DFT-D3 calculations of the charge-modulated CO2 capture of N/Sc-embedded graphyne: Compilation of some factors

On assessing the carbon capture performance of graphynes with particle swarm optimization

Tackling climate change is one of the greatest challenges of current times and therefore the development of efficient technologies to limit anthropogenic emissions is of utmost urgency. Recent research towards this goal has alluded to the use of carbon-based solid sorbents for carbon capture. Graphynes (GYs), an interesting class of porous carbon membranes, have recently proven their potential as excellent membranes for gas adsorption and separation. Herein, we explored the CO2 and N2 adsorption characteristics and CO2/N2 selectivities of a class of GYs, namely γ-GY-1, γ-GY-2 and γ-GY-4. We investigated the putative global minimum geometries of adsorbed unary (n = 2-10) and binary (n : m; n, m ∈ [1, 8]) clusters of CO2 and N2 by employing a stochastic global optimization method called particle swarm optimization in conjunction with empirical intermolecular force field formulations. The intervening interactions are modeled using various pairwise potentials, including Lennard-Jones potential, improved Lennard-Jones potential, Buckingham potential and Coulombic potential. The binding energies for both unary and binary clusters are highest for adsorption on γ-GY-1, followed by γ-GY-2. The putative global minimum geometries suggested that N2 molecules preferred binding over the pore centres while CO2 molecules showed higher clustering propensity than any binding site preference. The predicted interaction energies suggested higher selectivity for CO2 over N2 for all the three γ-GYs.

DFT-Based Study for the Enhancement of CO2 Adsorption on Metal-Doped Nitrogen-Enriched Polytriazines

Nitrogen-enriched polytriazine (NPT), a carbon nitride-based material, has received much attention for CO₂ storage applications. However, to enhance the CO₂ uptake capacity more efficiently, it is necessary to understand the interaction mechanism between CO₂ molecules and NPT through appropriate modification of the structures. Here, we introduce a method to enhance the CO₂ adsorption capacity of NPT by incorporating metal atoms such as Sn, Co, and Ni into the polytriazine network. DFT calculations were used to investigate the CO₂ adsorption mechanism of the polytriazine frameworks by tracking the interactions between CO₂ and the various interaction sites of NPT. By optimizing the geometry of the pure and metal-containing NPT frameworks, we calculated the binding energy of metal atoms in the NPT framework, the adsorption energy of CO₂ molecules, and the charge transfer between CO₂ molecules and the corresponding adsorption systems. In this work, we demonstrate that the CO₂ adsorption capacity of NPT can be greatly enhanced by doping transition-metal atoms into the cavities of NPT.

An in silico study of the selective adsorption and separation of CO2 from a flue gas mixture (CH4, CO2, N2) by ZnLi5+ clusters

Due to the increasing concentration of CO₂ in the atmosphere and its negative effect on the environment, selective adsorption of CO₂ from flue gas has become significantly important. In this study, we have considered a Zn-doped lithium cluster, ZnLi₅⁺ cluster, featuring a planar pentacoordinate Zn centre, as a potential candidate for selective CO₂ capture and separation from a flue gas mixture (CH₄, CO₂, N₂). The binding energy calculation and non-covalent interaction study showed that CO₂ molecules bind relatively strongly as compared to N₂ and CH₄ molecules. The metal cluster can bind five CO₂, five CH₄, and four N₂ molecules with average binding energies of -9.2, -4.4, and -6.1 kcal mol^-1, respectively. Decomposition of the binding energy through symmetry-adapted perturbation theory analysis reveals that the electrostatic component plays a major role. The cationic cluster may be a promising candidate for selective CO₂ capture and can be used as a pollution-controlling agent. The calculated adsorption energy of H₂S is quite closer to that of CO₂, suggesting competitive adsorption between CO₂ and H₂S. The adsorption energies of H₂O and NH₃ are higher compared to CO₂, indicating that these gases may be a potential threat to CO₂ capture.

Study on the Reaction Path of -CH3 and -CHO Functional Groups during Coal Spontaneous Combustion: Quantum Chemistry and Experimental Research

Coal spontaneous combustion (CSC) is a disaster that seriously threatens safe production in coal mines. Revealing the mechanism of CSC can provide a theoretical basis for its prevention and control. Compared with experimental research is limited by the complexity of coal molecular structure, the quantum chemical calculation method can simplify the complex molecular structure and realize the exploration of the mechanism of CSC from the micro level. In this study, toluene and phenylacetaldehyde were used as model compounds, and the quantum chemical calculation method was adopted. The reaction processes of the methyl and aldehyde groups with oxygen were investigated with the aid of the Gaussian 09 software, using the B3LYP functional and the 6-311 + G(d,p) basis set and including the D3 dispersion correction. On this basis, the generation mechanisms of CO and CO2, two important indicator gases in the process of CSC, were explored. The calculation results show that the Gibbs free energy changes and enthalpy changes in the two reaction systems are both of negative values. Accordingly, it is judged that the reactions belong to spontaneous exothermic reactions. In the reaction processes, the activation energy of CO is less than that of CO2, indicating that CO is formed more easily in the above-two reaction processes. In addition, the variations in concentrations of important oxidation products (CO and CO2) and main active functional groups (such as methyl, carboxyl and carbonyl) with temperature were revealed through a low-temperature oxidation experiment. The experimental results verify the accuracy of the above quantum chemical reaction path. Moreover, it is also found that the generation mechanisms of CO and CO2 in coal samples with different metamorphic degrees are different. To be specific, for low-rank coal (HYH), CO and CO2 mainly come from the oxidation of alkyl side chains; for high-rank coal (CQ), CO is produced by the oxidation of alkyl side chains, and CO2 is attributed to the inherent oxygen-containing structure.

Sc-functionalized porphyrin-like porous fullerene for CO2 storage and separation: A first-principles evaluation

In recent years, there has been a lot of interest in capturing and storing carbon dioxide (CO₂) on porous materials as an efficient method for decreasing the adverse effects of this greenhouse gas on the environment and climate change. The current work introduces a Sc-decorated porphyrin-like porous fullerene (Sc₆@C₂₄N₂₄) as an efficient material for CO₂ capture, storage, and separation using density functional theory calculations. While CO₂ is physisorbed over pristine C₂₄N₂₄, the addition of Sc atoms on the N₄ sites of C₂₄N₂₄ greatly enhances CO₂ adsorption energy. Each Sc atom in Sc₆@C₂₄N₂₄ may adsorb up to three CO₂ molecules, resulting in a gravimetric density of 48%. Moreover, temperature may be used to modulate CO₂ adsorption/desorption over the substrate. The Sc-decorated C₂₄N₂₄ fullerene exhibits a lower affinity for adsorbing N₂, CH₄, and H₂ molecules than CO₂. As a consequence, this material might be considered for purifying CO₂ molecules from CO₂/N₂, CO₂/CH₄, and CO₂/H₂ mixtures. This study also sheds light on the nature of the Sc-CO₂ interaction as well as the underlying mechanism of selective CO₂ adsorption on Sc decorated C₂₄N₂₄.

Li-doped beryllonitrene for enhanced carbon dioxide capture

In recent years, the scientific community has given more and more attention to the issue of climate change and global warming, which is largely attributed to the massive quantity of carbon dioxide emissions. Thus, the demand for a carbon dioxide capture material is massive and continuously increasing. In this study, we perform first-principle calculations based on density functional theory to investigate the carbon dioxide capture ability of pristine and doped beryllonitrene. Our results show that carbon dioxide had an adsorption energy of -0.046 eV on pristine beryllonitrene, so it appears that beryllonitrene has extremely weak carbon dioxide adsorption ability. Pristine beryllonitrene could be effectively doped with lithium atoms, and the resulting Li-doped beryllonitrene had much stronger interactions with carbon dioxide than pristine beryllonitrene. The adsorption energy for carbon dioxide on Li-doped beryllonitrene was -0.408 eV. The adsorption of carbon dioxide on Li-doped beryllonitrene greatly changed the charge density, projected density of states, and band structure of the material, demonstrating that it was strongly adsorbed. This suggests that Li-doping is a viable way to enhance the carbon dioxide capture ability of beryllonitrene and makes it a possible candidate for an effective CO2 capture material.

SiC3 as a Charge-Regulated Material for CO2 Capture

The increasing CO2 emission rate is deteriorating the atmospheric environment, leading to global warming and climate change. The potential of the SiC3 nanosheet as a functioning material for the separation of CO2 from the mixture of CO2, H2, N2 and CH4 by injecting negative charges is studied by DFT calculations in this paper. The results show that in the absence of injecting negative charges, CO2 interacts weakly with the SiC3 nanosheet. While the interaction between CO2 and the SiC3 nanosheet can be strengthened by the injection of negative charges, the absorption mechanism of CO2 changes from physisorption to chemisorption when the injection of negative charges is switched on. H2/N2/CH4 are all physiosorbed on the SiC3 nanosheet with/without the injection of negative charges. The mechanism of CO2 adsorption/desorption on the SiC3 nanosheet could be tuned by switching on/off the injection of negative charges. Our results indicate that the SiC3 nanosheet can be regarded as a charge-regulated material for the separation of CO2 from the CO2/H2/N2/CH4 mixture.

B3O3 monolayer: an emerging 2D material for CO2 capture

The calculated CO2 capture capacity of the desired B3O3 monolayer in the present study is high that it can be recognized as an emerging material for efficient CO2 capture.