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Hydraulic energy is a key component of the global energy mix, yet there exists no practical way of harvesting it at small scales, from flows with low Reynolds number. This has triggered a search for alternative hydroelectric conversion methodologies, leading to unconventional proposals based on droplet triboelectricity, water evaporation, osmotic energy, or flow-induced ionic Coulomb drag. Yet, these approaches systematically rely on ions as intermediate charge carriers, limiting the achievable power density. Here, we predict that the kinetic energy of small-scale “waste” flows can be directly and efficiently converted into electricity thanks to the hydroelectronic drag effect, by which an ion-free liquid induces an electronic current in the solid wall along which it flows. This effect originates in the fluctuation-induced coupling between fluid motion and electron transport. We develop a nonequilibrium thermodynamic formalism to assess the efficiency of such hydroelectric energy conversion, dubbed hydronic energy. We find that hydronic energy conversion is analogous to thermoelectricity, with the efficiency being controlled by a dimensionless figure of merit. However, in contrast to its thermoelectric analogue, this figure of merit combines independently tunable parameters of the solid and the liquid, and can thus significantly exceed unity. Our findings suggest strategies for blue energy harvesting without electrochemistry, and for waste flow mitigation in membrane-based filtration processes. [ABSTRACT FROM AUTHOR]

Water motion‐induced energy harvesting has emerged as a prominent means of facilitating renewable electricity from the interaction between nanostructured materials and water over the past decade. Despite the growing interest, comprehension of the intricate solid–liquid interfacial phenomena related to solid state physics remains elusive and serves as a hindrance to enhancing energy harvesting efficiency up to the practical level. Herein, the study introduces the energy harvester by utilizing inversion on the majority charge carrier in graphene materials upon interaction with water molecules. Specifically, various metal electrode configurations are employed on reduced graphene oxide (rGO) to unravel its distinctive charge carriers that experience the inversion in semiconductor type upon water contact, and exploit this characteristic to leverage the efficacy of generated electricity. Through the strategic arrangement of the metal electrodes on rGO membrane, the open‐circuit voltage (Voc) and short‐circuit current (Isc) have exhibited a remarkable augmentation, reaching 1.05 V and 31.6 µA, respectively. The demonstration of effectively tailoring carrier dynamics via electrode configuration expands the practicality by achieving high power density and elucidating how the water‐induced carrier density modulation occurs in 2D nanomaterials. [ABSTRACT FROM AUTHOR]

Nanoscale materials often undergo structural, morphological, or chemical changes, especially in solution processes, where heterogeneity and defects may significantly impact the transformation pathways. Liquid phase transmission electron microscopy (TEM), allowing us to track dynamic transformations of individual nanoparticles, has become a powerful platform to reveal nanoscale materials transformation pathways and address challenging issues that are hard to approach by other methods. With the development of modern liquid cells, implementing advanced imaging and image analysis methods, and strategically exploring diverse systems, significant advances have been made in liquid phase TEM, including improved high-resolution imaging through liquids at the atomic level and remarkable capabilities in handling complex systems and reactions. In the past more than a decade, we spent much effort in developing and applying liquid phase TEM to elucidate how atomic level heterogeneity and defects impact various physicochemical processes in liquids, such as growth, self-assembly of nanoparticles, etching/corrosion, electrodeposition of alkali metals, catalyst restructuring during reactions, and so on. This article provides a brief review of the liquid phase TEM study of nanoscale materials transformations, focusing on the growth of nanomaterials with distinct shape/hierarchical structures, such as one-dimensional (1D) growth by nanoparticle attachment, two-dimensional (2D) growth with nanoparticles as intermediates, core-shell structure ripening, solid-liquid interfaces including those in batteries and electrocatalysis, highlighting the impacts of heterogeneity and defects on broad nanoscale transformation pathways. [ABSTRACT FROM AUTHOR]

Understanding the role of surface morphology and molecular structure interface thermal transport is essential for designing thermal management materials. In the present work, models of solid–liquid interfaces were created by placing liquid n-alkane between two platinum crystals. The effect of different levels of crystal surface roughness–flat, small, and large-scale grooves–and polymer chain lengths, under varying solid–liquid affinity, on the interface thermal resistance (ITR) were assessed using non-equilibrium molecular dynamics simulations. The overall trend confirmed that grooved surfaces have higher ITR than flat surfaces at low affinity, and lower ITR values were observed at high affinity. Large grooves enabled more favourable polymer orientations than those of small grooves, resulting in a smaller ITR. However, long chains did not facilitate heat transfer normal to the interface because they preferentially aligned parallel to it. For efficient heat transfer, a balance between the roughness scale and polymer length must be considered. [ABSTRACT FROM AUTHOR]

Strong metal‐support interaction (SMSI) plays a vital role in tuning the geometric and electronic structures of metal species. Generally, a high‐temperature treatment (>500 °C) in reducing atmosphere is required for constructing SMSI, which may induce the sintering of metal species. Herein, we use molten salts as the reaction media to trigger the formation of high‐intensity SMSI at reduced temperatures. The strong ionic polarization of the molten salt promotes the breakage of Ti−O bonds in the TiO2 support, and hence decreases the energy barrier for the formation of interfacial bonds. Consequently, a high‐intensity SMSI state is achieved in TiO2 supported Ir nanoclusters, evidenced by a large number of Ir−Ti bonds at the interface, at a low temperature of 350 °C. Moreover, this method is applicable for triggering SMSI in various supported metal catalysts with different oxide supports including CeO2 and SnO2. This newly developed SMSI construction methodology opens a new avenue and holds significant potential for engineering advanced supported metal catalysts toward a broad range of applications. [ABSTRACT FROM AUTHOR]

The boundary slip condition is pivotal for nanoscale fluid motion. Recent research has primarily focused on simulating the interaction mechanism between the electronic structure of two-dimensional materials and slip of water at the nanoscale, raising the possibility for ultralow friction flow of water at the nanoscale. However, experimentally elucidating electronic interactions at the dynamic solid–liquid interface to control boundary slip poses a significant challenge. In this study, the crucial role of electron structures at the dynamic solid–liquid interface in regulating slip length was revealed. Notably, the slip length of water on the molybdenum disulfide/graphene (MoS2/G) heterostructure (100.9 ± 3.6 nm) significantly exceeded that of either graphene (27.7 ± 2.2 nm) or MoS2 (5.7 ± 3.1 nm) alone. It was also analyzed how electron transfer significantly affected interface interactions. Excess electrons played a crucial role in determining the type and proportion of excitons at both MoS2–water and MoS2/G–water interfaces. Additionally, by applying voltage, distinct photoluminescence (PL) responses at static and dynamic interfaces were discovered, achieving a 5-fold modulation in PL intensity and a 2-fold modulation in the trion to exciton intensity ratio. More electrons transfer from the top graphene to the bottom MoS2 at the MoS2/G–water interface, reducing surface charge density. Thus, the reduction of electrostatic interactions between the solid and water leads to an increased slip length of water on the MoS2/G heterostructure. The process aids in comprehending the origin of frictional resistance at the subatomic scale. This work establishes a foundation for actively controlling and designing of fluid transport at the nanoscale. [ABSTRACT FROM AUTHOR]

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In this work, the advantage of Coulomb repulsion in the intermolecular forces experienced by molecules on the solid-liquid nanosized contact interface is taken, and the superior friction-reducing property of Cu3(PO4)2·3H2O (CuP) oil-based additives has been confirmed for titanium alloy. Three-dimensional (3D) CuP nanoflowers (CuP-Fs) with a strong capillary absorption effect are prepared to achieve the homogeneous mixing of solid CuP and lubricating oil. Lubrication by CuP-Fs additives for titanium alloy, friction coefficient (COF) can be reduced by 73.68%, and wear rate (WR) reduced by 99.69%. It is demonstrated that the extraordinary friction-reducing property is due to the repulsive solid-liquid interface with low viscous shear force originating from Coulomb repulsion between polar water molecules in CuP and non-polar oil molecules. However, any steric hindrance or connection between this repulsive solid-liquid interface will trigger the adhesion and increase the viscous shear force, for example, dispersant, hydrogen bondings, and shaky adsorbed water molecules. Besides, the lamellar thickness of CuP and the molecular size of lubricant both have a great influence on tribological properties. Here the lubrication mechanism based on interface Coulomb repulsion is proposed that may help broaden the scope of the exploration in low-friction nanomaterial design and new lubricant systems. [ABSTRACT FROM AUTHOR]

Abstract Water motion‐induced energy harvesting has emerged as a prominent means of facilitating renewable electricity from the interaction between nanostructured materials and water over the past decade. Despite the growing interest, comprehension of the intricate solid–liquid interfacial phenomena related to solid state physics remains elusive and serves as a hindrance to enhancing energy harvesting efficiency up to the practical level. Herein, the study introduces the energy harvester by utilizing inversion on the majority charge carrier in graphene materials upon interaction with water molecules. Specifically, various metal electrode configurations are employed on reduced graphene oxide (rGO) to unravel its distinctive charge carriers that experience the inversion in semiconductor type upon water contact, and exploit this characteristic to leverage the efficacy of generated electricity. Through the strategic arrangement of the metal electrodes on rGO membrane, the open‐circuit voltage (Voc) and short‐circuit current (Isc) have exhibited a remarkable augmentation, reaching 1.05 V and 31.6 µA, respectively. The demonstration of effectively tailoring carrier dynamics via electrode configuration expands the practicality by achieving high power density and elucidating how the water‐induced carrier density modulation occurs in 2D nanomaterials.

In-situ electrochemical Raman spectroscopy measures the relationship between the Raman spectrum signal and the electrode's potential or current intensity, by utilizing the scattering phenomenon of the substance molecules induced by the incident light. It can provide molecular-level structural information about the electrode's surface（interface）. This technology enables the acquisition of molecular vibrational information and real-time monitoring of structural information related to chemical reactions at the electrochemical interface, making it widely applicable in the field of material interface characterization. Starting from the principle of in-situ electrochemical Raman spectroscopy, this paper comprehensively describes the progress of in situ electrochemical Raman spectroscopy based on rough metal electrodes in solid-liquid interface analysis, such as molecular adsorption, oxygen evolution, hydrogen evolution, and oxygen reduction reaction. Furthermore, this paper explores the relationship between the interface structure, reaction processes, catalytic intermediates, and the Raman signal intensity. The catalytic process reaction mechanism and the catalytic mechanism of the catalytic material were presented. Lastly, an outlook was provided on the scientific challenges pertaining to insitu electrochemical Raman spectroscopy at solid-liquid interfaces in the subsequent phase. [ABSTRACT FROM AUTHOR]

High-purity copper is essential for fabricating advanced microelectronic devices, particularly integrated circuit interconnects. As the industry increasingly emphasizes scalable and efficient purification methods, this study investigates the multi-physics interactions during the semi-continuous directional solidification process, utilizing a Cu-1 wt.%Ag model alloy. Coupled simulation calculations examine the spatial distribution patterns of the impurity element silver (Ag) within semi-continuously solidified ingots under varying pulling rates and melt temperatures. The objective is to provide technical insights into the utilization of the semi-continuous directional solidification method for high-purity copper purification. The findings reveal that increasing the pulling rate and melt temperature leads to a downward shift in the solid–liquid interface relative to the mold top during processing. Alongside the primary clockwise vortex flow, a secondary weak vortex emerges near the solid–liquid interface, facilitating the migration of the impurity element Ag toward the central axis and amplifying radial impurity fluctuations. Furthermore, diverse pulling rates and melt temperature conditions unveil a consistent trend along the ingot's height, which is characterized by an initial increase in average Ag content, followed by stabilization and then a rapid ascent during the late stage of solidification, with higher pulling rates and melt temperatures expediting this rapid ascent. Leveraging these insights, a validation experiment using 4N-grade recycled copper in a small-scale setup demonstrates the effectiveness of the semi-continuous directional solidification process for high-purity copper production, with copper samples extracted at 1/4 and 3/4 ingot heights achieving a 5N purity level of 99.9994 wt.% and 99.9993 wt.%, respectively. [ABSTRACT FROM AUTHOR]

In this study, molecular dynamics (MD) simulations were employed to elucidate the processes and underlying mechanisms that govern the adsorption and accumulation of gas (represented by N2) at the hydrophobic solid–liquid interface, using the GROMACS program with an AMBER force field. Our findings indicate that, regardless of surface roughness, the presence of water molecules is a prerequisite for the adsorption and aggregation of N2 molecules on solid surfaces. N2 molecules dissolved in water can cluster even without a solid substrate. In the gas–solid–liquid system, the exclusion of water molecules at the hydrophobic solid–liquid interface and the adsorption of N2 molecules do not occur simultaneously. A loosely arranged layer of water molecules is initially formed on the hydrophobic solid surface. The two-stage process of N2 molecule adsorption and accumulation at the hydrophobic solid/liquid interface involves initial adsorption to the solid surface, displacing water molecules, followed by N2 accumulation via self-interaction after saturating the substrate's surface. The process and underlying mechanisms of gas adsorption and accumulation at hydrophobic solid/liquid interfaces elucidated in this study offer a molecular-level understanding of nano-gas layer formation. [ABSTRACT FROM AUTHOR]

Protocell models play a pivotal role in the exploration of the origin of life. Vesicles are one type of protocell model that have attracted much attention. Simple single-chain amphiphiles (SACs) and organic small molecules (OSMs) possess primitive relevance and were most likely the building blocks of protocells on the early Earth. OSM@SAC vesicles have been considered to be plausible protocell models. Pyrite (FeS2), a mineral with primitive relevance, is ubiquitous in nature and plays a crucial role in the exploration of the origin of life in the mineral–water interface scenario. "How do protocell models based on OSM@SAC vesicles interact with a mineral–water interface scenario that simulates a primitive Earth environment" remains an unresolved question. Hence, we select primitive relevant sodium monododecyl phosphate (SDP), isopentenol (IPN) and pyrite (FeS2) mineral particles to build a protocell model. The model investigates the basic physical and chemical properties of FeS2 particles and reveals the effects of the size, content and duration of interaction of FeS2 particles on IPN@SDP vesicles. This deepens the understanding of protocell growth mechanisms in scenarios of mineral–water interfaces in primitive Earth environments and provides new information for the exploration of the origin of life. [ABSTRACT FROM AUTHOR]

PbF2 single crystals are usually grown in the temperature gradient region by the Bridgman–Stockbarger method. Temperature distribution during the growth process is particularly important for the preparation of high-quality crystals. In this study, the temperature field during the growth of the PbF2 single crystals was simulated based on the finite element method. The temperature distribution and temperature gradient changes in the crucible were investigated at different growth stages, including the seeding, shouldering, and iso-diameters stages. The calculated results show that as the crucible position continues downward during the growth process, the axial temperature gradient increases and then decreases from the bottom to the top of the crucible, with almost flat isotherms near the solid–liquid interface where the axial temperature gradient is larger. At the shoulder below the crucible, the solid–liquid interface was improved by adjusting the tilt angle. Furthermore, based on a novel design of the heat-insulating baffle, the concave solid–liquid interface in the iso-diameter stage can be effectively adjusted to realize a lower radial temperature gradient. This study provides theoretical guidance for the optimization of the growth of high-quality PbF2 crystals by the Bridgman method. [ABSTRACT FROM AUTHOR]

The roles of surface characteristics of the feldspar surface on ice nucleation have remained elusive. Here, simple strategies are reported to quantitatively analyze the effects of the surface morphology and molecular composition of the potassium‐feldspar surface on ice nucleation. The steps are found to be responsible to the high ice nucleation efficacy according to the fact that water drop freezing temperature increases by about 4.5 °C atop the freshly cleavage feldspar surface being rich of steps comparing to the flattened ones. After the molecular component and atomic structure are destroyed by the fluorination, a tremendous decrease of the ice nucleation temperatures by around 9.0 °C is observed on both cleavage and flattened surfaces, and the steps still improve the ice nucleation activity of the hydrophobic cleavage surfaces. The influence of the surface composition also implies the importance of the molecular component and structure specificity on K‐feldspar in facilitating ice nucleation. [ABSTRACT FROM AUTHOR]

Within the kinetic-atomistic approach, a new approach is proposed for constructing the temperature dependence of the stationary velocity of propagation of the solid–liquid interface (SLI) in metals: aluminum, copper, and iron with different crystallographic orientations. The considered temperature range includes the range of maximum allowable overheating/overcooling values for each of the metals. A significant modification to the well-known kinetic model with the Wilson–Frenkel (WF) diffusion constraint, which is used to construct the response function, is made. An atomistic simulation of the processes of melting/crystallization of metals aluminum, copper, and iron is carried out over the entire temperature range using three interaction potentials of the "embedded atom" family. By comparing the simulation results with the data of the modified kinetic model, the response function of the interface velocity in the range of maximum allowable overheating/overcooling values in metals is constructed using the least squares criterion. The use of the modified WF kinetic model in calculations significantly improves the accuracy of the response function over the considered temperature range. The resulting temperature dependence of the interface velocity is diffusion-limited and is described by the same equation for each metal over the considered temperature range. [ABSTRACT FROM AUTHOR]

The nanoscale structure and dynamics of proteins on surfaces has been extensively studied using various imaging techniques, such as transmission electron microscopy and atomic force microscopy (AFM) in liquid environments. These powerful imaging techniques, however, can potentially damage or perturb delicate biological material and do not provide chemical information, which prevents a fundamental understanding of the dynamic processes underlying their evolution under physiological conditions. Here, we use a platform developed in our laboratory that enables acquisition of infrared (IR) spectroscopy and AFM images of biological material in physiological liquids with nanometer resolution in a cell closed by atomically thin graphene membranes transparent to IR photons. In this work, we studied the self-assembly process of S-layer proteins at the graphene-aqueous solution interface. The graphene acts also as the membrane separating the solution containing the proteins and Ca2+ ions from the AFM tip, thus eliminating sample damage and contamination effects. The formation of S-layer protein lattices and their structural evolution was monitored by AFM and by recording the amide I and II IR absorption bands, which reveal the noncovalent interaction between proteins and their response to the environment, including ionic strength and solvation. Our measurement platform opens unique opportunities to study biological material and soft materials in general.

Oil film vortex severely reduces the stability of hydrostatic bearings. A solid-liquid interface with drag and slip properties can weaken the oil film vortex of the bearing. Here, a combined picosecond laser ablation and chemical modification method is proposed to prepare surfaces with microbulge array structure on 6061 aluminum alloy substrates. Because of the low surface energy of the perfluorododecyltriethoxysilane modification and the bulge geometry of the microbulge array structure, the surface shows excellent superhydrophobicity. The optimum contact angle in air for water is 164°, and that for oil is 139°. Two surfaces with "lotus-leaf effect" and "rose-petal effect" were obtained by controlling the processing parameters. The drag reduction properties of superhydrophobic surfaces were systematically investigated with slip lengths of 22.26 and 36.25 µm for deionized water and VG5 lubricant, respectively. In addition, the superhydrophobic surface exhibits excellent mechanical durability and thermal stability. The proposed method provides a new idea for vortex suppression in hydrostatic bearings and improves the stability of bearings in high-speed operation. [ABSTRACT FROM AUTHOR]

Zeta potential (ζ potential) is a significant parameter to characterize the electric property of the electric double layer (EDL), which is important at the solid–liquid interface. Non-uniform ζ potential could be developed on a chemically uniform solid–liquid interface due to external flow. However, its influence on the flow has never been concerned. In this investigation, we numerically studied the influence of non-uniform 2D ζ potential on the flow at the solid–liquid interface. It is found, that even without any external electric field and only considering the influence of 2D ζ potential distribution, swirling flow can be generated near EDL, according to the rotational electric volume force. The streamwise vortices, which are important in the turbulent boundary layer, are theoretically predicted in this laminar flow model when considering the 2D distribution of ζ potential, implying the necessity of considering the origin of streamwise vortices of the turbulent boundary layer from the perspective of electrokinetic flow. In addition, the ζ potential distribution can promote the wall shear stress. Therefore, more attention must be paid to shear-sensitivity circumstances, like biomedical, medical devices, and in vivo. We hope that the current investigation can help us to better understand the effect of charge distribution on interfacial flow and provide theoretical guidance for the development of related applications in the future. [ABSTRACT FROM AUTHOR]

Constructing uniform covalent organic framework (COF) film on substrates for electronic devices is highly desirable. Here, a simple and mild strategy is developed to prepare them by polymerization on a solid‐liquid interface. The universality of the method is confirmed by the successful preparation of five COF films with different microstructures. These films have large lateral size, controllable thickness, and high crystalline quality. And COF patterns can also be directly achieved on substrates via hydrophilic and hydrophobic interface engineering, which is in favor of preparing device array. For application studies, the PyTTA‐TPA (PyTTA: 4,4′,4′′,4′′′‐(1,3,6,8‐Tetrakis(4‐aminophenyl)pyrene and TPA: terephthalaldehyde) COF film has a high photoresponsivity of 59.79 μA W−1 at 420 nm for photoelectrochemical (PEC) detection. When employed as an active material for optoelectronic synaptic devices for the first attempt, it shows excellent light‐stimulated synaptic plasticity properties such as short‐term plasticity (STP), long‐term plasticity (LTP), and the conversion of STP to LTP, which can be used to simulate biological synaptic functions. [ABSTRACT FROM AUTHOR]

A three-dimensional multi-physics model of the effect of process parameters on the evolution of the solid–liquid interface during solidification of large-scale Ti-6 wt% Al-4 wt% V (TC4) alloy by[Ballantyne, 1977 #483] (VAR) and a macroscopic model of grain nucleation and growth was established. The simulation results qualitatively reveal the evolution of solid–liquid interface and central cross-sectional solidification structure under various melting conditions, indicating that the melting zone depth increased while the mushy zone width and the number of grains decreased with the increase of melting power; the depth of the melting zone and the width of the mushy zone increase sharply with the increase in solidification velocity, the average grain radius increased, while the number of grains decreased; when the ingot diameter increased from 260 mm to 660 mm, the depth of the melting zone increased and gradually remained stable, and the width of the mushy zone gradually decreased. [ABSTRACT FROM AUTHOR]

During the growth of Czochralski single crystal silicon, the change of solid–liquid interface shape leads to uneven distribution of thermal stress, and the concentration of thermal stress leads to crystal defects in the process of single crystal formation, which reduces the efficiency of solar cells. In order to avoid a large number of crystal defects caused by the concentration of thermal stress near the solid–liquid interface, the effect of the solid–liquid interface shape on thermal stresses is investigated in this study using numerical calculations to determine the most favourable solid–liquid interface shape for single crystal silicon growth. The results show that the von Mises stress on the m-shaped solid–liquid interface is smaller; von Mises stress distribution on the solid–liquid interface of a shape is more uniform; the von Mises stress on the solid–liquid interface of the n-shaped solid–liquid interface is large, and the von Mises stress can be released by controlling the solid–liquid flipping through a small range of pulling speed fluctuations, thereby reducing defects in single-crystal silicon. [ABSTRACT FROM AUTHOR]

Reaction intermediates buried within a solid-liquid interface are difficult targets for physiochemical measurements. They are inherently molecular and locally dynamic, while their surroundings are extended by a periodic lattice on one side and the solvent dielectric on the other. Challenges compound on a metal-oxide surface of varied sites and especially so at its aqueous interface of many prominent reactions. Recently, phenomenological theory coupled with optical spectroscopy has become a more prominent tool for isolating the intermediates and their molecular dynamics. The following article reviews three examples of the SrTiO3-aqueous interface subject to the oxygen evolution from water: reaction-dependent component analyses of time-resolved intermediates, a Fano resonance of a mode at the metal-oxide–water interface, and reaction isotherms of metastable intermediates. The phenomenology uses parameters to encase what is unknown at a microscopic level to then circumscribe the clear and macroscopically tuned trends seen in the spectroscopic data. [ABSTRACT FROM AUTHOR]

Free energies of a solid surface and a solid–liquid interface play significant roles in thermodynamics. Due to the limited availability of experimental data, computational methods offer effective alternatives for calculating these properties. This study adopts advanced frameworks of the logarithmic mean force dynamics method to present an enhanced sampling approach for the calculation of the free energy at different temperatures. To achieve this, the free energy profile is constructed along with a pre‐established collective variable within the melting transition and cleavage processes. The values of the solid surface and solid–liquid interface free energies are then extrapolated from the excess free energy related to the formation and persistence of the solid surface or the solid–liquid interface. Furthermore, this methodology is employed to calculate the temperature dependence of the free energy measurements for the (100) and (110) surfaces and interfaces of Cu. It is shown that this methodology is robust and readily applicable in contemporary models of atomic interactions and various systems. [ABSTRACT FROM AUTHOR]

A system of steady lamellar eutectic growth in directional solidification is considered with the case of small tangent values of the contact angles. The mathematical model is given in the non-dimensional rectangular coordinate system and the uniformly valid asymptotic solutions are obtained based on the method of the asymptotic expansions. The necessary condition for existing asymptotic solutions was obtained. The results indicate that the curvature undercooling and the solute undercooling determined the patterns of the solid–liquid interface. The dimensional average undercooling presents a relationship with eutectic spacing and pulling velocity. It can be seen that the dimensional average undercooling in front of both phases is not equal, and the total average undercooling as a function of the lamellar eutectic spacing exhibits a minimum. The minimum undercooling spacing decreases with an increase in the pulling velocity, which is in good agreement with Jackson and Hunt's results. [ABSTRACT FROM AUTHOR]

The present study focuses on the computation of the distribution of local solid–liquid interfacial thermal resistances (ITRs) at a solid–liquid interface with a nanostructured surface, at a spatial resolution of 1.96 10-1nm based on the non-equilibrium molecular dynamics method. As a calculation parameter, three different interaction strengths between the solid atoms and the liquid molecules were employed to reproduce the hydrophobic and hydrophilic conditions. In our calculation system, liquid molecules occupy the gap between the sidewalls of the nanostructure. We showed that the combined interfacial thermal resistance calculated from the local ITRs agrees with the overall ITR. We investigated the spatial distribution of the local ITRs via spectral analysis. The results showed that the local ITRs increased at the bottom corners and decreased at the top corners of the nanostructure. When the interaction parameter between the solid atoms and the liquid molecules is large, we find evidence of adsorption of liquid molecules on the solid, which causes fluctuations of the local ITR. The local vibrational states of the solid atoms and liquid molecules varied at each local interface. The local ITRs were negatively correlated with the overlaps of these vibrational densities of states, implying that each local vibrational state is one of the factors that determines the corresponding local ITR. In addition, the peak frequencies of the local spectral heat flux agreed with those of the vibrational density of states. These results indicate that the vibrational states of the solid atoms are dominant factors in the vibrational properties of the thermal transport across the local solid–liquid interfaces.

The invention of triboelectric nanogenerators (TENGs) provides an effective approach to the sustainable power of energy. Liquid-solid interface-based TENGs have been researched in virtue of less friction for harvesting energy from raindrops, rivers, and oceans in the form of water flows. However, TENGs based on droplet tubes have been rarely investigated. In this study, we proposed a new droplet tube-based TENG (DT-TENG) with free-standing and reformative grating electrodes. Both straight and curved DT-TENGs have been designed and fabricated including straight and curved TENG at different inclination angles. The electric properties of DT-TENGs have been evaluated and different materials and hydrophobicity treatments for the tubes have been studied. Initial studies on different liquids demonstrated significant electricity output differences to recognize polar and nonpolar solvents. This DT-TENG was also made into a smart fishing float that can recognize different movement speeds brought about by different weights and generate corresponding electric signals to remind the angler. Furthermore, flexible PVC helix TENG demonstrated similar performance under both straight and helix situations. This study provides a foundation and academic insight into the design and fabrication of droplets based TENGs for energy harvesting in smart cities.

In this work, the interface characteristics between alumina and the steel liquid with different sulfur and oxygen concentrations were measured by an improved sessile drop method. And the behavior of alumina inclusions in front of the solid–liquid interface of steel liquid with different oxygen and sulfur concentrations was investigated by in-situ observation. Furthermore, the behavior of alumina particles in front of the solid–liquid interface on the surface of the steel liquid was discussed from the interface characteristics between alumina and the steel liquid with different sulfur and oxygen concentrations based on the interface gradient force, coulombic force, and Marangoni effect viewpoints. The results show that the large and small inclusion particles were engulfed and pushed, respectively, at the interface of solid–liquid, while the critical average radius for engulfed inclusion particles decreased from 7.73 μm to 6.21 μm and 4.84 μm, respectively, with sulfur and oxygen concentrations increasing. And the behavior can be described by a function formula concerning the interface characteristics between alumina and the steel liquid with the different sulfur and oxygen concentrations based on the interface gradient force, coulombic force, and Marangoni effect viewpoints. Further, it is found that the aggregation ability due to capillary force is weakened and even dispersed at the solid–liquid interface, which leads to the inclusion being easily pushed away from the front of the solid–liquid interface with the increase in sulfur and oxygen concentrations.

The adsorption mechanism of different polymers containing ionic polyamino acids monomers in the chain structure at the solid–liquid interface was investigated. Initially, the influence of molecular weight and solution pH on simple polyamino acids (poly(L-aspartic acid) and poly(L-lysine) binding was determined. Considering the obtained dependencies, the polymer adsorption layer conformation was proposed in the systems containing block copolymers (both diblock and symmetrical triblock) consisting of polypeptide as well as poly(ethylene glycol) fragments. The presented studies focused on the application of two experimental methods. The polymer adsorption was carried out using the batch method and the adsorbate concentration was determined spectrophotometrically. Then, the turbidimetric measurements were taken. The analysis of the obtained results showed that the adsorption process of block copolymers depends on two factors. Firstly, the solution pH determines both the nature of the interactions of the copolymer structural units with the solid surface and the conformation of the polypeptide chains. The second parameter influencing the adsorption layer structure is the ratio of the lengths of both blocks. Introducing a short PEG fragment into the polymer main chain may improve the polymer adsorption properties by increasing the number of interactions with the adsorbent surface. [ABSTRACT FROM AUTHOR]

Friction is a fundamental force that impacts almost all interface-related applications. Over the past decade, there is a revival in our basic understanding and practical applications of the friction. In this review, we discuss the recent progress on solid-liquid interfacial friction from the perspective of interfaces. We first discuss the fundamentals and theoretical evolution of solid-liquid interfacial friction based on both bulk interactions and molecular interactions. Then, we summarize the interfacial friction regulation strategies manifested in both natural surfaces and artificial systems, focusing on how liquid, solid, gas, and hydrodynamic coupling actions mediate interfacial friction. Next, we discuss some practical applications that are inhibited or reinforced by interfacial friction. At last, we present the challenges to further understand and regulate interfacial friction. [ABSTRACT FROM AUTHOR]

The Fenton method to remediate oil-contaminated soils has long suffered from low utilization of ·OH, resulting in waste of costs during practical application. This study investigated the efficient utilization of ·OH in oxidation using three different soils contaminated with oil (S1, S2, and S3). The mechanisms of promoting oxidation of long-chain alkanes by self-produced surfactant-like substance at the solid-liquid interface were studied. These results (take S1 as an example) showed that the average ·OH utilization rate of oxidized long-chain alkanes (Ka) at the solid-liquid interface reached 88.34 (mg/kg∙(a.u.)), which was higher than the non-solid-liquid interface stage (I: 54.02 (mg/kg∙(a.u.)), II: 67.36 (mg/kg∙(a.u.))). Meanwhile, the average oxidation of long-chain alkanes could increase unit ·OH intensity added (Kb) in the solid-liquid interface (990.00 mg/kg), which was much higher than Kb of the non-solid-liquid interface stage (I: 228.34 mg/kg, II: −1.48 mg/kg). Furthermore, there was a significant correlation between the proportion of humic acid-like in soil organic matter and the oxidation of long-chain alkanes at the solid-liquid interface. Thus, the surfactant-like substance generated during oxidation promoted the oxidation of long-chain alkanes at the solid-liquid interface. Moreover, when the surfactant-like substance had a matching degree (φ) with the long-chain alkanes (S1 0.18, S2 0.15, and S3 0.25), the efficiency of the ·OH utilization reached the peak, and the direct oxidation of long-chain alkanes at the solid-liquid interface was finally achieved (S1: 1373.00 mg/kg, S2: 1473.18 mg/kg, and S3: 1034.37 mg/kg). The appropriate surfactant-like substance agents in the construction can reduce the dosing of H2O2 and the construction costs by improving the efficient utilization of ·OH. Study on the mechanism promoting oxidation of long-chain alkanes by self-produced surfactant-like substance at the solid-liquid interface. [ABSTRACT FROM AUTHOR]

The rational design of electrocatalysis has emerged as one of the most thriving means for mitigating energy and environmental crises. The key to this effort is the understanding of the complex electrochemical interface, wherein the electrode potential as well as various internal factors such as H‐bond network, adsorbate coverage, and dynamic behavior of the interface collectively contribute to the electrocatalytic activity and selectivity. In this context, the authors have reviewed recent theoretical advances, and especially, the contributions to modeling the realistic electrocatalytic processes at complex electrochemical interfaces, and illustrated the challenges and fundamental problems in this field. Specifically, the significance of the inclusion of explicit solvation and electrode potential as well as the strategies toward the design of highly efficient electrocatalysts are discussed. The structure‐activity relationships and their dynamic responses to the environment and catalytic functionality under working conditions are illustrated to be crucial factors for understanding the complexed interface and the electrocatalytic activities. It is hoped that this review can help spark new research passion and ultimately bring a step closer to a realistic and systematic modeling method for electrocatalysis. [ABSTRACT FROM AUTHOR]

Composite phase change materials with sugar alcohol as the phase change material and highly thermally conductive ceramics as the porous skeleton are widely used in various thermal storage systems. The interfacial thermal conductance (ITC) between the phase change materials under different phases and the skeleton is an important factor affecting the rate of heat storage (release) in thermal storage systems. The ITC between ceramics(AlN, SiC) and sugar alcohols (mannitol and galactitol) in the solid and liquid states is investigated by means of both time-domain thermoreflectance and molecular dynamics simulations. The results show that the ITC between phase change materials and ceramic is better in liquid state than in solid state, and that the ITC between mannitol and ceramic is better, and that the ITC betweenAlN and sugar alcohol is better. More low-frequency phonons are involved in the thermal transport of the sugar alcohols in the liquid state, with an average overlap energy of about 9.5% higher than that of the solid state and an average phonon participation rate of about 6.8% higher. It was also found that it isthe H atom in the sugar alcohol that is linked to the C atom that governs the ITC. [ABSTRACT FROM AUTHOR]

A mathematical model is developed that makes it possible, within the framework of a single phenomenological approach, to investigate the stability of a planar phase boundary during directional solidification of binary alloy, taking into account the effect of a density change and heat transfer in the solid phase. The study reveals a complex picture of alternating areas of stability and instability, which is sensitive to changes in parameters of growth and temperature gradient at the interface. Areas of instability are formed by the development of a set of disturbances of different frequencies and rates of propagations. As shown, the irreducible liquid-phase flow caused by density change plays a major role in the loss of stability of the solidification front and is realized for perturbations with any wave number k > 0.

High-purity copper is essential for fabricating advanced microelectronic devices, particularly integrated circuit interconnects. As the industry increasingly emphasizes scalable and efficient purification methods, this study investigates the multi-physics interactions during the semi-continuous directional solidification process, utilizing a Cu-1 wt.%Ag model alloy. Coupled simulation calculations examine the spatial distribution patterns of the impurity element silver (Ag) within semi-continuously solidified ingots under varying pulling rates and melt temperatures. The objective is to provide technical insights into the utilization of the semi-continuous directional solidification method for high-purity copper purification. The findings reveal that increasing the pulling rate and melt temperature leads to a downward shift in the solid–liquid interface relative to the mold top during processing. Alongside the primary clockwise vortex flow, a secondary weak vortex emerges near the solid–liquid interface, facilitating the migration of the impurity element Ag toward the central axis and amplifying radial impurity fluctuations. Furthermore, diverse pulling rates and melt temperature conditions unveil a consistent trend along the ingot’s height, which is characterized by an initial increase in average Ag content, followed by stabilization and then a rapid ascent during the late stage of solidification, with higher pulling rates and melt temperatures expediting this rapid ascent. Leveraging these insights, a validation experiment using 4N-grade recycled copper in a small-scale setup demonstrates the effectiveness of the semi-continuous directional solidification process for high-purity copper production, with copper samples extracted at 1/4 and 3/4 ingot heights achieving a 5N purity level of 99.9994 wt.% and 99.9993 wt.%, respectively.

Protocell models play a pivotal role in the exploration of the origin of life. Vesicles are one type of protocell model that have attracted much attention. Simple single-chain amphiphiles (SACs) and organic small molecules (OSMs) possess primitive relevance and were most likely the building blocks of protocells on the early Earth. OSM@SAC vesicles have been considered to be plausible protocell models. Pyrite (FeS2), a mineral with primitive relevance, is ubiquitous in nature and plays a crucial role in the exploration of the origin of life in the mineral–water interface scenario. “How do protocell models based on OSM@SAC vesicles interact with a mineral–water interface scenario that simulates a primitive Earth environment” remains an unresolved question. Hence, we select primitive relevant sodium monododecyl phosphate (SDP), isopentenol (IPN) and pyrite (FeS2) mineral particles to build a protocell model. The model investigates the basic physical and chemical properties of FeS2 particles and reveals the effects of the size, content and duration of interaction of FeS2 particles on IPN@SDP vesicles. This deepens the understanding of protocell growth mechanisms in scenarios of mineral–water interfaces in primitive Earth environments and provides new information for the exploration of the origin of life.

In this study, molecular dynamics (MD) simulations were employed to elucidate the processes and underlying mechanisms that govern the adsorption and accumulation of gas (represented by N2) at the hydrophobic solid–liquid interface, using the GROMACS program with an AMBER force field. Our findings indicate that, regardless of surface roughness, the presence of water molecules is a prerequisite for the adsorption and aggregation of N2 molecules on solid surfaces. N2 molecules dissolved in water can cluster even without a solid substrate. In the gas–solid–liquid system, the exclusion of water molecules at the hydrophobic solid–liquid interface and the adsorption of N2 molecules do not occur simultaneously. A loosely arranged layer of water molecules is initially formed on the hydrophobic solid surface. The two-stage process of N2 molecule adsorption and accumulation at the hydrophobic solid/liquid interface involves initial adsorption to the solid surface, displacing water molecules, followed by N2 accumulation via self-interaction after saturating the substrate’s surface. The process and underlying mechanisms of gas adsorption and accumulation at hydrophobic solid/liquid interfaces elucidated in this study offer a molecular-level understanding of nano-gas layer formation.

PbF2 single crystals are usually grown in the temperature gradient region by the Bridgman–Stockbarger method. Temperature distribution during the growth process is particularly important for the preparation of high-quality crystals. In this study, the temperature field during the growth of the PbF2 single crystals was simulated based on the finite element method. The temperature distribution and temperature gradient changes in the crucible were investigated at different growth stages, including the seeding, shouldering, and iso-diameters stages. The calculated results show that as the crucible position continues downward during the growth process, the axial temperature gradient increases and then decreases from the bottom to the top of the crucible, with almost flat isotherms near the solid–liquid interface where the axial temperature gradient is larger. At the shoulder below the crucible, the solid–liquid interface was improved by adjusting the tilt angle. Furthermore, based on a novel design of the heat-insulating baffle, the concave solid–liquid interface in the iso-diameter stage can be effectively adjusted to realize a lower radial temperature gradient. This study provides theoretical guidance for the optimization of the growth of high-quality PbF2 crystals by the Bridgman method.

Real-time monitoring of oxygen species during the oxygen evolution reaction (OER) on cobalt oxide, one of the major OER electrocatalysts, was achieved through operando observation using wavelength-dispersive X-ray absorption spectroscopy (XAS) at the oxygen K-edge. The XAS spectra were collected every 3 s during electrode potential sweeping for the OER, and oxygen intermediate species related to the rate-determining step of the OER were detected just below the onset potential. Moreover, the cobalt L-edge XAS results demonstrate that the Co3O4 species dominates the surface of the electrode at a relatively high potential region, where the OER occurs. The present technique has significant potential for application in the analysis of solid–liquid interfaces, whose fundamental understanding is useful for further improvement of electrocatalysis.

Abstract Ionovoltaics is a breakthrough concept in energy conversion that harnesses water motion with ion dynamics to generate electrical energy. This phenomenon is based on the interaction between the nanoscopic ionic behavior at the solid–liquid interface and the flow of electrons in a semiconductor electrode. Ionovoltaic research aims to present the most rational and convincing mechanism for the much‐debated principle of energy conversion by water motion through a deeper understanding of solid–liquid interfacial phenomena and to discuss the potential to transform related fields through the development of enabling technologies such as novel energy harvesters, interfacial analysis tools, and bio/chemical sensors. Furthermore, efforts to develop high‐efficiency ionovoltaic device powered by small water droplets indicate a potential contribution to the advancement of green energy systems that complement solar and wind power generation and address environmental pollution and energy shortages. This review paper explores the evolution of energy harvesting technologies using water motion, with a particular focus on ionovoltaics as an emerging field. By establishing the fundamentals, this study investigates solid–liquid interfaces, semiconductor properties, and natural water motion‐driven ionovoltaic phenomena and also highlights that extensive research on complex ion/interface phenomena can have practical applications in diverse industrial fields.

Abstract The rational design of electrocatalysis has emerged as one of the most thriving means for mitigating energy and environmental crises. The key to this effort is the understanding of the complex electrochemical interface, wherein the electrode potential as well as various internal factors such as H‐bond network, adsorbate coverage, and dynamic behavior of the interface collectively contribute to the electrocatalytic activity and selectivity. In this context, the authors have reviewed recent theoretical advances, and especially, the contributions to modeling the realistic electrocatalytic processes at complex electrochemical interfaces, and illustrated the challenges and fundamental problems in this field. Specifically, the significance of the inclusion of explicit solvation and electrode potential as well as the strategies toward the design of highly efficient electrocatalysts are discussed. The structure‐activity relationships and their dynamic responses to the environment and catalytic functionality under working conditions are illustrated to be crucial factors for understanding the complexed interface and the electrocatalytic activities. It is hoped that this review can help spark new research passion and ultimately bring a step closer to a realistic and systematic modeling method for electrocatalysis.

A comprehensive understanding of surface reconstruction was critical to developing high performance lattice oxygen oxidation mechanism (LOM) based perovskite electrocatalysts. Traditionally, the primary determining factor of the surface reconstruction process was believed to be the oxygen vacancy formation energy. Hence, most previous studies focused on optimizing composition to reduce the oxygen vacancy formation energy, which in turn facilitated the surface reconstruction process. Here, for the first time, we found that adding oxyanions (SO42−, CO32−, NO3−) into the electrolyte could effectively regulate the solid–liquid interface, significantly accelerating the surface reconstruction process and enhancing oxygen evolution reaction (OER) activities. Further studies indicated that the added oxyanions would adsorb onto the solid–liquid interface layer, disrupting the dynamic equilibrium between the adsorbed OH− ions and the OH− ions generated during surface reconstruction process. As such, the OH− ions generated during surface reconstruction process could be more readily released into the electrolyte, thereby leading to an acceleration of the surface reconstruction. Thus, it was expected that our finding would provide a new layer of understanding to the surface reconstruction process in LOM‐based perovskite electrocatalysts. [ABSTRACT FROM AUTHOR]

The interfacial free energy $ \gamma $, (between solid-gas, solid-liquid or liquid-gas interfaces) plays a critical role in many physical and chemical processes involving material surfaces. Due to experimental difficulties in measuring $ \gamma $ various alternative theoretical or computational approaches have been suggested to date. However, despite being commonly used in interface modeling, phase fields models have not been fully exploited for addressing the question of anisotropy in $ \gamma $. In this work we propose phase field methodologies that use real parameters to directly obtain $ \gamma $ and its anisotropy. The approach is successfully applied to Lennard-Jones system for liquid-gas and solid-gas interfaces. In particular, a novel discrete version of phase field method is introduced for modeling of the solid-gas interfaces of Lennard-Jones systems on the actual fcc lattice. The approach provides a methodology to understand the process of transfer of microscopic anisotropy to the macroscopic scale. Interfacial free energy, $ \gamma $, is calculated at multiple different conditions (including the triple point) for different orientations. Results show that $ \gamma $ is larger in the [100] direction than [110] direction by several percent. The results are compared with the literature. [ABSTRACT FROM AUTHOR]

Triboelectrification between a liquid and a solid is a common phenomenon in our daily life and industry. Triboelectric charges generated at liquid/solid interfaces have effects on energy harvesting, triboelectrification-based sensing, interfacial corrosion, wear, lubrication, etc. Knowing the amount of triboelectric charge transfer is very useful for studying the mechanism and controlling these phenomena, in which an accurate method is absolutely necessary to measure the triboelectric charge generated at the solid—liquid interface. Herein, we established a method for measuring the charge transfer between different solids and liquids. An equipment based on the Faraday cup measurement was developed, and the leakage ratio (rl) was quantified through simulation based on an electrostatic field model. Typical experiments were conducted to validate the reliability of the method. This work provides an effective method for charge measurement in triboelectrification research. [ABSTRACT FROM AUTHOR]

The development of novel drug delivery systems (DDSs) with promising antibacterial properties is essential for facing the emergency of increasing resistance to antimicrobial agents. The antibacterial features of quercetin and its metal complexes have been broadly investigated. However, several drawbacks affect their activity and effectiveness. In this work, we propose a DDS based on a pH-responsive cobalt(II)-coordinated assembly containing quercetin and polyacrylic acid. This system is suggested to trigger the release of the model drug in a pH-dependent mode by exploiting the localized acidic environment at the bacterial infection sites under anaerobic conditions. The delivery system has been designed by accurately examining the species and the multiple equilibria occurring in solution among the assembly components. The formation of cobalt(II) complexes with quercetin in the absence or presence of the pH-responsive polyacrylic acid was investigated in buffered aqueous solution at pH 7.4 using spectrophotometric (UV-Vis) and calorimetric (ITC) techniques. The determined binding affinities and thermodynamic parameters that resulted are essential for the development of a DDS with improved binding and release capabilities. Furthermore, the affinity of the polymer–cobalt(II) complex toward the model antimicrobial flavonoid was explored at the solid–liquid interface by quartz crystal microbalance (QCM-D) experiments, which provided marked evidence for drug loading and release under pH control. [ABSTRACT FROM AUTHOR]

This work is concerned with the improvement of silicon photovoltaic solar cells using elec- tromagnetic stirring in prior processing by controlling the hydrodynamics of the silicon bath during ingot solidification. The vertical Bridgman directional solidification furnace called VB2 was numerically investigated using a controlled power-down technique under forced convection generated by a travelling magnetic field, i.e. a full 3D numerical model of the VB2 furnace has been developed using the Comsol MultiphysicsTM software. Enthalpy formulation based on fixed-grid techniques is used for the phase-change phenomena considering magnetohydro- dynamic forced convection created by a Lorentz force generated by a specific cylindrical Bitter coil. The model provides the temperature distribution in the entire furnace as well as specific details regarding the solidification process (i.e. solidification fraction and solid-liquid interface shape), flow patterns and melt velocities. The obtained numerical results show good consist- ency with experimental measurements and analysis, on the one hand, and can be considered as useful orientation to improve the solidification process, on the other hand. It is shown that the travelling magnetic field acting in the melt drives a moderately turbulent flow which has a significant impact on the solid-liquid interface in terms of morphology and symmetry during silicon solidification and, consequently, on the tight control of the crystallization process that can affect the silicon crystal morphology and impurity distributions. [ABSTRACT FROM AUTHOR]

Electrochemistry is a promising building block for the global transition to a sustainable energy market. Particularly the electroreduction of CO2 and the electrolysis of water might be strategic elements for chemical energy conversion. The reactions of interest are inner-sphere reactions, which occur on the surface of the electrode, and the biased interface between the electrode surface and the electrolyte is of central importance to the reactivity of an electrode. However, a potential-dependent observation of this buried interface is challenging, which slows the development of catalyst materials. Here we describe a sample architecture using a graphene blanket that allows surface sensitive studies of biased electrochemical interfaces. At the examples of near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) and environmental scanning electron microscopy (ESEM), we show that the combination of a graphene blanket and a permeable membrane leads to the formation of a liquid thin film between them. This liquid thin film is stable against a water partial pressure below 1 mbar. These properties of the sample assembly extend the study of solid-liquid interfaces to highly surface sensitive techniques, such as electron spectroscopy/microscopy. In fact, photoelectrons with an effective attenuation length of only 10 Å can be detected, which is close to the absolute minimum possible in aqueous solutions. The in-situ cells and the sample preparation necessary to employ our method are comparatively simple. Transferring this approach to other surface sensitive measurement techniques should therefore be straightforward. We see our approach as a starting point for more studies on electrochemical interfaces and surface processes under applied potential. Such studies would be of high value for the rational design of electrocatalysts.