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This paper investigates the dynamic behavior of EthylChlorophyllide A (EChlideA) molecules in a methanol solution confined within a 4 nm silica nanoslit, using molecular dynamics simulations over a duration of 1 ms. Three systems, containing 1, 2, and 4 solutes, were studied at 298 K. The results demonstrate that EChlideA molecules predominantly adsorb onto the silica surfaces, driven by specific interactions between chlorin ring's methyl group and the hydroxyl groups of the silica. This adsorption leads to stable binding, particularly in less crowded environments, as indicated by the potential of mean force analysis. Higher molecular concentrations, such as those with four EChlideA molecules, introduce variation in binding strength due to molecular aggregation and complex interactions. The orientation analysis reveals that the chlorin ring tends to align parallel to the surface, requiring rotational adjustments during surface diffusion. In addition, solvent coordination around the Mg ion remains consistent under bulk conditions, although with some variation in higher concentrations. This study also highlights a decrease in linear diffusion and an increase in rotational relaxation times for EChlideA molecules within the confined nanoslit, reflecting the influence of molecular concentration and arrangement on their dynamics. These findings provide valuable insights into the role of surface interactions, molecular orientation, and solvent coordination in confined environments, offering implications for the design of nanoscale systems. [ABSTRACT FROM AUTHOR]

Understanding the nucleation and growth of tungsten (W) is technologically important in spin-to-charge interconversion for realizing energy-efficient spintronic devices. Here, we have systematically investigated the effect of Ar deposition pressure (P A r ) on the nucleation and growth of W. The observed surface topography as a function of P A r reveals a microstructural transition from zone T to zone 1 in the structure zone model. The physical origin for the increasing roughness as a function of P A r correlates with the surface diffusion of adatoms and growth kinetics in the Volmer–Weber growth mechanism. Grazing incidence x-ray diffraction (GIXRD) results show that W exhibits a structural phase transition from a mixed phase of (α + β) - W to a single phase of β - W as a function of P A r . The analysis of the electron diffraction patterns obtained from the films grown on amorphous-SiNx windows also supports these observations. The observed transition is fundamentally correlated with the growth kinetics in zone T and zone I. Thickness-dependent GIXRD results qualitatively prove that the film grown in zone T exhibits compressive strain, whereas that grown in zone I exhibits only tensile strain. The critical thickness for the phase transition is strongly attributed to the strain during nucleation and growth. The increasing resistivity as a function of P A r corroborates the change in structural phases. Thickness-dependent resistivity measurements correlate with the degree of crystallinity via relative intensity observed from the GIXRD results. Our results strongly suggest that W structural phases can be deterministically controlled via P A r for developing low-power spintronic devices. [ABSTRACT FROM AUTHOR]

Adsorbed molecules on a catalyst almost always arrange themselves in a manner that is far from perfectly random, which gives rise to spatial correlations. These correlations are a result of the interactions between the adsorbed species (adspecies) as well as elementary processes such as diffusion and reaction events that shape the adspecies arrangements. Despite their importance, spatial correlations are usually ignored while writing species balance equations for the modeling of heterogeneous catalytic systems. Recently, we have introduced a probabilistic microkinetic modeling (p-MKM) framework that aims at incorporating spatial correlations in the form of a short-ranged order (SRO) parameter into species balance equations. Here, we extend the approach to catalytic systems of higher complexity, namely, longer interactions and multiple species. This is made possible by including multiple pair probabilities in the p-MKM model for the first time. The interplay between different SRO parameters is probed. An important consideration is how many pair probabilities should be included to capture the underlying complexity with sufficient accuracy. [ABSTRACT FROM AUTHOR]

We develop an adaptive scheme in the kinetic Monte Carlo simulations, where the adsorption and activation energies of all elementary steps, including the effects of other adsorbates, are evaluated "on-the-fly" by employing the neural network potentials. The configurations and energies evaluated during the simulations are stored for reuse when the same configurations are sampled in a later step. The present scheme is applied to hydrogen adsorption and diffusion on the Pd(111) and Pt(111) surfaces and the CO oxidation reaction on the Pt(111) surface. The effects of interactions between adsorbates, i.e., adsorbate–adsorbate lateral interactions, are examined in detail by comparing the simulations without considering lateral interactions. This study demonstrates the importance of lateral interactions in surface diffusion and reactions and the potential of our scheme for applications in a wide variety of heterogeneous catalytic reactions. [ABSTRACT FROM AUTHOR]

The design of heterogeneous catalysts generally involves optimizing the reactivity descriptor of adsorption energy, which is inevitably governed by the structure of surface-active sites. A prerequisite for understanding the structure–properties relationship is the precise identification of real surface-active site structures, rather than relying on conceived structures derived from bulk alloy properties. However, it remains a formidable challenge due to the dynamic nature of nanoalloys during catalytic reactions and the lack of accurate and efficient interatomic potentials for simulations. Herein, a generalizable deep-learning potential for the Ag–Pd–F system is developed based on a dataset encompassing the bulk, surface, nanocluster, amorphous, and point defected configurations with diverse compositions to achieve a comprehensive description of interatomic interactions, facilitating precise prediction of adsorption energy, surface energy, formation energy, and diffusion energy barrier and is utilized to investigate the structural evolutions of AgPd nanoalloys during fluorination. The structural evolutions involve the inward diffusion of F, the outward diffusion of Ag in Ag@Pd nanoalloys, the formation of surface AgFx species in mixed and Janus AgPd nanoalloys, and the shape deformation from cuboctahedron to sphere in Ag and Pd@Ag nanoalloys. Moreover, the effects of atomic diffusion and dislocation formation and migration on the reconstructing pathway of nanoalloys are highlighted. It is demonstrated that the stress relaxation upon F adsorption serves as the intrinsic driving factor governing the surface reconstruction of AgPd nanoalloys. [ABSTRACT FROM AUTHOR]

Shale gas reservoirs generally have ultra-low water saturation, and the water in reservoirs is closely bound to the walls of inorganic nanopores, forming a water film structure on the hydrophilic surface. When shale gas enters the inorganic nanopores, the water films in the inorganic pores will be removed by evaporation instead of being driven away by the gas, which increases the difficulty of predicting production during shale gas extraction. Based on molecular dynamics simulations, a water film evaporation model is proposed, considering the evaporation of water films during shale gas transport and the influence of water film evaporation on the shale gas transport mechanism. The Green–Kubo method is employed to calculate the viscosity of the water film. The evaporation flux of the water film under the influence of viscosity is discussed in the evaporation model. The transport mechanisms of shale gas in nanopores and the effect of water film evaporation on shale gas transport mechanisms are analyzed in detail. The result indicates that the water films in the inorganic nanopores are constrained on the hydrophilic surface, and the viscosity normal to the surface of the water film of 4 Å is 0.005 26 Pa⋅S, which is 6.12 times the reference value of viscosity at 298 K. In the process of water film evaporation, the evaporation flux of the water film is influenced by viscosity. In the study of the shale gas transport mechanism, water films in inorganic nanopores can hinder the surface diffusion of the methane molecules adsorbed on boundary and significantly reduce the mass flux of shale gas. [ABSTRACT FROM AUTHOR]

Beyond well-documented confinement and surface effects arising from the large internal surface and severely confining porosity of nanoporous hosts, the transport of nanoconfined fluids remains puzzling in many aspects. With striking examples such as memory, i.e., non-viscous effects, intermittent dynamics, and surface barriers, the dynamics of fluids in nanoconfinement challenge classical formalisms (e.g., random walk, viscous/advective transport)—especially for molecular pore sizes. In this context, while molecular frameworks such as intermittent Brownian motion, free volume theory, and surface diffusion are available to describe the self-diffusion of a molecularly confined fluid, a microscopic theory for collective diffusion (i.e., permeability), which characterizes the flow induced by a thermodynamic gradient, is lacking. Here, to fill this knowledge gap, we invoke the concept of "De Gennes narrowing," which relates the wavevector-dependent collective diffusivity D0(q) to the fluid structure factor S(q). First, using molecular simulation for a simple yet representative fluid confined in a prototypical solid (zeolite), we unravel an essential coupling between the wavevector-dependent collective diffusivity and the structural ordering imposed on the fluid by the crystalline nanoporous host. Second, despite this complex interplay with marked Bragg peaks in the fluid structure, the fluid collective dynamics is shown to be accurately described through De Gennes narrowing. Moreover, in contrast to the bulk fluid, the departure from De Gennes narrowing for the confined fluid in the macroscopic limit remains small as the fluid/solid interactions in severe confinement screen collective effects and, hence, weaken the wavevector dependence of collective transport. [ABSTRACT FROM AUTHOR]

Atomic layer deposition is a key technique for preparing large area uniformity, three-dimensional conformal, and ultrathin films due to its sequential self-limiting saturated chemisorption properties. Electric fields of varying magnitudes and directions were applied on Si, Al2O3, Au, and Ni substrates in Pt plasma enhanced atomic layer deposition processes. Studying the influences of electric fields on the initial nucleation and growth of Pt films on different substrates helps to understand the dynamic knowledge and underlying physical mechanisms so as to obtain ultrathin, continuous films and full control over the morphology and distribution of deposited materials. The XPS results reveal that the Pt coverage rate increases on all substrates with applied voltages. The induced dipole moment causes the (MeCp)PtMe3 molecule to rotate in a certain direction resulting in a more compact arrangement, and the energy generated by electric fields also helps the dissociation of methyl, ethyl, Cp, and MeCp ligands, which greatly mitigate the spatial site resistance effect, thus improving initial monolayer chemisorption efficiency and the Pt coverage. We also find that Pt prefers to grow in the (111) direction due to the increase in adsorption of (MeCp)PtMe3 molecules caused by the gradient forces under electric fields. However, applied electric fields can also influence the morphology by inducing surface diffusion and acting on plasma species. [ABSTRACT FROM AUTHOR]

Dissociative adsorption onto a surface introduces dynamic correlations between neighboring sites not found in non-dissociative absorption. We study surface coverage dynamics where reversible dissociative adsorption of dimers occurs on a finite linear lattice. We derive analytic expressions for the equilibrium surface coverage as a function of the number of reactive sites, N, and the ratio of the adsorption and desorption rates. Using these results, we characterize the finite size effect on the equilibrium surface coverage. For comparable N's, the finite size effect is significantly larger when N is even than when N is odd. Moreover, as N increases, the size effect decays more slowly in the even case than in the odd case. The finite-size effect becomes significant when adsorption and desorption rates are considerably different. These finite-size effects are related to the number of accessible configurations in a finite system where the odd-even dependence arises from the limited number of accessible configurations in the even case. We confirm our analytical results with kinetic Monte Carlo simulations. We also analyze the surface-diffusion case where adsorbed atoms can hop into neighboring sites. As expected, the odd-even dependence disappears because more configurations are accessible in the even case due to surface diffusion. [ABSTRACT FROM AUTHOR]

The stability of holes in solid thin films is crucial, as an absence of holes is necessary in some applications and holes are needed in others. We develop an axisymmetric two grain model with a central hole, with surface diffusion governing the exterior surfaces and mean curvature motion governing the grain boundary. The model can exhibit grooving, wetting, dewetting, as well as void, hole, and hillock formation. Here, we extend an earlier work [Zigelman and Novick-Cohen, J. Appl. Phys. 130, 175301 (2021)], where it was shown for an axisymmetric single grain system with a hole at the center that there exists a critical effective radius, which is independent of the contact angle. The stability of the steady states, which consist of coupled nodoidal and catenoidal surfaces, is analyzed numerically by imposing the steady state configurations as initial conditions. This approach yields stability criteria in terms of (i) the effective energy, (ii) the ratio between the maximal thickness of the inner and outer grains, (iii) a generalized effective radius, and (iv) the ratio between the mean curvature of the exterior surfaces and the total volume of the system. Some of these criteria partially reflect the Rayleigh stability criterion. Hillock formation tends to be stabilizing. Modes of instability include growth of one grain at the expense of the other, breakup induced by grooving, and hole closure. [ABSTRACT FROM AUTHOR]

While metal nanoparticles are widely used, their small size makes them mechanically unstable. Extensive prior research has demonstrated that nanoparticles with sizes in the range of 10-50 nm fail by the surface nucleation of dislocations, which is a thermally activated process. Two different contributions have been suggested to cause the weakening of smaller particles: first, geometric effects such as increased surface curvature reduce the barrier for dislocation nucleation; second, surface diffusion happens faster on smaller particles, thus accelerating the formation of surface kinks which nucleate dislocations. These two factors are difficult to disentangle. Here we use in situ compression testing inside a transmission electron microscope to measure the strength and deformation behavior of platinum particles in three groups: 12 nm bare particles, 16 nm bare particles, and 12 nm silica-coated particles. Thermodynamics calculations show that, if surface diffusion were the dominant factor, the last two groups would show equal strengthening. Our experimental results refute this, instead demonstrating a 100% increase in mean yield strength with increased particle size and no statistically significant increase in strength due to the addition of a coating. A separate analysis of stable plastic flow corroborates the findings, showing an order-of-magnitude increase in the rate of dislocation nucleation with a change in particle size and no change with coating. Taken together, these results demonstrate that surface diffusion plays a far smaller role in the failure of nanoparticles by dislocations as compared to geometric factors that reduce the energy barrier for dislocation nucleation.

Organic-inorganic hybrid nanocomposites are rapidly evolving as a new generation of materials with attractive properties for electrochemical energy storage. Unfortunately, their practical applications in sodium-ion batteries (SIBs) still require further research due to the unsatisfactory cycling stability and rate performance. This work explores using zinc antimony oxide/reduced graphene oxide (ZSO/rGO) hybrid nanocomposite as an anode material in SIBs. After 150 cycles at 0.05 A g−1, the ZSO/rGO electrode delivers a specific capacity of 357.21 mAh g−1 with a coulombic efficiency of 99.3 %, which is almost 2.5-fold higher than the specific capacity of the pristine ZSO electrode. An in-situ Raman spectroscopy study demonstrates that the sodiation/desodiation mechanism in the ZSO/rGO electrode involves the conversion and alloying reactions in the ZSO nanoparticles. Further electrochemistry analysis reveals that the nanocomposite anode shows synergistic effects by coupling diffusion and surface contribution, in which the latter plays an important role. [ABSTRACT FROM AUTHOR]

This paper investigates the numerical behavior of the radial basis functions least-squares collocation (RBF-LSC) method of lines (MoL) for solving surface diffusion problems, building upon the theoretical analysis presented in [Chen et al. SIAM J. Numer. Anal. 61(3), 1386–1404 (2023)]. Specifically, we examine the impact of the oversampling ratio, defined as the number of collocation points used over the number of RBF centers for quasi-uniform sets, on the stability of the eigenvalues, time-stepping sizes taken by Runge–Kutta methods, and overall accuracy of the method. By providing numerical evidence and insights, we demonstrate the importance of the oversampling ratio for achieving accurate and efficient solutions with the RBF-LSC-MoL method. Our results reveal that the oversampling ratio plays a critical role in determining the stability of the eigenvalues, and we provide guidelines for selecting an optimal oversampling ratio that balances accuracy and computational efficiency. [ABSTRACT FROM AUTHOR]

This research provides a flexible approach to manipulate formation of InGaAs nanostructures on the GaAs (100) surface by varying arsenic (As4) beam equivalent pressure (BEP). By selecting the As4/(In+Ga) BEP ratio to be 4, 8, 20, 50 and 100, we were able to obtain different quantum structures from quantum well (QW) to quantum dots (QDs), then to spatially ordered quantum dot chains (QD-chains), and finally to quantum wires (QWRs), respectively. This transformation of nanostructures was explained by anisotropic surface diffusion coupled with the strain relieving Stranski–Krastanov growth mode, while the anisotropy was modulated by increasing As4 flux and subsequently enhanced by multilayer-stacking growth with a suitable spacer thickness. Photoluminescence characteristics show correlation to the nanostructure morphology for each sample. In particular, the formation of QD-chains and QWRs results in anisotropic features that offer potential device applications. [ABSTRACT FROM AUTHOR]

La 2- x Pr x Ni 1- y Cu y O 4+δ (x = 0.5, 1, 1.5, y = 0.4, 0.6, 0.8) were synthesized by a citrate-nitrate method and studied as cathode materials for IT-SOFCs by Electrochemical Impedance Spectroscopy (EIS) in symmetrical cells based on the Ce 0.8 Sm 0.2 O 2-δ (SDC) and La 28- z W 4+ z O 54+1.5 z (z = 0.85, LWO) electrolytes. Phase identification and crystal structure analysis by means of X-ray powder diffraction (XRPD) shows that solubility of copper y decreases with the increase in praseodymium content x due to increasing structural distortions. Thermodynamic stability of La 2- x Pr x Ni 1- y Cu y O 4+δ at intermediate temperatures in air tends to decrease with praseodymium doping level x and increases with copper substitution for nickel y. Oxides with x = 0.5 and 0.6≤ y ≤ 0.8 are shown to be thermodynamically stable at 700 °C in air. Electrochemical performance of the La 2- x Pr x Ni 1- y Cu y O 4+δ electrodes improves with praseodymium and copper doping. The results of EIS measurements at different temperatures and oxygen partial pressures (P (O 2)) reveal that the rate-determining step of the overall electrochemical process is charge transfer, which can be a combination of surface diffusion and bulk diffusion. EIS studies in dry and wet air indicate the presence of proton conduction in the studied electrodes. The area-specific resistances (ASRs) for La 2- x Pr x Ni 1- y Cu y O 4+δ with x = 0.5, y = 0.6 and y = 0.8 in contact with SDC are comparable with those reported for Pr 2 NiO 4+δ and equal to 0.07 and 0.065 Ω cm2 at 800 °C. [Display omitted] • Thermodynamic stability of La 2-x Pr x Ni 1-y Cu y O 4+δ (LPNC) in air increases with Cu doping. • Increase in Pr and Cu content improves the electrochemical performance of LPNC. • The overall electrochemical reaction is limited by the charge transfer in electrode. • Rate-determining step can be a combination of surface diffusion and bulk diffusion. • Impedance spectroscopy studies indicate the possibility of proton conduction in LPNC. [ABSTRACT FROM AUTHOR]

Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3- δ (BSCF) generally exhibits superior cathode activity compared to La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3- δ (LSCF) for intermediate-temperature solid oxide fuel cells (IT-SOFCs). However, the chemical stability of BSCF is inferior to that of LSCF. When BSCF cathodes are sintered at a high temperature of 1050 °C, performance was compromised due to the formation of (Ba,Sr)ZrO 3 between the scandia-stabilized zirconia (ScSZ) electrolyte and gadolinia-doped ceria (GDC) interlayer. The oxide ionic conductivity of (Ba,Sr)ZrO 3 was low, decreasing the cathode performance. Furthermore, the BSCF grains enlarged, and cobalt oxide formed due to BSCF decomposition, decreasing the active specific surface area. However, by incorporating GDC into the BSCF cathode, the morphology remained unchanged and cobalt oxide formation was prevented, despite (Ba,Sr)ZrO 3 still forming. The performance of the cell with the BSCF-GDC composite cathode surpassed that with the BSCF cathode due to decreased polarization resistance attributed to the oxygen surface exchange and diffusion processes in the cathode. [ABSTRACT FROM AUTHOR]

The twin boundaries and inherent lattice strain of five-fold twin (5-FT) structures offer a promising and innovative approach to tune nanocrystal configurations and properties, enriching nanomaterial performance. However, a comprehensive understanding of the nonclassical growth models governing 5-FT nanocrystals remains elusive, largely due to the constraints of their small thermodynamically stable size and complex twin configurations. Here, we conducted in situ investigations to elucidate the atomic-scale mechanisms driving size-dependent and twin configuration-related aggregation phenomena between 5-FT and other nanoparticles at the atomic scale. Our results reveal that surface diffusion significantly shapes the morphology of aggregated nanoparticles, promoting the symmetrical formation of 5-FT, especially in smaller nanoparticles. Moreover, the inherent structural characteristics of 5-FT mitigate the dominance of surface diffusion in its morphological evolution, retarding the aggregation evolution process and fostering intricate twin structures. These findings contribute to advancing our capacity to manipulate the configuration of twinned particles, enabling more predictable synthesis of functional nanomaterials for advanced engineering applications. The mechanisms underlying the nonclassical growth of penta-twinned gold nanocrystals remain unclear. Here, the authors elucidate the atomic-level processes that drive size-dependent and twin configuration-related aggregation phenomena. [ABSTRACT FROM AUTHOR]

Lithium‐ion batteries (LIBs) with ternary oxide cathode materials are the prevalent energy storage devices for electric vehicles, and the huge amounts of spent LIBs pose severe challenges in terms of environmental impact and resource management. Particularly, the proper handling of degraded cathode materials is of central importance for the sustainable and closed‐loop development of LIBs industry. In this context, direct regeneration of degraded ternary oxides toward reusable high‐performance cathode materials is environmentally and economically favorable in contrast to present metallurgical recycling methods. In this work, a simple and effective two‐step method is demonstrated to regenerate the degraded NCM 622 (LiNi0.6Co0.2Mn0.2O2) materials by elemental compensation and structural restoration. Moreover, a multi‐functional LTO (Li4Ti5O12) surface coating is simultaneously designed to guarantee rapid Li+ diffusion and stable surface of the regenerated product. Therefore, the regenerated LTO‐coated NCM materials show excellent electrochemical performance; specifically, the initial discharge capacity (183.0 mAh g−1 at 0.1 C), rate capability (90.0 mAh g−1 at 10 C), and cycling stability (79.3% capacity retention after 200 cycles) are even comparable with those of fresh materials. The as‐established upcycling strategy may shed light on the value‐added recycling of degraded cathode materials and thereby a virtuous cycle of LIBs. [ABSTRACT FROM AUTHOR]

In this study, we expand the computational investigation of selenium, which has previously been limited to metals such as Cu, Fe, Pd, Au, and Pt. Utilizing density functional theory calculations, we explore the adsorption and diffusion of selenium at a low‐coverage regime of 0.25 ML on a broader range of metal surfaces, including Ni, Cu, Rh, Pd, Ag, Ir, Pt, and Au. Our results reveal that selenium exhibits a distinct preference for three‐fold or four‐fold high‐coordination sites on most studied surfaces. We further analyze the minimum energy diffusion pathways, demonstrating that the energy barrier for selenium's surface diffusion varies significantly based on the orientation and nature of the metal surfaces. Specifically, on (100) surfaces, selenium exhibits the highest diffusion energy, ranging from 0.60 eV in Au(100) to 1.12 eV in Pd(100). The diffusion behavior on (110) and (211) surfaces is also elaborated, emphasizing the unique trends observed compared to previously studied elements like sulfur. Importantly, this study is a new reference for future computational analyses, filling existing gaps by providing comprehensive data on selenium adsorption on various face‐centered cubic metal surfaces not previously reported. [ABSTRACT FROM AUTHOR]

We reported nucleation mechanisms of InP directly on Si (8% lattice mismatch) under confined structures, called micro-crucibles, at ultra-high vacuum (UHV) by chemical beam epitaxy. These micro-crucibles are used to induce lateral growth in the presence of a micro-scale Au catalyst. It is found that at this UHV condition, the kinetics is dictated predominantly by adatom surface diffusion. Using a two-step growth process ((1) In-only exposure, then, (2) simultaneous In and P exposures), InP islands have been successfully nucleated on Si substrates under micro-crucible structures. The nucleation of these InP islands strongly depends on the metal catalyst location relative to the micro-crucible opening with metal catalysts residing closer to the opening having a higher chance to get incorporated with In and P atoms. Importantly, we found that using smaller micro-crucibles with double openings can increase the possibility of having metal catalysts reside near either opening and nucleate InP under micro-crucibles. [ABSTRACT FROM AUTHOR]

Manganese (Mn) oxides are promising cathode materials for rechargeable aqueous Zn‐ion batteries. However, the Mn dissolution in weakly acidic electrolytes always hinders the development of better aqueous Zn–Mn batteries. Herein, a hydroxylated manganese oxide cathode material (H‐MnO2) is fabricated using an electrochemical method for stable aqueous Zn–Mn batteries without relying on the Mn2+ electrolyte additives. The partial hydroxylation of the oxides leads to charge redistribution of the material, changing the reaction thermodynamics and kinetics. Theoretical simulation suggests that the hydroxylation of manganese oxide promotes both Zn2+ adsorption thermodynamics and diffusion kinetics on the surface of H‐MnO2 but weakens the interaction between H+ and the electrode. Therefore, Zn2+ ions can be more reactive with the hydroxylated manganese oxide than H+ ions. Experimental results show that the Zn2+ insertion mechanism dominates the charge storage process of H‐MnO2, and the H+‐induced Mn dissolution reaction is effectively alleviated. Importantly, H‐MnO2 exhibits good cycling stability with 95% capacity retention over 5000 cycles at the current density of 3.8 A g−1 in the ZnSO4 electrolyte, outperforming the state‐of‐the‐art aqueous Zn–Mn batteries, even those with Mn2+ electrolyte additives. The findings provide new insights for designing stable manganese oxide cathodes in aqueous Zn–Mn batteries. [ABSTRACT FROM AUTHOR]

Activity-dependent modulations of N-methyl-D-aspartate glutamate receptor (NMDAR) trapping at synapses regulate excitatory neurotransmission and shape cognitive functions. Although NMDAR synaptic destabilization has been associated with severe neurological and psychiatric conditions, tuning NMDAR synaptic trapping to assess its clinical relevance for the treatment of brain conditions remains a challenge. Here, we report that ketamine (KET) and other clinically relevant NMDAR open channel blockers (OCBs) promote interactions between NMDAR and PDZ-domain-containing scaffolding proteins and enhance NMDAR trapping at synapses. We further show that KET-elicited trapping enhancement compensates for depletion in synaptic receptors triggered by autoantibodies from patients with anti-NMDAR encephalitis. Preventing synaptic depletion mitigates impairments in NMDAR-mediated CaMKII signaling and alleviates anxiety- and sensorimotor-gating-related behavioral deficits provoked by autoantibodies. Altogether, these findings reveal an unexpected dimension of OCB action and stress the potential of targeting receptor anchoring in NMDAR-related synaptopathies. [Display omitted] • Open channel blockers (OCBs) such as ketamine promote NMDAR synaptic trapping • OCB binding enhances interactions between NMDARs and scaffolding proteins • Ketamine prevents NMDAR depletion at synapses exposed to anti-NMDAR autoantibodies • Ketamine alleviates behavioral deficits provoked by anti-NMDAR autoantibodies Villéga, Fernandes, Jézéquel et al. report that NMDAR open channel blockers, such as ketamine, favor receptor trapping at excitatory synapses through enhanced interactions with scaffolding proteins. They further show that ketamine-elicited trapping enhancement alleviates NMDAR synaptic impairments and behavioral deficits caused by autoantibodies from patients with anti-NMDAR encephalitis. [ABSTRACT FROM AUTHOR]

Molecular dynamics (MD) simulation of the green ionic liquid [C₄mim][PF₆] mixed with polar benzonitrile (BNZ) solvent provides detailed insights into their structural and dynamic properties, essential for electrochemistry and materials science applications. The simulations we carried out at varying mole fractions (XBZN) reveal the mixtures' physical, structural, and dynamic properties, with radial, spatial, and combined distribution functions, highlighting the effective interaction through H-bonding involved. The simulation indicates that BZN stacks on the cation butyl tail, providing a significant explanation for the unique experimental observations (following). Adding BZN causes the mixture's liquid dynamics to increase linearly at low XBZN and exponentially at high XBZN, with a notable singular transition at 0.5XBZN. Comprehensive efforts were made to verify and support experimental sum frequency generation (SFG) spectroscopy by simulating the surface structure of the mixtures. Consequently, the simulated BZN stacking structure explains (1) the absence of the C≡N vibrational mode in the SFG spectrum for XBZN < 0.8, and (2) the gradual diminishing of the CH3 SFG signal, which disappears as XBZN approaches 0.5. Finally, this research removes a persistent ambiguity, proving that only the molecular moieties on the surface generate the SFG vibrational signal, while those in the subsurface do not. [ABSTRACT FROM AUTHOR]

We investigate the geometric features in the bifurcation and chaos of a partial differential equation describing the unsteady combustion of solid propellants. Driven by the interaction of the unsteady combustion at the surface and the diffusion inside solids, the motion of the combustion fronts can be steady, harmonically oscillatory, and become more complicated to chaos through a series of bifurcations. We examined the dynamics in both free and forced oscillations. In the free oscillation, by varying a parameter related to the solid property, the intrinsic instability of the combustion is discovered. We find the typical period-doubling to chaos route and verify it via both qualitative and quantitative universalities. In the forced oscillation case, the system is perturbed by an external pressure excitation, leading to a more complicated bifurcation diagram with richer dynamics. Concentrating on the topological characteristics of the periodic orbits, we discover two new types of bifurcation other than the period-doubling bifurcation. In present work, we extract a series subtle topological structures from an infinite-dimensional dynamical systems governed by a partial differential equation with free boundary. We find the results provide an explanation for the period-3 orbits in the experimental data of a full-scale motor. [ABSTRACT FROM AUTHOR]

Lakes are important sentinels of climate change and may contribute over 30% of natural methane (CH4) emissions; however, no earth system model (ESM) has represented lake CH4 dynamics. To fill this gap, we refined a process‐based lake biogeochemical model to simulate global lake CH4 emissions, including representation of lake bathymetry, oxic methane production (OMP), the effect of water level on ebullition, new non‐linear CH4 oxidation kinetics, and the coupling of sediment carbon pools with in‐lake primary production and terrigenous carbon loadings. We compiled a lake CH4 data set for model validation. The model shows promising performance in capturing the seasonal and inter‐annual variabilities of CH4 emissions at 10 representative lakes for different lake types and the variations in mean annual CH4 emissions among 106 lakes across the globe. The model reproduces the variations of the observed surface CH4 diffusion and ebullition along the gradients of lake latitude, depth, and surface area. The results suggest that OMP could play an important role in surface CH4 diffusion, and its relative importance is higher in less productive and/or deeper lakes. The model performance is improved for capturing CH4 outgassing events in non‐floodplain lakes and the seasonal variability of CH4 ebullition in floodplain lakes by representing the effect of water level on ebullition. The model can be integrated into ESMs to constrain global lake CH4 emissions and climate‐CH4 feedback. Plain Language Summary: Lakes are highly sensitive to climate change and can produce over 30% of natural methane (CH4) emissions. However, these emissions are not well understood or included in global CH4 assessments. Current lake CH4 models either miss key processes or haven't been tested with observations from different environments. To address this, we improved the Advanced Lake Biogeochemistry Model (ALBM) to better simulate CH4 production, oxidation, and transport. We also created a new data set of CH4 emissions from 106 lakes worldwide to validate the model. Our improved model shows promising performance in simulating observed emissions. Our findings highlight the importance of including CH4 production in oxygen‐rich water, the impact of water level change on CH4 bubble release, and a new method for CH4 oxidation in lake CH4 models. The improved ALBM can now be used in Earth system models to better predict global lake CH4 emissions and their impact on climate change. Key Points: We enhanced and validated the Advanced Lake Biogeochemistry Model for lake CH4 emissions using a new global data setThe model captures lake CH4 emissions across diverse environments and accounts for seasonal and inter‐annual variationsLake CH4 models should include oxic CH4 production, water level impact on ebullition, and a new method for CH4 oxidation [ABSTRACT FROM AUTHOR]

[Display omitted] • Swelling-assisted pyrolysis was proposed for the recovery of glass fibers from WTBs. • Resin decomposition ratio reached 76.8 % at 350 °C in swelling-assisted pyrolysis. • The swelling treatment physically disrupted the cross-linked structure of the WTBs. • The oxidation duration was reduced owing to the less content of pyrolysis char. • Tensile strength of fibers from swollen-WTB was higher than that from original-WTB. The recycling of end-of-life wind turbine blades has become a global environmental challenge driven by the rapid growth of wind power. Pyrolysis is a promising method for recovering glass fibers from these discarded blades, but traditional pyrolysis is often operated at high temperatures, which degrades the mechanical properties of recovered fibers. To address this issue, a swelling-assisted pyrolysis method was proposed to recover high-quality glass fibers from end-of-life wind turbine blades at low temperatures. The results confirmed that the decomposition of the resin matrix within the blade was significantly promoted at low temperatures in the swelling-assisted pyrolysis process, achieving a resin decomposition ratio of 76.8 % at 350 °C. This improvement was attributed to enhanced heat transfer and co-pyrolysis with acetic acid. Swelling could physically disrupt the cross-linked structure of the blade, creating a more porous and layered structure, thereby enhancing heat transfer during the pyrolysis process. Simultaneously, the co-pyrolysis with acetic acid could generate hydrogen radicals, which promoted the cracking of macromolecular oligomers into lighter products or gaseous alkanes. Consequently, the formation of pyrolysis char within the solid pyrolysis product was reduced, shortening the oxidation duration to 30 min. In comparison to traditional pyrolysis, the swelling-assisted pyrolysis process effectively suppressed the diffusion of surface defects over the recovered fibers, leading to promising improvements in their flexibility, elasticity, and mechanical properties, with tensile strength notably increased by 27.5 %. These findings provided valuable insights into recovering high-quality glass fibers from end-of-life wind turbine blades. [ABSTRACT FROM AUTHOR]

Cation-based (or electrochemical) resistive memory devices are gaining increasing interest in neuromorphic applications due to their capability to emulate the dynamic behavior of biological neurons and synapses. The utilization of such devices in neuromorphic systems necessitates a reliable physical model for the resistance switching mechanism, which is based on the formation and dissolution of a conductive filament in a thin dielectric layer, sandwiched between two metal electrodes. We propose a comprehensive model to simulate the evolution of the filament geometry under the effect of both surface diffusion caused by curvature gradient and electromechanical stress, and mass injection due to electrodeposition of cations. The model has been implemented in a C++ platform using a level-set approach based on a mixed finite element formulation, enriched by a mesh adaptation strategy to accurately and efficiently track the evolution of the filament shape. The numerical scheme is initially validated on various benchmark case studies. We then simulate the growth and self-dissolution of the filamentary geometry, incorporating an electrical model allowing a comparison with conventional cation-based memories. The simulations showcase filament formation under varying applied voltages and filament dissolution under different initial resistances. • Modeling of nanoscale cation-based RRAMs, including electric field and surface diffusion. • Level-set formulation of the electric field-assisted evolution of the conductive filament morphology. • Efficient decoupling of the level-set equation and the generalized Poisson model. • Tailored mesh adaptation strategy to ensure accurate solutions within a reasonable computational time. • Reliable reproduction of conductive filament growth and self-dissolution in agreement with experimental data. [ABSTRACT FROM AUTHOR]

In thin LiNi1/3Mn1/3Co1/3O2 (NMC111) electrodes, pseudocapacitive behavior is notably enhanced due to their increased surface-to-volume ratio, which intensifies the role of the electrode–electrolyte interface. This behavior is driven by fast, reversible redox reactions and ion intercalation occurring near the surface, where the shorter diffusion path allows for more efficient ionic transport. The reduced thickness of the electrodes shortens the Li-ion diffusion distance, improving the diffusion coefficient by a factor of 40 compared to thicker electrodes, where ion transport is hindered by longer diffusion paths. The increased surface area and shorter diffusion paths promote faster electrochemical kinetics, allowing for quicker ion intercalation and deintercalation processes. The thin-film configuration enhances pseudocapacitive charge storage, which is essential for applications requiring rapid charge and discharge cycles. As a result, the combination of improved Li-ion diffusion and enhanced surface activity contributes to superior electrochemical performance, offering higher power densities, faster energy delivery, and better rate capability. This improvement in performance makes thin NMC111 electrodes particularly advantageous for applications such as high-power energy storage systems, where fast kinetics and high power densities are critical. These findings highlight the importance of interface engineering and material morphology in optimizing the performance of Li-ion batteries and similar electrochemical energy storage devices. [ABSTRACT FROM AUTHOR]

Heterogeneous microstructures in Cu-Mo-W alloy thin films formed by magnetron co-sputtering immiscible elements with concentrated compositions are characterized using scanning transmission electron microscopy (STEM) and nanoindentation. In this work, we modified the phase separated structure of a Cu-Mo immiscible system by adding W, which impedes surface diffusion during film growth. The heterogeneous microstructures in the Cu-Mo-W ternary system exhibited bicontinuous matrices and agglomerates composed of Mo(W)-rich phase. This is unique, as these are the slower-diffusing species, contrasting past reports of binary Cu-Mo thin films that exhibited Cu-rich agglomerates. The bicontinuous matrices comprised of Cu-rich and Mo(W)-rich phases exhibited bilayer thicknesses of less than 5 nm. The hardness of these thin films measured using nanoindentation is reported and compared to similar multilayers and nanocomposites in binary systems. [ABSTRACT FROM AUTHOR]

AbstractThis study investigates the continuous flow behavior of a fixed-bed column for Pb2+ removal using calcined Ni/Mo hydrotalcite. The sorbent was characterized using FTIR, XRD, TEM, and BET surface area analysis to evaluate its removal efficiency. Experiments explored different operating conditions, such as feed flowrate (5–20 mL/min), inlet Pb2+ concentration (20–50 mg/L), bed height (10–15 cm), and solution pH (3–8). Results show that exhaustion time increased with higher bed heights, while lower flowrates, and inlet Pb2+ concentrations extended the column’s lifespan. Enhanced removal capacities were observed at higher Pb2+ concentrations and bed heights, as well as with lower flowrates, particularly at an optimal solution pH of 6, due to an increased driving force. Regeneration tests demonstrated good sorbent reusability for up to five consecutive sorption–desorption cycles without affecting its removal efficiency. Therefore, calcined Ni/Mo hydrotalcite shows promising potential for treating Pb2+-containing wastewater. Analytical solutions for diffusion mechanisms were applied to predict the experimental data under various conditions, revealing that surface diffusion accurately describes the sorption kinetics (average percentage errors <5%), while pore diffusion can be neglected. The proposed model effectively predicts column performances for scaling up wastewater treatment operations. [ABSTRACT FROM AUTHOR]

This study focuses on mixed‐conducting perovskite membranes for efficient oxygen supply, aiming to replace energy‐intensive cryogenic distillation with a more practical alternative. A La and Nb co‐doped BaCoO3−δ perovskite is introduced, Ba0.95La0.05Co0.8Fe0.12Nb0.08O3−δ (BLCFN) with a record‐breaking oxygen permeation flux, surpassing all known single‐phase perovskite membranes. To elucidate its superior membrane performance, the mass/charge transport properties and equilibrium bulk properties are investigated and quantitative indicators (DO = 5.8 × 10−6 cm2 s−1, kO = 1.0 × 10−4 cm s−1, σion = 0.93 S cm−1 at 900 °C) reveal fast diffusion and excellent surface gas‐exchange kinetics. The oxygen permeability of 12.4 mL cm−2 min−1 and over 200 h of long‐term stability is achieved in an air/He atmosphere at 900 °C. By presenting a material that demonstrates higher performance than Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF), currently known for its highest permeability, it is believed that this marks a significant step toward innovative performance enhancement of perovskite oxide‐based membranes. [ABSTRACT FROM AUTHOR]

Porous graphene membranes (PGMs) have nanopores with single atomic thickness, which enables the precise and stable supply of ultralow flow rate gas below 10−14 Pa·m3·s−1. Different from a conventional channel, the surface diffusion (SD) process in PGM has become increasingly important and unique. However, the physical process and mathematical model of gas molecule transport in nanopores with single atomic thickness remain unclear. These inadequacies constrained the application of PGM in ultrasensitive leak detection. In this paper, the SD process in PGM was investigated using molecular dynamics simulation. A test rig was constructed to verify the simulation results. The nanopores in PGM were quantitatively characterized using a transmission electron microscope. Results show that a transfer region encircling the nanopores was identified, which plays a crucial role in the SD process. Furthermore, the physical model of SD process is described with a two-step model. Finally, a mathematical model of the SD process is established and validated. This paper provides nanoscale insights for an in-depth understanding of the SD process in PGM and promotes ultrasensitive leak detection technology. [ABSTRACT FROM AUTHOR]

1H spin–lattice relaxation experiments have been performed for gels based on fish collagen in order to analyze water dynamics. The covered frequency range ranges from 10 kHz to 10 MHz; in some cases, the temperature has varied as well. The relaxation data have been reproduced in terms of two models of water motion—a model including two relaxation contributions associated with the diffusion of water molecules on the macromolecular surfaces and a second model being just a phenomenological power law. The concept of surface diffusion has led to a very good agreement with the experimental data and a consistent set of parameters, with the diffusion coefficients being about five orders of magnitude slower compared to bulk water for one of the pools and considerably faster for the second one (smaller by factors between 2 and 20 compared to bulk water). In some cases, the attempt to reproduce the data in terms of a power law has led to a good agreement with the experimental data (the power law factor varying between 0.41 and 0.57); however, in other cases, the discrepancies are significant. This outcome favors the concept of surface diffusion. [ABSTRACT FROM AUTHOR]

(111)-oriented nanotwinned Cu ((111)nt-Cu) has shown its high surface diffusion rate and better oxidation resistance over common polycrystalline Cu (C-Cu). The application of (111)nt-Cu as an interface metallization layer in Ag-sintered technology under the role of oxygen was investigated in this work, and its connecting behavior was further clarified by comparing it with C-Cu. As the sintering temperature decreasing from 300 to 200 °C, the shear strength on the (111)nt-Cu substrate was still greater than 55 MPa after sintering for 10 min. The fracture surface correspondingly changed from the interface of Ag/die to mixed fracture mode, involving the interface of the Ag/Cu substrate and Ag/die. The existence of copper oxide provided a tight connection between Ag and the (111)nt-Cu substrate at all of the studied temperatures. Although lots of small dispersed voids were seen at the interface between copper oxide and (111)nt-Cu at 300 °C, these impurity-induced voids would not necessarily be a failure position and could be improved by adjusting the sintering temperature and time; for example, 200 °C/10 min or heating to 300 °C, and then start cooling at the same time. The microstructure of Ag-Cu joint on (111)nt-Cu behaved better than that on C-Cu. The thinner copper oxide layer and the higher connection ratio of the interface between copper oxide and Ag were still found on the (111)nt-Cu connection's structure. The poor connection between copper oxide and Ag on C-Cu easily became the failure interface. By controlling the thickness of copper oxide and the content of impurity-induced voids, the use of (111)nt-Cu in advanced-packaging could be improved to a new level. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations were carried out to study the structural and diffusion properties of a cyanobiphenyl monolayer composed of pentyl cyano biphenyl (5CB) and pentyloxy cyano biphenyl (5OCB) molecules on a graphene surface coated with alkane and alcohol molecules. To investigate the diffusion properties of 5CB and 5OCB molecules on the graphene surface, the molecules of pentane (C5) and dodecane (C12) from alkanes and dodecanol (C12OH) from alcohols with a polar hydroxyl (−OH) terminal functional group were chosen as orienting surfactant molecules. It was found that the diffusion ability of cyanobiphenyl molecules in a graphene substrate coated with alkane and alcohol molecules depends on the chain length of these molecules and on the presence of polar hydroxyl –OH terminal groups. With an increase in the length of alkane molecules from C5 to C12, the value of the diffusion coefficient Dz5CB (or Dz5OCB), it decreases slightly, while the presence of the polar hydroxyl −OH terminal group leads to a significant decrease in this diffusion coefficient of cyanobiphenyl molecules. [ABSTRACT FROM AUTHOR]

A finite difference numerical scheme is proposed and analyzed for the Cahn-Hilliard-Stokes system with Flory-Huggins energy functional. A convex splitting is applied to the chemical potential, which in turns leads to the implicit treatment for the singular logarithmic terms and the surface diffusion term, and an explicit update for the expansive concave term. The convective term for the phase variable, as well as the coupled term in the Stokes equation, is approximated in a semi-implicit manner. In the spatial discretization, the marker and cell difference method is applied, which evaluates the velocity components, the pressure and the phase variable at different cell locations. Such an approach ensures the divergence-free feature of the discrete velocity, and this property plays an important role in the analysis. The positivity-preserving property and the unique solvability of the proposed numerical scheme are theoretically justified, utilizing the singular nature of the logarithmic term as the phase variable approaches the singular limit values. An unconditional energy stability analysis is standard, as an outcome of the convex-concave decomposition technique. A convergence analysis with accompanying error estimate is provided for the proposed numerical scheme. In particular, a higher order consistency analysis, accomplished by supplementary functions, is performed to ensure the separation properties of numerical solution. In turn, using the approach of rough and refined error estimates, we are able to derive an optimal rate convergence. To conclude, several numerical experiments are presented to validate the theoretical analysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • NiFe-W-O/NF pre-catalyst exhibits an ultrathin nanosheet structure (∼ 4.0 nm). • The active phase γ-NiOOH and FeOOH are efficiently activated by the high-valent W ions. • The synergistic effect of NiFeW tri-centers modulates the electronic structure and accelerates the reaction kinetics. • The assembled water splitting electrolyzer achieves current density of 10 mA cm−2 in alkaline at voltage of only 1.52 V. The efficient oxygen evolution reaction (OER) is crucial for various electrochemical processes, especially for overall water splitting (OWS). In this study, we focus on the utilization of WO 3-x as an activation medium to enhance the OER performance of NiFe-based electrocatalysts. Firstly, we synthesize WO 3-x nanowires supported on nickel foam (NF) and then incorporate NiFe on WO 3-x nanowires by a simple hydrothermal method. The WO 3-x self-supported NiFe (Oxy)hydroxide (denoted as NiFe-W-O/NF) shows a three-dimensional stereostructure composed of ultrathin nanosheets (∼ 4.0 nm). This unique structure provides a large open surface for fuller diffusion of the electrolyte while exposing more active sites. The electronic interaction of tri-centers of NiFeW accelerates the surface reconstruction process of γ-NiOOH and FeOOH, which are converted into the main active species in a short time. The electrochemical measurements confirm that the NiFe-W-O/NF has low OER overpotentials (233 mV at 10 mA cm−2, 298 mV at 100 mA cm−2) and excellent stability (100 h in total) in 1 M KOH electrolyte. In addition, the NiFe-W-O/NF || NiFe-W-O/NF battery also exhibits a low cell voltage (1.52 V at 10 mA cm−2) with a stable lifetime (50 h) under alkaline conditions. These results highlight the great potential of NiFe-W-O/NF for practical applications. [ABSTRACT FROM AUTHOR]

The rapid development of alternative energy vehicles has raised higher requirements for electrode materials. Silicon, with superhigh specific capacity, is highly anticipated in the field of lithium‐ion batteries (LIBs). Unfortunately, the original drawbacks of serious volumetric effect and poor conductivity have confined its commercial steps severely. Herein, a novel composite, based on submicron silicon flakes embedded into carbon shell, with heterojunction‐bearing MnOx nanoparticles, is designed and synthesized successfully via sanding process and in situ thermal reduction methods. The results of electrochemical performance tests and related fitting data show that the presence of MnOx particles facilitates rapid Li+ transport and reduces the impedance associated with Li+ diffusion from the surface to the inner core of the MnOx/Si@C material. The two‐dimensional (2D) silicon flakes and uniform carbon shell have positive influence on structural stability and electronic conductivity. Benefit from the rational design, the optimized MnOx/Si@C composite delivers an outstanding cycling stability of 1106.59 mAh·g−1 at 1 A·g−1 over 1000 cycles with a capacity retention of 71.09%. Besides, the goal material possesses a lithium‐ion diffusion coefficient of ≈1.04×10−9 cm2·s−1. This work provides a reference for the mass preparation of advanced anode materials for lithium‐ion batteries. [ABSTRACT FROM AUTHOR]

The adsorption isotherms and intraparticle mass transfer coefficients of a novel adsorbent with various VOCs at different temperatures during the desorption process are investigated. Firstly, the adsorption isotherms of an HCP-5 adsorbent with o-xylene and ethyl acetate systems were determined at temperatures ranging from 30 to 160 °C, and the data were fitted using the Langmuir adsorption isotherm equation. Subsequently, a mathematical model for the fixed-bed desorption breakthrough of VOCs was established. By combining with fixed-bed desorption breakthrough experiments, the intraparticle mass transfer coefficients of o-xylene and ethyl acetate during the desorption process at different temperatures were obtained through the least squares method. This study revealed that the intraparticle mass transfer coefficients of o-xylene and ethyl acetate during the desorption process were basically equal. The intraparticle mass transfer coefficients increased and then decreased with temperature during the desorption process. Compared with the adsorption process, the contribution of surface diffusion inside the adsorbent pores to intraparticle mass transfer decreased during the desorption process, leading to a significant decrease in the intraparticle mass transfer coefficients, which were approximately one-twentieth of those during the adsorption process. [ABSTRACT FROM AUTHOR]

When preparing films through magnetron sputtering, atoms of the target material ejected during sputtering adhere, diffuse across the surface, condense, nucleate, and grow on the substrate surface, ultimately forming a film. However, due to the short time scales involved in this process, it is difficult to acquire detailed knowledge about the adsorption, surface diffusion, and film formation of target material atoms on the substrate surface in experimental settings. Therefore, this paper employs first-principles calculation methods to investigate the strongest adsorption sites, optimal diffusion paths, and the impact of diffusion distance of Ti atoms on the Fe(110) and Fe(100) surfaces on the film's microstructure. Through theoretical calculations, this study enriches the theoretical understanding of this process, providing a theoretical basis for the design and analysis of experimental schemes. The calculation results indicate that the adsorption energy of Ti atoms is the highest at the B sites on the Fe(100) surface. The diffusion barrier for Ti atoms on the Fe(100) surface is the lowest, making it easier for Ti atoms to diffuse on this surface. Under the condition of a relative substrate temperature labeled as T s / T m < 0.3 , the average diffusion distance of Ti atoms on the Fe(100) surface is the greatest, facilitating the formation of T-zone structures with superior mechanical properties. [ABSTRACT FROM AUTHOR]

We investigate diffusion in fluids near surfaces that may be coated with polymer films. We first consider diffusion in hard sphere fluids near a planar hard wall. We specifically consider color diffusion, where hard spheres are labeled A or B but are otherwise identical in all respects. In this inhomogeneous fluid, we consider a surface reaction–diffusion problem. At the left wall, a particle of species A is converted to one of species B upon a wall collision. At the opposing wall, the reverse reaction takes place: B → A. Using molecular dynamics simulation, we study the steady state of this system. We demonstrate that in the homogeneous region, a diffusing particle is subject to an equilibrium oscillatory force, the solvation force, that arises from the interfacial structuring of the fluid at the wall. For the hard sphere/hard wall system, the solvation force can be determined in various ways. We use the solvation force [the potential of mean force (PMF)] to solve the continuum diffusion equation. This provides an adequate and accurate description of the reaction–diffusion problem. The analysis is then extended to consider both color diffusion in the presence of a slowly varying one-body field such as gravity and a more applied problem of diffusion of free species through a surface film consisting of tethered chains. In both cases, the PMF experienced by the free particles is affected, but the diffusion problem can be treated in the same way as for the simpler hard sphere color diffusion case. [ABSTRACT FROM AUTHOR]

The theoretical investigation of gas adsorption, storage, separation, diffusion, and related transport processes in porous materials relies on a detailed knowledge of the potential energy surface of molecules in a stationary environment. In this article, a new algorithm is presented, specifically developed for gas transport phenomena, which allows for a highly cost-effective determination of molecular potential energy surfaces. It is based on a symmetry-enhanced version of Gaussian process regression with embedded gradient information and employs an active learning strategy to keep the number of single point evaluations as low as possible. The performance of the algorithm is tested for a selection of gas sieving scenarios on porous, N-functionalized graphene and for the intermolecular interaction of CH4 and N2. [ABSTRACT FROM AUTHOR]

The morphological evolution of nanoporous gold is generally believed to be governed by surface diffusion. This work specifically explores the dependence of mass transport by surface diffusion on the curvature of a gold surface. The surface diffusivity is estimated by molecular dynamics simulations for a variety of surfaces of constant mean curvature, eliminating any chemical potential gradients and allowing the possible dependence of the surface diffusivity on mean curvature to be isolated. The apparent surface diffusivity is found to have an activation energy of ∼0.74 eV with a weak dependence on curvature, but is consistent with the values reported in the literature. The apparent concentration of mobile surface atoms is found to be highly variable, having an Arrhenius dependence on temperature with an activation energy that also has a weak curvature dependence. These activation energies depend on curvature in such a way that the rate of mass transport by surface diffusion is nearly independent of curvature, but with a higher activation energy of ∼1.01 eV. The curvature dependencies of the apparent surface diffusivity and concentration of mobile surface atoms is believed to be related to the expected lifetime of a mobile surface atom, and has the practical consequence that a simulation study that does not account for this finite lifetime could underestimate the activation energy for mass transport via surface diffusion by ∼0.27 eV.

[Display omitted] • RuO 2 (1 1 0) surface is reported as an active catalyst for ethylene production from methane. • Diffusion of intermediates and ethylene desorption on RuO 2 (1 1 0) surface are facile. • The temperature of catalytic conversion of methane can be remarkably low as 200 K. • 100 % ethylene selectivity could be reached at low temperatures (300 – 450 K). Despite significant progress in low-temperature methane (CH 4) activation, commercial viability, specifically obtaining high yields of C 1 /C 2 products, remains a challenge. High desorption energy (>2 eV) and overoxidation of the target products are key limitations in CH 4 utilization. Herein, we employ first-principles density functional theory (DFT) and microkinetics simulations to investigate the CH 4 activation and the feasibility of its conversion to ethylene (C 2 H 4) on the RuO 2 (1 1 0) surface. The C H activation and CH 4 dehydrogenation processes are thoroughly investigated, with a particular focus on the diffusion of surface intermediates. The results show that the RuO 2 (1 1 0) surface exhibits high reactivity in CH 4 activation (E a = 0.60 eV), with CH 3 and CH 2 are the predominant species, and CH 2 being the most mobile intermediate on the surface. Consequently, self-coupling of CH 2 * species via C C coupling occurs more readily, yielding C 2 H 4 , a potential raw material for the chemical industry. More importantly, we demonstrate that the produced C 2 H 4 can easily desorb under mild conditions due to its low desorption energy of 0.97 eV. Microkinetic simulations based on the DFT energetics indicate that CH 4 activation can occur at temperatures below 200 K, and C 2 H 4 can be desorbed at room temperature. Further, the selectivity analysis predicts that C 2 H 4 is the major product at low temperatures (300–450 K) with 100 % selectivity, then competes with formaldehyde at intermediate temperatures in the CH 4 conversion over RuO 2 (1 1 0) surface. The present findings suggest that the RuO 2 (1 1 0) surface is a potential catalyst for facilitating ethylene production under mild conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • An electronic-ionic bi-functional conduction β-LPS/SG/Li 4.4 Sn was prepared for lithium anode skeleton. • Internally loaded Li 4.4 Sn has high Li binding energy and low nucleation overpotential. • Externally coated β-L 3 PS 4 has high ion conductivity and low Li+ activation energy. • The bi-functional framework guides Li deposition in the hollow SG, inhibits the dendrite growth and side reactions. • The anode has a long life of up to 2800 h, low overpotential (∼13 mV) and high coulomb efficiency of 99.8 % after 470 cycles. Although Li metal is considered the most potential anode for Li based batteries, the repeatedly large volume variation and low Coulombic efficiency (CE) are still serious challenges for commercial application. Herein, the interconnect closed hollow graphene spheres with electronic-ionic bi-functional conduction network containing Li 4.4 Sn nanoparticles loaded internally and β-Li 3 PS 4 solid electrolyte layer coated externally (β-LPS/SG/Li 4.4 Sn) is proposed to achieve uniform and dense Li deposition. Density functional theory (DFT) calculation and experimental results show that Li 4.4 Sn owns larger Li binding energy and lower nucleation overpotential than spherical graphene (SG), thus being able to guide Li traversing and depositing inside the hollow spheres. The Tafel curves, Li+ diffusion activation energy and experimental results reveal that the β-Li 3 PS 4 coating layer significantly improves the ionic conductivity of the negative skeleton, covers the defect sites on the SG surface, provides continuous ion transmission channels and accelerates Li+ migration rate. The synergy of both can inhibit the formation of dendritic Li and reduce side reaction between freshly deposited lithium and the organic electrolyte. It's found that Li is preferentially deposited within the SG, evenly deposited on the spherical shell surface until it's completely filled to obtain a dense lithium layer without tip effect. As a result, the β-LPS/SG/Li 4.4 Sn anode exhibits a long life of up to 2800 h, an extremely low overpotential (∼13 mV) and a high CE of 99.8 % after 470 cycles. The LiFePO 4 -based full cell runs stably with a high capacity retention of 86.93 % after 800 cycles at 1C. It is considered that the novel structure design of Li anode skeleton with electron-ionic bi-functional conduction is a promising direction to construct long-term stable lithium metal anodes. [ABSTRACT FROM AUTHOR]

The separation of He/H2 using membrane technology has gained significant interest in the field of He extraction from natural gas. One of the greatest challenges associated with this process is the extremely close kinetic diameters of the two gas molecules, resulting in low membrane selectivity. In this study, we investigated the structure-performance relationship of metal-organic framework (MOF) membranes for He/H2 separation through molecular simulations and machine learning approaches. By conducting molecular simulations, we identified the potential MOF membranes with high separation performance from the Computation-Ready Experimental (CoRE) MOF database, and the diffusion-dominated mechanism was further elucidated. Moreover, random forest (RF)- based machine learning models were established to identify the crucial factors influencing the He/H2 separation performance of MOF membranes. The pore limiting diameter (PLD) and void fraction (), are revealed as the most important physical features for determining the membrane selectivity and He permeability, respectively. Additionally, density functional theory (DFT) calculations were carried out to validate the molecular simulation results and suggested that the electronegative atoms on the pore surfaces can enhance the diffusion-based separation of He/H2, which is critical for improving the membrane selectivities of He/H2. This study offers useful insights for designing and developing novel MOF membranes for the separation of He/H2 at the molecular level. [ABSTRACT FROM AUTHOR]

Crystals with penta-twinned structures can be produced from diverse fcc metals, but the mechanisms that control the final product shapes are still not well understood. By using the theory of absorbing Markov chains to account for the growth of penta-twinned decahedral seeds via atom deposition and surface diffusion, we predicted the formation of various types of products: decahedra, nanorods, and nanowires. We showed that the type of product depends on the morphology of the seed and that small differences between various seed morphologies can lead to significantly different products. For the case of uncapped decahedra seeds, we compared predictions from our model to nanowire morphologies obtained in two different experiments and obtained favorable agreement. Possible extensions of our model are indicated. [ABSTRACT FROM AUTHOR]

Computational predictions of the polymorphic outcomes of a crystallization process, referred to as polymorph selection, can accelerate the process development for manufacturing solid products with targeted properties. Polymorph selection requires understanding the interplay between the thermodynamic and kinetic factors that drive nucleation. Moreover, post-nucleation events, such as crystal growth and polymorphic transformation, can affect the resulting crystal structures. Here, the nucleation kinetics of the Lennard-Jones (LJ) fluid from the melt is investigated with a focus on the competition between FCC and HCP crystal structures. Both molecular dynamics (MD) simulations and 2D free energy calculations reveal that polymorph selection occurs not during nucleation but when the cluster sizes exceed the critical cluster size. This result contrasts with the classical nucleation mechanism, where each polymorph is assumed to nucleate independently as an ideal bulk-like cluster, comprised only of its given structure. Using the 2D free energy surface and the MD simulation-derived diffusion coefficients, a structure-dependent nucleation rate is estimated, which agrees with the rate obtained from brute force MD simulations. Furthermore, a comprehensive population balance modeling (PBM) approach for polymorph selection is proposed. The PBM combines the calculated nucleation rate with post-nucleation kinetics while accounting for the structural changes of the clusters after nucleation. When applied to the LJ system, the PBM predicts with high accuracy the polymorphic distribution found in a population of crystals generated from MD simulations. Due to the non-classical nucleation mechanism of the LJ system, post-nucleation kinetic events are crucial in determining the structures of the grown crystals. [ABSTRACT FROM AUTHOR]