Interfacial Structure Research Articles

Molecular dynamics-based study of the effects of grain size and temperature on the nanoscratching groove characteristics of grating polycrystalline layered Al films

Abstract As a special diffraction grating, the echelle grating has excellent beam splitting ability with the periodic groove pattern on it, which is characterized by low number of lines per millimeter and large flash angle. Al films with a layered structure determined by the coating technology are the first blanks for the echelle grating in mechanical scratching. However, the special interlayer structure of the layered Al films and the need for large depth and high precision triangular diffraction grooves have increased the difficulty of controlling the scratching process, and the traditional mechanical scratching “trial and error” process is still the main means. Therefore, in the study, molecular dynamics (MD) is utilized to simulate the mechanical response and deformation mechanism of polycrystalline layered Al films during the scratching process at different grain sizes and temperatures. The results represent that the friction force and normal force show a decreasing trend with increasing temperature, and the decrease in grain size leads to smaller friction and normal force; The number of removed atoms of polycrystalline layered Al films shows an increasing trend with increasing temperature, which improves the material removal rate and facilitates precise shape control of the groove; In addition, the presence of layered grain boundary interface hinders the downward propagation of defects such as dislocations and can accommodate dislocations. At the same time, the total length of dislocation lines decreases with increasing temperature, the high temperature promotes the transformation of crystals to an amorphous structure, and the grain boundaries between grains and the interlayer grain boundaries at the delamination limit the movement of dislocations. The deformation behavior indicates that grain boundaries play a key role in inhibiting the propagation of strain and stress, and a gradient distribution is formed at the layered grain boundary interface structure, which further hinders the downward transfer.

The interface and lamellar structures in Mg–Gd–Ag alloys investigated by experiment and first principles

The interface and lamellar structures in Mg–Gd–Ag alloys investigated by experiment and first principles

Cu2O/TiO2 Heterostructure‐Based Photoelectrochemical Photodetector with Enhanced Performance and Stability

Cu2O/TiO2 heterostructure is prepared by electrodepositing Cu2O on rutile phase TiO2 particles. The morphology, structural, and optical properties of Cu2O/TiO2 heterostructure are determined by scanning electron microscopy, Raman spectroscopy, X‐ray diffractometer, and UV–vis absorption spectrum. The Cu2O/TiO2 heterostructure photoelectrochemical‐type photodetector is constructed based on this heterostructure. Experimental results show that the photoresponsivity and visible light absorption of the Cu2O/TiO2 heterostructure are significantly enhanced compared to those of TiO2 and Cu2O which demonstrate that the Cu2O/TiO2 heterostructure with a special interfacial structure is conducive to accelerating the separation and transfer of photogenerated carriers. The photoresponsivity and photocurrent density of Cu2O/TiO2 can reach 154 μA W−1 and 15.6 μA cm−2 at 0 V. In addition, the photocurrent density of the Cu2O/TiO2 heterostructure steadily increases with the enhancement of irradiation power density. Moreover, no significant attenuation of the photocurrent density is observed in the prepared Cu2O/TiO2 heterostructure after 1800 s of photo‐on/off cycles. These results suggest that the Cu2O/TiO2 heterostructure‐based photodetector holds great potential in the photodetection field.

The Role of Interfacial Effects in the Impedance of Nanostructured Solid Polymer Electrolytes

The role of interfacial effects on an ion-conducting poly(styrene-b-ethylene oxide) (PS-b-PEO or SEO) diblock copolymer doped with lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) was investigated by electrochemical impedance spectroscopy (EIS). Coating the surface of commonly used stainless steel electrodes with a specific random copolymer brush increases the measured ionic conductivity by more than an order of magnitude compared to the uncoated electrodes. The increase in ionic conductivity is related to the interfacial structure of the block copolymer domain morphology on the electrode surface. We show that the impedance associated with the electrode–electrolyte interface can be detected using nonmetallic electrodes, allowing us to distinguish the ionic conductivity behaviors of the bulk electrolyte and the interfacial layers for both as-prepared and annealed samples.

A Novel Anion Receptor Additive for −40 °C Sodium Metal Batteries by Anion/Cation Solvation Engineering

AbstractSodium metal batteries, known for their high theoretical specific capacity, abundant reserves, and promising low‐temperature performance, have garnered significant attention. However, the large ionic radius of Na+ and sluggish transport kinetics across the interfacial structure hinder their practical application. Previous reviews have rarely regulated electrolyte performance from the perspective of anions, as important components of the electrolyte, the regulation mechanism is not well understood. Herein, a novel anion receptor additive, 4‐aminophenylboronic acid pinacol ester (ABAPE), is proposed to weaken the coupling between anions and cations and accelerate Na+ transport kinetics. The results of theoretical calculations and X‐ray photoelectron spectroscopy with deep Ar‐ion etching demonstrate that the introduction of this additive alters the solvation structure of Na+, reduces the desolvation barrier and forms a stable and dense electrode‐electrolyte interface. Moreover, ABAPE forms hydrogen bonds (−NH ⋅ ⋅ ⋅ O/F) with H2O/HF, effectively preventing the hydrolysis of NaPF6 and stabilizing acidic species. Consequently, the Na||Na symmetric cell exhibits excellent long‐cycle performance of 500 h at 1 mA cm−2 and 0.5 mAh cm−2. The Na||Na3V2(PO4)3 (NVP) cell with the addition of ABAPE maintains a capacity retention of 84.29 % at 1 C after 1200 cycles and presents no capacity decay over 150 cycles at −40 °C.

A superlattice interface and S-scheme heterojunction for ultrafast charge separation and transfer in photocatalytic H2 evolution

The rapid recombination of photoinduced charge carriers in semiconductors fundamentally limits their application in photocatalysis. Herein, we report that a superlattice interface and S-scheme heterojunction based on Mn0.5Cd0.5S nanorods can significantly promote ultrafast charge separation and transfer. Specifically, the axially distributed zinc blende/wurtzite superlattice interfaces in Mn0.5Cd0.5S nanorods can redistribute photoinduced charge carriers more effectively when boosted by homogeneous internal electric fields and promotes bulk separation. Accordingly, S-scheme heterojunctions between the Mn0.5Cd0.5S nanorods and MnWO4 nanoparticles can further accelerate the surface separation of charge carriers via a heterogeneous internal electric field. Subsequent capture of the photoelectrons by adsorbed H2O is as fast as several picoseconds which results in a photocatalytic H2 evolution rate of 54.4 mmol·g−1·h−1 without any cocatalyst under simulated solar irradiation. The yields are increased by a factor of ~5 times relative to control samples and an apparent quantum efficiency of 63.1% at 420 nm is measured. This work provides a protocol for designing synergistic interface structure for efficient photocatalysis.

Interface‐Induced Anomalous Behavior of Magnetism in FexGeTe2/Pt Bilayer

AbstractInterface engineering is a promising strategy for controlling the Curie temperature (Tc) and perpendicular magnetic anisotropy (PMA) in magnetic 2D van der Waals (2D vdWs)‐based heterostructures. However, establishing high‐quality interface structures in magnetic 2D vdWs/metal stacks, crucial for maximizing interface effects, remains a significant challenge. Here, a Fe5‐xGeTe2/Pt (F5GT/Pt) prototype with a superior interface quality is achieved using a low‐power physical vapor deposition technique. The magnetic properties of the F5GT/Pt heterostructures are strongly influenced by employing the specific physical deposition method. Stable ferromagnetism at 400 K is observed when depositing Pt atoms with relatively high energy, despite the Tc of pristine F5GT being below 300 K. This unexpected high‐temperature ferromagnetism is attributed to the formation of a ferromagnetic alloy at the interface, commonly present in vdWs‐based stacks fabricated through physical deposition but often overlooked. The deposit of Pt atoms with ultralow energy leads to the formation of a unique Fe5‐xGeTe2/Fe3‐xGeTe2 heterojunction at the interface, significantly enhancing the PMA. This work emphasizes the importance of interface structures in vdWs‐based devices, suggesting that controlling the growth process offers an effective approach to construct and engineer vdWs heterostructures, thus improving the performance and introducing new functionalities to spintronic devices.

Surface‐Interface Engineering of Electrocatalysts for Two‐Electron Water Oxidation Reaction to Produce H2O2

AbstractElectrochemical two‐electron water oxidation reaction (2e− WOR) driven by renewable energy offers an attractive route to produce H2O2, while the corresponding electrocatalyst still requires further improvement for the activity, selectivity, and the resulting H2O2 yield. Surface‐interface engineering of electrocatalysts has great potential to advance 2e− WOR performance. This review provides a succinct yet comprehensive insight into the functional mechanisms of surface‐interfacial properties affecting 2e− WOR performance on electrocatalyst. The Gibbs free energy theoretical framework related to surface electronic structure and interfacial reactive kinetics mechanism related to electrolyte, electrode–electrolyte interface structure, and interfacial microenvironment properties are firstly discussed. Afterward, various surface‐interface engineering strategies toward high performance electrocatalysts including the regulation of surface electronic structure, the electrode–electrolyte interface structure, and the interfacial microenvironment have been overviewed. Rational manipulations of the above surface‐interfacial engineering strategies are critical to design highly efficient 2e− WOR electrocatalysts, leading to the development of the green H2O2 production.

Recalibration of MARTINI-3 Parameters for Improved Interactions between Peripheral Proteins and Lipid Bilayers.

The MARTINI force field is one of the most used coarse-grained models for biomolecular simulations. Many limitations of the model including the protein-protein overaggregation have been improved in its latest version, MARTINI-3. In this study, we investigate the efficacy of the MARTINI-3 parameters for capturing the interactions of peripheral proteins with model plasma membranes. Particularly, we consider two classes of proteins, namely, annexin and epsin, which are known to generate negative and positive membrane curvatures, respectively. We find that current MARTINI-3 parameters are not able to correctly describe the protein-membrane interface and the protein-induced membrane curvatures for any of these proteins. The problem arises due to the lack of proper hydrophobic interactions between the protein residues and lipid tails. Making systematic adjustments, we show that a combination of reduction in the protein-water interactions and enhancement of protein-lipid hydrophobic interactions is essential for accurate prediction of the interfacial structure including the protein-induced membrane curvature. Next, we apply our model to a couple of other peripheral proteins, namely, Snf7, a core component of the ESCRT-III complex, and the PH domain of evectin-2. We find that our model captures the protein-membrane interfacial structure much more accurately than the MARTINI-3 model for all of the peripheral proteins considered in this study. However, the strategy described in this study may not be suitable for oligomeric transmembrane proteins where protein-protein hydrophobic interactions should be increased instead of protein-lipid hydrophobic interactions.

Stabilizing 4.6 V LiCoO2 via Surface‐to‐Bulk Titanium Modification

AbstractElevating the charging cut‐off voltage is an effective strategy to increase the energy density of LiCoO2. However, unstable interfacial structures and unfavorable phase transitions in bulk are inevitably triggered during deep de‐lithiation at high voltage. Herein, an integrated surface‐to‐bulk Ti‐modification strategy is applied to LiCoO2, enabling uniform Li2TiO3 coating on the surface and gradient Ti‐doping toward the structural bulk. The resultant Ti‐modified LiCoO2 (T‐LCO) electrode can be stably cycled up to 4.6 V, providing a high‐rate capability of 137 mAh g−1 at 5C and a long‐life stability with 80.5% capacity retention after 400 cycles at 1C, far outperforming the unmodified LiCoO2 electrode with only 50.7% capacity retention. In situ X‐ray diffraction characterization and density functional theory calculation reveal that the synergistic modification of T‐LCO enhances Li+ diffusion, facilitates the construction of high‐quality cathode/electrolyte interphase, reduces the phase transition from O3 to H1‐3 and Co3d/O2p band overlap, and restrains layer‐to‐spinel phase distortion, thus improving structural stability at 4.6 V. This work presents a “two birds one step” strategy to enhance the cycling stability and achievable capacity of high‐voltage LiCoO2 for developing high energy density lithium‐ion batteries.

Zn interlayer-induced modifications in interfacial structure and fracture behavior of Cyclic Hot-Pressed Mg/Al laminated composites

In this study, a new type of cyclic hot pressing technology was used to prepare magnesium-aluminum composites. In order to further simplify the process, the active zinc interlayer was introduced, and the interfacial bonding strength of Mg/Al LMCs was increased by 43.25%. The traditional Mg/Al LMCs interface is mainly composed of Mg-Al IMCs (β-Mg2Al3 and γ-Mg17Al12), in which the highly regular HCP-β phase leads to brittle fracture of the material. After adding zinc layer, the interface of the composites mainly presents Al-SS, η (MgZn2) and Mg-SS phases. During the preparation process, the solid solution treatment and aging treatment occurred at the composite interface, and a chain GPII zone was formed at the interface between Al-SS and η phase. This region is mainly composed of structurally unstable η′(Al-Mg-Zn), resulting in the GP II band becoming a region rich in lattice defects and a fracture source of the composite.

CORROSION BEHAVIOUR OF ADVANCED COMPOSITES CONTAINING SURFACE MODIFIED SIC AS REINFORCEMENT

The interface structure, micro-voids, pits, delamination, intermetallic compounds and internal stresses are the utmost critical factors influencing the corrosion performance of composite materials making them unsuitable for use in structural applications. One useful technique to control such adverse effect in composites is surface modification of the reinforcement. The present investigation involved the implementation of chemical techniques, particularly electroless plating (EP), to modify the surface of silicon carbide (SiC) particles by depositing a layer of nickel phosphorous (Ni-P) onto them. These plated SiC particles were subsequently employed in the production of Al/Ni-pSiC composites using the powder metallurgy (PM) method, with different weight percentages of plated SiC content ranging from 5% to 15%. The corrosion behaviour was assessed by potentio-dynamic polarization tests in 3.5% NaCl solution at room temperature. Results confirmed that AlNi-pSiC composites exhibit a greater resistance to pitting, in contrast to pure aluminium and Al/SiC composites without plating. The enhanced corrosion resistance in Al/Ni-pSiC composites can be attributed to strong interfacial bond, grain refinement, CTE difference, formation of Ni3Al, and reduced potential difference.

Stimulated Pickering emulsion stabilized by binary particles with contrasting wettability and trace surfactant

The investigationof self-assembled particle structures at fluid interfaces has gained considerable interest across various fields. In particular, Pickering emulsions (PEs) stabilized by binary particles co-assembling at these interfaces have attracted even more attention. To explore the self-assembly process of superhydrophobic and superhydrophilic particles at oil–water (O/W) interfaces influenced by a trace amount of surfactant, a series of experiments were conducted. A small quantity (0.01 mmol·L−1) of dodecyltrimethylammonium bromide (DTAB) was introduced, establishing a variable stable emulsion system with high salt tolerance, capable of withstanding up to 6 mol·L−1 NaCl, in synergism with the particles. The DTAB concentration required to stabilize the O/W emulsion with particles was as low as 0.001 mmol·L−1. The stability and type of the resulting emulsion could be adjusted by varying the ratio of hydrophobic to hydrophilic particle (R) or by modifying acid/base conditions. The systems exhibited robust cyclic acid/base regulated demulsification and phase inversion behavior, maintaining stability over at least 10 cycles. Results indicated that the stability and nature of the emulsion were influenced by the curvature of the interface formed by the self-assembled interfacial particle structures, arising from the competitive adsorption of both types of particles and trace surfactant. Further analysis revealed a correlation between interfacial curvature and the surface charges of the particles, which could be modulated through DTAB adsorption. This study elucidated the behavior of hydrophilic and hydrophobic particle self-assembly at interfaces, provided a straightforward strategy for co-preparing switchable emulsions using superhydrophilic and superhydrophobic particles, and expanded the range of amphiphilic particles available for producing PEs. This approach presents significant potential for future research and applications in the field of PEs.

Engineering the interfacial hetero-structure for high-current-density hydrogen evolution

Modulating the hetero-structures with abundant interfaces in catalyst is a feasible but challenging strategy to improve the catalytic performance. In this work, a highly efficient catalyst (R-CoMoOx/Ni (Co)) was prepared with plentiful interfacial structures to accelerate the hydrogen evolution reaction (HER), which contained both reduced CoO and MoO2 as a R-CoMoOx substrate and metallic Ni (Co) particles as the catalytic center. The combination of CoO and MoO2 with a Co-O-Mo local structure in R-CoMoOx led to an electron-enriched Co center to catch the dissociated H+, while the abundant interfacial interaction between R-CoMoOx and Ni (Co) could accelerate the charge transfer and then facilitate the production of H2 through a fast Volmer-Tafel pathway. As a result, the integrated R-CoMoOx/Ni (Co) catalyst could drive alkaline HER with ultra-low overpotentials of 16 mV for 10 mA cm−2 (25 °C) and 186 mV for 1000 mA cm−2 (60 °C), respectively, with a good stability over 100 h. Moreover, by coupling with RuO2 electrode in an anion exchange membrane system, it could achieve 1000 mA cm−2 at 1.78 V for overall water splitting with a high energy conversion efficiency of 70.4 %. The H2 production cost at 1000 mA cm−2 was merely $ 0.952 per gasoline gallon equivalent, much less than the target cost of the US Department of Energy.

Interfacial structure modification and enhanced emulsification stability of microalgae protein through interaction with anionic polysaccharides

Microalgae protein (MP) have emerged as a focal point of research within food processing due to its nutritional value and foaming properties. However, its isoelectric point around pH 4 leads to it susceptible to collision, binding, and precipitation. Additionally, MP has poor emulsification properties and only shows stability under strongly alkaline conditions. This study investigated the effects of food-grade anionic polysaccharides (guar gum (GG), gum arabic (GA), low acyl gellan gum (LG), and pectin (PT)) on the molecular structure and emulsification properties of MP. Results indicated that these anionic polysaccharides enhanced the UV absorption of MP near 620 nm, especially at 14 % content, while fluorescence intensity decreased due to amino acid residues masking without structural changes. The addition of polysaccharides resulted in bimodal or multimodal particle size distributions, with LG and PT showing larger particle sizes. At pH 4, negatively charged polysaccharides formed stable complexes with near-neutral MP, improving solution stability via electrostatic repulsion and diminishing turbidity. The droplet distribution analysis indicated that higher anionic polysaccharide ratios (1:4, 1:2, and 1:1) correlated with smaller droplet sizes and increased emulsion stability. Zeta-potential measurements revealed negative charges for emulsions, with LG-MP and PT-MP complexes displaying higher absolute values (15.0 to 20.7 mV) compared to GG-MP and GA-MP complexes, indicating superior stability. Storage stability analysis showed that LG-MP and PT-MP complexes stabilized emulsions had minimal delamination over two weeks. Rheological assessments showed that increasing GG and GA contents from 14 % to 50 % had negligible effects on apparent viscosity, while LG-MP (1:1) complexes stabilized emulsion displayed higher viscosity compared to PT-MP emulsions. Frequency sweep results showed that GG-MP, GA-MP, and LG-MP emulsions had greater elastic moduli (G') than viscous moduli (G"), indicating elastic behavior, whereas PT-MP emulsions transitioned from liquid-like to solid-like behavior as frequency increased. This study illustrates the advantages of high LG and PT content in preventing particle aggregation and enhancing emulsion stability, providing a theoretical and practical foundation for MP applications in food processing.

Atomic-scale insights into the microstructure and interface evolution mechanism of copper/tantalum nanofilms during ultra-precision grinding

The copper (Cu)/tantalum (Ta) nanofilms are the vital component in the through silicon via (TSV) wafer. However, the current lack of research on the ultra-precision machining of Cu/Ta nanofilms limits the development of TSV-based 3D integration technologies. In this work, molecular dynamics simulations are conducted to reveal the microstructure and interface evolution mechanism of Cu/Ta nanofilms during nano-grinding under various grinding depths. The results show that the material removal mode differs between the Cu and Ta layers, and the thickness of the subsurface damage layer of the Cu layer is greater than that of the Ta layer. The Cu/Ta interface is well stabilized, and small amounts of micro-defects appear only at larger grinding depths after grinding. The lattice mismatch of the constituent layers and the hindering role by the interface lead to stress concentration at the interface, and it is more obvious with increasing grinding depth. Nevertheless, there is a significant stress release after grinding. Our computations indicate that the competition between the evolution of interfacial structures and discrepancies in the physical properties of constituent layers leads to an increase in grinding forces at the interface. Furthermore, the heat transfer is obstructed by the Cu/Ta interface. This study provides valuable insights into the grinding mechanisms of Cu/Ta nanofilms, which is conducive to further improving the manufacturing process of the TSV wafer and enhancing the performance of microelectronic devices.

Fabricating model heterostructures of large-area monolayer or bilayer MoS2 on an Au(111) surface under ultra-high vacuum

Fabricating heterojunctions with precisely controlled interfacial structures is crucial for exploring novel low-dimensional physics and for realizing high-performance devices. However, such capabilities are often constrained by contamination from the ambient environment or by the limitations of applicable methods and materials under vacuum conditions. In this study, MoS2/Au(111) heterostructures were fabricated by exfoliating MoS2 thin layers onto a crystallized Au(111) surface using a gold-assisted exfoliation method in an ultra-high vacuum environment. This method yields millimeter-sized monolayer or sub-millimeter-sized bilayers with contamination-free interfaces, which are unattainable for samples made in air. Scanning tunneling microscopy revealed that both the monolayer and the bilayer exhibit uniform and well-ordered moiré superlattices controlled by the twisting angle between the Au(111) surface and the MoS2 overlayer. The direct contact with the Au surface renders the monolayer MoS2 weakly metallic, while a less coupled bilayer is semiconducting, indicating a 0.54 eV Schottky barrier for the MoS2/Au(111) contact. This method is applicable to various combinations of van der Waals materials and metal surfaces. The uniform and controllable heterojunctions can serve as ideal model systems for exploring semiconductor–metal interfaces and atomic structures formed within.

On the transition between two-phase and single-phase interface dynamics in ammonia sprays

This study explores the application of the density gradient theory to assess the validity of the two-phase spray atomization theory in multi-component ammonia sprays under conditions relevant to practical applications. The research focuses on analyzing the liquid–vapor interface structure at thermodynamic equilibrium. The most recent Helmholtz energy equation of state was employed to compute density profiles for ammonia and the surrounding nitrogen gas. The study investigates species distribution at equilibrium by examining minimal Helmholtz free energy states and evaluates critical parameters, such as interface thickness. The Knudsen number was also calculated as a temperature function to characterize the spray regime. The findings indicate that when the reduced temperature exceeds 0.95, a diffuse interface forms in ammonia-nitrogen systems, supporting using phase-field models for simulating ammonia injection in practical scenarios.

Correlation of interface structure and optical properties of Ga(N,As) and Ga(As,Bi) based type-II hetero structures

The type-II band alignment of particular III/V heterostructures is a promising route towards achieving certain wavelengths on specific substrates, which would not be possible with type-I structures. One example is telecommunication lasers on GaAs substrates. This study reports on the progress in combining dilute nitrides and dilute bismides in W-type hetero structures to improve the luminescence intensity, which is a fundamental prerequisite for future incorporation in a laser structure. Increasing the emission wavelength of these structures is challenging and the interface formation is critical, especially as two metastable materials are combined. Here, we investigate the impact of different interface configurations by growing Ga(N,As)/Ga(As,Bi) and Ga(As,Bi)/Ga(N,As) type-II structures. We employ metal–organic vapor phase epitaxy (MOVPE) to grow Ga(N,As) and Ga(As,Bi) layers and investigate the effects of interlayer thicknesses on the structural and optical properties of the hetero structures. The results indicate that − while the introduction of a GaAs interlayer can affect the direct and indirect transitions intensities − it does not significantly improve the interface quality. However, this is strongly influenced by the order in which the materials are grown. The growth of Ga(N,As) on Ga(As,Bi) shows no peculiarities, while the type II transition energy is shifted to lower energies when Ga(As,Bi) is grown on Ga(N,As). High-resolution X-ray diffraction (HR-XRD), photoluminescence (PL) spectroscopy, atomic force microscopy (AFM), and scanning transmission electron microscopy (STEM) were used to characterize the samples.

Influence of Substrate Polarity on Thermal Stability, Grain Growth and Atomic Interface Structure of Au Thin Films on ZnO Surfaces

Influence of Substrate Polarity on Thermal Stability, Grain Growth and Atomic Interface Structure of Au Thin Films on ZnO Surfaces