Density Functional Theory Study Research Articles

Highly selective guanidine-linked covalent organic framework for efficient removal of perfluoroalkyl carboxylic acids from water samples

In this study, guanidine-linked covalent organic framework (TPDGCl) was synthesized via a solvothermal method. The presence of guanidine groups in its structure facilitates electrostatic interactions and provides hydrogen bonding sites, enabling the selective enrichment of perfluoroalkyl carboxylic acids (PFCAs) from environmental water samples. The material exhibits rapid kinetic mass transfer, which facilitates the efficient removal of samples containing PFCAs from aqueous solutions within 5 min. Furthermore, TPDGCl exhibits several advantageous properties, including high selectivity for PFCAs, a high adsorption capacity (2005 mg/g), excellent chemical stability, and remarkable recyclability (five cycles). Additionally, density functional theory (DFT) studies have demonstrated that the adsorption of PFCAs on TPDGCl is enhanced by ion exchange, hydrophobic interactions, hydrogen bonding interactions and ordered channel structures. Finally, TPDGCl was used as an adsorbent for dispersive solid-phase extraction (d-SPE), in combination with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), to develop an analytical method for the efficient extraction and sensitive detection of PFCAs. The developed method exhibits highly sensitivity, with detection and quantification limits of 0.64–0.85 ng/L and 2.6–3.4 ng/L, respectively. The recoveries of actual water samples ranged from 75.4% to 113.7%. Moreover, TPDGCl effectively reduces the levels of PFCAs in real water samples to less than 70 ng/L within only 1 h. These results indicate that TPDGCl is an effective adsorbent for removing PFCAs from environmental water samples.

Heteroatom-Controlled Three-Component [4 + 3] or [3 + 2] Annulation of Isatin-Derived Azomethine Ylide with Azadiene: Selective Synthesis of Spirooxindole-diazepines and Density Functional Theory Studies.

A novel three-component [4 + 3] annulation reaction of isatin-derived azomethine ylides with azadienes was developed for the first time to efficiently synthesize spirooxindole-diazepines incorporating a benzothiophene moiety under catalyst-free conditions. Effects of the heteroatom of azadiene on the chemoselectivity was investigated. With the use of the azadiene bearing a benzofuran moiety as a substrate, the dominant reaction pathway was changed to an α-[3 + 2] annulation. When azadiene bearing an indenone moiety was used, a distinct γ-[3 + 2] annulation was observed. Density functional theory calculations revealed that a delicate balance between kinetic accessibility and the thermodynamic driving force controlled the competition of different annulation reactions.

Tuning the photocatalytic performance of halide perovskites for efficient solar hydrogen production: A DFT study of CsGeCl3-xXx (X= Br, I)

Photoelectrochemical water splitting holds immense potential for sustainable hydrogen production to address mounting energy demands. However, the development of efficient and cost-effective photocatalysts remains a significant challenge. Perovskites, recognized for their cost-effectiveness and tunable characteristics, show potential as viable candidates in this context. Our investigation is the first to mark the photocatalytic efficacy of CsGeCl3. The findings reveal a modest solar-to-hydrogen (STH) efficiency of 0.74 % due to its wide bandgap energy. Halide mixing with iodine and bromine significantly improves the STH efficiencies, reaching approximately 8.47 %. In addition, applying uniaxial compressive stress further boosts the efficiency to 14.6 %. In this study, we employed the density functional theory (DFT) through the WIEN2k software to scrutinize the structural, electronic, optical, photocatalytic, and thermoelectric properties of all the studied structures. Furthermore, the study evaluated the compounds' capacity for CO2 photoreduction, susceptibility to degradation, and the influence of pH on their photocatalytic performance. The insights gained from this work contribute to the development of efficient and cost-effective perovskite-based photocatalysts for renewable hydrogen production.

Experimental and DFT studies of mercury adsorption and oxidation on CuCo2O4(110) surface

Elemental mercury (Hg0) is a typical toxic pollutant in flue gas from coal-fired power plants. The specific role of oxygen transfer on Hg0 oxidation over CuCo2O4 oxygen carrier and the involved reaction mechanisms were systematically studied by experimental and theoretical methods. In this study, the CuCo2O4 oxygen carrier with spinel-structure was prepared with salt-assisted combustion method. To reduce the grain size and increase the specific surface area of the oxygen carrier, the optimal KCl: CuCo2O4 ratio of 1:1 was obtained. Oxygen uncoupling ability of CuCo2O4 oxygen carrier was very strong, and the oxygen-releasing performance was slightly decreased after ten cyclic processes. Simulation based on density functional theory (DFT) shows that CuCo2O4 has relative low oxygen vacancy formation energy and oxygen transport energy barrier, and the oxygen vacancy is the preferred O2 adsorption site. Hg0 removal experiments show that CuCo2O4 has a strong ability to remove Hg0. The proportion of Hg2+ increases with the temperature, and the proportion of HgP decreases accordingly. Simulation shows that the 3-Co site on the surface of the CuCo2O4 oxygen carrier is the optimum Hg0 adsorption site. CuCo2O4 is found as a strong oxygen-releasing oxygen carrier, which can effectively promote the oxidation of Hg0.

Update of the present decomposition mechanisms of ammonia: A combined ReaxFF, DFT and chemkin study

Ammonia, a promising carbon-free fuel, offers significant potential for reducing carbon emissions. The decomposition of NH3 is crucial for improving NH3 combustion, yet its mechanisms remain unclear. This study uses ReaxFF simulations, density functional theory (DFT), and Chemkin calculations to explore NH3 decomposition and refine the Konnov mechanism. Our results show that the NH3 to N2 conversion is highly temperature-dependent. At high temperatures, the pathway is NH3→NH2→N2H4→N2H2→N2. As temperature decreases, the N2H pathway becomes more significant, shifting the reaction to NH3→NH4→NH2→N2H→N2 pathway. Additionally, temperature affects H dissociation: at lower temperatures, NH3 to NH2 follows NH3→NH4→NH2, while the NH4 pathway's influence diminishes with rising temperatures. The updated Konnov mechanism improves NH3 decomposition prediction accuracy by about 72.79% and enhances predictions of decomposition rates and intermediate formations (NH, NH2, NH4). This research advances the understanding of NH3 decomposition mechanisms and is vital for optimizing burners for efficient and stable NH3 combustion.

Computational exploration of acefylline derivatives as MAO-B inhibitors for Parkinson's disease: insights from molecular docking, DFT, ADMET, and molecular dynamics approaches.

Monoamine oxidase B (MAO-B) plays a pivotal role in the deamination process of monoamines, encompassing crucial neurotransmitters like dopamine and norepinephrine. The heightened interest in MAO-B inhibitors emerged after the revelation that this enzyme could potentially catalyze the formation of neurotoxic compounds from endogenous and exogenous sources. Computational screening methodologies serve as valuable tools in the quest for novel inhibitors, enhancing the efficiency of this pursuit. In this study, 43 acefylline derivatives were docked against the MAO-B enzyme for their chemotherapeutic potential and binding affinities that yielded GOLD fitness scores ranging from 33.21 to 75.22. Among them, five acefylline derivatives, namely, MAO-B14, MAO-B15, MAO-B16, MAO-B20, and MAO-B21, displayed binding affinities comparable to the both standards istradefylline and safinamide. These derivatives exhibited hydrogen-bonding interactions with key amino acids Phe167 and Ile197/198, suggesting their strong potential as MAO-B inhibitors. Finally, molecular dynamics (MD) simulations were conducted to evaluate the stability of the examined acefylline derivatives over time. The simulations demonstrated that among the examined acefylline derivatives and standards, MAO-B21 stands out as the most stable candidate. Density functional theory (DFT) studies were also performed to optimize the geometries of the ligands, and molecular docking was conducted to predict the orientations of the ligands within the binding cavity of the protein and evaluate their molecular interactions. These results were also validated by simulation-based binding free energies via the molecular mechanics energies combined with generalized Born and surface area solvation (MM-GBSA) method. However, it is necessary to conduct in vitro and in vivo experiments to confirm and validate these findings in future studies.

Investigation of a new group of low band-gap semiconducting double perovskite K2MgSnZ6 (Z = Cl, Br, & I) materials and their structural, electronic, mechanical, and optical behaviors via DFT study

This study focuses on potassium based double perovskite materials, specifically a series of K2MgSnZ6 (Z = Cl, Br, & I) halide materials. For the investigated materials, all primary calculations were performed using the Full-Potential Linearized Augmented Plane-Wave (FP-LAPW) method, supported by density functional theory (DFT), and implemented in the WIEN2k code. The Gold-Schmidt tolerance factor values confirm the structural stability of the compounds, while the negative values of formation energy indicate the feasibility of experimental synthesis of the studied materials. The lattice constants were observed to increase as the halide element at the ‘Z’ position was replaced by one with a larger ionic radius. The recorded band-gap values were 2.60 eV, 2.00 eV, and 1.37 eV for K2MgSnCl6, K2MgSnBr6, and K2MgSnI6, respectively. After calculating the elastic constants for all K2MgSnZ6 (Z = Cl, Br, & I) materials, it was found that they satisfy the primary conditions for Born stability required for cubic-phase materials: (1) C11 > B > C12, (2) C11 + 2C12 > 0, (3) C11 > 0, (4) C44 > 0, and (5) C11–C12 > 0. The optical parameters of the K2MgSnZ6 (Z = Cl, Br, & I) double perovskite materials suggest that these materials could play a significant role in practical applications such as solar cells, UV detectors, and various optoelectronic devices.

Orchestrating a Supercapacitive Symphony: Copper–Metal Organic Framework Integrated MXene Nanosheets on Graphite Sheet Electrodes Unveiling Its Synergistic Interactions by Density Functional Theory Study

Orchestrating a Supercapacitive Symphony: Copper–Metal Organic Framework Integrated MXene Nanosheets on Graphite Sheet Electrodes Unveiling Its Synergistic Interactions by Density Functional Theory Study

Can ZnO/Cu catalyst provide promising activity for glycerol direct dehydrogenation? A combined density functional theory and coverage-dependent microkinetics study

Non-oxidative dehydrogenation (NODH) reaction of glycerol is a perfect atom economical technical route to produce higher-value 1,3-dihydroxyacetone (DHA). Cu-based catalyst (especially ZnO/Cu system), is known as active species for alcohol dehydrogenation, which may be also promising one for glycerol NODH. In this study, we combine coverage-dependent free energy profile using first-principle calculation, and microkinetic model, to investigate the NODH of glycerol on the ZnO/Cu(111) surface, and a detailed comparison is made with Cu (111) surface. The coverage-dependent microkinetic model takes into account the lateral adsorbate–adsorbate self-interactions and cross-interactions, and their effect on binding energy of both intermediate and transition state. Besides, it guarantees the reaction kinetics is based on the coverage self-consistent between surface model and microkinetic result under practically reaction conditions. Compared with coverage-dependent kinetics simulation (20 %–30 %), coverage-independent model overestimates the DHA selectivity on Cu (111) (over 90 %). Our coverage-dependent kinetics simulation illustrates that both glycerol conversion and DHA selectivity are most determined by the first dehydrogenation step (OH bond scission) of glycerol on Cu (111). However, when ZnO cluster adsorbed on the Cu (111) surface, ZnO cluster promotes the electron transferring between glycerol and Cu sites, which accelerates OH bond scission process of glycerol. Under coverage-dependent microkinetic model, the turnover frequency and selectivity of DHA on ZnO/Cu(111) get much improvement compared with Cu (111). Finally, the superior of ZnO/Cu(111) is further proved by continuous stirred tank reactor simulation, where NODH of glycerol need shorter residence times or lower temperature to reach 100 % conversion, as well as keep higher DHA selectivity.

Mechanism of CeO2 modified CO2 adsorbent with SO2 resistance: Experimental and DFT study

The flue gas emitted from coal-fired boilers contains a trace amount of SO2 after desulfurization, resulting in poor performance of CO2 adsorbent. In this paper, CO2 adsorption performance of potassium adsorbent modified by CeO2 doping and the effect of SO2 on CO2 adsorption were investigated by simulated flue gas. Theoretical research on the reaction between SO2 and CO2 with dopant was conducted by Density Functional Theory (DFT) method. The results showed that the cumulative CO2 adsorption capacity of the 4% Ce doped adsorbent without SO2 and with SO2 were 10.2% and 53.6% higher than that of the undoped adsorbent. The oxygen vacancy could cause the f orbital of Ce to exert greater influence, making the surface properties more unstable. The activation energy of the adsorption reaction between SO2 and H2O on Ce doped adsorbent was 266.5 kJ/mol, and there were three transition states in this reaction, with O vacancy formation as the rate-controlling step.

Computational Study on Flavin-Catalyzed Aerobic Dioxygenation of Alkenyl Thioesters: Decomposition of Anionic Peroxides.

Flavin-dependent catalysts are widely applied to aerobic monooxygenation/oxidation reactions. In contrast, flavin-catalyzed aerobic dioxygenation reactions exhibit higher atomic economy but are less reported, not to mention the relevant mechanistic studies. Herein, a density functional theory study on flavin-catalyzed aerobic epoxidation-oxygenolysis of alkenyl thioesters was performed for the first time. Different from the previous mechanistic proposal, a pathway featuring two catalytic stages, monoanionic flavin-C(4a)-peroxide/oxide intermediates, and a reverse reaction sequence (epoxidation goes prior to oxygenolysis) was revealed. In comparison, the pathways involving dianionic flavin catalysts, monoanionic flavin-N(5)-(hydro)peroxide/C(10a)-peroxide, or neutral flavin-C(4a)-hydroperoxide/hydroxide/N(5)-oxide, and the pathways where oxygenolysis goes prior to epoxidation are less favored. Epoxidation goes through intramolecular substitution of the O-O bond of anionic flavin-C(4a)-peroxide by β-carbon, while the resulting flavin-C(4a)-oxide accomplishes the oxygenolysis. Furthermore, two other reaction modes, i.e., concerted O-O cleavage/1,2-shift of α-substituents and dyotropic rearrangement were discovered for the decomposition of other anionic peroxides, and preliminary rules were summarized for understanding the chemoselectivity for this process. This study sheds light on the different reaction features of numerous flavin-dioxygen derivatives, providing deeper insights into flavin-catalyzed dioxygenation reactions, and is expected to inspire experimental design based on unconventional anionic peroxides.

Validation of experimental results for polyhedral oligomeric silsesquioxane, carbon nanotube and functionalized carbon nanotube/polymer nanocomposites through density functional theory study

The mechanical and thermal properties of polymer nanocomposites could be influenced by different parameters. Interfacial interaction between nanomaterial and polymer composite can effectively influence the properties of nanocomposite. In this paper, the interaction between carbon nanotube (CNT), functionalized carbon nanotube with Amin (CNT-Amin), and Polyhedral Oligomeric Silsesquioxane (POSS), absorbing on PA/EVA composite surface theoretically were investigated based on the density functional theory (DFT) calculations. The interaction energy of −36.64 kJ/mol between PA and CNT-Amin and −22.31 kJ/mol between EVA and CNT-Amin means that the absorption of CNT-Amin on PA and EVA monomer are stronger than CNT and POSS which could affect the mechanical and thermal properties of the nanocomposites. However, the interaction between the polymer composite and the nanomaterials was physisorption. Additionally, thermal and mechanical tests were conducted on nanocomposite samples. Thermal and mechanical results show that the DFT calculations are in good agreement with the experiment. DSC analysis shows that the melting temperature for PA in PA/EVA/CNT-Amin changed from 221.6 to 225.2 °C and crystallization temperature from 188.8 to 191.9 °C which illustrates that the CNT-Amin nanomaterial adsorbed to PA in PA/EVA composite. Finally, mechanical properties show that the modulus of PA/EVA/CNT-Amin nanocomposite changed from 307.4 to 327.2 MPa compared to neat PA/EVA composite emphasizing that the interaction between CNT-Amin nanomaterial and PA improves the strength of the nanocomposite and in addition, EVA adsorbs the CNT which affected the strain of the nanocomposite at break by 16 % which corresponds to the calculation result prediction.

Insights into the Effect of Crystal Facets and Sulfur Defects on the Product Selectivity of Various CdS Configurations for CO2 Photoreduction: A DFT Study

CO2 photoreduction into valuable hydrocarbons, such as CO, CH4, and C2H4, delivers a promising approach to address both environmental and energy challenges. Transition metal chalcogenides, particularly cadmium sulfide (CdS), have emerged as prominent candidates due to their tunable electronic properties and availability. This study delves into a comprehensive investigation of how CdS crystalline facets and sulfur-deficient surfaces modulate the product selectivity. Through employing density functional theory (DFT), we unravel the catalytic performance of various CdS crystal orientations and sulfur vacancy configurations. The results have shown that different CdS facets exhibit unique electronic characteristics and surface energetics, which influence the adsorption dynamics and reaction pathways. The introduction of sulfur vacancies further modulates the nature of active sites, leading to substantial shifts in product selectivity. A detailed investigation on the reaction mechanisms unveils that specific facets preferentially facilitate the formation of CO, while others are more conducive to the generation of hydrocarbons such as CH4 and C2H4, due to the variations in activation barriers and intermediate stabilities. These findings underscore the importance of crystal facet engineering and defect manipulation in tailoring catalyst performance thus providing valuable insights for the rational design of efficient and selective CO2 reduction metal catalysts.

Novel benzothiophene‒tethered 1,3,4‒oxadiazoles as potent antimicrobial targets: Design, synthesis, biological evaluation, DFT exploration and in silico docking study

Based on previous developments of oxadiazole research programs in trying to find novel compounds with multiple biological targets, such as antibacterial and antitubercular medications. In the context, a new series of 1,3,4-oxadiazole derivatives based on benzo[b]thiophene moiety 6a‒d, 7a‒d, and 8a‒d was synthesized from 5-(3-methylbenzo[b]thiophen-2-yl)-1,3,4-oxadiazole-2-thiol. The structures of 1,3,4‒oxadiazole derivatives were elucidated via NMR (1H and 13C), IR, and HRMS spectrum data as well as physical data. Subsequently, the derivatives were evaluated for their inhibitory activity against different bacterial microorganisms, and the MICs were determined in vitro tubercular activity against the sensitive M. tuberculosis H37Rv strain. Remarkably, hybrids 6c and 7a exhibited excellent antibacterial activity against S. aureus with ZI values of 31 ± 0.99, and 30 ± 0.32 mm, and it has been noticed that 8b demonstrated the most prominent antibacterial efficiency with MICs = 3.1, 3.6, 5.6, and 5.1 μg/mL against S. pneumoniae, S. pyrogenes, E. coli, and K. pneumoniae. Among them, compound 8b, featuring a benzo[b]thiophene moiety linked to oxadiazole, exhibited a significant tubercular inhibitory effect with an MIC value of 2.2.5 μM. Additionally, the docked compound 7a showed the strongest key active key amino acids Arg44(A), Arg45(A), Ala126(A), Gly18(A), Ser49(A), Asp48(A) in the antitubercular active site of 1DG5 protein. The study of computer aided ADMET was also carried out, using SwissADME and ADMETlab2.0 to investigate the pharmacokinetic properties of the tested triazole compounds. To support the experimental data, molecular docking and density functional theory (DFT) studies help in understanding the interactions better.

Photodegradation Pathways of Aliphatic Polyamide through Conical Intersection between Ground and Excited States.

Time-dependent density functional theory studies were performed to investigate the photochemistry properties of the widely used aliphatic polyamide (APA), alias nylon, under ultraviolet radiation with N-ethylacetamide (NEA) being the model molecule. The characteristics of the transition molecular orbitals for the low-order excited states (ESs) of NEA were clarified, and the ES geometries related to the transition worthy of study were optimized. Our research proved that there is a conical intersection between the ground and excited states featured by the transition from the lone pair orbital to the σ antibonding orbital on the C-N bond within the peptide group or the N-C bond adjacent to the carbonyl group, and the C-N or N-C bond has the probability to be disrupted after internal conversion. These original quantum chemistry discoveries depict the C-N and N-C bond cleavage scheme that initiates the primary and secondary paths in the scission processes of the APA chain, respectively, which is helpful for giving new insight into the overall photodissociation mechanism of APA and designing advanced polyamide-based synthetic fibers.

New Charge Transfer Complex between Melamine and 4-Nitrobenzoic Acid: Synthesis, Spectroscopic Characterization, and DFT Studies

The charge transfer (CT) complex [MA(NBA)] was synthesized by combining melamine (MA) as the electron donor with 4-nitrobenzoic acid (NBA) as the acceptor in a stoichiometric ratio of 1:1. The complex was characterized using IR, NMR, and UV-vis spectroscopy, as well as elemental analysis. Computational analysis was carried out by density functional theory (DFT) studies using the B3LYP function with basis set 6-311G (d, p) in the gas phase and DMSO. DFT calculations were in good agreement with the experimental data, providing further evidence of the complex's structure and stability. The gap energy (∆Eg) value for the [MA(NBA)] complex is 4.019 eV. This outcome provides strong proof of the charge transfer process occurring from the donor part (mainly HOMO) to the acceptor part (mainly LUMO), leading to the formation of the CT complex. Thermodynamic and molecular quantum parameters were also calculated to understand the stability and reactivity of the charge transfer complex and to show the spontaneity of the complex formation.

Single crystal structure features, optimization of ultrasonic conditions, density functional theory studies, and antibacterial activity of a new organic compound

The synthesis of a novel water-soluble organic compound, N’-acetyl-4-nitrobenzohydrazide, was successfully achieved using hydrothermal and sonochemical methods. The resulting products, denoted as 1 and 2, were obtained as single crystals and powder, respectively. Characterization of the crystals through single-crystal X-ray diffraction (SC-XRD) indicated a monoclinic system with space group -P 2yn. Elemental analysis (CHN), energy-dispersive X-ray spectrometer (EDS), Fourier transform infrared spectroscopy (FT-IR), thermal analysis (TGA/DTA), and powder X-ray diffraction pattern (PXRD), were utilized to analyze the molecular structure of 1 and 2, confirming their identical nature. Furthermore, scanning electron microscopy (SEM) was employed to examine the surface morphology of compounds 1 and 2, revealing distinct morphological features and varying particle dimensions. The impact of time, temperature, and ultrasonic energy was examined to optimize the morphology and particle size of compound 2. A density functional theory (DFT) study was performed to find the role of intramolecular hydrogen bond (IHB) interactions on the capability of the different tautomers of newly synthesized organic compounds. Various properties such as total energies of tautomers, energies of the most important molecular orbitals, electronegativity, thermodynamic functions, molecular electrostatic potential (MEP) maps, electron charge densities, and aromaticity were computed. The antimicrobial activity of 1, and 2 have been evaluated against one Gram-positive (Staphylococcus aureus, ATCC 25923) and one Gram-negative (Escherichia coli, ATCC 25922) using the disc diffusion method. The analysis of the inhibition zones revealed that 2 exhibit enhanced antibacterial efficacy compared to 1. This observation suggests that particle size reduction may contribute to increased antibacterial activity, potentially due to enhanced interaction with bacterial targets.

Enhanced VOCs adsorption on Group VIII transition metal-doped MoS2: A DFT study

Volatile organic compounds (VOCs) represent a significant category of toxic and harmful air pollutants. Among the various abatement techniques available for VOCs, adsorption technology is widely recognized as a cost-effective solution. In this study, density functional theory (DFT) was employed to calculate and compare the adsorption capacities of six typical VOCs on pristine MoS2 and MoS2 modified with Group VIII (MVIII) transition metals atoms. It is found that MVIII-MoS2 monolayer demonstratesa significant enhancement in adsorption capabilities for VOCsrelative to pristine MoS2. Among these Group VIII transition metals atoms, Fe, Ru and Os atoms exhibited the most significant VOCs adsorption enhancement, with Fe atoms demonstrating a particularly pronounced effect. This suggests a synergistic interaction between the metal dopants and the substrate. Density of states (DOS) and charge density difference analyses provided further insights into the mechanisms underlying improved adsorption capability. Interestingly, the introduction of MVIII atoms results in the emergence of a novel state density within the surface state of MoS2, thereby facilitating enhanced electron transfer between VOCs and the substrate. Charge density difference calculations further corroborated these findings, with certain configurations exhibiting significant electron cloud overlap. Such modification leads to more active electron transfer, thereby increasing the substrate’s affinity for VOC molecules and consequently improving the adsorption efficiency. The findings not only enhance the comprehension of VOC adsorption mechanisms on MoS2 but also underscore the potential of metal-doped two-dimensional materials for environmental applications.

Acidity and stability of Nb(V) active sites doped in SBA-15 and ZrSBA-15: A DFT study

Mesoporous silicas are of great interest in heterogeneous catalysis due to the structural characteristics of their pores and the adjustable catalytic properties that arise from incorporating heteroatoms. The substitution of Zr and Nb into SBA-15 introduces active sites into the material, rendering it a potential catalyst for acid catalysis reactions. However, discussions regarding the acid properties and metal-support interactions in amorphous silicas functionalized with metals are limited in computational chemistry. This study aims to determine the acid strength and charge transfer effects between Zr(IV) and Nb(V) species in mesoporous silica by proposing a representative SBA-15 cluster of type 5–6. Density Functional Theory (DFT) simulations were conducted using the B3LYP/6-31G(d,p)/def2TZVP levels. The model successfully replicated trends from larger clusters, demonstrating that the more grafted onto the silica structure (i.e. have more Si-O-M bonds), the greater the acid strength of the active site. Additionally, it was found that ZrSBA-15 structures are more stable than NbSBA-15 and possess higher acid strength, a trend supported by experimental observations. The results also suggest that Nb(V) species are more effectively stabilized in ZrSBA-15 than SBA-15, likely due to the presence of Zr(IV) centers in ZrSBA-15. This research contribute to a better understanding of how the support affects the stabilization of active phases, paving the way for the rational design of silica-based heterogeneous catalysts.

Al‐Decorated C20 Fullerene as a Promising Noble Metal‐Free Catalyst for CO Oxidation: A DFT Study

AbstractTo remove the toxic carbon monoxide (CO) gas from the environment, recently, researchers have taken great interest in single‐atom catalysts (SACs). In this study, we investigated various reaction pathways and barrier energies for the CO oxidation process onto Al‐decorated C20 fullerene (Al@C20) employing density functional theory (DFT). The outcomes validate that Al decoration on C20 is energetically stable while the corresponding electronic properties show that the Al atom acts as the reactive site for catalytic activity. The bond distances and larger negative adsorption energies (−0.65 and −2.53 eV) evince that CO and O2 species adsorbed strongly to the Al atom. For the oxidation of CO, two popular mechanisms are examined: Eley Rideal (ER) and Langmuir Hinshelwood (LH). The assessment of energy barriers discloses that the CO oxidation reaction progresses via the LH mechanism. Additionally, the CO + O* → CO2 reaction proceeds very quickly onto the Al@C20 catalyst, with a very small energy barrier (0.13 eV), indicating the excellent catalytic reactivity of the studied catalyst. These results propose that the designed catalyst can be valuable in the progress of novel noble metal‐free catalysts for harmful CO elimination from the environment.