Variation Of Free Energy Research Articles

Theoretical investigation of graphdiyne-supported single-cluster catalysts for electroreduction of nitric oxide

The electrochemical NO reduction reaction (NORR) to NH3 offers an efficient, environmentally friendly strategy for NO removal and NH3 production, but developing effective catalysts to facilitate the conversion of NO into NH3 remains a challenge. Single-cluster catalysts (SCCs) with multi-metallic sites show promise due to the synergistic interactions among the active atoms. Herein, utilizing density functional theory (DFT) and grand-canonical DFT (GC-DFT), we systematically investigated the potential of late transition metal (TM = Fe, Co, Ni, Cu, Ru, Rh, Pd, Pt) clusters on graphdiyne (TMx/GDY, x = 1–5) for NORR. Ni3/GDY, Pd3/GDY, and Pt3/GDY emerged as the most promising candidates, demonstrating stability, excellent NORR activity, and HER suppression. Their outstanding performance is attributed to the moderate adsorption of NO, with the dxz/dyz orbitals playing a key role in NO activation. GC-DFT results highlight nonlinear variation of intermediate grand free energies with the applied potential. Detailed electronic property analyses were conducted to reveal the charge effects induced by the applied chemical potential. This study provides valuable insights into SCC-catalyzed NO reduction and highlights the significance of potential effects in theoretical simulations of electrochemical systems.

Investigation on the structural, elastic, electronic, thermodynamic, and vibrational properties of the full heusler Sc2XAl (X =Cd and Zn): An ab initio study

The structural, mechanical, electronic, thermodynamic, and phonon characteristics of Sc2CdAl and Sc2ZnAl in L21 phase were the main focuses on this investigation. The density of states (DOS) and electronic band spectra signify the metallic behavior of the L21 phase of both materials. The impact of atomic arrangement with respect to the Wyckoff sites on the mechanical stability were additionally studied. The elastic constants of Sc2CdAl and Sc2ZnAl alloys indicated that these alloys convened Born mechanical stability criteria. Using the density functional perturbation theory's first-principle linear response method, complete phonon spectra have been acquired. Moreover, the quasi-harmonic approximation, specific heat capacity at constant volume, the internal free energy, entropy, and vibrational free energy variations of Sc2CdAl and Sc2ZnAl as full Heusler alloys have been utilized in examination the change over the temperature between 0 and 800 K. Both alloys might find application in real industrial applications.

Impingement of binary nanodroplets on rough surfaces: a molecular dynamics study

Roughness or texture endow the solid surface with the ability of some particular property of water repellency that has been employed in a variety of practical applications, including self-cleaning, icing-resistant, and so forth. However, the understanding of the dynamic evolution of impacting binary droplets on rough surfaces is not satisfactory, especially at the nanoscale. In this work, we investigate the impact process of the binary droplet system, a suspending droplet impacts a sessile one deposited on hydrophobic textured surfaces, via molecular dynamics (MD) simulations. Dynamic evolutions from MD simulations under various impact conditions are discussed, including coalescence, spreading, retraction and vibration, and bouncing. The free energy variation during the impacting process is calculated to reveal the mechanisms behind the impact dynamics. The effect of the surface texture on the spreading and retraction is investigated, and the corresponding maximum spreading diameter is also discussed. Finally, we investigate the effect of the surface texture on bouncing behavior, which is found to promote the droplet bouncing at low We range but suppress the bouncing behavior at high We range.

Comparison of electronic structures, thermodynamic, optical and mechanical properties of MgB2 and MgMB4(M=Al, Pb, W) based on first-principles

As an important superconducting material, MgB2 has a wide range of applications in electronics and communication fields. The optimization of its properties has been a hot research topic. In this paper, it uses first-principles calculations to delve into the impact of doping Type-I superconducting elements M (M = Al, Pb, W) on the properties of MgB2. The main focus is on exploring improvements in thermodynamic, optical and mechanical properties in conjunction with the analysis of electronic properties. For thermodynamic properties, MgPbB4 demonstrates significant variation in entropy and free energy as temperature increases, reaching 356.84 KJ/mol and −411.46 KJ/mol, respectively, at 2000 K. Regarding optical properties, the absorption band edge disappears and the range widens with the introduction of M elements. Specifically, MgWB4 exhibits the highest reflectivity R (0) and static dielectric constant ε1 (0) in the [001] direction, measured at 0.49 and 32.2, respectively. In terms of mechanical properties, the elastic modulus of MgAlB4 and MgWB4 enhances notably with B/G ratios less than 1.75, indicating their brittleness. MgWB4, in particular, stands out with the highest elastic modulus and the weakest elastic anisotropy AU (0.703), exhibiting a spatial distribution nearer to spherical. Conversely, MgPbB4 transforms the material into a ductile one, with reduced elastic modulus and the strongest anisotropy AU (4.963). This study can provide a more comprehensive perspective for the future design of MgB2-based materials.

First-Principles Computational Screening of Two-Dimensional Polar Materials for Photocatalytic Water Splitting.

The band gap constraint of the photocatalyst for overall water splitting limits the utilization of solar energy. A strategy to broaden the range of light absorption is employing a two-dimensional (2D) polar material as photocatalyst, benefiting from the deflection of the energy level due to their intrinsic internal electric field. Here, by using first-principles computational screening, we search for 2D polar semiconductors for photocatalytic water splitting from both ground- and excited-state perspectives. Applying a unique electronic structure model of polar materials, there are 13 photocatalyst candidates for the hydrogen evolution reaction (HER) and 8 candidates for the oxygen evolution reaction (OER) without barrier energies from the perspective of the ground-state free energy variation calculation. In particular, Cu2As4Cl2S3 and Cu2As4Br2S3 can catalyze HER and OER simultaneously, becoming promising photocatalysts for overall water splitting. Furthermore, by combining ground-state band structure calculations with excited-state charge distribution and transfer calculated by linear-response time-dependent density functional theory (LR-TDDFT) and time-dependent ab initio nonadiabatic molecular dynamics (NAMD), respectively, the rationality of the 2D polar material model has been manifested. The intrinsic built-in electric field promotes the separation of charge carriers while suppressing their recombination. Therefore, our computational work provides a high-throughput method to design high-performance photocatalysts for water splitting.

تحضير وتقييم بوليمرات رخيصة كمضادات للبكتريا ،الاكسدة ومثبطات تاكل لسبيكة من نوع N80 في تركيز 0.1N من حامض الفسفوريك

في هذا العمل ، تم تحضير بولي بوتادين (PBD) من نفايات الاطارات . وطعم البولي بوتادين المهلجن باستخدام أحادي وثنائي وثلاثي إيثانول امين ، ودرس التطعيم عن طريق حيود الأشعة السينية والمسح المجهري الإلكتروني. وتشير الخواص الحرارية (TGA, DSC) إلى أن المركبات المحضرة تمتلك ثابتًا حرارياً حتى 202 درجة مئوية. باستخدام تقنيات الاستقطاب الديناميكي الفعال ، تم قياس تأثيرات الامتزاز والتآكل للبوليمرات الثلاثة المطعمة على فولاذ N80 في.0.1N H3PO4 في اربع درجات حرارية مختلفة : 25 و 35 و 45 و 55 درجة مئوية. وقد اظهرت البوليمرات المحضرة كفاءة تثبيط ممتازة عند درجات الحرارة المختلفة. يعتبر pBut-g-mono ethanol amine هو الأكثر فعالية كمثبط للتآكل في جميع درجات الحرارة المختبرة. كما ان سلوك الامتزاز للبوليمرات الثلاث تخضع لمخطط لانجموير ، وقيم الطاقة الحرة المتحصلة توضح ان الامتزاز الذي يحدث على سطح N80هو من النوع المختلط كما تشير منحنيات تافل إلى أن البوليمرات المختبرة تعمل كمثبطات أنوديك وكاثودية مختلطة. من ناحية أخرى ،وجد أن جميع البوليمرات المحورة أظهرت خصائص متميزة كمضادة للأكسدة وللبكتيريا.

Molecular modeling of multi-target analogs of huperzine A and applications in Alzheimer's disease.

Given the diverse pathophysiological mechanisms underlying Alzheimer's disease, it is improbable that a single targeted drug will prove successful as a therapeutic strategy. Therefore, exploring various hypotheses in drug design is imperative. The sequestration of Fe(II) and Zn(II) cations stands out as a crucial mechanism based on the mitigation of reactive oxygen species. Moreover, inhibiting acetylcholinesterase represents a pivotal strategy to enhance acetylcholine levels in the synaptic cleft. This research aims to investigate the analogs of Huperzine A, documented in scientific literature, considering of these two hypotheses. Consequently, the speciation chemistry of these structures with Fe(II) and Zn(II) was scrutinized using quantum chemistry calculations, molecular docking simulations, and theoretical predictions of pharmacokinetics properties. From the pharmacokinetic properties, only two analogs, HupA-A1 and HupA-A2, exhibited a theoretical permeability across the blood-brain barrier; on the other hand, from a thermodynamic standpoint, the enantiomers of HupA-A2 showed negligible chelation values. The enantiomers with the most favorable interaction parameters were S'R'HupA-A1 (ΔGBIND = -40.0 kcal mol-1, fitness score = 35.5) and R'R'HupA-A1 (ΔGBIND = -35.5 kcal mol-1, fitness score = 22.61), being compared with HupA (ΔGBIND = -41.75 kcal mol-1, fitness score = 39.95). From this study, some prime candidates for promising drug were S'R'HupA-A1 and R'R'HupA-A1, primarily owing to their favorable thermodynamic chelating capability and potential anticholinesterase mechanism. Quantum chemistry calculations were carried out at B3LYP/6-31G(d) level, considering the IEF-PCM(UFF) implicit solvent model for water. The coordination compounds were assessed using the Gibbs free energy variation and hard and soft acid theory. Molecular docking calculations were conducted using the GOLD program, based on the crystal structure of the acetylcholinesterase protein (PDB code = 4EY5), where the ChemScore function was employed with the active site defined as the region within a 15-Å radius around the centroid coordinates (X = -9.557583, Y = -43.910473, Z = 31.466687). Pharmacokinetic properties were predicted using SwissADME, focusing on Lipinski's rule of five.

Guanidine Hydrochloride-Induced Hepatitis B Virus Capsid Disassembly Hysteresis.

Hepatitis B virus (HBV) displays remarkable self-assembly capabilities that interest the scientific community and biotechnological industries as HBV is leading to an annual mortality of up to 1 million people worldwide (especially in Africa and Southeast Asia). When the ionic strength is increased, hepatitis B virus-like particles (VLPs) can assemble from dimers of the first 149 residues of the HBV capsid protein core assembly domain (Cp149). Using solution small-angle X-ray scattering, we investigated the disassembly of the VLPs by titrating guanidine hydrochloride (GuHCl). Measurements were performed with and without 1 M NaCl, added either before or after titrating GuHCl. Fitting the scattering curves to a linear combination of atomic models of Cp149 dimer (the subunit) and T = 3 and T = 4 icosahedral capsids revealed the mass fraction of the dimer in each structure in all the titration points. Based on the mass fractions, the variation in the dimer-dimer association standard free energy was calculated as a function of added GuHCl, showing a linear relation between the interaction strength and GuHCl concentration. Using the data, we estimated the energy barriers for assembly and disassembly and the critical nucleus size for all of the assembly reactions. Extrapolating the standard free energy to [GuHCl] = 0 showed an evident hysteresis in the assembly process, manifested by differences in the dimer-dimer association standard free energy obtained for the disassembly reactions compared with the equivalent assembly reactions. Similar hysteresis was observed in the energy barriers for assembly and disassembly and the critical nucleus size. The results suggest that above 1.5 M, GuHCl disassembled the capsids by attaching to the protein and adding steric repulsion, thereby weakening the hydrophobic attraction.

Exploring Antiviral Drugs on Monolayer Black Phosphorene: Atomistic Theory and Explainable Machine Learning-Assisted Platform.

Favipiravir (FP) and ebselen (EB) belong to a diverse class of antiviral drugs known for their significant efficacy in treating various viral infections. Utilizing molecular dynamics (MD) simulations, machine learning, and van der Waals density functional theory, we accurately elucidate the binding properties of these antiviral drugs on a phosphorene single-layer. To further investigate these characteristics, this study employs four distinct machine learning models-Random Forest, Gradient Boosting, XGBoost, and CatBoost. The Hamiltonian of antiviral molecules within a monolayer of phosphorene is appropriately trained. The key aspect of utilizing machine learning (ML) in drug design revolves around training models that are efficient and precise in approximating density functional theory (DFT). Furthermore, the study employs SHAP (SHapley Additive exPlanations) to elucidate model predictions, providing insights into the contribution of each feature. To explore the interaction characteristics and thermodynamic properties of the hybrid drug, we employ molecular dynamics and DFT calculations in a vacuum interface. Our findings suggest that this functionalized 2D complex exhibits robust thermostability, indicating its potential as an effective and enabled entity. The observed variations in free energy at different surface charges and temperatures suggest the adsorption potential of FP and EB molecules from the surrounding environment.

Structural insights into variation of intramolecular acid site using phase transition experiments and computation

AbstractMass transfer from liquid to gas phase is a crucial process in chemical engineering. Due to the heterogeneity and dynamic nature of the phase transition process, monitoring the structural changes of compounds during this process is challenging. In this work, a combining of the mass spectrometry‐based method and quantum chemistry calculations was used to study the structural changes during liquid‐to‐gas phase transitions. Electrospray is used to induce the transition of phenolic acid molecules from the liquid phase to the gas phase. The deprotonated structures were captured and separated using ion mobility mass spectrometry. Deprotonated structures helped to identify the most acidic functional group within the molecule. These deprotonated structures were confirmed by collision‐induced dissociation and molecular collision cross‐section measurements. Quantum chemistry calculations revealed the mechanisms about the variation of intramolecular acid site and “kinetic trapping.” Three liquid‐to‐gas phase transformation models were proposed, demonstrating that the variation in free energy among different deprotonated structures governs the thermodynamic/kinetic process of the liquid‐to‐gas phase conversion.

The Polyperfluoromethylisopropyl Ether used as a surface tensiometry tool for non-invasive quality assessment of peloids (TVS mud index®): An overview

Background Surface tensiometry consented to characterize the surface free energy of geomaterials in an integrated and non-destructive way. A new surface tensiometry tool, based on the contact angle measurement of Polyperfluoromethylisopropyl Ether (TVS mud index), has thus developed in the early 2000s. The TVS mud index was for the first time employed from 2005 to 2010 for surface tensiometry characterization of peloids for pelotherapy from Abano Terme and Montegrotto Terme (Pa-dova, Italy). We aim to report the surface tensiometry application in the thermal field, and show the potentialities of TVS mud index as a marker for the non invasive quality control of the peloids and their maturation process. Methods The determination of the typical chemical-mineralogical characteristics of a Euganean Thermal Mud (ETM) and their surface tensiometry allowed us to demonstrate the link between the chemical data from X-ray fluorescence (XRF) analysis and they performed using a tensiometer to assess the quality of the peloid and its biological maturation process. Results The liquid test Polyperfluoromethylisopropyl Ether-based demonstrated the link between variations in volume elements and surface free energy of muddy matrices. The research results here showed that the TVS mud index is linked to the chemical pattern of peloids. Conclusions The research work implemented in the period 2005-2010 showed the potentialities of surface tensiometry in the assessment of peloids for pelotherapy using Polyperfluoromethylisopropyl Ether as a liquid test.

Designing grain refinement passes for multi-direction forging: A phase-field crystal study

Multi-directional forging is an effective plastic deformation method for polycrystalline grain refinement, and the degree of refinement is closely related to the number of forging passes. However, the relationship between the degree of refinement and the number of forging passes is almost ambiguous. Focusing on the forging passes, the grain refinement and dislocation nucleation mechanisms were revealed by combining the free energy variation and the strain field distribution using the dual-mode phase-field crystal model in our work. The results show that the nucleated dislocations within the grain can divide the grain into many finer grains under continuous stress. The nucleation mechanism of dislocation mainly includes two forms: grain boundary emission dislocation and atomic misalignment near the twin boundary. The strain field distribution reveals the mechanism of dislocation annihilation. The grain refinement effect of triple pass stress loading is the best, being 59 %, 18 %, and 43 % higher than that of the one forging pass, two forging passes, and four forging passes stress loading respectively. Moreover, the cause of the above phenomenon was further revealed by atomic analysis. This study reveals the response rule of forging passes to fine grain strengthening and gives feedback to guide the actual production experiment.

Formation process, microstructure, and mechanical properties of an ultrafine dual-phase alloy formed through phase transition of 18R-type long-period stacking ordered in Mg85Zn6Y9 under high pressure

The 18R-type long-period stacking ordered (LPSO) structure in Mg85Zn6Y9 exhibits phase transition into D03 and α-Mg (D03/α-Mg) before it transforms into a liquid phase with the increase in temperature at 7.8 GPa. First-principles calculations suggest that the energy barrier between 18R-type LPSO and D03/α-Mg decreases with pressure. A further increase in the temperature decreases the energy difference between LPSO and D03/α-Mg. Therefore, the free energy variations due to the effects of both pressure and temperature cause phase transition. The D03/α-Mg phases formed at high pressure can be recovered at 0.1 MPa and room temperature. The phase transition from 18R-type LPSO structure to D03/α-Mg causes inner-grain diffusion and generates a lamellar structure. The thickness of the lamellar structure decreases with the increasing pressure until it reaches 65 nm at 15 GPa. Moreover, the alloy solidified above 5 GPa also comprises D03/α-Mg phases. The alloy solidified at 5 GPa exhibits a typical eutectic lamellar structure. However, spherulite-like polycrystalline microstructures containing ultrafine grains are obtained when the alloys are solidified at 10 and 15 GPa. The microstructure variations are caused by an increase in the degree of supercooling due to atomic diffusion suppression with the increasing pressure. The alloys containing D03/α-Mg exhibit both low modulus and ultrahigh strength. The Young’s modulus is related to the presence of the D03 and α-Mg phases in the alloy structure. In contrast, the increase in σy can be attributed to the grain refinement strengthening.

Catalytic effect of high thermal conductive SiC on the kinetics and thermodynamics of vulcanization reaction of SBR/BR-filled nano-SiC

Nano-silicon carbide (SiC) as a high thermal conductive material with an intrinsic thermal conductivity of ~ 490 W/m K was used to improve the cure characteristics, kinetics, and thermodynamics of curing reaction of styrene-butadiene rubber/butadiene rubber (SBR/BR) compounds. The considerations were carried out by non-isothermal differential scanning calorimetry (DSC). Results revealed that the presence of SiC shifted the peak and end temperatures of the curing peak to lower temperatures. The calculated activation energy of the curing reaction based on the Kissinger approach showed a descent from 409.8 to 93.8 kJ/mol by adding SiC from 0 to 7.5 phr (part per hundred rubber). Moreover, the obtained Gibbs free energy variation and equilibrium constant of the curing reaction proved that the reaction was absolutely forced and irreversible, which can be increasingly characterized as a one-way process. According to the results, SiC accelerated the curing reaction because of the increment of heat transfer into the compound. This phenomenon caused the increment of enthalpy variation of the vulcanization reaction, particularly at the SiC content of 5 phr. The achieved kinetic parameters via fitting an autocatalytic model based on the Sestàk–Berggren model by the Màlek method to describe the kinetics of the curing reaction indicated that the SiC filler had a catalytic effect on the curing reaction of SBR/BR-SiC, particularly after 2.5 phr of the filler.

Theoretical investigation on the bifunctional hydrogen/oxygen electrode catalysis in Cd–N–C-doped graphene systems regulated by the active center configuration

Clean energy devices such as fuel cells and metal-air batteries can effectively solve the problems of environmental pollution and energy shortage. The common electrochemical reactions on hydrogen electrode (oxidation as HOR and evolution as HER) and oxygen electrode (reduction as ORR and evolution as OER) are important reaction in the conversion process of chemical energy and electric energy. However, the electrochemical conversion of these reactions is relatively low, with high overpotential (ƞ) even on Pt and Ru based catalysts, respectively, in addition to the high cost, which hinder the successful commercialization. Therefore, it is of great important to develop novel catalysts with acceptable ƞ at the same time cost effective. Here, the novel Cd–N–C-doped graphene catalyst systems with active center configuration (ACC) formed by low-boiling point non-precious metals Cd with a carbon and nitrogen coexist coordination environment are reported through a detailed study of density functional theory (DFT). The stability of catalyst was proved by energy calculations and dynamic simulations. Based on Gibbs free energy change (ΔG), ƞ and mechanisms of catalytic reactions were studied. Cd–N1C3-gra is a high efficiency HER and HOR catalyst with ƞ as low as 0.01 V. Cd–N2C2-o-gra is an efficient ORR and OER bifunctional catalyst with ƞOER = 0.48 V and ƞORR = 0.64 V. Based on the comparison of the free energy variation of principal and secondary reactions, their negligible yield of hydrogen peroxide was confirmed. Our research has further promoted the development of low-boiling point non-precious metals in electrocatalysis.

Preparation of new alginate capsules enclosing diatomite and organic extractants to uptake lanthanum

The present study conducted syntheses of Ca-alginate composite beads, which involved trioctyl-amine (TOA), tributyl phosphate (TBP), trioctylphosphine oxide (TOPO) organic extractants, and diatomite for separation of La(III) ions from dilute aqueous solutions. The surface morphology of the capsules was examined under Scanning Electron Microscopy, while their chemical structure was characterized using Fourier Transform Infrared Spectroscopy. Alginate composites were prepared by adding concentrations of TBP (1%–10%), TOPO (0.005 M–0.09 M) and TOA (1%–10%) organic extractants to the Na-alginate-diatomite mixture.The effects of various parameters on adsorption such as solution pH, contact time, metal ion concentration, and temperature, were individually tested using standard solutions of La(III). The maximum uptake capacity of the alginate composite adsorbent, consisting of TOA, diatomite, and alginate for La(III) ions, was examined at 25 °C. Adsorption data were analyzed using Langmuir, Freundlich, Dubinin–Radushkevich (D-R), Temkin, Flory-Huggins and Brunauer, and Emmett and Teller (BET) isotherm models. The biosorption isotherm parameters were estimated by both linear and nonlinear regression analyses. The results indicate that the Langmuir model provides a better fit than the other models for the adsorption equilibrium data.Thermodynamic parameters such as variations of enthalpy, entropy, and Gibbs free energy were calculated. The maximum uptake capacity of the alginate composite adsorbent, including TOA, diatomite, and alginate for La(III) ions from aqueous solutions was found to be 146.4 mg/g. The adsorption efficiency in dilute solutions was determined to be 97.2%.

Molecular Geometries and Vibrational Contributions to Reaction Thermochemistry Are Surprisingly Insensitive to the Choice of Basis Sets.

Calculation of molecular geometries and harmonic vibrational frequencies are pre-requisites for thermochemistry calculations. Contrary to conventional wisdom, this paper demonstrates that quantum chemical predictions of the thermochemistry of many gas and solution phase chemical reactions appear to be very insensitive to the choice of basis sets. For a large test set of 80 diverse organic and transition-metal-containing reactions, variations in reaction free energy based on geometries and frequencies calculated using a variety of double and triple-zeta basis sets from the Pople, Jensen, Ahlrichs, and Dunning families are typically less than 4 kJ mol-1, especially when the quasiharmonic oscillator correction is applied to mitigate the effects of low-frequency modes. Our analysis indicates that for many organic molecules and their transition states, high-level revDSD-PBEP86-D4 and DLPNO-CCSD(T)/(aug-)cc-pVTZ single-point energies usually vary by less than 2 kJ mol-1 on density functional theory geometries optimized using basis sets ranging from 6-31+G(d) to aug-pcseg-2 and aug-cc-pVTZ. In cases where these single-point energies vary significantly, indicating sensitivity of molecular geometries to the choice of basis set, there is often substantial cancellation of errors when the reaction energy or barrier is calculated. The study concludes that the choice of basis set for molecular geometry and frequencies, particularly those considered in this study, is not critical for the accuracy of thermochemistry calculations in the gas or solution phase.

Design of atomic cobalt selenide-doped sulfurized polyacrylonitrile cathode with enhanced electrochemical kinetics for high performance lithium-SPAN batteries

In this work, sulfurized polyacrylonitrile (SPAN) cathodes with atomically dispersed Co and Se active site, namely cobalt selenide doped-sulfide polyacrylonitrile (CoSe2-x@SPAN, x = 6, 10, 15) with different CoSe2 doping concentrations of 6, 10, and 15 wt%, were fabricated by co-heating approach to strengthen the charge conductivity and catalytic activity of SPAN cathode. Atomic scale CoSe2 were doped into the SPAN skeleton to expediating the redox kinetics of lithium storage process, and the catalytic mechanism was made clear by a viewing angle of frontier molecular orbital theory. The DFT calculation results show that CoSe2@SPAN has a more uniform electrostatic potential distribution with a smaller LUMO-HOMO band gap, which is more conducive to electron transport. The Co/Se loaded SPAN polymer constructed by N-Co-S chemical coordination improves the matching degree between the highest occupied molecular orbital (HOMO) of the nucleophile S2− and the lowest unoccupied molecular orbital (LUMO) of the electrophile Li+ during the discharge process, and effectively reduces the bonding orbital σ level of the deposited product Li2S, thereby promoting the lithium storage kinetics of CoSe2@SPAN cathode material and avoiding the shuttle effect. Meanwhile, the larger Gibbs free energy variation during the lithiation process indicates the enhanced reaction kinetics of the CoSe2@SPAN cathode. Ultimately, The Li-SPAN battery with CoSe2-10@SPAN cathode delivers high reversible capacity of 1475 mAh g−1 at 0.2 A/g, superior rate capability and long-term capacity retention of 71.1% after 500 cycles at 1.0 A/g. Accordingly, this study offers insights into the utilization of frontier molecular orbital theory (FMO) to improve the redox kinetics and sulfur utilization of Li-SPAN batteries.

Molecular-level understanding on complexation-adsorption-degradation during the simultaneous removal of aqueous binary pollutants by magnetic composite aerogels

Heavy metals and organic pollutants were universally co-existing in water, except for dissociated pollutants, their complexes have caused huge damage to the environment and humans too. Hence, two new kinds of microcrystalline cellulose modified hyper-branched chitosan aerogels and magnetic aerogels (HCS/MCCs, M-HCS/MCCs) were fabricated to realize the simultaneous adsorption of the dissociative pollutants and the advanced treatment of the complex pollutants. HCS/MCCs exhibited fast and efficient adsorption performance towards dissociated pollutants (Pb(II), Cu(II), Methyl orange and Congo red) in 240 min reaching a maximum adsorption capacity of 412.50, 425.14, 435.13, 538.46 mg/g in their mono-polluted solution, respectively. More importantly, M-HCS/MCCs showed a synergistic effect of adsorption-catalytic degradation in Cu(II)-MO and Pb(II)-CR binary-polluted systems, in which the evolution, configuration, free energy variation and total density-of-states (TDOS) of the complexes were figured out by Density Functional Theory (DFT) calculation. Both radical and non-radical pathways were discovered in the two process of self-catalysis of the complexes and activating-catalysis of magnetic nanoparticles for persulfate (PS), and the organics were degraded to CO2 and H2O ultimately. Finally, the synergistic effect of complexation-adsorption-catalytic degradation and removal mechanism were revealed.

Investigation of dynamic characteristics of impacting nanodroplets on solid surfaces decorated with a stepped texture

This work mainly focuses on the passive manipulation of the impact dynamics of nanodroplets using superhydrophobic surfaces decorated with a stepped surface via molecular dynamics (MD) simulations. Based on various impact conditions, we observe a series of novel impact dynamics that are quite different from the normal impact on smooth surfaces, mainly including the deflected rebound at the top/base of the stepped surface, and directional transport and splitting of droplets. The reason why the stepped texture can produce these fascinating dynamic characteristics is detailly investigated by calculating the centroid coordinate, free energy, and spread factor variations. The asymmetric dynamics of impacting droplets on stepped surfaces should be the primary reason for observed phenomena. The phase diagram is established to obtain overall insights into the impacting dynamics. This work can pave the way to assist practical applications, which require manipulating droplets at the nanoscale.