Density functional theory study the effects of oxygen-containing functional groups on oxygen molecules and oxygen atoms adsorbed on carbonaceous materials

Abstract

Density functional theory was used to study the effects of different types of oxygen-containing functional groups on the adsorption of oxygen molecules and single active oxygen atoms on carbonaceous materials. During gasification or combustion reactions of carbonaceous materials, oxygen-containing functional groups such as hydroxyl(-OH), carbonyl(-CO), quinone(-O), and carboxyl(-COOH) are often present on the edge of graphite and can affect graphite’s chemical properties. When oxygen-containing functional groups appear on a graphite surface, the oxygen molecules are strongly adsorbed onto the surface to form a four-member ring structure. At the same time, the O-O bond is greatly weakened and easily broken. The adsorption energy value indicates that the adsorption of oxygen molecules changes from physisorption to chemisorption for oxygen-containing functional groups on the edge of a graphite surface. In addition, our results indicate that the adsorption energy depends on the type of oxygen-containing functional group. When a single active oxygen atom is adsorbed on the bridge site of graphite, it gives rise to a stable epoxy structure. Epoxy can cause deformation of the graphite lattice due to the transition of graphite from sp2 to sp3 after the addition of an oxygen atom. For quinone group on the edge of graphite, oxygen atoms react with carbon atoms to form the precursor of CO2. Similarly, the single active oxygen atoms of carbonyl groups can interact with edge carbon atoms to form the precursor of CO2. The results show that oxygen-containing functional groups on graphite surfaces enhance the activity of graphite, which promotes adsorption on the graphite surface.

Bismuthene nanosheets produced by ionic liquid assisted grinding exfoliation and their use for oxygen reduction reaction

“…Such -OH and ]O moieties being surface-or edge-bound are expected to lead to the spin redistribution and charge delocalization on the neighbouring metal atoms, 34 affording active centers. 35…”

Performance and Sustainability Tradeoffs of Oxidized Carbon Nanotubes as a Cathodic Material in Lithium‐Oxygen Batteries

“…As a result, electron transfer requires oxygen molecules to interact directly with the carbon surface through physisorption or chemisorption. Density functional theory (DFT) models have shown that the energy required for adsorption of oxygen molecules to graphitic surfaces near carboxyl moieties is nearly twice that of the same process near carbonyl moieties [57] . This indicates that the presence of carboxyl functionalities makes the physisorption of oxygen molecules less likely, while the physisorptive interactions of oxygen molecules with graphitic surfaces containing carbonyl are more stable [57] .…”

“…Density functional theory (DFT) models have shown that the energy required for adsorption of oxygen molecules to graphitic surfaces near carboxyl moieties is nearly twice that of the same process near carbonyl moieties [57] . This indicates that the presence of carboxyl functionalities makes the physisorption of oxygen molecules less likely, while the physisorptive interactions of oxygen molecules with graphitic surfaces containing carbonyl are more stable [57] . Other DFT models have found that the carboxyl group itself interacts only weakly with O 2 molecules, while the interaction between pristine and defective CNT surfaces can lead to physisorption and chemisorption, respectively [58] .…”

Synthesis and Spectroscopic Characterization of an Unusual Succinylated Starch Applied to Carbon Paste Electrodes

“…A recent work reported that graphite layers can present oxidized groups in some extension, such as hydroxyl, carbonyl, and carboxyl . The existence of such hydrophilic spots along the structure could favor the charging of the electric double layer, and then increase the associated capacitive current.…”

“…[28,29] A recent work reported that graphite layers can present oxidized groups in some extension, such as hydroxyl, carbonyl, and carboxyl. [30] The existence of such hydrophilic spots along the structure could favor the charging of the electric double layer, and then increase the associated capacitive current. Considering that most of the hydroxyl groups present in the starch structure are involved in hydrogen bonds between different chains that present little interaction with the external environment, [31] we believe that the incorporation of the studied starch samples in the carbon paste could attenuate the effect of the hydrophilic groups from the graphite structure, which would result in a lower background current.…”