Density Functional Theory Study Research Articles

Investigation of titanium(IV)-oxo complexes stabilized with α-hydroxy carboxylate ligands: structural analysis and DFT studies.

This paper explores the findings on the structures and physicochemical properties of titanium-oxo complexes (TOCs) stabilized by 9-hydroxy-9-fluorenecarboxylate ligands. Two complexes, with the overall formulas [Ti4O(OiPr)10(O3C14H8)2] (1) and [Ti6O4(OiPr)2(O3C14H8)4(O2CEt)6] (2), have been synthesized. The structures of the isolated crystals (1 and 2) were determined using single-crystal X-ray diffraction. Molecular structure analysis of the crystals also employed vibrational spectroscopic techniques (IR and Raman), UV-Vis diffuse reflectance spectroscopy (UV-Vis-DRS), and powder X-ray diffraction (XRD). Density functional theory (DFT) was utilized to elucidate the electronic structures of these complexes. Furthermore, the theoretical charge distribution in 1 and 2 and their reactivity were calculated. The results of these investigations suggest that the reactivity of 2 is significantly greater than that of 1.

Understanding the Nonlinear Hammett Relationship in Osmylation of Olefins with OsO4-Amine Ligands: Importance of Singlet-Diradical Character.

Although the concerted [3 + 2] mechanism of osmium-catalyzed asymmetric dihydroxylation has been generally accepted, the unusual nonlinear Hammett relationship induced by amine-type ligands remains unexplained. To understand this, we carried out a density functional theory (DFT) study for the osmylation of substituted styrenes by the following: OsO4, OsO4-pyridine, OsO4-4-cyanopyridine, OsO4-4-pyrrolidinopyridine, and OsO4-quinuclidine. Calculations using the M06 functional successfully reproduce the experimentally observed nonlinear relationships. The transition states exhibit considerable singlet-diradical character, which causes the nonlinear Hammett relationship. Regardless of the presence or absence of an amine-type ligand, an electron donation from styrene to OsO4 is observed, indicating no mechanistic change. Calculations indicate that the electronic interaction between the amine-type ligand and styrene also influences the reaction rate.

Reactivity Switch in Glycal Dienes toward Different Nucleophiles: Mechanistic Insight and Applications toward the Synthesis of Naphthalene-Fused Pyran Derivatives.

The stereo- and regioselective formation of chiral molecules is an interesting and important topic in organic synthesis due to its wide applicability and intricacy during synthesis. Herein, we disclose a method for the selective functionalization of glycal dienes for synthesizing different glycosides and branched sugars stereo- and regioselectively. The methodology is broad regarding the substrate scope in which various nucleophiles and glycals were explored. Furthermore, we delve into converting the synthesized products into naphthalene-fused pyran derivatives, achieved through a 4 + 2 cycloaddition followed by aromatization. Additionally, we conducted density functional theory studies to gain insight into the formation of regioselective products when different nucleophiles were employed.

Coadsorption mechanisms of copper and sulfamethoxazole by functionalized cellulose: A kinetic and DFT study

In order to address the issue of compound pollution from heavy metals and antibiotics in aquatic environments, multibranched functionalized cellulose materials (DACS) with abundant adsorption affinity groups (such as amino, carboxyl and imine groups) were prepared by oxidation, etherification and grafting. The maximum adsorption capacities of DACS for copper (Cu) and sulfamethoxazole (SMZ) were 42.27 and 117.92 mg/g, respectively. In addition, its excellent pH buffering capacity, resistance to coexisting interfering substances and great regeneration performance of up to 91 % after 5 cycles. In the coadsorption experiment, the multibranched structure strengthened the bridge effect during the coadsorption process, and weakened the inhibition of SMZ adsorption caused by competition. Kinetic models and error functions analysis showed that PNO model and F&S model were the most consistent with the adsorption process, and the limiting step of adsorption was the external diffusion of Cu and SMZ around the surface of DACS. Moreover, the density functional theory (DFT) was used to quantitatively calculate the adsorption binding energy of multiple sites on DACS, and clarified the adsorption tendency of DACS as electron donors for Cu and as acceptor for SMZ. In addition, the binding energy of sequential adsorption was greater than that of single and binary adsorption, and the binding stability of SMZ was significantly increased in sequential adsorption for the increasing of binding energy. The electron exchange process in the adsorption showed that SMZ played a bridging role in the binary adsorption, while Cu was the main reaction part of the complex adsorption.

Acid Mediated In‐Situ Catalytic Cleavage/Making of C=N Bonds in Bis‐Hydrazone Uranyl Complexes: Exploration of Photophysical, Electrochemical, Dye Sorption Properties and DFT Studies

AbstractTwo new uranium complexes [UO2L2(H2O)] (where L2=diacetyl bis‐isonicotinoyl hydrazone) complex 1, and [UO2(L1)2] (where L1=diacetylmonoxime isonicotinoylhydrazone) complex 2, have been synthesized by precisely adjusting the pH values of the reaction system. Complex 1 was formed in an acidic ethanolic solution (pH=3) through an in‐situ acid catalytic reaction of diacetylmonoxime isonicotinoylhydrazone and UO2(NO3)2.6H2O, while complex 2 was acquired in a neutral medium (pH=7) through self‐assembly of two ligands and one uranium (VI) metal centre. Both complexes were thoroughly characterized by elemental analysis, UV‐Visible spectroscopy, IR spectroscopy, NMR, TGA, cyclic voltammetry, and powder X‐ray diffraction. The studies indicate that the bis‐hydrazone in complex 1 is a dianionic tetradentate N2O2 donor, whereas in complex 2 it is a monoanionic tridendate N2O donor. The formation of complex 1 was further confirmed by a single‐crystal X‐ray diffraction study, which revealed the role of a water molecule in forming a pentagonal bipyramidal geometry of [UO2L2(H2O)]. Photophysical studies revealed that complexes 1 and 2 exhibited low band gap values of 2.07 and 2.12 eV, respectively, indicating their semiconducting nature. From the CV measurements, the higher negative potentials of the complexes 1 & 2 {1, −0.6 V and 2, −0.5 V vs. ferrocenium/ferrocene (Fc+/Fc)} in DMSO are assigned to the presence of {UO2}2+/{UO2}+ couple signifying their redox active nature. Dye adsorption studies show that both the complexes were able to remove 90 % of Methylene blue (MB) and Rhodamine B (RhB) from the solutions with the concentration of 10−5 M. The structural insights and electronic properties of Ligand HL1 and complex 1 were further explored by density functional theory (DFT) calculations.

Computational drug repositioning for IL6 triggered JAK3 in rheumatoid arthritis using FDA database.

Rheumatoid Arthritis (RA) is a persistent autoimmune disease affecting approximately 0.5-1 percent of the world population. RA prevalence is higher in woman aged between 35 and 50years than in age matched men, though this difference is less evident among elderly patients. The profound immune specific effects of disrupted JAK 3 (Janus kinase 3) signaling highlight the possibility of therapeutic targeting of JAK3 as a highly specific mode of immune system suppression. To address the above problem which is unendurable to patients and in the hope to cater some respite to such suffering we have targeted JAK 3 protein and JAK/STAT signaling pathway with compounds downloaded from FDA database, and performed screening of all available compounds docked against JAK3 protein. The difference between the target protein and other proteins of the same family was studied using cross docking and the compounds having higher binding affinity to JAK3 protein also showed more selectivity towards the particular protein. Density functional theory and molecular dynamics simulation study was done to study the compounds at their atomic level to know more about their drug likeliness. At the end of the study and based on our analysis we have come up with three FDA approved drugs that can be proposed as a treatment option for Rheumatoid Arthritis.

Density Functional Theory Study of the Crystal Structure and Infrared Spectrum of a Synthetized Ettringite Mineral

One of the most important hydration phases of Portland cement is ettringite, a calcium sulfo-aluminate mineral (Ca6Al2(OH)12(SO4)3·26H2O) showing a great capacity of adsorbing radionuclides and other contaminant cationic and anionic species, or incorporating them into its crystal structure. In this work, the X-ray diffraction pattern and infrared spectra of a synthetized ettringite sample are recorded and simulated, employing theoretical methods based on Density Functional Theory. Despite the complexity of this phase, the calculated structure, X-ray diffraction pattern and infrared spectrum are in excellent agreement with their experimental counterparts. Since the calculated and experimental spectra are consistent, the main infrared bands are assigned using a normal coordinate analysis, some of them being completely reassigned with respect to other experimental works. The good agreement found provides strong support for the computational methods employed towards their use for studying the surface adsorption properties and the incorporation of contaminations in its structure. The density of reactive groups at the surfaces of ettringite is reported, and the surface adsorption of water molecules is studied. These surfaces appear to be highly hydrophilic, in agreement with the experimental finding that the ettringite structure may include more water molecules, at least up to 27, one more than in its standard formula.

Silica-supported Bi2O3[sbnd]Cr2O3 nanocomposite: Efficient catalyst for Pyrano[3,2-c]chromenes synthesis and DFT studies

Synthesis of a new nanocomposite catalyst, consisting of Bi and Cr loaded on silica (Bi2O3Cr2O3@SiO2), is achieved using the incipient wetness impregnation approach. This catalyst is used to synthesize Dihydropyrano[3,2-c]chromene scaffold via one-pot reaction method involves the mixture of 4-Hydroxycoumarin, Malononitrile or Ethyl cyanoacetate and different aromatic aldehydes in methanol at room temperature. The catalyst was characterized using several methods such as XRD, FT-IR, FE-SEM, and EDS. The efficacy of this heterogeneous catalyst Bi2O3Cr2O3@SiO2 was evaluated by loading different wt% of bismuth and chromium on silica. The wt% of Bi2O3Cr2O3 (2.5–1) on SiO2 was proven to be extremely suitable catalytic activity to get high yield of products (up to 98 %) in short span of time (up to 15 min) with high selectivity as outlined in the proposed mechanism. Additionally, density functional theory (DFT) studies of the Dihydropyrano[3,2-c]chromenes were conducted to elucidate their electronic properties and reactivity. It provided insights into the frontier molecular orbitals, electrostatic potential maps of these synthesized compounds, offering valuable information for future rational design of related Chromene-based molecules. The catalyst was successfully recovered and reused for up to five reaction cycles without any significant decline in its catalytic efficiency. Future work will focus on expanding the use of this catalyst for synthesizing library of bioactive compounds.

A DFT study of eugenol adsorption onto pure and Si-doped Al12N12 and B12N12 fullerene-like nanocages

Density functional theory (DFT) methods have been employed in this work to study the adsorption behavior of eugenol (Eug) on the external surface of pure and Si-doped Al12N12 and B12N12 fullerene-like nanocages. All calculations were performed using the M062X-D3 functional combined with the 6-311 + G(d,p) basic sets. In order to probe the reliability of the DFT method, three other functionals (B3LYP-D3, CB3LYP-D3 and WB97XD) were employed and no significant difference was observed in the adsorption energy values of the most stable configurations (AEII and BEII). Also, the complexes are found to be stable in standard conditions in gas and aqueous phases, and the adsorption process is found to be exothermic and spontaneous. Interestingly, Si-doped nanomaterials (Si-AEII and Si-BEII) form the most stable adsorbent-adsorate molecular states (Eads = −90.07 and −61.42 kcal/mol respectively) in gas phase. Furthermore, Si-AEII and Si-BEII complexes exhibit the highest reactivity, characterized by the lowest values of the HOMO-LUMO energy gap (5.50 and 7.07 eV respectively). MEP map of the studied systems showed electron rich and electron deficient sites. Natural bond orbital analyses revealed that the interaction of Al12N12 with Eug is mainly due to the strong electron delocalization LP(2)O10 → LP*(2)Al47 (E(2) = 34 kcal/mol), whereas in Eug-B12N12 complex, it is mainly due to the electron delocalization LP(2)O10 → P*(4)B36 (E(2) = 96.53 kcal/mol). The QTAIM analysis revealed that Si–O and Al–C/B–C bonds linking eugenol to doped cages are attractive weak interactions and their nature have been confirmed via RDG/NCI analyses. Indeed, the present study revealed the suitability of Si-doped Al12N12 and B12N12 fullerene-like nanocages for the efficient drug delivery of eugenol.

Uniform Molecular Adsorption Energy‐Driven Homogeneous Crystallization and Dual‐Interface Modification for High Efficiency and Thermal Stability in Inverted Perovskite Solar Cells

AbstractInterfacial defects between perovskite and adjacent charge transport layers present a significant obstacle, hindering the enhancement of power conversion efficiency (PCE) and stability in perovskite solar cells (PSCs). To address this challenge, a dual‐interface modification is proposed to aim at improving the performance of mixed‐halide PSCs. Specifically, the hole‐collecting side is modified with 5‐Aminopyridine‐2‐carboxylic Acid (APC), while the electron‐collecting side is modified with 2‐thiopheneethylammonium chloride (TEACl). The multifunctional APC enhances charge transfer by tailoring the interface between the perovskite and poly(triarylamine) (PTAA) through multiple bonding interactions, thereby suppressing interfacial nonradiative recombination. Density functional theory studies reveal that APC on the perovskite surface induces uniform adsorption energy, promoting homogenous crystallization without residual stress. Additionally, APC interlayer eliminates the localized edge states induced by the iodine vacancies near the conduction band edge. Further improvement in the device performance is achieved by passivating the top perovskite surface with TEACl, leading to well‐matched energy bands and reduced vacancy trap states. As a result, champion cell achieves a PCE of 24.87% with an open‐circuit voltage of 1.188 V. Furthermore, The dual‐interface modification improves thermal stability due to enhanced ion‐migration activation energy.

Exciplex, Not Heavy-Atom Effect, Controls the Triplet Dynamics of a Series of Sulfur-Containing Thermally Activated Delayed Fluorescence Molecules.

The efficiency of thermally activated delayed fluorescence (TADF) in organic materials relies on rapid intersystem crossing rates and fast conversion of triplet (T) excitons into a singlet (S) state. Heavy atoms such as sulfur or selenium are now frequently incorporated into TADF molecular structures to enhance these properties by increased spin-orbit coupling [spin orbit coupling (SOC)] between the T and S states. Here a series of donor-acceptor (D-A) molecules based on 12H-benzo[4,5]thieno[2,3-a]carbazole and dicyanopyridine is compared with their nonsulfur control molecules designed to probe such SOC effects. We reveal that unexpected intermolecular interactions of the D-A molecules with carbazole-containing host materials instead serve as the dominant pathway for triplet decay kinetics in these materials. In-depth photophysical and computational studies combined with organic light emitting diode measurements demonstrate that the anticipated heavy-atom effect from sulfur is overshadowed by exciplex formation. Indeed, even the unsubstituted acceptor fragments exhibit pronounced TADF exciplex emission in appropriate carbazole hosts. The intermolecular charge transfer and TADF in these systems are further confirmed by detailed time-dependent density functional theory studies. This work demonstrates that anticipated heavy-atom effects in TADF emitters do not always control or even impact the photophysical and electroluminescence properties.

Anchoring Cs+ Ions on Carbon Vacancies for Selective CO2 Electroreduction to CO at High Current Densities in Membrane Electrode Assembly Electrolyzers

AbstractElectrolyte cations have been demonstrated to effectively enhance the rate and selectivity of the electrochemical CO2 reduction reaction (CO2RR), yet their implementation in electrolyte‐free membrane electrode assembly (MEA) electrolyzer presents significant challenges. Herein, an anchored cation strategy that immobilizes Cs+ on carbon vacancies was designed and innovatively implemented in MEA electrolyzer, enabling highly efficient CO2 electroreduction over commercial silver catalyst. Our approach achieves a CO partial current density of approximately 500 mA cm−2 in the MEA electrolyzer, three‐fold enhancement compared to pure Ag. In situ Raman and theoretical analyses, combined with machine learning potentials, reveal anchored Cs induces an electric field that significantly promotes the adsorption of *CO2− intermediates through performing muti‐point energy calculations on each structure. Furthermore, reduced adsorption of *OH intermediates effectively hampers competing hydrogen evolution reaction, as clarified by disk electrode experiments and density functional theory studies. Additionally, coupling our system with commercial polysilicon solar cells yields a notable solar‐to‐CO energy conversion efficiency of 8.3 %. This study opens a new avenue for developing effective cation‐promoting strategy in MEA reactors for efficient CO2RR.

Anchoring Cs+ Ions on Carbon Vacancies for Selective CO2 Electroreduction to CO at High Current Densities in Membrane Electrode Assembly Electrolyzers.

Electrolyte cations have been demonstrated to effectively enhance the rate and selectivity of the electrochemical CO2 reduction reaction (CO2RR), yet their implementation in electrolyte-free membrane electrode assembly (MEA) electrolyzer presents significant challenges. Herein, an anchored cation strategy that immobilizes Cs+ on carbon vacancies was designed and innovatively implemented in MEA electrolyzer, enabling highly efficient CO2 electroreduction over commercial silver catalyst. Our approach achieves a CO partial current density of approximately 500 mA cm-2 in the MEA electrolyzer, three-fold enhancement compared to pure Ag. In situ Raman and theoretical analyses, combined with machine learning potentials, reveal anchored Cs induces an electric field that significantly promotes the adsorption of *CO2 - intermediates through performing muti-point energy calculations on each structure. Furthermore, reduced adsorption of *OH intermediates effectively hampers competing hydrogen evolution reaction, as clarified by disk electrode experiments and density functional theory studies. Additionally, coupling our system with commercial polysilicon solar cells yields a notable solar-to-CO energy conversion efficiency of 8.3 %. This study opens a new avenue for developing effective cation-promoting strategy in MEA reactors for efficient CO2RR.

Organotin (IV) complexes: Synthesis, characterization, DFT, and molecular docking studies unveiling their potential biomedical uses

This study investigates organotin (IV) complexes derived from the recently synthesized quinazoline Schiff base ligand (L). The research involves synthesizing and characterizing these complexes, including elemental analysis, UV–visible, FT‐IR, mass spectra, and conductometric measurements. Advanced studies such as density functional theory (DFT) are employed to gain insights into the stable electronic configuration. Specifically, the study explores the proposed geometry, revealing a distorted octahedral structure for the complexes. The findings contribute as critical molecular characteristics of these newly synthesized complexes, paving the way for potential applications in diverse fields, including medicinal chemistry. Through an investigation into the antimicrobial properties, the efficacy of the synthesized compounds was assessed against a diverse range of bacterial and fungal strains. Remarkably, the complexes demonstrated significant antimicrobial activities, showing potential applications in combating various microbial infections. In an extended exploration of their medical utility, the compounds were examined for their antibiotic properties against Helicobacter pylori. The Schiff base and its metal complexes emerged as promising antibiotics with notable efficacy against H. pylori, suggesting their potential in addressing infections associated with this bacterium. Furthermore, the antitumor potential of the synthesized complexes was investigated, focusing on their impact on MCF‐7 (Breast carcinoma) cells. The organotin (IV) Schiff base complexes in this research showed remarkable efficacy, evidenced by their notably low IC50 values (9, 10, 11 μg/mL) in comparison with cisplatin. In addition to their potent antitumor effects, these complexes exhibited reduced cytotoxicity toward normal cells (VERO cells) compared with cisplatin. The investigation extends to molecular docking, where this approach aims to elucidate their interactions with specific protein structures, including (2JFZ, 1SC7, and 6W41). The primary objective is to clarify the potential properties of these compounds, focusing on their antibiotic efficacy, anti‐H. pylori activity, antitumor potential, and anti‐COVID‐19 properties.

Modification of metals and ligands in two-dimensional conjugated metal-organic frameworks for CO2 electroreduction: A combined density functional theory and machine learning study

Electrochemical carbon dioxide reduction reaction (CO2RR) is a promising technology to establish an artificial carbon cycle. Two-dimensional conjugated metal–organic frameworks (2D c-MOFs) with high electrical conductivity have great potential as catalysts. Herein, we designed a range of 2D c-MOFs with different transition metal atoms and organic ligands, TMNxO4-x-HDQ (TM = Cr∼Cu, Mo, Ru∼Ag, W∼Au; x = 0, 2, 4; HDQ = hexadipyrazinoquinoxaline), and systematically studied their catalytic performance using density functional theory (DFT). Calculation results indicated that all of TMNxO4-x-HDQ structures possess good thermodynamic and electrochemical stability. Notably, among the examined 37 MOFs, 6 catalysts outperformed the Cu(211) surface in terms of catalytic activity and product selectivity. Specifically, NiN4-HDQ emerged as an exceptional electrocatalyst for CO production in CO2RR, yielding a remarkable low limiting potential (UL) of −0.04 V. CuN4-HDQ, NiN2O2-HDQ, and PtN2O2-HDQ also exhibited high activity for HCOOH production, with UL values of −0.27, −0.29, and −0.27 V, respectively, while MnN4-HDQ, and NiO4-HDQ mainly produced CH4 with UL values of −0.58 and −0.24 V, respectively. Furthermore, these 6 catalysts efficiently suppressed the competitive hydrogen evolution reaction. Machine learning (ML) analysis revealed that the key intrinsic factors influencing CO2RR performance of these 2D c-MOFs include electron affinity (EA), electronegativity (χ), the first ionization energy (Ie), p-band center of the coordinated N/O atom (εp), the radius of metal atom (r), and d-band center (εd). Our findings may provide valuable insights for the exploration of highly active and selective CO2RR electrocatalysts.

Reasonable construction of low migration energy barrier and continuous proton transfer channels via bimetallic MOFs nanofibers (MIL-(Cr Al)–NH2) for its composite proton exchange membrane

Reasonable construction of low migration energy barrier and continuous proton transfer channel is the key to improving the performance of composite proton exchange membranes. In this paper, we prepared a novel bimetallic MOFs (MIL-(Cr Al)–NH2) nanofibers (MCANs) consisting of Cr and Al elements by electro-blown spinning method (EBS) and hydrothermal synthesis, and subsequently introduced them into non-fluorinated sulfonic acid polymer sulfonated polysulfone (SPSF) matrix to obtain composite proton exchange membranes (MCANs@SPSF). Importantly, MCANs successfully constructed relatively long-range continuous unsaturated metal site proton transfer channels provided by the Cr-based MOFs, thereby reducing the proton migration energy barrier in the MCANs@SPSF, which confirmed by the density functional theory (DFT) calculation. In detail, DFT studies indicated that the migration energy barrier between H+ and MCANs was 1.677 eV, while that of single Al-based MOF (MAN) and single Cr-based MOF (MCN) were 1.879 eV and 1.762 eV respectively. The existence of efficient low migration energy barrier and continuous proton transfer channels made the proton conduction efficiency of MCANs@SPSF greatly improved, that was under the condition of 80 °C and 100 % RH, the proton conductivity of MCANs@SPSF reached the maximum value of 0.358 S cm−1 and the power density reached 104 mW cm−2. Moreover, MCANs@SPSF-5 displayed best DMFC durability performance with only 14.65 % voltage loss under 24h test. In addition, due to the acid-base pair interaction between MCANs and SPSF enhanced the interface binding force between the two phases, meanwhile, the pore structure of MOFs also had a certain adsorption effect on methanol, thus reducing the methanol permeability, and the addition of 5 wt% MCANs in SPSF was tested to reduce the methanol permeability to 5.53 × 10-7 cm2 s−1. Overall, this work provided a new strategy for construction of low migration energy barrier and continuous proton transfer channels, which was beneficial for the development of high performance proton exchange membranes.

Mechanistic Insights on Direct Ammonia Solid Fuel Cell Using Ni-YSZ Anode: Experimental and Density Functional Theory Studies

While Ni-Yttria-stabilized zirconia (Ni-YSZ) cermet exhibits a great potential to realize high-efficiency ammonia to power using direct ammonia solid oxide fuel cell (DA-SOFC), the mechanisms of NH3 cracking and H2 oxidation reactions as well as direct electro-oxidation of ammonia are still unclear. In this context, with the motivation, the DA-SOFC performance of fuel electrode (Ni-YSZ) using conventional anode-supported cell (Ni-YSZ|YSZ|GDC-LSCF) is studied through microscale observation coupled with density functional theory (DFT) calculations to unravel the reaction mechanisms on Ni-YSZ(111) anode. The performance of DA-SOFC is examined using NH3, H2 and N2/H2 mixture as fuel at the temperature range of 700-800℃. In addition to XRD and SEM-EDX characterizations, the electrochemical characterization is performed using the impedance spectroscopy (EIS) measurements at three different temperatures of 700, 750 and 800 °C. Interestingly, the experimentally observed trend in Open-circuit voltage (OCV) implies that direct electro-oxidation of ammonia is the dominant reaction mechanism. Notably, polarization resistance is primarily contributed by ammonia anodic reaction and secondarily by the gas diffusion impedance. DFT results revealed that ammonia adsorbs favorably on the Ni cluster, and hydrogen follows a dissociative mode of adsorption on the Ni cluster. The activation barriers of elementary steps involved in the proposed mechanisms for fuel cracking and oxidation reactions are computed. This work is anticipated to provide valuable insights into the rational design of Ni-YSZ-based fuel electrodes. Keywords: ammonia, hydrogen, SOFC, fuel cells, DFT, reaction mechanism

(Invited) Density Functional Theory Study on Molecular Structures of Polyhydroxy Fullerenes

Polyhydroxy fullerenes (PHF), also known as fullerenols or fullerols, are water-soluble fullerenes that are being studied for several applications. PHF is usually synthesized by acid or alkali method and is assumed to have only hydroxyl groups. These approaches use uncontrolled oxidation method and it is possible to have unintended functionalization. In fact, few studies have proposed presence of hemi-ketal and carbonyl groups based on NMR, XPS and FTIR studies. However, a complete understanding of their molecular structures is still lacking. Theoretical quantum chemical calculations based on density functional theory (DFT) are commonly used to predict and corroborate vibrational spectrum of molecules. Interestingly, in silico studies thus far have considered fullerenes with only hydroxyl groups with a big mismatch in their calculated vibrational energies and experimental FTIR spectrum.In this study, we investigated the presence of carbonyl and hemi-ketal functional groups on hydroxylated fullerenes using DFT. We also evaluated the influence of counterions on oxygen-containing functional groups. All DFT calculations were carried out on Gaussian19 with hybrid B3LYP functional and 6-31G(d,p) basis set. By bridging the gap between theoretical calculations and experimental measurements, we offer an alternative interpretation for the characteristic peaks observed in the FTIR spectrum. Furthermore, our theoretical calculations suggest a dynamic nature inherent in these oxygen-containing functional groups residing on the carbon cage of the fullerene structure.

Exploring zero-valent iron nanoparticles (nZVI) for Bisphenol A removal: Experimental investigations and Monte-Carlo simulation insights

ABSTRACT Numerous personal care products contain Bisphenol-A (BPA), a hormone disruptor that ultimately finds its way into waterways. A combination of experimental investigations and Monte-Carlo simulations (MCS) were used to explore zerovalent iron nanoparticles (nZVI) for their removal. The nZVI exhibited an absorption peak (λmax) at 373 nm with a mesoporous structure (pore size 2.138 nm), 159.419 m2 g−1 surface area, and crystalline peaks. The adsorption processes were positively influenced by batch parameters. BPA adsorption on nZVI varied with temperature as predicted by Freundlich and Langmuir isotherms, achieving a maximum adsorption capacity (qmax) of 982.13 mgg−1 at 308 K and pH 2. The adsorption process at 303 and 308 K was physisorption, whereas, at 313 K, it was chemisorption suitably described by pseudo-second-order kinetics. The exothermic and spontaneous nature of the adsorption processes were demonstrated by the negative values of enthalpy (−ΔH°) and free energy (−ΔG°) that decreased with increasing temperatures (308–328 K). The density function theory and MCS studies showed that BPA's phenyl ring, isopropyl, and hydroxyl groups interacted electrostatically with nZVI, specifically crystal plane 121 with the most negative adsorption energy (ΔEads), enhancing BPA removal. Through optimized adsorption mechanisms, nZVI can effectively remove BPA from wastewater.

Modeling Interfacial Proton-Coupled Electron Transfer Reactions Involving Imidazolium Proton Donors

Proton-coupled electron transfer (PCET) is an elementary reaction that plays a pivotal role in various electrochemical energy conversion and storage processes. PCET reactions involving nonaqueous proton donors are of interest for applications in energy storage such as redox flow batteries, as well as in CO2 and O2 reduction catalysis. Yet, there remains much to be understood about the molecular reactivity of these systems. In this talk, I will describe periodic density functional theory (DFT) studies of interfacial PCET reactions involving different imidazolium proton donors on Pt(111) electrode surfaces.The imidazole conjugate bases adsorb strongly to the electrode surface; however, this adsorption behavior varies with isomers that feature distinct proton positions and with different functional substituent groups. Because the adsorption of imidazole conjugate bases could affect reactivity, these models are used as a foundation to understand the intrinsic PCET kinetics of these systems. The Volmer and Heyrovsky steps of hydrogen evolution reaction are two of the most basic heterogeneous electrochemical PCET reactions and are therefore chosen as model interfacial PCET reactions in this study. Potential-dependent reaction energies and activation barriers are calculated using the charge extrapolation method, where the electrode potential is tuned by modifying proton coverage for different-sized unit cells. This approach is used to develop relationships between PCET reaction thermodynamics and kinetics through Brønsted–Evans–Polanyi (BEP) relationships for different imidazoles, where BEP slopes are analogs to charge transfer coefficients in the Butler–Volmer equation. Investigating reaction parameters influencing charge transfer kinetics at the electrode-electrolyte interface is crucial for designing efficient energy storage systems, impacting overall device performance. These studies show trends in the kinetic behavior of different functionalized imidazoles, which can aid in the design of catalytic and energy storage systems.