Structure Of Interfacial Layer Research Articles

Theoretical investigations on exploring Si-based heterostructures with cubic and ground-state perovskites

First principles calculations in the framework of density functional theory (DFT) are performed to exploit replaceable perovskite oxides against the instability of traditional cubic SrTiO3 grown on silicon substrate. In this work, we consider more thermostable CaTiO3 and CaZrO3 with cubic and ground-state phase as the candidates to perform the gate dielectric. After the calibration of total energy and lattice transformation of ground-state perovskites to match with Si substrate, three categories of 2 × 2 heterostructures have been constructed and investigated through the geometrical change, atom displacement around interfacial layer, total energy and electronic structure change, under the variations on perovskite species, the concentration of interfacial layer and the thickness of perovskite film. And the results demonstrate that the category with half a monolayer of Ca/Sr atoms in interfacial layer and two unit-cell perovskite thicknesses show the type-I band alignment through their band alignment. Among this category, the heterostructure with Pnma CaZrO3 shows semiconductivity and excellent electrical property with larger band offset for the candidate of gate dielectric. This work provides a creative perspective to expand the perovskite diversity for the booming growth of integrated circuit technology.

Superabsorbent starch protective layer modulates zinc anode interface for long-life aqueous zinc ion batteries

Aqueous zinc ion batteries (AZIBs) have attracted much attention for their safety, low cost and high theoretical capacity. Nevertheless, Zn dendrites and the adverse reactions such as corrosion, hydrogen evolution and passivation on the anode affect the cycle life and stability of AZIBs. Herein, superabsorbent starch (SS) was employed on Zn foil to form an artificial interface protection layer, which inhibited the formation of dendrites by guiding the uniform deposition of Zn2+. SS with a large amount of oxygen-containing functional group is superabsorbent, which can attract the active water around the hydrated Zn2+, promoting the desolvation process of the hydrated Zn2+ and significantly inhibiting the occurrence of hydrogen evolution reaction. In addition, the inherent pore structure of the SS artificial interfacial layer can induce uniform nucleation of Zn2+ and inhibit the dendrites growth. Moreover, compared to bare Zn//MnO2 cell (44.1 %), the capacity retention of Zn@SS//MnO2 cell remained as high as 87.8 % after 1000 cycles at 1.5 A g−1. The simple method provided a new method for the rapid development of AZIBs.

Interfacial engineering of Pickering emulsions stabilized by pea protein-alginate microgels for encapsulation of hydrophobic bioactives

This study aims to investigate the effects of interfacial layer composition and structure on the formation, physicochemical properties and stability of Pickering emulsions. Interfacial layers were formed using pea protein isolate (PPI), PPI microgel particles (PPIMP), a mixture of PPIMP and sodium alginate (PPIMP-SA), or PPIMP-SA conjugate. The encapsulation and protective effects on different hydrophobic bioactives were then evaluated within these Pickering emulsions. The results demonstrated that the PPIMP-SA conjugate formed thick and robust interfacial layers around the oil droplet surfaces, which increased the resistance of the emulsion to coalescence, creaming, and environmental stresses, including heating, light exposure, and freezing-thawing cycle. Additionally, the emulsion stabilized by the PPIMP-SA conjugate significantly improved the photothermal stability of hydrophobic bioactives, retaining a higher percentage of their original content compared to those in non-encapsulated forms. Overall, the novel protein microgels and the conjugate developed in this study have great potential for improving the physicochemical stability of emulsified foods.

Electrolyte Design for High-Voltage Lithium-Metal Batteries with Synthetic Sulfonamide-Based Solvent and Electrochemically Active Additives.

Considering practical viability, Li-metal battery electrolytes should be formulated by tuning solvent composition similar to electrolyte systems for Li-ion batteries to enable the facile salt-dissociation, ion-conduction, and introduction of sacrificial additives for building stable electrode-electrolyte interfaces. Although 1,2-dimethoxyethane with a high-donor number enables the implementation of ionic compounds as effective interface modifiers, its ubiquitous usage is limited by its low-oxidation durability and high-volatility. Regulation of the solvation structure and construction of well-structured interfacial layers ensure the potential strength of electrolytes in both Li-metal and LiNi0.8Co0.1Mn0.1O2 (NCM811). This study reports the build-up of multilayer solid-electrolyte interphase by utilizing different electron-accepting tendencies of lithium difluoro(bisoxalato) phosphate (LiDFBP), lithium nitrate, and synthetic 1-((trifluoromethyl)sulfonyl)piperidine. Furthermore, a well-structured cathode-electrolyte interface from LiDFBP effectively addresses the issues with NCM811. The developed electrolyte based on a framework of highly- and weakly-solvating solvents with interface modifiers enables the operation of Li|NCM811 cells with a high areal capacity cathode (4.3 mAh cm-2) at 4.4V versus Li/Li+.

Microstructural characterization and corrosion-resistance behavior of friction stir-welded A390/10 wt% SiC composites-AA2024 Al alloy joints

This study examined the effect of traverse speed on the mechanical properties, corrosion-resistance behavior, and microstructure of friction stir-welded A390/10 wt% SiC composites-AA2024 Al alloy joints. The laminar flow of both materials was found to diminish in the stir zone (SZ) when the traverse speed of the tool increased from 40 to 80 mm/min, lowering their mixing rate. Large aspect ratio Si particles are broken by the tool pin-induced applied plastic strain, which turns them into refined equiaxed particles. Their aspect ratio remains unchanged in the SZ, despite their decreasing size. SiC and Si particles progressively come into view when moving from the AA2024 alloy's SZ to the composite workpieces. These changes happen abruptly as traverse speed increases due to the lack of an interfacial layer structure. The advancing side (AS)'s SZ grain size drops from 4.2 ± 0.3 μm to 1.2 ± 0.2 μm as the traverse speed drops from 80 to 40 mm/min. Increased traverse speed from 40 to 80 mm/min will result in a 5.8% decrease in elongation percentage (EP) and 8.4%, 36%, and 10.3% increases in the ultimate tensile strength (UTS), corrosion resistance, and yield strength, respectively.

Effect of interface layer on the enhancement of thermal conductivity of SiC-Water nanofluids: Molecular dynamics simulation

To investigate the impact of interfacial layer effects on the thermal conductivity of nanofluids and the microscopic mechanisms of enhanced thermal conductivity, this study employed non-equilibrium molecular dynamics to compute the thermal conductivity, number density, radial distribution function, and mean square displacement distribution of SiC nanofluids. The impact of nanoparticle volume fraction and particle size parameters on the thermal conductivity of nanofluids and the structure of interfacial adsorption layers was discussed. The simulation calculation results show that the coefficient of thermal conductivity of nanofluid is positively related to the volume fraction of nanoparticles, increasing from 0.6529 W/(m·K) to 0.8159 W/(m·K), and the enhancement of thermal conductivity by the volume fraction can be up to 33.97 %. The thermal conductivity is inversely correlated with the change in particle size, and the maximum improvement in thermal conductivity by particle size can reach up to 12.05 %. The simulated results of the thermal conductivity of nanofluid are almost consistent with the predicted results of the Yu&Choi model, and the error is controlled within 5 %. Simultaneously, the thickness of the interfacial adsorption layer decreases with an increase in particle size. This reduction arises due to larger particles having a smaller specific surface area, resulting in fewer particle surfaces covered by the interface layer. Moreover, the impact of particle size on the arrangement and affinity of molecules within the interface layer contributes to this decrease. Overall, interface layer effects exhibit a dual impact on the thermal conduction of nanofluids. The structured formation and high-density distribution of the adsorption layer contribute to enhanced heat transfer, while thermal resistance between nanoparticle surfaces and the fluid restricts heat transmission.

Two-dimensional water-molecule-cluster layers at nanobubble interfaces

HypothesisBulk nanobubbles (NBs) have high surface charge densities and long lifetimes. Despite several attempts to understand the lifetime of NBs, their interfacial layer structure remains unknown. It is hypothesized that a specific interfacial layer exists with a hydrogen bond network that stabilizes NBs. ExperimentsIn situ infrared reflectance–absorption spectroscopy and density functional theory were used to determine the interfacial layer structure of NBs. Furthermore, nuclear magnetic resonance spectroscopy was used to examine the interfacial layer hardness of bubbles filled with N2, O2, and CO2, which was expected to depend on the encapsulated gas species. FindingsThe interfacial layer was composed of three-, four-, and five-membered ring clusters of water molecules. An interface model was proposed in which a two-dimensional layer of clusters with large electric dipole moments is oriented toward the endohedral gas, and the hydrophobic surface is adjacent to the free water. The interfacial layer hardness was dependent on the interaction with the gas (N2 > O2 > CO2), which supports the proposed interface model. These findings can be generalized to the structure of water at gas–water interfaces.

Effect of carbon/tantalum hybrid film on the properties of carbon fiber and its composites based on magnetron sputtering

To simultaneously improve the strength and toughness of carbon fiber-reinforced polymer composites (CFRPs) using the hybrid effect, a multi-size film with carbon/tantalum (C/Ta) hybrid structure was constructed on the surface of carbon fibers (CFs) by magnetron sputtering using carbon and tantalum as the target materials. Carbon fiber epoxy composites (CFEPs) were prepared by injection molding. The effects of the C/Ta hybrid interface layer on the interfacial bonding and mechanical properties of the CFEPs were analyzed by testing their in-plane shear and bending properties. The results show that the C/Ta hybrid interface layer structure can effectively improve the interfacial bonding and mechanical properties of the CFEP. The in-plane shear and flexural strengths of CFEP modified by double C/Ta magnetron sputtering were 63.53% and 33.15% higher than those of unmodified CFEP, respectively, the in-plane shear modulus increased by 1.53 times, and the bending modulus by 63.26%.

Interfacial polymerization layer with CNT providing fast water channels under electric field for efficient desalination of nanofiltration membranes

In order to solve the contradiction between permeability flux and selectivity in nanofiltration membrane desalination technology, a novel interfacial polymerization layer structure was designed. In this structure, the hydrophilic modified carbon nanotubes (CNT) untangled and protruded the PA layer under the electric field, resulting in the generation of microporous water channels between CNT and polyamide molecules. Thanks to this unique membrane surface structure, the permeability of the nanofiltration membrane was significantly enhanced, reaching 24.4 L·m−2·h−1·bar−1, in which the rejection of MgCl2 and Na2SO4 were also maintained at 96.1 % and 97.3 %, respectively. At the same time, the surface of the nanofiltration membrane remained intact in the chlorine resistance test, and the total fouling rate caused by lysozyme (LYZ) protein solution was only 2.89 %, demonstrating excellent chlorine resistance and pollution resistance. The design of changing surface structure through electric field-assisted nanomaterials provides a new innovative strategy for the development of separation membrane.

Improvement of compressive property and damping capacity of multilayer aluminum matrix foams with 316 L hollow spheres and NiTi alloy sheets

To optimize the mechanical behavior and damping property of aluminum matrix foams (AMFs) with reinforcements of 316 L stainless steel hollow spheres (316 L HSs), multilayer aluminum matrix foams (MAMFs) were fabricated using the pressure casting method by adding NiTi alloy sheets into AMFs. The microstructure of MAMFs, and the influence of NiTi alloy sheets addition on compressive behavior and damping capacity were performed. In MAMFs, the interfacial reaction layers are formed between 316 L HSs and A356 matrix, and between NiTi alloy sheets and A356 matrix. The first maximum compressive strength of MAMFs is around 133 MPa, which increases by ∼35% than that of AMFs. The energy absorption of MAMFs is slightly higher than that of AMFs, while the energy absorption efficiencies of the two materials are similar. The loss factor of MAMFs is 0.032, which increases by 100% compared with that of AMFs (0.016). The experimental results obtained in the current work confirmed that the compressive property and damping capacity of MAMFs are improved significantly compared with that of AMFs. The influence factors that related to reinforcements of NiTi alloy sheets have been discussed, which include material type, interfacial reaction layer structure, microcracks and dislocations.

Surfactant Adsorption Layers: Experiments and Modeling.

During recent years, great progress has been made in understanding the adsorption of surfactants at liquid interfaces. In addition to tensiometry, new efficient methodologies have been developed, in particular interfacial selective optical methods which allow direct access to the adsorbed amounts and interfacial layer compositions. In addition to these new experimental tools, the thermodynamic description by equations of state now allows one to provide a quantitative picture of surfactant interfacial layers. This is most notable for surfactant layers at water/oil interfaces. Additional knowledge about the structure of interfacial layers was gained through different types of molecular modeling. Improved interrelationships between these three aspects are the challenges for current and future work. Particular attention must be paid to dilational interfacial rheology studies, as these mechanical quantities are much more sensitive to small changes in the interfacial composition and structure.

Role of Graphene in Oxidation of Underlying Cu Substrates Elucidated through Angle-Resolved X-ray Photoelectron Spectroscopy: Implications for Corrosion Protection of Graphene/Cu

The role of single-layer graphene in the oxidation process of Cu substrates underlying graphene remains controversial, and the evolution of interfacial oxide layers of graphene/Cu (Gr/Cu) over time has not been reported. Qualitative and quantitative studies of the interfacial oxide layer of Gr/Cu samples upon exposure to ambient conditions for long periods are crucial for revealing the role of graphene in the oxidation process of underlying Cu substrates, so as to further promote the research on corrosion protection of copper surfaces. Angle-resolved X-ray photoelectron spectroscopy (ARXPS) is a practical characterization technology for studying the structure, composition, and thickness of interfacial oxide layers. In this work, we propose an extended model to elucidate the role of graphene in oxidation of underlying Cu substrates through ARXPS study of evolution of interfacial oxide layers. The thickness of an interfacial oxide layer is positively correlated with air exposure time, and it is thinner than that of an oxide layer on a Cu surface; the fractional coverage of the island-like interfacial oxide layer is within the range of 0.4–0.6. For Gr/Cu samples exposed to ambient conditions for less than 6 months, graphene can inhibit the formation of Cu2O, whereas it promotes the formation of CuO in the interfacial oxide layer for long-term oxidized Gr/Cu samples (≥12 months), leading to the embedded structure of the interfacial oxide layer. The results of this study can serve as a guide for the corrosion protection of copper-based devices.

Interfacial behavior of cyclodextrins at the oil-water interface of Pickering emulsion

An oil-in-water (O/W) Pickering emulsion stabilized by cyclodextrins (CDs), including α-, β-, γ-CD, and the hydroxypropyl (HP) derivatives, was prepared by high-speed homogenization. The interfacial behavior of CDs was studied by the contact angle, surface tension, interface tension, and adsorption kinetics. The physicochemical properties of CD Pickering emulsion were characterized by adsorption content, microstructure, rheology, and instability index. The results showed that the contact angles (85.30° and 75.93°), diffusion rates (−0.2481 and −0.1285), and adsorption rates (−0.0045 and −0.0028) of α-CD and β-CD were significantly higher than those of HP-CD derivatives, and emulsions possessed smaller droplet size (both about 7.5 μm) and better stability compared with HP-CDs derivatives. The formation of Pickering emulsion was attributable to the interfacial adsorption layer structure at the oil-water interface formed by the self-assembly of CD. Subsequent studies on the physiochemical properties of emulsion showed that Pickering emulsions stabilized by α-CD and β-CD had better storage modulus, loss modulus, viscosity, storage stability, and centrifugal stability. HP-α-CD, HP-β-CD, and HP-γ-CD stabilized emulsions delaminated and sedimented within a short time. The amorphous HP-α-CD, HP-β-CD, and HP-γ-CD were difficult to form stable interfacial layers and adsorb on the surface of oil droplets due to their high-water solubility and poor crystallinity. • Interfacial behavior of cyclodextrins in the Pickering emulsion was investigated. • α-CD, β-CD, and γ-CD formed rigid interfacial adsorption layer structure, the emulsions exhibited small droplet size and high apparent viscosity. • HP-α-CD, HP-β-CD, and HP-γ-CD were difficult to form stable interfacial layer, the emulsions exhibited low moduli and poor stability.

The inhibition of MnO on Fe2Al5Znx growth and associated three-dimensional nested phase distribution in the galvanized coating of high-Al low-Si dual phase steel

Continuous hot-dip galvanizing is an important process for dual phase (DP) steel and other advanced high-strength steels (AHSSs). During this process, the formation of a Fe-Al inhibition layer and the selective oxidation of alloying elements will change the interfacial layer structure, and affect the galvanized coating structure. So far, the interfacial layer structure and its relationship with galvanized coating in high-Al low-Si DP steel are still unclear. In this paper, the interfacial layer and galvanized coating of hot-dip galvanized high-Al low-Si DP steel were characterized by electron microscopy. The results showed that there exists abundant nano-size MnO phases and Fe2Al5Znx phases inside the interfacial layer, and the galvanized coating consists of Fe3Zn10 nanophases and η-Zn phase. The competitive relationship between those interfacial phases strongly affects the phase distribution inside the galvanized coating adjacent to the interfacial layer. The MnO phases in the interfacial layer hinder the nucleation and growth of Fe2Al5Znx phases. As a result, the inhibition of the Fe-Zn reaction is weakened and the final galvanized coating exhibited a three-dimensional nested distribution of coexistence of Fe3Zn10 nanophases and η-Zn phase.

A one-step surface modification technique improved the nutrient release characteristics of controlled-release fertilizers and reduced the use of coating materials

Controlled-release fertilizers (CRFs) are a valid solution to agriculture's nonpoint source pollution problem. Due to surface structural defects in the fertilizer core, however, a large amount of coating material was wasted. A simple, fertilizer surface modification technique (SMT) that is based on abrasives was created in this study to modify the micro/nanostructure of the core surface, thereby considerably minimizing the amount of coating material and ensuring precise and long-term nutrient release. The effects of the SMT on the surface structure, roughness, and roundness of fertilizer cores were investigated, and a finite, element-based, interface polishing removal kinetic model and a discrete element, simulation-based, two-phase, fluid dynamics model were developed. The effect of core surface structural defects on the coating formation of CRFs and the controlled-release behavior of nutrients was observed at the micro- and nanoscale. The SMT improved the formed weak interfacial layer structure by urea crystals adsorbing water vapor, by reducing surface roughness by 64.43%, by improving overall particle fluidity, by increasing the proportion of urea with high roundness (0.950–0.975) by 8.72%, and by lessening the surface area of a single particle by 2.18%. At high temperatures, the surface was softened and deformed, allowing for the reconstruction of the surface microstructure and for a considerable improvement in interfacial bonding performance. The CRF nutrient release characteristics showed that the SMT enhanced the tightness and consistency of the coating, improved the precision of nutrient release, and reduced the use of coating material by up to 28.6% during the same release period. This novel technology has the potential to significantly optimize the production of CRF by reducing coating materials and residues in soil generated after nutrient release.

Preparation and interfacial layer microstructure of multilayer heterogeneous composite

The appropriate hetero interfacial layer structure between metal and ceramic matrix composites is a very interesting topic in materials science. In this work, an adaptive diffusion reactive interfacial layer composed of “Mo–Mo2C–Mo5Si3–MoSi2–SiC” between Mo and SiCf/SiC composite is successfully prepared by chemical vapor infiltration (CVI). This reactive interfacial system is among three possible structures of interfacial layers predicted by Density-functional theory (DFT) calculations, which has the largest total interfacial energy (5.679 J/m2). At the same time, the formation process of the reaction interface layers is elucidated by thermodynamic calculations. In addition, dislocations are observed in Mo5Si3 and Mo2C grains, and it is worth mentioning that the Mo5Si3 grains are broken through dislocation movement to form fine grains, which release the residual thermal stress of the interfacial layer system caused by thermal mismatch during the long-term CVI process. Overall, our work provides a practical strategy for developing multilayer heterogeneous composites.

Dual In Situ Laser Techniques Underpin the Role of Cations in Impacting Electrocatalysts.

Understanding the electrode/electrolyte interface is crucial for optimizing electrocatalytic performances. Here, we demonstrate that the nature of alkali metal cations can profoundly impact the oxygen evolution activity of surface‐mounted metal–organic framework (SURMOF) derived electrocatalysts, which are based on NiFe(OOH). In situ Raman spectroscopy results show that Raman shifts of the Ni−O bending vibration are inversely proportional to the mass activities from Cs+ to Li+. Particularly, a laser‐induced current transient technique was introduced to study the cation‐dependent electric double layer properties and their effects on the activity. The catalytic trend appeared to be closely related to the potential of maximum entropy of the system, suggesting a strong cation impact on the interfacial water layer structure. Our results highlight how the electrolyte composition can be used to maximize the performance of SURMOF derivatives toward electrochemical water splitting.

Dual In Situ Laser Techniques Underpin the Role of Cations in Impacting Electrocatalysts

AbstractUnderstanding the electrode/electrolyte interface is crucial for optimizing electrocatalytic performances. Here, we demonstrate that the nature of alkali metal cations can profoundly impact the oxygen evolution activity of surface‐mounted metal–organic framework (SURMOF) derived electrocatalysts, which are based on NiFe(OOH). In situ Raman spectroscopy results show that Raman shifts of the Ni−O bending vibration are inversely proportional to the mass activities from Cs+ to Li+. Particularly, a laser‐induced current transient technique was introduced to study the cation‐dependent electric double layer properties and their effects on the activity. The catalytic trend appeared to be closely related to the potential of maximum entropy of the system, suggesting a strong cation impact on the interfacial water layer structure. Our results highlight how the electrolyte composition can be used to maximize the performance of SURMOF derivatives toward electrochemical water splitting.

Experimental evidence of a mixed amorphous-crystalline graphene/SiC interface due to oxygen-intercalation

The introduction of atoms of different chemical species between epitaxial graphene and the SiC substrate by means of an intercalation process has been a reliable route to modify the interaction of this 2D material and its underlying substrate. Distinct atomic species have been intercalated so far and studies focusing on bond states of the electronically active layers were successful, retrieving the local chemical environment. However, the structure of interfacial layers is strongly affected whenever a more reactive atom is used in the intercalation process. In this work, we present experimental evidence based on X-ray crystal truncation rod scattering and photoelectron diffraction showing the coexistence of crystalline and amorphous regions in the oxidized interface. This interface between a bilayer graphene and the SiC substrate is generated by O-intercalation. Such fluctuations of the local structure are crucial to understand the abundant existence of silicon oxycarbides structures (SiOXCY) within the interfacial layer, which has been associated with the limited electronic properties of O- intercalated graphene bilayers. Consequently, this may be considered as a deterministic factor that affects device potentialities in these systems.

Water contact angles on charged surfaces in aerosols

Interactions between water and solid substrates are of fundamental importance to various processes in nature and industry. Electric control is widely used to modify interfacial water, where the influence of surface charges is inevitable. Here we obtain positively and negatively charged surfaces using LiTaO3 crystals and observe that a large net surface charge up to 0.1 C/m2 can nominally change the contact angles of pure water droplets comparing to the same uncharged surface. However, even a small amount of surface charge can efficiently increase the water contact angle in the presence of aerosols. Our results indicate that such surface charges can hardly affect the structure of interfacial water molecular layers and the morphology of the macroscopic droplet, while adsorption of a small amount of organic contaminants from aerosols with the help of Coulomb attraction can notably decrease the wettability of solid surface. Our results not only provide a fundamental understanding of the interactions between charged surfaces and water, but also help to develop new techniques on electric control of wettability and microfluidics in real aerosol environments.