Density functional theory study of CH₄and CO₂adsorption by fluorinated graphene

Abstract

Phenomena related to global warming have been of particular interest among researchers, strongly encouraging them to identify various methods of adsorbing contributing gases, such as CH 4 and CO 2 [1,2]. Many adsorbents have been widely proposed and studied to remove greenhouse gases from the atmosphere and protect the environment [3,4]. Carbon-based materials for adsorption are an intriguing subject owing to their very high specific surface area, low weight, and elasticity [5,6]. Among various carbonaceous materials, graphene has attracted much attention from researchers for these reasons; consequently, this material has been empirically and theoretically investigated for possible applications, such as gas sensors [7][8][9][10].Yoon et al. [7] reported the fabrication of a graphene-based CO 2 sensing device that exhibited a fast response to CO 2 and high recyclability due to the weak interaction between CO 2 and graphene. Schrier [8] studied the adsorption of several gas molecules, including CO 2 and CH 4 , on pristine graphene and fully fluorinated graphene at finite temperature. He reported that complete fluorination of graphene is not an effective method for nonpolar gas molecules, such as CH 4 and CO 2 , because the fluorine atom has the lowest polarizability of all atoms, and its dispersion interaction is weak. In addition, for nonpolar molecules, dispersion interactions play the largest role in adsorption. Lee et al. [9] reported the effect of fluorination of a carbon-based substrate on CH 4 /CO 2 separation. They reported that the CO 2 adsorption capacity increased up to 22.5% owing to fluorination with an F/C ratio (%) of 32%-43%.Although experimental studies on the adsorption of gas molecules onto carbon-based substrates have provided much useful information, computational studies at the molecular level can provide detailed information to investigate the interaction between adsorbed gas molecules and substrates. In this study, density functional theory (DFT) calculations were performed to investigate CH 4 and CO 2 adsorption on pristine and fluorinated graphene. This research extends existing knowledge of fluorinated carbon-based materials and their adsorption efficiency from a theoretical viewpoint. The results of this investigation also shed light on further possibilities for computational research on fluorinated carbon-based materials.The DFT calculations were conducted using the Biovia DFT package DMol3 [11], considering the generalized-gradient-approximation (GGA) as well as the Perdew-Burke-Ernzerhof (PBE) exchange and correlation functionals with the double numerical polarized basis set. The GGA-PBE functional has been successfully used to describe the interaction between organic molecules and a carbon-based substrate [12][13][14][15][16][17][18] or an inorganic substrate [19][20][21][22][23]. We used a 5 × 5 × 1 Monkhorst-Pack k-point mesh [24] with a 12.30 Å × 12.30 Å × 15.00 Å periodic boundary condition for the graphene substrate.The adsorption energy (E ads ) was defined aswhere E substrate...

Organic Gas Sensing Performance of the Borophene van der Waals Heterostructure

“…The adsorption energies of the three organic molecules are smaller than 0.5 eV, further verifying that the adsorption of the three organic molecules is a kind of typical physisorption. In fact, for these organic molecules, the adsorption type on borophene is the same as that on graphene. − For example, the adsorption energy of CH 4 on graphene is about −0.15 eV, very close to the result of borophene obtained here (−0.17 eV). On the two 2D nanomaterials CH 4 adopts the same adsorption type.…”

“…In fact, for these organic molecules, the adsorption type on borophene is the same as that on graphene. 47−49 For example, the adsorption energy of CH 4 on graphene is about −0.15 eV, 47 very close to the result of borophene obtained here (−0.17 eV). On the two 2D nanomaterials CH 4 adopts the same adsorption type.…”

Tunable Electronic Properties of Nitrogen and Sulfur Doped Graphene: Density Functional Theory Approach

“…Geometries were optimized, and the total energies and forces were calculated using a planewave basis set with the projector augmented wave (PAW) method [ 36 ]. The generalized gradient approximation (GGA) with the Perdew–Burke–Ernzerhof (PBE) exchange-correlation functional [ 37 ] was used, and the planewave cutoff energy was set to 500 eV; the GGA-PBE functional has been successfully used to describe carbon-based systems [ 38 , 39 , 40 , 41 , 42 , 43 ]. All structures were optimized such that the total energy converged to less than 1.0 × 10 −6 eV per atom and the maximum force converged to below 0.05 eV Å −1 .…”

Electrochemical Oxygen-Reduction Activity and Carbon Monoxide Tolerance of Iron Phthalocyanine Functionalized with Graphene Quantum Dots: A Density Functional Theory Approach

“…DFT+ U calculations were implemented within the Vienna Ab Initio Simulation Package (VASP). , We used Grimme’s dispersion corrections for describing van der Waals interactions in all calculations, and the Coulomb interaction parameter U was set to 4.0 eV for Fe. , The generalized gradient approximation (GGA) of the Perdew–Burke–Ernzerhof (PBE) functional was used to calculate exchange-correlation energies; the GGA-PBE functional has been shown to described carbon-based systems reasonably well. − The configuration of GQD prefers to be the hexagonal graphene network along with the zigzag orientation . In addition, Hassanien et al showed that C 96 H 24 has a lower HOMO–LUMO gap than the gap of other possible sizes of GQD.…”