Adsorption Energy Values Research Articles

Highly efficient H2S capture using pentagonal B2C monolayer: A periodic DFT study

AbstractThe adsorption and storage properties of the chalcogenide H2S gas by pentagonal B2C nanosheet (penta‐B2C) have been explored utilizing periodic density functional theory. The present results disclose that pristine penta‐B2C nanosheet can take up eight H2S molecules with an H2S capture capacity of 50.28 wt%. Average adsorption energy values for the 1H2S/penta‐B2C, 2H2S/penta‐B2C, 3H2S/penta‐B2C, 4H2S/penta‐B2C, and 8H2S/penta‐B2C complexes are −0.876, −0.808, −0.725, −0.721, and −0.535 eV, respectively. The band structure and the total and partial density of states analyses displayed the reduction in the band gap of the penta‐B2C nanosheet after H2S adsorption of about 13%–25%. Hirshfeld charge analysis reports the charge transfer from the H2S molecules toward the penta‐B2C sheet. As the number of the adsorbed H2S molecules increases, the amount of charge transferred increases. The molecular dynamics (MD) calculations results for the pristine penta‐B2C nanosheet and ultimate 8H2S/penta‐B2C complex confirm their thermal stability at 300 K. Based on the reported analysis, penta‐B2C nanosheet can be introduced as an investible substrate for efficient H2S capture and storage.

Quantitative characterizations of mOR-EG activated by vanilla odorants using advanced statistical physics modeling.

An advanced monolayer adsorption model of an ideal gas was successfully employed to investigate the adsorption of vanillin, vanillin methyl ether, vanillin ethyl ether, and vanillin acetate odorants on mouse eugenol olfactory receptor mOR-EG. In order to understand the adsorption process putatively introduced in olfactory perception, model parameters were analyzed. Hence, fitting results showed that the studied vanilla odorants were linked in mOR-EG binding pockets with a non-parallel orientation, and their adsorption was a multi-molecular process (n>1). The adsorption energy values that ranged from 14.021 to 19.193kJ/mol suggested that the four vanilla odorants were physisorbed on mOR-EG (ΔEa<40kJ/mol) and the adsorption mechanism may be considered as an exothermic mechanism (ΔEa>0). The estimated parameters may also be utilized for the quantitative characterization of the interactions of the studied odorants with mOR-EG to determine the corresponding olfactory bands ranging from 8 to 24.5kJ/mol.

Quinoxaline derivatives as corrosion inhibitors of zinc in 1.0 M hydrochloric and sulphuric acid solutions: Adsorption, electrochemical, spectroscopic, and computational studies

The corrosion inhibition properties of and methyl quinoxaline-6-carboxylate (MQ6CA), and quinoxaline-6-carboxylic acid (Q6CA) on zinc in 1.0 M HCl and 1.0 M H2SO4 were studied using gravimetric, electrochemical, spectroscopic, and theoretical studies utilizing density functional theory (DFT). Experimental findings reveal that zinc corrodes more in 1.0 M H2SO4 than in 1.0 M HCl and both the studied quinoxalines show good protection efficiency on zinc. The results obtained from the gravimetric analysis indicate that the inhibition efficiency increased with an increase in temperatures and concentration of the inhibitors. The adsorption of the inhibitors followed the Langmuir isotherm, and the thermodynamic and activation parameters were determined and discussed. The electrochemical studies suggested that the studied quinoxalines possess characteristics of mixed type inhibitors but are predominantly cathodic in nature. The Fourier transform infrared spectroscopy confirmed the formation of the inhibitor-Zn2+ complex. Atomic absorption spectroscopy revealed a decrease in the concentration of zinc ions in the presence of the studied inhibitors as compared to the blank solutions. Calculated values of adsorption energies indicated that the adsorption of studied quinoxalines on zinc surface supports a mixed type of adsorption mechanism.

Identification and sensing of hydrogen fluoride (HF) on aluminum phosphide (Al24P24) nanocage in both gas and water phases: electronic study via density-functional theory computations.

Hydrogen fluoride (HF) is extensively present in environmental and industrial pollutants. It may harm the health of humans and animals. This work evaluated the adsorption of an (HF)n linear chain (n = 1, 2, 3, and 4) onto an AlP nanocage through ab initio calculations for the evaluation of its performance in sensing and monitoring (HF)n within aqueous and gaseous media. The present work adopted density functional theory (DFT) at the 6-311 G (d, p) basis set to analyze (HF)n linear chain adsorption onto AlP nanocages with the B3LYP functional. This paper examined the adsorption energy, configuration optimization, work function, and charge transfer. In addition, the contributions of the HF linear chain size to electronic properties and adsorption energy were measured. The dimer form of HF on the surface of AlP nanocages was found to have the highest stability based on the adsorption energy values. Once (HF)n was adsorbed onto the nanocage, the HOMO-LUMO energy gap experienced a large reduction from 3.87 to 3.03 eV, enhancing electrical conductivity. In addition, AlP nanocages may serve in the sensing of (HF)n under multiple environmental pollutants.

Effects of pore size, water content, and oxygen-containing functional groups on oxygen adsorption in bituminous coal

To further explore the mechanism of coal spontaneous combustion and better grasp the laws of spontaneous combustion, this article studied the adsorption behavior of O2 in coal. Materials studio software was applied to study the adsorption of oxygen under different water content, different pore sizes, and different oxygen-containing functional groups by means of grand canonical Monte Carlo and molecular dynamics simulation methods. The results show that the adsorption capacity of O2 decreases with the increase in water content. With the increase of molecular pore size of coal, the adsorption capacity of O2 increases, and the tight adsorption amounts decrease. The equivalent adsorption heat is less than 42 kJ/mol, indicating that the adsorption of O2 in coal pores is physical adsorption. The smaller the physical adsorption energy and charge transfer value of the hydroxyl group for O2, it indicates that the hydroxyl group is the active group for the physical adsorption of O2.

Adsorption and modification behavior of single atoms on the surface of single vacancy graphene: Machine learning accelerated first principle computations

During the preparation or processing of graphene, the emergence of structural flaws is an unavoidable circumstance, and these structural defects present a detrimental impact on the mechanical properties of graphene and its corresponding composite materials. In this paper, we use a first-principles computation to compute single-atom adsorption behavior on single vacancy graphene, from which adsorption energy and distance values are derived to create a dataset for machine learning. The comparative analysis of different machine learning models reveals that the BPNN model is best suited for the dataset. The BPNN model is enhanced by adjusting its node parameters using genetic algorithm, increasing its coefficient of determination to 0.9874 and 0.9608 for adsorption energy and distance models, respectively. The enhanced GA-BPNN model is utilized to predict the adsorption behavior of atoms across the entire periodic table onto single vacancy graphene’s surface. The accuracy of the machine learning model predictions is validated through the application of elemental modifications to the graphene. Employing machine learning to expedite first-principles calculations broadens the spectrum of available research approaches while accelerating the atomic modification process of single vacancy graphene. Our results provide valuable insights into the adsorption behavior of atoms on graphene surfaces and demonstrate the potential of machine learning for accelerating first principle computations in material science.

Novel Zinc ferrite composite with starch and carboxy methyl starch from biowaste precursor for the removal of Ni (II) ion from aqueous solutions

In the present work, Zinc ferrite composites with Mango starch (MS) and carboxymethyl mango starch (CMMS) were synthesized for the removal of Ni (II) ions from aqueous solutions. Composites prepared were characterized by Fourier Transform Infrared (FTIR) Spectroscopy, X-Ray Diffraction (XRD) analysis, pH of point zero charge (pHzpc), Scanning Electron Microscopy (SEM), and BET. Batch adsorption technique was used to study effect of various parameters such as pH, adsorbent dose, contact time, concentration, and temperature for removal of Ni (II) ions from aqueous solutions. The optimum time, pH, adsorbent dose and temperature required for ZFN@ MS and ZFN@ CMMS in this study was 110 min., 7 & 8, 0.1 g and 308 K, respectively. Out of various adsorption isotherms, Freundlich isotherm model fitted best with adsorption data. Maximum adsorption capacity for removal of Ni (II) were found to be 65.3 and 208.3 mg/g, respectively by using Zinc ferrite@ MS and Zinc ferrite@ CMMS adsorbents. Lagergren Pseudo second order model best fitted with results which indicated that the process of adsorption was chemical in nature. The value of adsorption energy for ZFN@ MS was 50 kJ/mol and for ZFN@ CMMS, it was 31.62 kJ/mol. Thermodynamic study revealed that process was endothermic and non-spontaneous in nature. Regeneration studies were conducted for five cycles where Zinc ferrite@ MS showed 71% regeneration efficiency and Zinc ferrite@ CMMS showed 78% regeneration efficiency for nickel ion removal from aqueous solution.

Investigating Chlorination and Migration Mechanism of NaCl on C−S−H: DFT and AIMD Study**

AbstractThe present study investigates the chlorination and migration mechanism of Tobermorite9 Å through the use of density functional theory (DFT) calculation and ab initio molecular dynamics (AIMD). The findings reveal a negative adsorption energy value of −2.19488 eV. The results of the charge density difference analysis reveal that the Ca atoms experience electron loss, while the Cl atom undergoes electron gain. The O atom situated at the end of the silicate chain (and silicate chain bridge) exhibits electron gain, and the Na atom experiences electron loss. The results of density of states (DOS) and partial density of states (PDOS) demonstrate that the Ca−Cl bond was created as a result of the interaction between Ca and Cl orbitals. The evident overlaps between Na‐p and O24‐p orbitals lead to the formation of Na−O bond. In AIMD simulation, the minimum energy barrier and activation energy of sodium chloride molecule are 0.09236 eV and 0.059 eV, respectively. The findings also suggest that chloride ion diffusion is facile on hydrated calcium silicate.

Effects of Flotation Reagents on the Morphology of Magnesium Hydroxide: Experimental and Simulation Study

The flotation process to extract potassium salt from carnallite ores could produce the MgCl2 mother liquor with flotation reagents─octadecyl amine hydrochloride (ODA) and dodecyl morpholine (DMP). The organic impurities would further affect MgCl2 resource-integrated utilization for preparing magnesium hydroxide (MH). In this study, the effects of flotation reagents with different concentrations on the morphology of MH were investigated at a hydrothermal temperature of 200 °C for 6 h with the hydrothermal medium of a 4 mol/L NaOH solution. It was observed that the average thickness of MH crystal plates increased and the morphology of crystals changed from regular hexagonal plates to irregular polygonal plates with the increase of ODA and DMP concentrations. Molecular dynamics (MD) simulation was applied to further explain the effect mechanism. The results indicated that ODA and DMP molecules were more likely to be adsorbed on the (1 1 0) plane in contrast to the (0 0 1) plane due to the larger absolute values of adsorption energy on the (1 1 0) plane. The long carbon chains far away from the (1 1 0) plane would form steric hindrance to affect the growth rate of MH crystals in the [1 1 0] direction.

Experimental insights into the adsorption of newly synthesized Gemini ethoxylated surfactant on C-steel in different acidic media accompanied by DFT and MCs studies

Abstract Bis ethoxylated cationic surfactant (BOECS) is synthesized. The prepared surfactant’s structure configuration was verified through a variety of spectral and physicochemical techniques, including FT-IR, MS,1HNMR, and surface activity evaluations. BOECS applications as a C-steel corrosion inhibitor in 1.0 N HCl and 1.0 N H2SO4 and sulfate reducing bacteria (SRB) mitigations have been investigated thoroughly. Physical properties of the BOECS indicate its potential adsorption affinity at the air/water interface. The electrical conductivity determines the CMC value in accordance with the surface tension value. Electrochemical kinetic parameters indicate the BOECS is sorted as a mixed-type inhibitor and has an inhibition efficacy of 91.22 % and 81.26% for HCl and H2SO4, respectively. Active centers of BOECS structure enhance its adsorption at the electrolyte/C-steel. Calculated adsorption energy change (∆G ads) and theoretical adsorption energy (E ads) values suggest strong and spontaneous BOECS adsorption. The cytotoxic performance of the synthesized BOECS exhibited a potent inhibitory potential against the SRB. The outcomes of this research exhibit that the BOECS can lower SRB growth from 106 to 102 cell/mL.

Functionalized (–HCO, –OH, –NH2) Iridium-doped graphene (Ir@Gp) nanomaterials for enhanced delivery of Piroxicam: Insights from quantum chemical calculations

Delivery of piroxicam into the body has been associated with various health complications, such as gastrointestinal problems, cardiovascular problems, renal problems, injection site reactions, systemic side effects, drug interactions, and localized tissue damage. In this study, the geometry of Ir@Gp functionalized with OH, HCO, and NH2 was investigated using density functional theory (DFT) at the ωB97XD/def2svp level of theory to determine the system with the best delivery potential for piroxicam. The results of the study showed that all studied systems had an increase in bond length, except for Pxm_NH2_Ir@Gp, which had a decrease in bond length. This suggests that Pxm_NH2_Ir@Gp is reactive to the drug's adsorption and is consistent with the chemical quantum descriptors calculated from frontier molecular orbital (FMO) and natural bond orbital (NBO) analysis. Substantially, the quantum theory of atom in molecules (QTAIM) established that partially covalent interactions were more evident in the Pxm_HCO_Ir@GP and Pxm_OH_Ir@GP systems, while noncovalent interactions were supported by the weakest bonds of the interaction at H65-H98 and H92-H64, respectively. The findings of the non-covalent interactions (NCI) further affirmed that the effectiveness of the drug's delivery to target sites depended on the presence of weak interactions between the studied systems. The calculated Eads calculated in the gas phase showed that weak chemical binding of the drug towards the adsorbent was obtained in Pxm_Ir@GP, Pxm_OH_Ir@GP, and Pxm_HCO_Ir@GP. Whereas, in the water phase, the adsorption energy values for all complexes (pxm_Ir@GP) were mostly negative, indicating that the water molecules energetically favor the adsorption of the drug onto the surfaces studied than the gas-phase. Among the water-phase complexes, pxm_Ir@GP revealed the highest negative adsorption energy of −5.116 eV, indicating that it has the highest affinity for water. This result, which corresponds with other analyses in this study, shows that Pxm_NH2_Ir@GP can be used as an efficient material for the effective carriage of pirixocam to the target cells in both gas and water phase. Overall, it can be said that the systems' adsorption efficiency is as follows: pxm_Ir@GP > pxm_NH2_Ir@GP > pxm_OH_Ir@G. Summarily, this results which undoubtedly corresponds with other analysis in this study shows that pxm_NH2_Ir@GP (in both gas and water phase), can be used as an efficient and sensitive biosensor material for the effective carriage of pxm drug to bio cells.

Study the single-atom Mn-doped catalysts on boron nitride sheet surface as cathode for oxygen reduction reaction in proton‐exchange membrane fuel cells

An important subject in improvement of polymer electrolyte membrane fuel cells (FCs) is sluggish kinetics of cathodic oxygen reduction reaction (ORR). In present work, Mn-doped vacancy boron nitride nanosheet has been offered as a noble-metal-free and efficient electrocatalyst for ORR process in fuel cells employing DFT computation. It is discovered that adsorption energy (Eads) values on Mn–N active site of selected catalysts enhance in order of: H2O > H2O2 > O2 > OOH > OH > O. For all intermediates containing oxygen, there is almost a consistent trend in Eads alteration. A slight thermodynamic force drives H2O2 formation and considerable ones for reduction of OOH into O* (or to 2OH*) indicate that 4e− pathway is more useful compared to 2e− pathway. Besides, from thermodynamic point of view, final stage of reduction (OH* + H+ + e− → H2O + *) within the highest value of ΔG for Mn-doped vacancy BN catalyst is rate-determining step (RDS). A larger HOMO-LUMO gap or a manganese d-band center remote from Fermi level indicates that catalyst doesn't favor adsorption of oxygen-containing species, which in turn results in higher ORR performance.

Systematic exo-endo encapsulation of hydroxyurea (HU) by Cu, Ag, and Au-doped gallium nitride nanotubes (GaNNT) for smart therapeutic delivery

Similar to the more well-known carbon nanotubes, gallium nitride nanotubes (GaNNT) are among the materials that scientists have found to be extremely helpful in transporting drugs and to provide significant potential for multi-modal medical therapies. Here, the potential of Cu, Ag, and Au-doped GaNNT for smart delivery of the anticancer medication hydroxyurea (HU) was extensively investigated employing quantum chemical analysis and density functional theory (DFT) computation at the B3LYP-GD3BJ/def2-SVP level of theory. The systematic approach used in this study entails examining the exo (outside)-and endo (inside) loading of HU utilizing the investigated nanotubes in order to understand the adsorption, sensing processes, bonding types, and thermodynamic properties. Results of the HOMO-LUMO studies show that metal-doped GaNNTs with the hydroxyurea (HU) at the endo - interaction of the drug of the nanotube produced more reduced energy gaps (0.911–2.039 eV) compared with metal-doped GaNNTs complexes at the outside – interaction of the drug on the nanotube (2.25–3.22 eV) and as such reveal their suitability for use as drug delivery materials. As observed in the endo-interaction of HU adsorptions in the tubes, HU_endo_Au@GaNNT possessed the highest adsorption energy values of −118.716 kcal/mol which shows the most chemisorption between the surfaces and the adsorbate while for HU_exo_Ag@GaNNT is −97.431 kcal/mol for the highest exo-interactions. These results suggest that HU drug interacted inside the Ag, Au, and Cu doped GaNNT will be very proficient as a carrier of the HU drug into bio systems. These results are along with visual studies of weak interactions, thermodynamics, sensor, and drug release mechanisms suggest strongly the endo-encapsulation of HU as the best mode for smart drug delivery.

Magnetically Separable Humic Acid-Chitin Based Adsorbent as Pb(II) Uptake in Synthetic Wastewater

Modification of humic acid (HA) from the peat soil of Jambi province, Indonesia with chitin and magnetite to form Fe3O4/HA-chitin has been successfully carried out. The successful synthesis was identified from characterization with functional group analysis, crystal analysis, magnetic strength measurement, and morphological and elemental analysis. The application of Fe3O4/HA-chitin to adsorb Pb(II) ion was analyzed using the Lagergren, Ho, Santosa, and RBS kinetics models (kinetics study) and the Langmuir, Freundlich, Dubinin-Radushkevich (DR), and Temkin isotherm model (isotherm study). The kinetics study followed the Ho model (pseudo-second order) with R2 and kHo of 0.9997 and 10264.59 g/mol min, respectively. The results of the data applicable to the Freundlich model showed that several sites were capable of multilayer adsorption (B) with a large enough adsorption capacity of 929.19 mg/g (about 28 times higher than the monolayer adsorption of Langmuir data). However, the outermost layer had a feeble adsorption energy of 0.51 kJ/mol, as measured by Temkin's adsorption energy. In the layer between the first layer (Langmuir) and the outermost layer (Freundlich), the DR isotherm was measured at a capacity of 104.87 mg/g (qD, the 3rd layer of the first layer) the adsorption energy was measured at 12.91 kJ/mol. A cross-study on the prediction of adsorption energy using the Santosa and RBS kinetics models showed that the RBS model had an adsorption energy value (26.45 kJ/mol) that was closer to the adsorption energy value of the Langmuir isotherm (27.55 kJ/mol).

Occurrence Modes of Critical Metals (Li+ and Ge4+) in the Organic Molecular Structures of Coal: A Density Functional Theory Study.

To explore the mechanism of critical metal (Li+ and Ge4+) occurrence in the organic molecular structures of different rank coals, simulations were investigated using quantum chemical density functional theory. In this paper, Wender lignite, bituminous, and anthracite molecular models were used as organic molecular structures in coal. The electrostatic potential (ESP), frontier molecular orbitals, and Mulliken charges were used to identify adsorption sites in organic molecular structures. Mulliken charge, bond length, Mayer bond order (MBO), and adsorption energy values were used to estimate the binding conformation and strength between organic molecular structures and critical metals (Li+ and Ge4+). The results showed that the negative ESP, the highest occupied molecular orbitals, and negative Mulliken charges in the organic molecular structures were located at the O atom of oxygen functional groups and the aromatic structures, respectively, which were the active sites for critical metal adsorption. Mulliken charge transfer, bond length, MBO, and adsorption energy data suggested that the binding of Li+ with organic molecular structures was controlled by the carbonyl group (C=O), while the aromatic structures had less effect on the occurrence of Li+ in the organic molecular structures. The maximum adsorption energy value for binding Li+ with organic molecular structures was -742.16 kJ/mol. The Ge4+ ions not only showed strong binding ability with oxygen functional groups, but also Ge4+ formed thermodynamically stable half-sandwich complexes with aromatic structures. Therefore, the coal rank had little effect on the binding of Ge4+ with organic molecular structures. Moreover, the binding of Ge4+ with organic molecule structures was enhanced by the synergistic interactions of oxygen functional groups and aromatic structures. The adsorption energy values were up to -8511.43 kJ/mol. The adsorption of organic matter in coal to critical metals (Li+ and Ge4+) generated changes in the spatial configuration of the organic molecular structure, including local twisting of the organic molecular structure in lignite and bending of the aromatic structure in anthracite.

DFT assessments of BN, AlN, and GaN decorated carbon cage scaffolds for sensing the thiamazole drug

Sensing drug substances by nanostructures are very important in accordance with the management of targeted drug delivery processes and drug substances detections. Boron nitride (BN), aluminum nitride (AlN), and gallium nitride (GaN) decorated carbon cage (BN-C, AlN-C, and GaN-C) scaffolds were assessed towards sensing the thiamazole (TMZ) drug through the wB97XD/6–31 + G* level of density functional theory (DFT) computations. The singular models were optimized and their combinations to each other were stabilized to obtain the interacting [email protected] bimolecular complexes and their corresponding features. The results indicated the existence of non-covalent physical interactions between the substances and their electronic features indicated possibility of sensing function for the investigated scaffolds. Based on the variations of values of adsorption energy and energy gap, the features of recovery time and conductance rate were achieved to predict a sensing function for the models; [email protected] was found at the highest suitability in comparison with [email protected] and [email protected] models. The obtained thermochemistry results indicated a spontaneous process for the formation of [email protected] complexes. Based on all the obtained results, an order of [email protected] > [email protected] > [email protected] was found for describing stability, formation, and electronic features suitability by assigning specific features for each of the singular BN-C, AlN-C, and GaN-C scaffolds towards the TMZ drug. As a consequence, two purposes of detections and adsorptions were approached for the investigated scaffolds to develop sensing functions of BN-C, AlN-C, and GaN-C scaffolds for the TMZ drug.

DFT Calculation and MD Simulation Studies on Gemini Surfactant Corrosion Inhibitor in Acetic Acid Media.

Gemini surfactant corrosion inhibitor (CI) is one type of CI mainly used in mitigating corrosion in the complex system of oil/gas production industries. Computer modeling methods such as density functional theory (DFT) calculation and molecular dynamic (MD) simulation are required to develop new CI molecules focusing on their application condition as a prediction or screening process before the physical empirical assessment. In this work, the adsorption inhibition efficiencies of two monomer surfactants (2B and H) and their respective Gemini structures with the addition of different spacers (alkyl, benzene, ester, ether, and ketone) are investigated using DFT calculation and MD simulation method in 3% sodium chloride (NaCl), and 1500 ppm acetic acid solutions. In DFT calculation, 2B-benzene molecules are assumed to have the most promising inhibition efficiency based on their high reactivity and electron-donating ability at their electron-rich benzene ring region based on the lowest bandgap energy (0.765 eV) and highest HOMO energy value (-2.879 eV), respectively. DFT calculation results correlate with the adsorption energy calculated from MD simulation, where 2B-benzene is also assumed to work better as a CI molecule with the most adsorption strength towards Fe (110) metal with the highest negative adsorption energy value (-1837.33 kJ/mol at temperature 323 K). Further, diffusion coefficient and molecular aggregation analysis in different CI concentrations through MD simulation reveals that only a small amount of Gemini surfactant CI is needed in the inhibition application compared to its respective monomer. Computer simulation methods successfully predict and screen the Gemini surfactant CI molecules that can work better as a corrosion inhibitor in acetic acid media. The amount of Gemini surfactant CI that needs to be used is also predicted. The future planning or way forward from this study will be the development of the most promising Gemini surfactant CI based on the results from DFT calculation and MD simulations.

Superior hydrogen storage capacity of Vanadium decorated biphenylene (Bi+V): A DFT study

Herein, the hydrogen storage competency of vanadium-decorated biphenylene (Bi+V) has been investigated using Density Functional Theory simulations. The metal atom interacts with biphenylene with a binding energy value of −2.49 eV because of charge transfer between V 3d and C 2p orbitals. The structure and electronic properties are studied in terms of adsorption energy values, the spin-polarized partial density of states (PDOS), band structure plots, and charge transfer analysis. The Kubas-type interactions lead to average hydrogen adsorption energy values of −0.51 eV/H2 which fulfills DOE-US criteria (0.2–0.7 eV/H2). The diffusion energy barrier value of 1.75 eV lowers the chances of metal clustering. The complex binds 5H2 on each V-atom resulting in a storage capacity of 7.52 wt% with an average desorption temperature of 595.96 K. The ab-initio molecular dynamics (AIMD) and phonon dispersions validates structural integrity at higher temperatures suggesting the excellent storage properties of this material at room temperature.

Investigation on removal of multi-component volatile organic compounds in a two-stage plasma catalytic oxidation system - Comparison of X (X=Cu, Fe, Ce and La) doped Mn2O3 catalysts

Mn2O3-X catalysts (X = Cu, Fe, Ce and La) were prepared based on γ-Al2O3 for the mixture degradation of muti-component volatile organic compounds (VOCs) composed of toluene, acetone, and ethyl acetate. The catalysts were characterized, and the density functional theory (DFT) simulation of ozone adsorption on Mn2O3-X were carried out to investigate the influence of adsorption energy on catalytic performance. The results showed that the removal efficiency (RE) of each VOC component was similarly improved by Mn2O3-X catalysts, and the greatest increase in VOCs' removal efficiency was obtained (7.8% for toluene, 86.2% for acetone, and 82.5% for ethyl acetate) at a special input energy (SIE) of 700 J L−1 with Mn2O3–La catalyst. Characterization results demonstrated that Mn2O3–La catalyst had the highest content of low valence Mn elements and the greatest Oads/Olatt ratio, as well as the lowest reduction temperature. Mn2O3–La catalyst also presented superior catalytic effect in improving carbon balance (CB) and CO2 selectivity (SCO2). The CB and SCO2 were increased by 47.7% and 12.61% respectively with Mn2O3–La at a SIE of 400 J L−1 compared with that when only γ-Al2O3 was applied. The DFT simulation results of ozone adsorption on Mn2O3-X catalysts indicated that the adsorption energy of catalyst crystal was related to the catalytic performance of the catalyst. The Mn2O3–La/γ-Al2O3 catalyst, which had the highest absolute value of adsorption energy, presented the best performance in improving VOCs’ RE.

Reaction mechanism between Gen (n = 2–5) clusters and single water molecule based on density functional theory

AbstractThe ground state structures of Gen (n = 2–5) clusters and their adsorption energy values with single water molecule were calculated using density functional theory. We also investigated the reaction pathways between Gen (n = 2–5) clusters and single water molecule. Based on molecular orbital and natural population analysis (NPA) figures, it was found that the O atom in H2O binds to the Gen (n = 2–5) clusters to form GenO (n = 2–5) and releases hydrogen. Notably, the Ge2 cluster exhibited the most efficient interaction with single water molecule based on the comparison of the energy values during the reaction of hydrogen generation. Furthermore, NPA and density of states analyses indicate that the Ge atoms in the products did not reach their highest oxidation state, suggesting that GenO (n = 2–5) may continue to react with more water molecules to generate hydrogen. Our results provide a deeper understanding of the chemical reaction properties.