Density Functional Theory Simulations Research Articles

Two-Dimensional Rare-Earth Metal Phosphides: From Weyl Semimetal to Semiconductor.

Two-dimensional (2D) nanomaterials have garnered extensive attention owing to their unique properties and versatile application. Here, a family of 2D rare-earth metal phosphides (M2P, M = Sc, Y, La) and their derivatives M2POT (T = F, OH) is developed to find their topological and electronic properties on the basis of density functional theory simulations. We show that the 2D M2P compounds are most possibly obtained from thermodynamically stable M2InP by chemical exfoliation. The In with a substantial atomic radius of 156 pm exhibits weak polarization ability, resulting in homogeneity of the electron cloud and a weakening of the M-In bond relative to the M-P bond. Upon exfoliation of the In layer, the M22+P3-:e- emerges as an electride with surface electrons, which is attributed to the larger ion radius and lower electronegativity of M2+ ions in M2P. The metallic M2P is found to be a Weyl semimetal derived from the contribution of surface electrons. Further, by leveraging the high reactivity of surface electrons, surface functionalization can produce M2POT compounds with the increased valence state of M3+, which results in their semiconducting properties characterized by high carrier mobilities and strong built-in electronic fields. These distinct topological and electronic characteristics position the 2D M2P and M2POT as promising candidates for a wide range of applications.

Molecular-level Modulation of N, S-Co-Doped Mesoporous Carbon Nanospheres for Selective Aqueous Catalytic Oxidation of Ethylbenzene.

Selective oxidation of aromatic alkanes into high value-added products through benzylic C-H bond activation is one of the main reactions in chemical industry. On account of the constantly increasing demand for mass production, efficient, eco-friendly and sustainable catalysts are urgently needed. Herein, we describe a facile and versatile emulsion-assisted interface self-assembly strategy towards molecular-level fabrication of co-doped mesoporous carbon nanospheres with controllable active N and S species. The method enables a high degree of control over nanoparticle sizes, mesoporous nanostructures, contents of heteroatoms and the chemical composition. The optimized catalyst exhibits high catalytic performance of 97 % ethylbenzene conversion and 98 % selectivity to acetophenone. Density functional theory simulations reveal that N, S-co-doping leads to the redistribution of charge and spin densities, introducing more active carbon atoms and realizing aerobic oxidation of ethylbenzene efficiently. This work presents a general strategy for molecular-level design of carbon-based catalysts, and also provides new insight into the influence of heteroatom-doping on catalytic properties.

Experimental and theoretical studies on antioxidant and antibacterial properties of chitosan-gelatin functional composite films loaded with flavonoids

Chitosan-gelatin-flavonoid functional composite films were prepared with chitosan, gelatin, and three flavonoids (Naringenin, Apigenin, and Luteolin). The effect of three flavonoids on physical, antioxidant, and antibacterial properties of functional composite film was investigated from experimental and Density functional theory (DFT) simulations. The tensile strength, thermal stability, water solubility, water vapor permeability, antioxidant activity, and antibacterial activity of chitosan-gelatin-flavonoid functional composite films were improved with flavonoid (Naringenin, Apigenin, and Luteolin) incorporation. The release behavior of Apigenin from functional composite film was much lower than that of Naringenin or Luteolin. ABTS+ radical scavenging ability values of functional composite films followed: Luteolin (69.53 %) > Naringenin (41.39 %) > Apigenin (36.13 %). The antibacterial activities of functional composite films against Staphylococcus aureus followed: Luteolin (52.03 mm) > Apigenin (49.34 mm) > Naringenin (43.15 mm). The total number, location of hydroxyl groups on ring-B, and the unsaturation degree on pyrone ring of flavonoids influenced antioxidant and antibacterial activities of functional composite films. The minimum bond dissociation enthalpy values of flavonoids followed: Luteolin < Apigenin < Naringenin. The interaction energy of Apigenin-chitobiose was stronger than that of Naringenin or Luteolin. These results will shed light on flavonoid selection for functional composite films of food packaging.

Multidimensional octahedron (de) intercalation cathode for aqueous zinc-ion battery

CuS is a suitable material for use in lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). Nevertheless, the Zn2+ reaction between CuS is challenging due to the high radius and the considerable electrostatic force between the Zn2+ and CuS cathode. In this work, CuS nanosheets were in situ grown on a template surface via the hydrothermal method. The composition, surface morphology, and microstructure were then studied in detail. The zinc storage properties and mechanism were investigated through electrochemical testing, density functional theory and molecular dynamics simulation. The findings demonstrate that CuS nanosheets are formed in situ along the octahedral surface, resulting in the development of multistage structures. The distinctive configuration is capable of efficaciously preventing nanosheet aggregation, augmenting the specific surface area and active site of electrochemical reactions. Furthermore, the formation of a hollow structure through ion exchange reduces the intercalation energy barrier of Zn2+, facilitates rapid ion diffusion, enhances the charge transfer rate, and markedly improves battery performance.

Dual influence of protonation on Li-ion transport in garnet solid electrolytes: A first-principles study

Garnet-type cubic Al-doped Li7La3Zr2O12 (LLZO) is a promising solid electrolyte for all-solid-state Li-ion batteries because of its excellent ionic conductivity and stability against Li metal. However, its sensitivity against moisture poses a significant challenge, as LLZO undergoes protonation upon exposure to water, which has been experimentally observed to reduce Li-ion conductivity. Despite this, the exact impact of protonation-induced structural changes and the role of protons in Li-ion transport within LLZO remain unclear. A thorough understanding of these mechanisms is crucial for enhancing the performance of LLZO as a solid electrolyte. In this study, we employed density functional theory (DFT) and DFT-based molecular dynamics (DFT-MD) simulations to investigate the effect of protonation on the structure, Li-ion transport, and proton dynamics in LLZO. Our results demonstrate that protonation induces a phase transition from the centrosymmetric Ia3‾d to a distorted non-centrosymmetric I4‾3d symmetry, concomitantly reducing the Li-ion conductivity, consistent with experimental observations. Furthermore, we identify two competing effects of protonation on Li-ion transport: protons tend to occupy octahedral sites, which trap Li-ions in more stable tetrahedral sites, thereby impeding their mobility. Conversely, proton insertion enlarges the bottlenecks along Li-ion diffusion pathways from a range of 1.78–1.90 Å to 1.80–1.92 Å, potentially lowering the diffusion barrier for Li transport. Therefore, protonation introduces both inhibitory and facilitating factors for Li-ion transport. Additionally, the reduction in Li-ion concentration due to protonation further diminishes the overall ionic conductivity of LLZO.

Strategic Design for High-Efficiency Oxygen Evolution Reaction (OER) Catalysts by Triggering Lattice Oxygen Oxidation in Cobalt Spinel Oxides.

High-efficiency catalysts with refined electronic structures are highly desirable for promoting the kinetics of the oxygen evolution reaction (OER) and enhancing catalyst durability. This study comprehensively explores strategies involving metal doping and oxygen vacancies for enhancing the acidic OER catalytic activity of Co3O4. Through extensive screening of 3d and 4d transition metals using density functional theory (DFT) simulations, we demonstrate that the incorporation of metal dopants and oxygen vacancies into Co3O4 potentially triggers a transition from the adsorbate evolution mechanism (AEM) to the lattice oxygen oxidation mechanism (LOM) in the oxygen evolution reaction (OER). While the formation of the O-O bond in the intermediate *OOH poses challenges, a significantly reduced overpotential facilitates efficient conversion of O to O2 through the LOM in *OH and lattice oxygen. Additionally, we find that Mn doping can significantly improve the stability of the catalyst. Building upon the rationale above, we employed a dual doping strategy in subsequent experiments to enhance both the activity and stability. Our final design involved the codoping of Mn and Ru in Co3O4, along with an appropriate amount of oxygen vacancies. This catalyst demonstrates a low overpotential (η10 = 230 mV) compared to pure Co3O4 and maintains stable operation for over 120 h, representing a 12-fold increase. By exploring and harnessing the LOM, more efficient, stable, and cost-effective OER catalysts can be designed, providing crucial support for technologies such as water electrolysis in clean energy.

Unraveling the mechanistic effects of oxidation and ionization on polydopamine-Pb(Ⅱ) interaction: MD and DFT study

Polydopamine (PDA), recognized for its straightforward synthesis and multifunctional groups, serves as an effective adsorbent for lead ions (Pb(II)). The structures of PDA are affected by different oxidation and ionization degrees, consequently influencing the adsorption performance for Pb(Ⅱ). Despite its extensive use, the detailed microscopic mechanisms by which these modifications affect Pb(II) adsorption remain poorly understood. In this study, all-atom molecular dynamics (AAMD) and density functional theory (DFT) simulations were employed to elucidate the interactions between PDA and Pb(II) under varying conditions of PDA’s ionization and oxidation. Enhancing PDA's ionization and oxidation degrees can effectively boost Pb(II)'s adsorption capacity. Specifically, heightened ionization significantly amplifies adsorption, as evidenced by the transfer of PDA monomer to the 6p vacant orbital of Pb(II), fostering strong coordination bonds through increased electron density. Meanwhile, escalated oxidation levels of PDA facilitate enhanced aggregation among polydopamine monomers, forming a more porous structure. Furthermore, oxidation activates inner orbital electrons within the polydopamine monomer, elevating electron transfer efficiency between PDA and Pb(II). These insights clarify the role of ionization and oxidation in optimizing PDA's performance as a Pb(II) adsorbent and provide valuable guidance for the design of advanced materials for heavy metal removal.

Electrochemical study and modeling of an innovative pyrazole carboxamide derivative as an inhibitor for carbon steel corrosion in acidic environment.

The impact of N,1-dibenzyl-5-methyl-1H-pyrazol-3-carboxamide (BPC) on the carbon steel (CS) corrosion in hydrochloric acid (1M) was studied in this work, considering concentration and temperature effects. Electrochemical investigation indicated that BPC functions as a mixed-type inhibitor. For an optimal BPC concentration of 125ppm, the inhibition efficiency of 91.55% was obtained at 298K. According to adsorption isotherm of Langmuir, the BPC adheres to the CS with standard adsorption free energy (ΔG°ads) of - 26.76kJmol-1. Furthermore, the calculation of dissolution activation parameters revealed an increase in energy (Ea) from 46.48 to 94.97kJmol-1, an elevation in the enthalpy (∆Ha) from 43.89 to 92.37kJmol-1, and a rise in the entropy (∆Sa) from - 91.17 to 51.43Jmol-1K-1 in the presence of 125ppm of BPC. The experimental results were confirmed by quantum chemistry calculations based on density functional theory (DFT) and molecular simulations using the Monte Carlo method. These theoretical approaches also allowed for a comparison of the inhibitory performances of BPC with its protonated form, BPCH, the latter being found more effective. Moreover, the study of the radial distribution function g(r) predicted that the nature of the bond formed with the steel surface is of a chemical type.

Enhancing the bonding reliability of titanium alloy / CFRTP hybrid joint by directionally inducing high-density covalent bond and secondary interaction via functional diblock copolymer

The hybrid joint of titanium alloy (Ti–6Al–4V)/carbon fibers reinforced thermoplastic (CFRTP) has gained high interest from the industry due to lightweight. However, the bonding reliability of fabricated joints is relatively low due to the confined mechanical interlocking and weak interfacial chemical interactions, which limits its application for engineering. Herein, the novel functional poly glycidyl methacrylate-b-poly methacryloxy propyl trimethoxyl silane (PGMA-b-PMPTS) diblock copolymers were synthesized and introduced at the contact interface of Ti–6Al–4V/carbon fibers reinforced polyether-ether-ketone joints for enhancing the bonding reliability by directional induction of chemical interactions. Fourier-transform infrared spectroscopy (FT-IR) analysis and density functional theory (DFT) simulation calculation proved that both the Si–O–Ti covalent bonds and secondary interactions were successfully induced directionally at the bonding interface. The tensile-shear strength and bending strength were thus significantly improved by 341 % to 40.17 MPa and 152 % to 238.53 MPa compared with that of 9.09 MPa and 94.53 MPa in pretreated case. The bonding reliability improved gradually with the increase of molecular weight and molecular weight ratios between functional groups of PGMA-b-PMPTS diblock copolymers. The adhesion ratio of resin-carbon fibers mixture on failure surface increased to 89.6 % after the modification with synthesized PGMA-b-PMPTS diblock copolymers, which further verified the feasibility of promoting bonding strength of Ti–6Al–4V/CFRTP by inducing the high-density interfacial interactions directionally. Current work exhibits a simple yet attractive interfacial modification strategy to achieve high-reliability hybrid joints between metal and thermoplastics.

Do the Hydrogen Evolution Reaction and Oxygen Reduction Reaction Really Need To Be Suppressed in O2-Tolerant CO2 Electroreduction Catalyzed by DAE-BPy-CoPor and Co-TAPP?

This letter chooses DAE-BPy-CoPor [DAE, 1,2-bis(5'-formyl-2'-methylthien-3'-yl)cyclopentene; BPy, 2,2'-bipyridine-5,5'-dicarbaldehyde; and CoPor, two-dimensional cobalt porphyrin-based covalent organic framework] and Co-TAPP [10,15,20-tetrakis(4-aminophenyl)porphinatocobalt] as two model catalysts to investigate the effect of the hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) in the O2-tolerant CO2 electroreduction reaction (CO2RR). Both catalysts have been proven to have CO2RR activity at a potential range from -0.60 to -1.10 V when CO2 and O2 are co-feeding (Zhu, H.-J.; Si, D.-H.; Guo, H.; Chen, Z.; Cao, R.; Huang, Y.-B. Oxygen-tolerant CO2 electroreduction over covalent organic frameworks via photoswitching control oxygen passivation strategy. Nat. Commun. 2024, 15, 1479, DOI: 10.1038/s41467-024-45959-9). The calculated results by grand canonical density functional theory (GC-DFT) and microkinetic (MK) simulation show that the effect of HER could be categorized into two groups: (1) Positive *H formation energy: HER would have no effect on the turnover frequency (TOF) of the CO2RR. (2) Negative *H formation energy: HER would also have no effect to the TOF of CO2RR when the calculated limiting potential for HER is larger than that for CO2RR. Otherwise, all active sites would be covered by *H and poisoned before CO2RR can happen. The effect of ORR could be categorized into three types: (1) ORR would have no effect to the TOF of the CO2RR when ORR happened with the CO2RR at the same time. (2) ORR is suppressed; the active site is covered by an intermediate state (such as *OH); and the CO2RR is also suppressed because of the poisoned active site. (3) ORR is suppressed; the active site is not covered; and the TOF of the CO2RR is not affected.

Enhanced Energy Storage Properties of PP/PA11 Dielectric Composite Films With PP‐g‐MAH as Compatibilizer

ABSTRACTAs an energy storage capacitor film material, polypropylene (PP) suffers from its low dielectric constant and limited energy density. To overcome the defects of pure PP, the PP‐based all‐organic composite films with multiple interfaces have been constructed to enhance the dielectric and energy storage properties. In this research, PA11 was used to blend with PP with polypropylene grafted maleic anhydride (PP‐g‐MAH) as compatibilizer. The prepared PP/PP‐g‐MAH/PA11 composites formed the typical “sea‐island” structure and double interfaces between PP/PP‐g‐MAH and PP‐g‐MAH/PA11. The higher molecular polarity of PP‐g‐MAH, PA11, and interfacial polarization significantly increases the dielectric constant of the composite films. Furthermore, the formation of interface traps suppressed the migration of charge carriers, resulting in lower leakage current and higher breakdown strength of the PP/PP‐g‐MAH/PA11 composite films. Density functional theory (DFT) simulation further proved the confinement of space charges. Energy storage results showed the optimal PP/PP‐g‐MAH/PA11‐2 film achieved high energy density (4.49 J/cm3) and excellent charge/discharge efficiency (97.4%), which behaved good application prospect in the field of thin film capacitors.

Copper(II)-Oxyl Formation in a Biomimetic Complex Activated by Hydrogen Peroxide: The Key Role of Trans-Bis(Hydroxo) Species.

Enzymes in nature, such as the copper-based lytic polysaccharide monooxygenases (LPMOs), have gained significant attention for their exceptional performance in C-H activation reactions. The use of H2O2 by LPMOs enzymes has also increased the interest in understanding the oxidation mechanism promoted by this oxidant. While some literature proposes Fenton-like chemistry involving the formation of Cu(II)-OH species and the hydroxyl radical, others contend that Cu(I) activation by H2O2 yields a Cu(II)-oxyl intermediate. In this study, we focused on a bioinspired Cu(I) complex to investigate the reaction mechanism of its oxidation by H2O2 using density functional theory and ab initio molecular dynamics simulations. The latter approach was found to be critical for finding the key Cu intermediates. Our results show that the highly flexible coordination environment of copper strongly influences the nature of the oxidized Cu(II) species. Furthermore, they suggest the favorable formation of trans-Cu(II)-(OH)2 moieties in low-coordinated Cu(II) species. This trans configuration hinders the formation of Cu(II)-oxyl species, facilitating intramolecular H-abstraction reactions in line with experimentally observed ligand oxidation processes.

Discovery of novel CDK2 inhibitors for cancer treatment: integrating ligand-based pharmacophore modelling, molecular docking, DFT, ADMET, and molecular dynamics simulation studies

BackgroundThe global landscape of public health faces significant challenges attributed to the prevalence of cancer and the emergence of treatment resistance. This study addresses these challenges by focusing on Cyclin-dependent Kinase 2 (CDK2) and employing a systematic computational approach for the discovery of novel cancer therapeutics.ResultsInitial ligand-based pharmacophore modelling, utilizing a training set of five reported CDK2 inhibitors, yielded a robust model characterized by Aro|Hyd| and |Acc|Don| features. Screening this validated model against the ZINC database identified 1881 hits, which were further subjected to molecular docking studies. The top 10 compounds (Z1–Z10) selected from the docking studies underwent Pharmacokinetic parameters Absorption, Distribution, Metabolism, Excretion and Toxicity profiling, Density Functional Theory (DFT) studies and the top two went for 100ns molecular dynamics (MD) simulations by comparing them with the standard Roscovitine. Compounds Z1 and Z2 emerged as the most promising, with docking scores of − 8.05 kcal/mol and − 8.02 kcal/mol, respectively. DFT analysis of the top 10 compounds revealed minimal variations in highest occupied molecular orbital–lowest unoccupied molecular orbital energy gaps, indicating consistent electronic stability and reactivity across the candidates. MD simulations of Z1 and Z2 confirmed their stable interactions with CDK2, with root mean square deviation (RMSD) values ranging from 1.4 to 2.5 Å for Z1 and 1.5 to 2.4 Å for Z2.ConclusionThe current research identified compounds Z1 and Z2, which demonstrated significant potential as potent CDK2 inhibitors for cancer therapy, providing valuable insights into the development of more effective CDK2 inhibitors and addressing the critical need for innovative therapeutic strategies in cancer treatment.Graphical abstract

Transition Metal Complexes of Turmeric Schiff Base: A New Avenue for the Development of Antioxidant, Anti‐Inflammatory, and Preliminary Anticancer Therapies via In Silico, In Vitro, and In Vivo Assessments

ABSTRACTIn the current study, Knoevenagel condensates mediated by ultrasound were created using cinnamaldehyde and physiologically active curcumin. These Knoevenagel condensates have been reacted with 4‐aminoantipyrene to create curcumin Schiff bases. The octahedral geometry of the synthesized transition metal complexes is verified by a range of analytical methods and spectroscopic techniques. It is interesting to note that viscosity tests against calf thymus‐DNA and UV–visible absorption titration are used to confirm the synthetic drugs intercalative binding effectiveness. VLS3D online program was utilized to examine the properties of SWISS ADME. The experimental validation of antioxidant and anti‐inflammatory activity demonstrates that theoretical expectations align with the experimental findings. The minimum inhibitory concentration values of the synthesized complexes show that they are more effective against microbes than ligand. Density functional theory simulations were performed at the B3LYP/6–31G(d) level to examine the complexes' thermodynamic stability and physiological accessibility. Every synthetic molecule has been docked against the bovine serum albumin 3v03 enzyme.

Investigation of the atomic layer etching mechanism for Al2O3 using hexafluoroacetylacetone and H2 plasma.

Atomic layer etching (ALE) is required to fabricate the complex 3D structures for future integrated circuit scaling. To enable ALE for a wide range of materials, it is important to discover new processes and subsequently understand the underlying mechanisms. This work focuses on an isotropic plasma ALE process based on hexafluoroacetylacetone (Hhfac) doses followed by H2 plasma exposure. The ALE process enables accurate control of Al2O3 film thickness with an etch rate of 0.16 ± 0.02 nm per cycle, and an ALE synergy of 98%. The ALE mechanism is investigated using Fourier transform infrared spectroscopy (FTIR) and density functional theory (DFT) simulations. Different diketone surface bonding configurations are identified on the Al2O3 surface, suggesting that there is competition between etching and surface inhibition reactions. During the Hhfac dosing, the surface is etched before becoming saturated with monodentate and other hfac species, which forms an etch inhibition layer. H2 plasma is subsequently employed to remove the hfac species, cleaning the surface for the next half-cycle. On planar samples no residue of the Hhfac etchant is observed by FTIR after H2 plasma exposure. DFT analysis indicates that the chelate configuration of the diketone molecule is the most favorable surface species, which is expected to leave the surface as volatile etch product. However, formation of the other configurations is also energetically favorable, which explains the buildup on an etch inhibiting layer. The ALE process is thus hypothesized to work via an etch inhibition and surface cleaning mechanism. It is discussed that such a mechanism enables thickness control on the sub-nm scale, with minimal contamination and low damage.

Synthesis, characterization and anti-corrosion property of graphitic carbon nitride for carbon steel in acid medium

The present study involved the synthesis of a 2D material known as graphitic carbon nitride (g-C3N4) using solvothermal method and characterized using Fourier transform infrared (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). Gravimetric and electrochemical methods, including electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR), electrochemical frequency modulation (EFM), and potentiodynamic polarization (PDP), in combination with surface analysis techniques such as SEM, EDS, optical profilometry (OP), and atomic force microscopy (AFM) are used to confirm its anti-corrosive properties. The findings revealed that the effectiveness of g-C3N4 increased proportionally with higher concentrations, reaching its peak potency of 85.0 % at a concentration of 100 ppm. Remarkably, the effectiveness of inhibition increased as the temperature rose until it reached 40 °C, but then decreased as the temperature continued to increase up to 60 °C. Density function theory and molecular dynamic simulation were used to correlate the experimental data to explain the intrinsic properties of g-C3N4 and the adsorption mechanism. The primary mechanism of corrosion inhibition was found to be the adsorption of g-C3N4 onto the steel surface. This was confirmed through surface analysis using SEM, EDS, AFM, OP and computational study.

Synergistic role of Cl- and Br- ions in growth control and mechanistic insights of high aspect ratio silver nanowires for flexible transparent conductive films.

Silver nanowires (AgNWs) with high aspect ratios are pivotal for the production of flexible transparent conductive films (TCFs). The growth of AgNWs is significantly influenced by the strong affinity of halogen ions for silver ions. This affinity plays a crucial role in the controlled deposition of silver along the nanowire axis. By precisely controlling the concentrations of Cl- and Br- ions, we have successfully synthesized AgNWs with remarkable lengths of 96 μm and diameters of 40 nm, achieving an impressive aspect ratio of 2400. Utilizing density functional theory and molecular dynamics simulations, we investigate the impact of these ions on the growth of AgNWs. Our findings reveal that halogen ions strongly adsorb onto the Ag (100) plane in the radial direction, with Cl- ions promoting anisotropic growth and Br- ions effectively limiting the nanowire diameter, thus achieving high aspect ratio AgNWs. The resulting TCFs exhibit a high transmittance of 95.0% at 550 nm and a low sheet resistance of 14.7 Ω sq-1. Moreover, when integrated into a flexible transparent heater, these TCFs demonstrate a high heating rate of 12.1 °C s-1. The development of AgNWs is poised to significantly enhance the performance and versatility of flexible TCFs.

Evaluating novel piperazine derivatives as aluminum corrosion inhibitor: a computational study

Purpose The aim of this study is to evaluate the corrosion inhibitory properties of three piperazine derivatives – Ethyl 5-(piperazine-1-yl) benzofuran-2-carboxylate (EPBC), 5-[4–(1-tert-butoxyethenyl) piperazin-1-yl]-1-benzofuran-2-carboxamide (BBPC) and Tert-butyl-4–(2-(ethoxycarbonyl)benzofuran-5-yl)-piperazine-1-carboxylate (TBPC) – on Al surfaces in the presence of hydrochloric acid (HCl). The research uses density functional theory (DFT) and molecular dynamics simulations to explore the effectiveness of these derivatives as corrosion inhibitors and to understand their adsorption behavior at the molecular level. Design/methodology/approach This study uses a computational approach using DFT at various levels (B3LYP/6–31+G(d,p), B3LYP/6–311+G(d,p), WB97XD/DGDZVP) to calculate essential quantum chemical parameters such as energy gap (ΔE), ionization energy (I), absolute electronegativity (χ), electron affinity (E), dipole moment (µ), absolute softness (s), fraction of electron transferred (ΔN) and absolute hardness (η). The Fukui function and local softness indices are used to assess the sites for electrophilic and nucleophilic attacks on the inhibitors. Molecular dynamics simulations are performed to analyze the adsorption behavior of these derivatives on the Al (110) surface using the adsorption locator method. Theoretical methods like DFT provide quantum chemical parameters, explaining inhibitor reactivity, whereas molecular dynamics simulate adsorption behavior on Al (110), both supporting and correlating with experimental inhibition efficiency trends. Findings This study demonstrates that all three piperazine derivatives exhibit strong adsorption on the Al surface, with high adsorption energies, good solubility and low toxicity, making them effective corrosion inhibitors in acidic environments. Among the three, TBPC showed superior inhibitory performance, particularly in the presence of HCl, due to its optimal electronic properties and stable adsorption on the Al (1 1 0) surface. Originality/value This research contributes to the field by combining DFT calculations and molecular dynamic simulations to evaluate the corrosion inhibition potential of piperazine derivatives comprehensively. This work advances the understanding of the adsorption mechanisms of organic inhibitors on metal surfaces and offers a detailed quantum chemical and adsorption behavior analysis.

Preferential graphitic-nitrogen formation in pyridine-extended graphene nanoribbons

Graphene nanoribbons (GNRs), nanometer-wide strips of graphene, have garnered significant attention due to their tunable electronic and magnetic properties arising from quantum confinement. A promising approach to manipulate their electronic characteristics involves substituting carbon with heteroatoms, such as nitrogen, with different effects predicted depending on their position. In this study, we present the extension of the edges of 7-atom-wide armchair graphene nanoribbons (7-AGNRs) with pyridine rings, achieved on a Au(111) surface via on-surface synthesis. High-resolution structural characterization confirms the targeted structure, showcasing the predominant formation of carbon-nitrogen (C-N) bonds (over 90% of the units) during growth. This favored bond formation pathway is elucidated and confirmed through density functional theory (DFT) simulations. Furthermore, an analysis of the electronic properties reveals metallic behavior due to charge transfer to the Au(111) substrate accompanied by the presence of nitrogen-localized states. Our results underscore the successful formation of C-N bonds on the metal surface, providing insights for designing new GNRs that incorporate substitutional nitrogen atoms to precisely control their electronic properties.

High-performance ammonia sensor at room temperature based on 2D conductive MOF Cu3(HITP)2

Sensitive detection of ammonia in the environment is crucial due to its potential danger to human ecology and health. In gas detection technology, resistive sensors utilizing golden cross finger electrodes combined with gas-sensitive materials are commonly employed. In this study, we demonstrated a room-temperature sensor for ambient ammonia detection. The sensor is composed of two-dimensional layer-stacked metal-organic framework (MOF) Cu3(HITP)2 nanomaterials drop-coated onto gold-forked finger electrodes. Density-functional theory simulation (DFT) and sensor gas-sensitive performance testing were conducted for characterization. The sensor exhibited high sensitivity, selectivity, low detection limit, excellent reproducibility, and stability. This can be attributed to the abundant Cu active sites exposed in the hexagonal ring and layer-stacked framework structure of Cu3(HITP)2 nanomaterials. Ammonia adsorption leads to electron transfer into the Cu3(HITP)2 framework, resulting in decreased sensor resistance. Real-time monitoring of sensor resistance changes enabled quantitative analysis. Results showed a 91.4 % response of the Cu3(HITP)2 sensor to 100 ppm NH3, with response and recovery times of 26 s and 20 s, respectively. The sensor's limit of detection (LOD) was approximately 15 ppb. The sensor exhibited a relatively high response to NH3 at 25 °C, as demonstrated by dynamic gradient test curves. These findings suggest that constituting a room-temperature ammonia sensor by uniformly drop-coating Cu3(HITP)2 onto a gold-forked finger electrode is a feasible strategy.