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Hydrogen peroxide (H 2 O 2 ) decomposition mechanism and its oxidative desulfurization activity on hexagonal boron nitride monolayer (h-BN) have been explored by density functional theory (DFT) at M06–2X/6-311 + G (d,p) level. A cluster model which contains seven rings has been constructed to simulate the h-BN surface. It is found that 7 possible species will be generated after the decomposition of H 2 O 2 . Among them, 2H*+O 2 * and 2H*+2O* are relatively unstable while other species, such as HOO*+H*, HO*+HO*, H*+HO + O*, H 2 O*+O* are relatively stable and may exist in the current system. In addition, 4 decomposition pathways have been explored. Results show that the H 2 O 2 * will first undergo an O-H bond break (HOO*+H*), then the HO-O bond decomposes into H*+HO*+O* (Pathway (b)). By considering the concentration and activation energy together, the H 2 O*+O* is proposed to be the most possible active species for oxidative desulfurization due to the relative higher concentration and lower activation energy. [ABSTRACT FROM AUTHOR]

To obtain the adsorption strength is the key point for materials design and parameters optimization in chemical engineering. Here we report a simple but accuracy method to estimate the adsorptive energies by counting the number of π-orbital involved atoms based on theoretical computations for hexagonal boron nitride (h-BN) and graphene. Computational results by density function theory (DFT) as well as spin-component scaled second-order Møller-Plesset perturbation theory (SCS-MP2) both confirm that the adsorptive energies correlate well with the number of π-orbital involved atoms for π-orbital contained molecules. The selected molecules (adsorbates) are commonly used in chemical industry, which contains C, N, S, O atoms. The predicted results for the proposed formulas agree well with the current and previous DFT calculated values both on h-BN and graphene surfaces. Further, it can be also used to predict the adsorptive energies for small π-orbital contained molecules on BN and carbon nanotubes. The interaction type for these adsorptions is typical π-π interaction. Further investigations show that the physical origin of these interactions source from the polar interactions between the adsorbents and adsorbates. Hence, for separation or removal of aromatic molecules, how to modify the aromaticity and polarity of both adsorbents and adsorbates will be the key points for experiments. [ABSTRACT FROM AUTHOR]

Deep eutectic solvents (DESs), as ionic liquid analogues for green solvents, have gained increasing attentions in chemistry. In this work, three typical kinds of DESs (ChCl/Gly, ChCl/AcOH and ChCl/Urea) were successfully synthesized and characterized by Fourier transform infrared spectroscopy (FTIR) and Raman. Then comprehensive and systematical analyses were performed by the methods of density functional theory (DFT). Two methods (B3LYP/6-311 + +G(2d,p) and dispersion-corrected B3LYP-D3/6-311 + +G(2d,p)) were employed to investigate the structures, vibrational frequencies and assign their ownership of vibrational modes for the DESs, respectively. Nearly all the experimental characteristic peaks of IR and Raman were identified according to the calculated results. By linear fitting of the combined calculated vs experimental vibration frequencies, it can be found that both of the two methods are excellent to reproduce the experimental results. Besides, hydrogen bonds were proved to exist in DESs by IR spectrum, structure analysis and RDG analysis. This work was aimed at predicting and understanding the vibrational spectra of the three typical DESs based on DFT methods. Moreover, by comparing experimental and theoretical results, it provides us a deep understanding of the formation mechanisms of DESs. [ABSTRACT FROM AUTHOR]

In this work, interaction nature between a group of aromatic sulfur compounds and [BMIM] + [FeCl 4 ] − have been investigated by density functional theory (DFT). A coordination structure is found to be critical to the mechanism of extractive desulfurization. Interaction energy and extractive selectivity follow the order: thiophene (TH) < dibenzothiophene (DBT) ≈ benzothiophene (BT). Alkylation of TH or BT ( e.g. 3-methylthiophene, and 3-methylbenzothiophene) leads to a stronger interaction with ionic liquid, but steric hindrance effects of some alkylic derivatives ( e.g. 2,7-dimethylbenzothiophene) lead to a weaker interaction with ionic liquid. The mechanism of extractive desulfurization is attributed to the charge transfer effect. During extractive desulfurization, electrons on aromatic sulfur compounds transfer into the Lewis part of ionic liquid, namely, [FeCl 4 ] − . Furthermore, it is better to consider the Lewis acidity of Fe-containing ionic liquid by the whole unit (such as [FeCl 4 ] − and aromatic sulfur compounds (X)) rather than only Fe or S atom. [ABSTRACT FROM AUTHOR]

Inspired by searching new forms of Boron Nitride (BN) compounds, the electronic structure and physicochemical property of a graphyne-like BN compound was explored by density functional theory with cluster models as well as periodic models. This graphyne-like BN compound is named Boron Nitridene in this work, based on geometry and bond order analysis as its B–N linking units take on double bond characteristics. Different cluster models of Boron Nitridene- x (x = 1–5) were constructed. Results show that the geometric parameters and molecular orbitals are similar for these models. The chemical stability of Boron Nitridene was estimated by the concept of heats of formation, vibrational frequency, and ab initio molecular dynamics. In addition, the IR and Raman spectra were predicted and the unique stretching modes were assigned to give a reference with experimental synthesis. Last, the adsorption strength of small molecules was calculated, and the results show the boron nitridene interacts stronger than hexagonal boron nitride (h-BN). Image 1 • Boron Nitridene as a new form of BN has been systematic studied. • Chemical stability of Boron Nitridene was estimated by the concept of heats of formation. • IR and Raman spectra were predicted and the unique stretching modes were assigned. • Adsorption strength of small molecules on boron nitridene was calculated. [ABSTRACT FROM AUTHOR]

As an acid gas, sulfur dioxide (SO 2) has caused serious pollution to the environment. Therefore, SO 2 capture is crucial. The silica-based porous ionic liquid possesses not only the porosity and high specific surface area of hollow silica, but also the fluidity of the liquid. The absorption mechanism of SO 2 absorption by porous ionic liquids through density functional theory (DFT) was systematically studied in this paper. First six kinds of absorption sites were predicted, and then various analyses such as structure, energy, and electrostatic potential analysis (ESP) were employed after optimization. The results show that SO 2 has the strongest adsorptive interaction between the canopy and the silica sphere. In addition, the main force between the porous ionic liquid and SO 2 is hydrogen bonding and π-hole bonding. Finally, by increasing the degree of polymerization of the canopy, that is, increasing the number of ether groups, will be beneficial to the absorption of SO 2. Image 1 • The absorption mechanism of SO 2 by PILs was systematically studied. • Six kinds of absorption sites were predicted. • Strongest absorption interaction is the canopy and the silica sphere. • The main force is hydrogen bonding and π-hole bonding. [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride (h -BN) has been used as adsorbent for many chemical applications. The doping strategy is an efficient way to enhance the adsorptive capacity. In the present work, the F-doped h -BN material was investigated by density functional theory (DFT). Five possible F doping h -BNF adsorbents were firstly considered. Results show that only the F_e_B and F_t_B models are thermodynamically favorable. The adsorptive energies of DBT for these five h -BNF materials are all enhanced as compared to the pristine h -BN. Then 2F doping h -BNF adsorbents were also explored. Results show that the combinations of F_e_B and F_t_B are still thermodynamically favorable. Moreover, adsorbents which contain F_t_B exhibits better adsorptive performance, especially the combination of F_t_B + F_t_B. Last, several quantum analysis schemes have been employed to analyze the interaction nature between h -BNF and DBT. Results show that F⋯H–C hydrogen bond, the π-π interaction, and strong electrostatic F⋯S–C interaction plays important roles during adsorptive desulfurization (ADS) process. This work proposed a promising strategy to enhance the capacity of ADS. Image 1 • F-doped hexagonal boron nitride adsorbents were studied by DFT. • There are five possible doping sites where the form of F_edge_B is most stable. • The adsorptive energies of DBT for these five h-BNF materials are all enhanced. • The interaction nature between DBT and F-doped h-BNF has been investigated. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO 2) is one of the main factors leading to the greenhouse effect, so the capture of CO 2 gas is currently a hot spot of research. Hollow silica-based porous ionic liquids (HS-liquids) are porous liquids containing cavities that are not only fluid but also have a high specific surface area and were used for the capture of CO 2. However, the mechanism of CO 2 absorption by HS-liquids has not been studied. In this work, the mechanism of CO 2 absorption by HS-liquids was systematic studied by density functional theory (DFT). First, five possible models for absorbing CO 2 in HS-liquids were constructed and optimized. The interaction energies between HS-liquids and CO 2 at different sites were obtained. Moreover, the effects of HS-liquids with different degrees of polymerization of polyethylene glycol and different alkyl chain lengths on CO 2 absorption were also investigated. Results show that the strongest absorption site locates near the polyethylene glycol unit. Then, the electrostatic potential (ESP) and reduced density gradient (RDG) methods were employed to further understand the interaction nature between them. The results show that hydrogen bonding dominates the weak interaction between the HS-liquid and CO 2. Image 1 • The mechanism of CO 2 absorption by PILs was studied by DFT. • Five possible models were constructed and optimized. • The strongest absorption site locates near the polyethylene glycol unit. • Hydrogen bonding dominates the weak interaction. [ABSTRACT FROM AUTHOR]