Diphenylamine-based hole-transporting materials for excessive-overall performance perovskite solar cells: Insights from DFT calculations

Density functional theory calculations were employed to identify the ability of some diphenylamine-based hole-transporting materials (HTMs) for use in top-performance perovskite solar cells. The effects of donor/acceptor electron groups and the new π-bridge section in the three-part of structures were investigated thoroughly. The results indicated that adding electron-withdrawing functional groups such as CN in the phenylazo-indol moiety and substituting electron donor groups such as CH3 in the NH2 hydrogen atoms of the diphenylamine section can cause higher power conversion light-harvesting efficiency in new HTMs. Also, the replacement of thieno [3,2-b] benzothiophene as a part of the π bridge with the phenyl group according to the optical and electronic structure properties improves the efficiency of the new phenylazoindole derivatives.

Efficient delivery of anticancer 5-fluorouracil drug by alkaline earth metal functionalized porphyrin-like porous fullerenes: A DFT study

Finding and developing effective targeted drug delivery systems has emerged as an attractive approach for treating a wide range of diseases. In the present study, the potential of alkaline earth metal functionalized porphyrin-like porous C₂₄N₂₄ fullerenes for delivering 5-fluorouracil (5FU) anticancer drug is assessed using density functional theory calculations. The goal is to evaluate how the addition of alkaline earth metals to C₂₄N₂₄ enhances the adsorption capabilities of this system towards 5FU drug. The adsorption energies and charge transfers are determined in order to evaluate the strength of the interaction between the 5FU and fullerene surfaces. According to the results, adding alkaline earth metals increases the drug's adsorption energy on the C₂₄N₂₄ fullerene. In all cases, the drug molecule interacts with the metal atom through its CO group. Furthermore, the adsorption strength of the 5FU increases with metal atom size (Ca > Mg > Be), which is connected to the polarizability of these atoms. The adsorption energies of 5FU are shown to be highly sensitive on solvent effects and the acidity of the environment. The adsorption strength of 5FU decreases within the solvent (water), allowing it to be released more easily. The moderate adsorption energies and short desorption times of 5FU imply that it is reversibly adsorbed on the functionalized fullerenes.

Anthracite based activated carbon impregnated with HMTA as an effectiveness adsorbent could significantly uptake gasoline vapors

In this study, we synthesized and employed the amine impregnated activated carbon as an efficacious adsorbent for uptaking gasoline vapor. For this regard, anthracite as activated carbon source and hexamethylenetetramine (HMTA) as amine were selected and utilized. Physiochemical characterization of made sorbents were evaluated and investigated using SEM, FESEM, BET, FTIR, XRD, zeta potential, and elemental analysis. The synthesized sorbents provided an excellent textural features as compared with the literature and other activated carbon based sorbents and impregnated with amine. Our findings also suggested that in addition to high surface area (up to 2150 m² / g), the micro- meso pores created (Vmeso / V micro = 0.79 Cm ³ / g) surface chemistry may significantly affect the gasoline sorption capacity, which here the role of mesoporous is further highlighted. V meso for amine impregnated sample and free activated carbon was 0.89 and 0.31 Cm ³ / g, respectively. According to the results, the prepared sorbents have a potential capability in uptaking gasoline vapor and with line this, we report a high sorption capacity of 572.56 mg / g. After, four cycles used the sorbent had a high durability and about 99.11% of the initial uptake was maintained. Taking together the synthesized adsorbents as an activated carbon provided an excellent and unique features and enhanced gasoline uptake, therefore its applicability in uptaking gasoline vapor can be substantially considered.

Hollow nano-CaCO3's VOC sensing properties: A DFT calculation and experimental assessments

Air is the most critical and necessary for life, and air quality significantly impacts people's health. Both indoor and outdoor pollution frequently contain volatile organic compounds (VOCs). Such contaminants provide immediate or long-term health risks to the living system. The present study investigates sorption characteristics of VOCs on hollow nano calcite (CaCO₃) particles with 250 nm and 40 nm pore sizes to remove from the air ambient using the quartz crystal microbalance (QCM) technique at room temperature both experimentally and theoretically. The results were supported by density functional theory (DFT), and adsorption-desorption characteristics were studied with Langmuir adsorption isotherms. The QCM measurements showed a stable signal without having hysteresis, and the response of polar VOCs on hollow nano-CaCO₃ particles such as ethanol, propanol, and humidity with higher polarity was less compared to solvents such as chloroform and dichloromethane, which revealed that the surfaces of CaCO₃ particles have mostly non-polar properties. CaCO₃ surface and VOC molecule interactions overlap with the Langmuir model. With DFT calculations, VOC and water molecule adsorption changes the CaCO₃ E_gap. Our findings show that the ΔE_gap values increase as chloroform > dichloromethane > propanol > ethanol > water. This order suggests that the sensing response of the hollow CaCO₃ structure is linearly proportional to the adsorption energies of VOC and water. The linear adsorption characteristics, high sensing response, and short recovery time illustrated that the newly synthesized nano-CaCO₃ could be implemented as a new VOC adsorbent material for health, environmental sustainability, and in vitro microbiome cultures.

Oxidation of methane and ethylene over Al incorporated N-doped graphene: A comparative mechanistic DFT study

It is generally recognized that developing effective methods for selective oxidation of hydrocarbons to generate more useful chemicals is a major challenge for the chemical industry. In the present study, density functional theory calculations are conducted to examine the catalytic partial oxidation of methane (CH₄) and ethylene (C₂H₄) by nitrous oxide (N₂O) over Al-incorporated porphyrin-like N-doped graphene (AlN₄-Gr). Adsorption energies for the most stable configurations of CH₄, C₂H₄, and N₂O molecules over the AlN₄-Gr catalyst are determined to be -0.25, -0.64, and -0.40 eV, respectively. According to our findings, N₂O can be efficiently split into N₂ and O_ads species with a negligible activation energy on the AlN₄-Gr surface. Meanwhile, CH₄ and C₂H₄ molecules compete for reaction with the activated oxygen atom (O_ads) that stays on the surface. The energy barriers for partial methane oxidation through the CH₄ + O_ads → CH₃° + HO_ads and CH₃° + HO_ads → CH₃OH reaction steps are 0.16 eV and 0.27 eV, respectively. Furthermore, the produced CH₃OH may be overoxidized by O_ads to give formaldehyde and water molecules by overcoming a relatively low activation barrier. The activation barriers for C₂H₄ epoxidation are small and comparable to those for CH₄ oxidation, implying that AlN₄-Gr is highly active for both reactions. The high energy barrier for the 1,2-hydrogen shift in the OCH₂CH₂ intermediate, on the other hand, makes the production of acetaldehyde impossible under normal conditions. According to the population analysis, the AlN₄-Gr serves as a strong electron donor to aid in the charge transfer between the Al atom and the O_ads moiety, which is necessary for the activation of CH₄ and C₂H₄. The findings of the present study may pave the way for a better understanding of the catalytic oxidation the CH₄ and C₂H₄, as well as for the development of highly efficient noble-metal free catalysts for these reactions.

Alkali metal decorated C60 fullerenes as promising materials for delivery of the 5-fluorouracil anticancer drug: a DFT approach

The development of effective drug delivery vehicles is essential for the targeted administration and/or controlled release of drugs. Using first-principles calculations, the potential of alkali metal (AM = Li, Na, and K) decorated C₆₀ fullerenes for delivery of 5-fluorouracil (5FU) is explored. The adsorption energies of the 5FU on a single AM atom decorated C₆₀ are −19.33, −16.58, and −14.07 kcal mol⁻¹ for AM = Li, Na, and K, respectively. The results, on the other hand, show that up to 12 Li and 6 Na or K atoms can be anchored on the exterior surface of the C₆₀ fullerene simultaneously, each of which can interact with a 5FU molecule. Because of the moderate adsorption energies and charge-transfer values, the 5FU can be simply separated from the fullerene at ambient temperature. Furthermore, the results show that the 5FU may be easily protonated in the target cancerous tissues, which facilitates the release of the drug from the fullerene. The inclusion of solvent effects tends to decrease the 5FU adsorption energies in all 5FU-fullerene complexes. This is the first report on the high capability of AM decorated fullerenes for delivery of multiple 5FU molecules utilizing a C₆₀ host molecule.

DFT calculations show the capability of alkali metal (AM = Li, Na, and K) decorated C60 fullerenes to deliver multiple 5-fluorouracil 5FU molecules. The results show 5FU may be protonated to target cancerous tissues, this causes the drug to be realised from the fullerene.

Electrochemical reduction of NO catalyzed by boron-doped C60 fullerene: a first-principles study

The electrochemical reduction of nitrogen monoxide (NO) is one of the most promising approaches for converting this harmful gas into useful chemicals. Using density functional theory calculations, the work examines the potential of a single B atom doped C₆₀ fullerene (C₅₉B) for catalytic reduction of NO molecules. The results demonstrate that the NO may be strongly activated over the B atom of C₅₉B, and that the subsequent reduction process can result in the formation of NH₃ and N₂O molecules at low and high coverages, respectively. Based on the Gibbs free energy diagram, it is inferred that the C₅₉B has excellent catalytic activity for NO reduction at ambient conditions with no potential-limiting. At normal temperature, the efficient interaction between the *NOH and NO species might lead to the spontaneous formation of the N₂O molecule. Thus, the findings of this study provide new insights into NO electrochemical reduction on heteroatom doped fullerenes, as well as a unique strategy for fabricating low-cost NO reduction electrocatalysts with high efficiency.

Using DFT calculations, the potential of B-doped C₆₀ fullerene is evaluated for electrochemical reduction of nitrogen monoxide. The B-doped C₆₀ exhibits exceptional catalytic activity and high selectivity for reduction of nitrogen monoxide.

Ca functionalized N-doped porphyrin-like porous C60 as an efficient material for storage of molecular hydrogen

It is widely known that decorating metal atoms on defective carbon nanomaterials is a useful approach to enhance the hydrogen storage capacity of these systems. Herein, density functional theory calculations are used to determine the H₂ storage capacity of Ca functionalized nitrogen incorporated defective C₆₀ fullerenes (Ca₆C₂₄N₂₄). The strong binding, uniform distribution, and significant positive charges of the Ca atoms make this system effective material for storage of H₂. Ca₆C₂₄N₂₄ may adsorb a maximum of 6 hydrogen molecules per Ca atom, yielding a total gravimetric density of 7.7 wt %.

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.

Y-shape structured azo dyes with self-transforming feature to zwitterionic form as sensitizer for DSSC and DFT investigation of their photophysical and charge transfer properties

Two novel azo dyes with D-π-A-π-D structures were designed and synthesized to investigate the relationship between molecular structure and sensitizing performance on applying for dye-sensitized solar cells (DSSCs) in comparison with their linear counterparts. Introducing hydroxyl auxiliary groups and arranging π-conjugation length as two parallel and series structural architectures, Y-shape and linear, led to red shift in absorption wavelength and increase in absorption intensity for the Y-shape pattern providing an efficient charge transfer pathway and improved J_sc and η of the DSSCs. Emerging a zwitterionic form, azonium structure, of the sensitizer in parallel configuration for the dyes 1a.p and 1b.p, enhanced light absorption domain and changed anchoring fashion could engendering improved electronic overlapping. The easily-synthesized dyes were evaluated for photophysical and electrochemical properties and turned out that the parallel-decorated dyes displayed better results than the series types as photosensitizers for DSSCs. ATR and Raman spectra clearly showed the adsorption of these dyes on the TiO₂ surface. Operational tests of DSSCs, coated by titled azo dyes, illustrated that decorating π-conjugation pattern as parallel structure as well as accessorizing the donor unit with hydroxyl groups improved the photovoltaic performance. Optimized band gap due to participating the azonium structure and restricted electron recombination as well as rectified dye regeneration were proposed as main elements in enhancing performance parameters. A higher solar conversion efficiency was recorded for DSSCs based on the Y-shape dyes compared to other meta azo dye-based cells that were previously reported. Computational calculations were used to corroborate the opto-electrochemical traits of the dyes with a special concern on the influence of structural pattern on photovoltaic features.

A DFT investigation into the effects of As-doping on the electronic structure and electrochemical activity of pyrite (FeS2)

Pyrite (FeS₂) is a semiconductor mineral with electronic structural properties that are heavily influenced by trace elements in its composition. It has been demonstrated experimentally that the reduction of Fe³⁺ ions is significantly enhanced in the presence of trace arsenic (As) atoms in FeS₂. Using density functional theory calculations, we compare the geometric and electronic structural properties of pure and As-doped (110) pyrite surfaces. The interaction of the Fe³⁺ ion, a common oxidant of sulfides in acidic solution and acid mine drainage, with the aforementioned surfaces is thoroughly investigated. The findings reveal that the addition of an As atom alters the electronic structure of pyrite and decreases its band gap. The adsorption energy of the Fe³⁺ ion on As-doped pyrite is greater than that on pure pyrite. The calculated Gibbs free energy changes show that the reduction of Fe³⁺ to Fe²⁺ ion on the As-modified surface is thermodynamically more favorable than on pure pyrite.

Reversible CO2 storage and efficient separation using Ca decorated porphyrin-like porous C24N24 fullerene: a DFT study

The search for novel materials for effective storage and separation of CO₂ molecules is a critical issue for eliminating or lowering this harmful greenhouse gas. In this paper, we investigate the potential application of a porphyrin-like porous fullerene (C₂₄N₂₄) as a promising material for CO₂ storage and separation using thorough density functional theory calculations. The results show that CO₂ is physisorbed on bare C₂₄N₂₄, implying that this material cannot be used for efficient CO₂ storage. Coating C₂₄N₂₄ with Ca atoms, on the other hand, can greatly improve the adsorption strength of CO₂ molecules due to polarization and charge-transfer effects. Furthermore, the average adsorption energy for each of the maximum 24 absorbed CO₂ molecules on the fully decorated Ca₆C₂₄N₂₄ fullerene is −0.40 eV, which fulfills the requirement needed for efficient CO₂ storage (−0.40 to −0.80 eV). The Ca coated C₂₄N₂₄ fullerene also have a strong potential for CO₂ separation from CO₂/H₂, CO₂/CH₄, and CO₂/N₂ mixtures.

Using dispersion-corrected DFT calculations, the potential application of a porphyrin-like porous fullerene (C₂₄N₂₄) as an efficient material for CO₂ storage and separation was investigated.

Defect engineering-induced porosity in graphene quantum dots embedded metal-organic frameworks for enhanced benzene and toluene adsorption

The emerging environmental issues necessitate the engineering of novel and well-designed nanoadsorbents for advanced separation and purification applications. Despite recent advances, the facile synthesis of hierarchical micro-mesoporous metal-organic frameworks (MOFs) with tuned structures has remained a challenge. Herein, we report a simple defect engineering approach to manipulate the framework, induce mesoporosity, and crease large pore volumes in MIL-101(Cr) by embedding graphene quantum dots (GQDs) during its self-assembly process. For instance, MIL-101@GQD-3 (V_meso: 0.68 and V_tot: 1.87 cm³/g) exhibited 300.0% and 53.3% more meso and total pore volume compared to those of the conventional MIL-101 (V_meso: 0.17 and V_tot: 1.22 cm³/g), respectively, resulting in 1.7 and 2.8 times greater benzene and toluene loading at 1 bar and 25 °C. In addition, we found that MIL-101@GQD-3 retained its superiority over a wide range of VOC concentrations and operating temperature (25-55 °C) with great cyclic capacity and energy-efficient regeneration. Considering the simplicity of the adopted technique to induce mesoporosity and tune the nanoporous structure of MOFs, the presented GQD incorporation technique is expected to provide a new pathway for the facile synthesis of advanced materials for environmental applications.

Catalytic CO oxidation reaction over N-substituted graphene nanoribbon with edge defects

Density functional theory calculations, including dispersion effects, are used to demonstrate how substitutional nitrogen atoms can improve the catalytic reactivity of graphene nanoribbons (GNR) with edge defects in the CO oxidation process. It is demonstrated that the addition of nitrogen impurities significantly enhances O₂ adsorption on GNR. Carbon atoms near the edges of defects are the most active sites for capturing O₂ molecules. The lower adsorption energy of CO relative to O₂ implies that the N-modified GNR is resistant to CO poisoning. The Eley-Rideal (E-R) mechanism has activation energies as low as 0.38 eV, making it the most energetically relevant pathway for the CO + O₂ reaction. The findings of this study might help in the design of catalysts for metal-free catalysis of CO oxidation.

Synergic effects between boron and nitrogen atoms in BN-codoped C59-n BN n fullerenes (n = 1-3) for metal-free reduction of greenhouse N2O gas

The geometries, electronic structures, and catalytic properties of BN-codoped fullerenes C_59−nBN_n (n = 1–3) are studied using first-principles computations. The results showed that BN-codoping can significantly modify the properties of C₆₀ fullerene by breaking local charge neutrality and creating active sites. The codoping of B and N enhances the formation energy of fullerenes, indicating that the synergistic effects of these atoms helps to stabilize the C_59−nBN_n structures. The stepwise addition of N atoms around the B atom improves catalytic activities of C_59−nBN_n in N₂O reduction. The reduction of N₂O over C₅₈BN and C₅₇BN₂ begins with its chemisorption on the B–C bond of the fullerene, followed by the concerted interaction of CO with N₂O and the release of N₂. The resulting OCO intermediate is subsequently transformed into a CO₂ molecule, which is weakly adsorbed on the B atom of the fullerene. On the contrary, nitrogen-rich C₅₆BN₃ fullerene is found to decompose N₂O into N₂ and O* species without the requirement for activation energy. The CO molecule then removes the O* species with a low activation barrier. The activation barrier of the N₂O reduction on C₅₆BN₃ fullerene is just 0.28 eV, which is lower than that of noble metals.

The synergic effects between B and N atoms make C₅₇BN₂ and C₅₆BN₃ highly active catalysts for reduction of greenhouse N₂O gas.

Molecular dynamics simulations of choline chloride and phenyl propionic acid deep eutectic solvents: Investigation of structural and dynamics properties

The prediction of deep eutectic composition is hard and so far, has been distinguished by trial and error. Therefore, in this work, molecular dynamics simulations were performed for specifying the composition of the eutectic point of phenyl propionic acid (Phpr) and choline chloride (ChCl) mixtures. The distinctive properties of the Phpr and ChCl eutectic mixture at the composition of the eutectic point were investigated and were compared to other eutectic mixtures with the different mole fractions of Phpr and ChCl. Structural properties such as radial distribution function (RDF), coordination number, hydrogen-bond number, interaction energies, and dipole moment of species, as well as dynamical properties such as mean square displacement (MSD), viscosity, and self-diffusion coefficient were analyzed. The obtained results of structural properties indicated that each chloride anion is surrounded by two Phpr molecules for deep eutectic point states that is in good agreement with available experimental reports. Moreover, the viscosity of studied mixtures evaluated by the Green-Kubo method was found to be consistent with the reported experimental data. Besides, the stress-autocorrelation function (SACF) and convergency of viscosity with time were calculated. Finally, the eutectic point could be detected by the changes in the trends of total van der Waals interaction energies and the viscosity.

A mechanistic first-principles study on N2 reduction reaction catalyzed by Ni4 supported defective graphene

The electrochemical reduction of N₂ is an important industrial process, which offers an alternative route to the Haber-Bosch procedure for NH₃ production. Here, by the method of first-principles calculations, we introduce Ni₄ supported defective graphene (Ni₄-Gr) as an efficient substrate to convert N₂ into NH₃. The enzymatic, alternating and distal mechanisms are investigated for N₂ reduction to explore catalytic activity of Ni₄-Gr surface. By analyzing the free energy diagrams, it is obtained that Ni₄-Gr exhibits high catalytic performance for N₂ reduction via the enzymatic pathway with an overpotential value of 0.50 V at normal temperature.

Efficient hydrogen storage on Al decorated C24N24: a DFT study

Hydrogen storage on Al-decorated C24N24 is explored by the dispersion corrected DFT calculations. Each Al site in the Al6C24N24 cluster can adsorb up to five H2 molecules, with an average adsorption energy of −0.30 eV.

Catalytic role of graphitic nitrogen atoms in the CO oxidation reaction over N-containing graphene: a first-principles mechanistic evaluation

The catalytic role of graphitic nitrogen atoms of a series of nitrogen-doped graphene surfaces is explored for low-temperature oxidation of CO using periodic DFT calculations.

Activation of the methane C–H bond by Al- and Ga-doped graphenes: a DFT investigation

The potential of Al- and Ge-embedded graphene to activate the C–H bond of CH4 in the presence of a N2O molecule was studied using DFT calculations.

Theoretical insights into oxygen reduction reaction catalyzed by phosphorus-doped divacancy C3N nanosheet

The catalytic reduction of O₂ molecule into H₂O is investigated over a P-doped divacancy C₃N nanosheet (P-Dv-C₃N) by using density functional theory calculations. A negative formation energy is calculated for P-Dv-C₃N, suggesting that the introduction of a P atom into divacancy defective C₃N would be thermodynamically favorable. The oxygen reduction reaction (ORR) over P-Dv-C₃N would proceed via a 4e^- pathway (O₂ + 4H⁺ + 4e^-→ 2H₂O) at room temperature. The rate-determining step of the ORR on P-Dv-C₃N is O + H⁺ + e^- → OH which requires an activation energy of 1.21 eV. These results provide helpful insights into design novel metal-free catalysts to improve the kinetics of ORR in fuel cells.

Preparation and characterization of a new waste-derived mesoporous carbon structure for ultrahigh adsorption of benzene and toluene at ambient conditions

In this work, a series of nanoporous carbon materials were synthesized using Iranian asphaltene as a low-cost carbon source and modified by melamine as a new nitrogen-rich promoter (M-IANC). The adsorption capacity of benzene and toluene on the synthesized M-IANCs was measured at low and high concentrations by an in-house built apparatus. The results demonstrated that the addition of melamine remarkably increased the mesoporous volume (up to 1.61 cm³/g) in the nanoporous carbon structure and, subsequently, created a large surface area (2692 m²/g) and pore volume (1.71 cm³/g). The resulting M-IANC-C nanostructure (melamine:PIA mass ratio of 1:2) depicted 228.18 wt.% and 82.08 wt.% adsorption capacity for benzene and toluene, respectively, which were 19.4 and 2.8 times higher than commercial activated carbon. In addition to the distinguished adsorptive behavior for benzene and toluene removal, M-IANC-C exhibited higher cyclic adsorption capacity than those of unmodified IANC sample after four consecutive cycles. The adsorption mechanism and the role of melamine groups in the adsorption of benzene and toluene were also studied by the density functional theory (DFT) calculations. Besides the inexpensive cost of the carbon source (asphaltene), results also indicate that the M-IANC can be a suitable candidate for VOC adsorption.

NO reduction over an Al-embedded MoS2 monolayer: a first-principles study

Converting toxic air pollutants such as nitric oxide (NO) and carbon monoxide (CO) into less harmful gases remains a critical challenge for many industrial technologies. Here, by performing first-principles calculations, we introduce a cheap, stable and novel catalyst for the conversion of NO and CO molecules into N₂O and CO₂ using Al-doped MoS₂ (Al–MoS₂). According to our results, dissociation of NO molecules on Al–MoS₂ has a large energy barrier (3.62 eV), suggesting that it is impossible at ambient temperature. In contrast, the coadsorption of NO molecules to form (NO)₂ moieties is characterized as the first step of the NO reduction process. The formed (NO)₂ is unstable on Al–MoS₂, and hence it is easily decomposed into N₂O molecules, and an oxygen atom is adsorbed onto the Al atom (O_ads). This reaction step is exothermic and needs an activation energy of 0.37 eV to be overcome. Next, the O_ads moiety is removed from the Al atom by a CO molecule, and thereby the Al–MoS₂ catalyst is recovered for the next round of reaction. The side reaction producing NO₂via the reaction of NO with the O_ads moiety cannot proceed on Al–MoS₂ due to its large activation energy.

By performing first-principles calculations, we introduce a stable and novel catalyst for the conversion of NO and CO molecules into N₂O and CO₂ using Al-doped MoS₂.

An effective approach for tuning catalytic activity of C3N nanosheets: Chemical-doping with the Si atom

It is well-known that the catalytic oxidation of CO molecule into CO₂ is one of the most important strategies for the removing of this toxic gas from the atmosphere. In the present study, we investigate the reaction pathways and energy barriers for the oxidation of CO by O₂ molecule over the Si-doped C₃N nanosheet. According to our results, doping of C₃N nanosheet with a Si atom could greatly modify its surface reactivity and electronic structure. Due to the large positive charge on the Si, this atom acts as the most active site to adsorb CO and O₂ molecules. Three possible reaction mechanisms are studied for the CO oxidation, namely the Eley-Rideal (ER), Langmuir-Hinshelwood (LH) and new Eley-Rideal (NER). Comparing the activation energies indicates that the CO oxidation reaction proceeds via the LH mechanism over the title surface. The energy barrier needed to remove the activated oxygen atom (O*) from the Si atom is only 0.22 eV, which is most likely to overcome at room temperature. The results of this study may be useful to fabricate noble-metal free catalysts to remove toxic CO molecules from the atmosphere.

Efficient DBT removal from diesel oil by CVD synthesized N-doped graphene as a nanoadsorbent: Equilibrium, kinetic and DFT study

Adsorptive Dibenzothiophene (DBT) removal from diesel oil stream on nitrogen doped graphene (N-doped graphene) was considered. The N-doped graphene was synthesized by chemical vapor deposition (CVD) method at 1000 °C using camphor and urea. The adsorbent was characterized by Field Emission Scanning Electron Microscopy (FE-SEM), X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR) and Nitrogen adsorption/desorption technique. Adsorption parameters such as temperature, time, concentration and mass loaded were optimized by experimental design method. Experimental kinetic data was fitted to Pseudo second order model successfully. Frendulich model was recommended for experimental isotherm data. However, Tempkin model was presented because of the importance of interaction between pyridinic nitrogen and DBT aromatic structure. The results indicate that not only the pore volume and surface area but also types of surface functionalities have an important role for DBT adsorption process, especially for the adsorbates with aromatic structures. The adsorption capacity was calculated up to 73.4 mg/g which is 1.25 times higher than the adsorption capacity of pristine. Thermal regeneration stability, fast adsorption kinetics and high adsorption capacity make N-G4 a potential promising adsorbent for DBT removal. Besides, density functional theory calculations revealed that an increase in the number of doped N atoms as well as the presence of a mono or divacancy defect in N-doped graphene can enhance the adsorption energy of DBT.