatalysts
27 mei 2020
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Organisatie / co-organisatie:
ONLINE Doctoraatsverdediging Parisa Nematollahi - Faculteit Wetenschappen, Departement Chemie
Since the industrial revolution, the global air and sea temperature has increased significantly because of the rise in the concentration of greenhouse gases. Therefore, extensive research is carried out to both minimize the carbon emission from the exhaust of automobiles, petrochemical, agricultural and chemical industries, and reduce the current high levels of greenhouse gases by converting them into carbon-neutral fuels and other value-added industrial chemicals.
Graphene-based nanocatalysts are of great interest to the catalysis community due to their outstanding catalytic activity, surface properties, environmental friendliness, and cost-effectiveness. Surface modification of graphene-based materials is of great interest since it enhances the catalytic activity, electronic property, mechanical strength, and thermal conductivity of the nanocatalyst. The most commonly used surface modification methods are introducing defects, and doping with single metal atoms.
Two promising nanocatalysts are graphene and BC2N nano-flakes. The surface modification includes introducing defects or doping with single metal atoms. Depending on the type of nanocatalyst, the type of defects may change. The exact characteristics of the modified surfaces, the detailed reaction mechanisms, and the potential energy surface of direct conversion of methane to methanol, along with CO and NO oxidation to CO2 and NO2 on these surfaces at ambient conditions are unclear. Therefore, finding the corresponding reactions, detailed mechanisms, and characteristics of the tailored nano-surfaces was the main goal of this Ph.D. All the simulations were carried out using density functional theory (DFT) calculations. Our results reveal that the modified graphene and BC2N nanoflakes hold great promise toward gas conversion. Using these tuned nanostructures is energetically and thermodynamically interesting since they reduce the oxidation steps and their energy barriers, the formation of sub-chemicals, the possibility of surface poisoning with unwanted species, and make the reactions occur at ambient conditions. Our results may serve as guidance for fabricating a cost-effective graphene-based single-atom catalyst.