Study of Fluorinated Graphene Reactivity Using Quantum Chemistry Methods

Mgr. Dagmar ZAORALOVÁ

Disertační práce

Study of fluorinated graphenes reactivity using quantum chemistry methods

Anotace:

An intriguing 2D world of graphene-based materials has significantly expanded in the last decade thanks to the successful preparation of fluorographene (FG). The surprising reactivity of FG has enabled covalent grafting of various functional groups and incorporation of heteroatoms into the graphene lattice which would be demanding or nearly impossible using pristine graphene. However, the number of studies addressing the reaction mechanisms and processes accompanying the substitution of C-F bonds and the substitution of carbon atoms in the structure of fluorographene is still scarce. To broaden the knowledge about FG chemistry, we have focused on the nature of C-F bonds and its influence on the formation of specific structural motifs of fluorine ad-atoms during (de)fluorination of the material. Further, we have unravelled the processes that cause the unexpected reactivity of FG. In particular, we have investigated the defluorination mechanisms in the presence of reducing agents and explained the reaction mechanism of nucleophilic substitution and nitrogen incorporation into the FG lattice. Very recently synthesized new graphene derivatives have enlarged the applicability of graphene-based materials. For instance, cyanographene (CG) and graphene acid (GA) may be utilized in single atom catalysis owing to the ability to immobilize metal atoms and cations. The outstanding performance of single atom catalysts (SACs) is based on the maximally reduced size of the metal particles. Consequently, a strong interaction between the metal and substrate is crucial since it prevents unwanted processes such as aggregation into bigger particles and subsequent decrease of the catalytic performance of the material. Therefore, we have studied a group of late 3d and 4d elements in different oxidation states anchored to cyanographene (CG) or graphene acid (GA) to explain the processes that affect the stability of these complexes. To demonstrate the catalytic activity of such carbon-based SACs, we have studied the hydrazine oxidation reaction catalysed by Co2+ cations anchored to cyanographene.

Abstract:

An intriguing 2D world of graphene-based materials has significantly expanded in the last decade thanks to the successful preparation of fluorographene (FG). The surprising reactivity of FG has enabled covalent grafting of various functional groups and incorporation of heteroatoms into the graphene lattice which would be demanding or nearly impossible using pristine graphene. However, the number of studies addressing the reaction mechanisms and processes accompanying the substitution of C-F bonds and the substitution of carbon atoms in the structure of fluorographene is still scarce. To broaden the knowledge about FG chemistry, we have focused on the nature of C-F bonds and its influence on the formation of specific structural motifs of fluorine ad-atoms during (de)fluorination of the material. Further, we have unravelled the processes that cause the unexpected reactivity of FG. In particular, we have investigated the defluorination mechanisms in the presence of reducing agents and explained the reaction mechanism of nucleophilic substitution and nitrogen incorporation into the FG lattice. Very recently synthesized new graphene derivatives have enlarged the applicability of graphene-based materials. For instance, cyanographene (CG) and graphene acid (GA) may be utilized in single atom catalysis owing to the ability to immobilize metal atoms and cations. The outstanding performance of single atom catalysts (SACs) is based on the maximally reduced size of the metal particles. Consequently, a strong interaction between the metal and substrate is crucial since it prevents unwanted processes such as aggregation into bigger particles and subsequent decrease of the catalytic performance of the material. Therefore, we have studied a group of late 3d and 4d elements in different oxidation states anchored to cyanographene (CG) or graphene acid (GA) to explain the processes that affect the stability of these complexes. To demonstrate the catalytic activity of such carbon-based SACs, we have studied the hydrazine oxidation reaction catalysed by Co2+ cations anchored to cyanographene.

Klíčová slova

Fluorographene reactivity, cyanographene, graphene acid, graphene derivatization, substitution reactions, heteroatom doping, (de)fluorination, C-F bond, single atom catalysis, transition metals, hydrazine oxidation reaction, density functional theory

Jazyk práce: čeština

Datum vytvoření / odevzdání či podání práce: 21. 9. 2021

Obhajoba závěrečné práce

• Vedoucí: doc. Miroslav Medveď, Ph.D., doc. Miroslav Medveď, Ph.D.

UNIVERZITA PALACKÉHO V OLOMOUCI

Přírodovědecká fakulta

Doktorský studijní program / obor:
Chemie / Fyzikální chemie