Composite Interface Research Articles

When audience takes stage: Pseudo-localized-high-concentration electrolyte with lithium nitrate as the only salt enables lithium metal batteries with excellent temperature and cathode adaptability

A new concept for pseudo-localized-high-concentration electrolytes (PLHCE) is developed using cheap and less corrosive lithium nitrate as the single lithium salt to improve the electrochemical performance of the lithium metal batteries with excellent temperature and cathode adaptability. Unlike conventional localized high-concentration electrolytes, a small number of the diluent molecules involved in the solvation structure by lithium nitrate and triethyl phosphate (TEP) promote the formation of an organic-inorganic composite solid electrolyte interface (SEI) layer. A good balance is achieved in terms of the mechanical properties of the SEI layer. A high coulombic efficiency of more than 98% for the Li||Cu cell and 1000 h of long-term cycling for the Li||Li cell is exhibited. Assisted with the PLHCE strategy, the Li||LFP cells display excellent performance at both room and high temperatures, and the Li||NCM523 cells with a high working voltage exhibit good electrochemical stability as well. Moreover, alternative solvents are selected as the pseudo-diluents, which proves the general applicability of the PLHCE approach. This work provides an innovative concept to use the solubility difference to manipulate the solvation structure, which paves a new but simple way to design advanced electrolytes for lithium secondary batteries.

Interface and strengthening mechanisms of Al matrix composites reinforced with in-situ CNTs grown on Ti particles

The strengthening effect of carbon nanotubes (CNTs) in Al matrix composites (AMCs) is significantly weakened by CNTs agglomeration and unsubstantial interfacial bonding with the Al matrix. In this study, CNTs were grown on the surface of Ti particles by chemical vapor deposition to obtain CNTs@Ti hybrid reinforcement, followed by powder metallurgy to prepare CNTs@Ti/Al composites. Evenly dispersed CNTs with good structural integrity were successfully obtained using the carrying effect of the micron-sized Ti particles. Meanwhile, TiC, Al4C3, and TiAl3 were generated at the CNT/Al interface, which strengthened the bearing capacity of the inner-wall of the CNTs, improved the wettability of the CNT/Al interface, and enhanced the strain-hardening ability of the Al matrix. The deficiencies in the CNTs/Al composites are compensated by this kind of materials design, and the two types of reinforcements have a synergistic strengthening effect, which greatly improves the comprehensive mechanical properties of AMCs. An excellent interface structure is formed by controlling the interface reaction such that the dispersion, grain boundary, dislocation, and load transfer strengthening mechanisms are fully realized.

Multi-span composite girders with composite dowels – Experimental investigations and design approach to account for the beneficial effect of shear force redistribution along the composite interface

The broad use of composite dowels as shear connectors in multi-span steel and concrete composite members is currently hindered by insufficient regulations for hogging moment regions, where the connectors are located in cracked concrete slabs and have reduced shear resistance. This paper reports on the results of three beam tests that illustrate the ability of continuous steel and concrete composite beams with composite dowels to redistribute shear forces from impaired connectors located in hogging bending regions to intact connectors in sagging bending regions. The effect of concrete cracking on the load-bearing behaviour of composite dowels is analysed with regard to their strength, stiffness and ductility by means of three full-scale member tests. This paper proofs the existence of a beneficial shear force redistribution process along the interface of multi-span composite members and quantifies the shear force transfer occurring between connectors in sagging and hogging bending regions. In addition, the paper provides an economical design method for continuous composite girders. Previously developed models regarding the shear resistance of single composite dowels in cracked concrete are refined aiming to provide both safety and ease of use. These models are subsequently extended into a comprehensive design strategy that allows us to consider the beneficial shear force redistribution processes along the interface when designing the shear connection of multi-span composite beams with composite dowels.

Plasmonic silver nanoparticle-deposited n-Bi2S3/p-MnOS diode-type catalyst for enhanced photocatalytic nitrogen fixation: Introducing the defective p-MnOS

Photocatalytic nitrogen reduction reaction (PNRR) is clean and sustainable, considered an ideal synthesis technology for ammonia (NH3). In this study, we in situ developed the n-Bi2S3 nanorod/p-MnOS cubic composite catalyst for the first time using a one-step hydrothermal method, as MnOS, listed in the X-ray diffraction standard data file as an uncharacterized compound, has not been reported since 1965. Then, using a photodeposition technique, Ag nanoparticles (NPs) were added to the surface of the Bi2S3/MnOS to enhance PNRR via the surface plasmon resonance. After different characterization techniques for evaluation, Ag-Bi2S3/MnOS is found to be highly effective in the spatial separation of photogenerated electron-hole pairs due to the charge transfer at the composite interface. Photodeposited Ag is applied as an electron trapper to enhance the spatial separation of charge carriers. Based on their ability to reduce nitrogen under simulated solar light irradiation, the PNRR activities of Bi2S3, MnOS, Bi2S3/MnOS, and 0.5 to 2 % Ag-Bi2S3/MnOS were evaluated. After two hours, the PNRR activity of 1 % Ag-Bi2S3/MnOS produced ammonia 5.9 mmol/g, double the amount of Bi2S3/MnOS composite and approximately 5 times the amounts of Bi2S3 and MnOS materials. PNRR enhancement involves the internal static electron field created at the n-type Bi2S3/p-type MnOS interface and the improved electron conductivity with the photodeposition of Ag NPs, to speed up the reaction of reactive species. The importance of solid solution engineering in material design is demonstrated in this work.

Heterojunction engineered MWCNT/Ag[formula omitted] via organic acid and its natural light-assisted photocatalytic efficiency

Compositing photoactive, but unstable semiconductors with low dimensional carbon-based materials and modulating the hetero junction between them can assure more efficient and stable systems for the remediation of severe pollutants. The current study has given emphasis to understand the role of sulfonic acid in making a compact heterojunction between AP and MWCNTs, considering the effective delocalization of carriers and the direct relationship with the photoactivity. The significant reduction in the band gap of AP from 2.320 to 2.0516ev after the introduction of MWCNTs unmistakably confirmed the compatibility between the composite moieties. The intensity of the photoluminescence peak observed at an emission wavelength of 350nm for pure AP was found to be minimized in the composite, which confirms the effective charge delocalization from AP to the conductive MWCNTs. The closest bond distance was observed in the range of 2.3 to 2.5Å between an O atom of Ag3PO4 and a C atom of CNT, which explains the tight contact between the species. The photoactivity studies unambiguously confirmed the potential of the organic acid at the composite interface as it could accomplish 99% dye degradation within a span of 8min, whilst the system without the organic acid exhibited complete degradation within a span of 60min. The p-XRD analysis of the catalyst recovered from the reaction mixture revealed its high stability.

Boundary layers in the vicinity of the prepreg interface in layered composites and the homogenized delamination criterion

Boundary layers in the vicinity of the prepreg interface in layered composites and the homogenized delamination criterion

Ion-Beam Surface Modification of Carbon Fibers

Carbon fibers are used in the production of automobiles, airplanes, sporting goods, energy, and biomedicine due to their unique properties such as high specific strength, high specific tensile strength, low coefficient of thermal expansion, and low density. The research and development of both the technology of carbon fibers production and their modification for a wide range of applications have been and remain relevant. The summary of the accumulated experience in the modification of carbon fibers shows that ion-beam treatment allows to obtain a variety of geometry of the developed surface topography, in particular, whisker-shaped and corrugated oriented across or along the fiber. Such processing compares favorably with ordinary fiber whiskering both by a variety of geometry of the composite interface, and by the absence of the problem of whisker-fiber adhesion. Ion-beam treatment also makes it possible to modify the surface layer structure from amorphized to ordered with different degrees of graphitization. Irradiation with chemically active ions leads to functionalization of carbon fiber due to formation, for example, of nitrides and carbon oxides. The choice of nitrogen ions for the technology of carbon-carbon and carbon-ceramic composites seems to be more preferable due to less stringent requirements for the temperature of the irradiated fiber. For ion-beam corrugation of polyacrylonitrile-based carbon fiber surface, only its heating above the temperature of dynamic annealing of radiation damage is required. The use of helium ions in technological plasma acceleration systems leads to a significant efficiency increase in ion-beam processing.

Study on Interfacial Properties of Carbon Nanotube Modified Epoxy Resin/T1000 Carbon Fiber Composites

This study was made on domestic T1000 carbon fiber to investigate its surface condition, precursor, multifilament, fiber/resin contact angle, fiber/resin interfacial shear strength and interlaminar shear strength. Analysis was carried out to examine the surface physical state of domestic T1000 carbon fiber, the micro-scale interfacial properties and mechanical properties of the composites. The results show that domestic T1000 grade carbon fiber has no inherent characteristic defects such as visible bumps, rough edges or grooves on its surface. It can obtain higher tensile strength. The fiber/resin interfacial test shows that carboxylated carbon nanotubes are well dispersed in the epoxy resin matrix by physical method. The mixed resin matrix has good wettability on carbon fibers and the contact angle of the composite interface decreases. The interfacial shear strength of SYT65 carbon fibers/resin increases by 10.6%, and the interlaminar shear strength increases by 15.7%. Toray T1000 carbon fiber/resin interfacial shear strength increases by 6.1%, and interlaminar shear strength increases by 14.1%. Compared with Toray T1000, the resin system used in this study is more compatible with SYT65 carbon fiber, which can give full play to the mechanical properties of SYT65 carbon fiber.

Investigations of thermo-mechanical properties of cryogenic and dual alkali-anhydrous treated hemp fibre and its composites

Physicochemical/thermal modifications on the organic fibres increase the cellulose exposure, potentially improving the thermo-mechanical properties of the composites. This work aims to investigate the thermo-mechanical properties of hemp fibres and their composites to understand the effect of the proposed novel cryogenic treatment using physicochemical characterization like scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Fourier transmission infrared spectroscopy (FTIR). The study compares them with conventional dual alkali-anhydrous treatment on the fibres. Dual alkali-anhydrous treatment on the fibres didn’t change its thermal properties, but specific chemical changes were detected. In comparison, investigations of cryogenic treatment on fibres showed improved thermal stability and wettability due to increased cellulose exposure in the primary cell wall. It also reduced the moisture absorption in the fibres. Improvement in mechanical properties was observed in cryogenic treated hemp composite due to increased frictional bond in the composite interface. Hence the proposed cryogenic treatment provides new directions for developing bio-composites for potential engineering applications like automobile interiors and insulation panels in mining applications.

Thermal conductivity and mechanical properties of graphite/Mg composite with a super-nano CaCO3 interfacial layer

Incorporating graphite/graphene into a Mg alloy matrix is a promising approach for developing lightweight heat dissipation materials. However, carbon material is inherently incompatible with Mg because of their distinctly different surface characteristics, resulting in the challenge of composite fabricating and interface controlling. Herein, a new strategy of in situ interfacial modification was proposed to achieve excellent thermal conductivity and mechanical properties in graphite/Mg composites. A super-nano CaCO3 interfacial layer was reported in this paper. The detailed interfacial structure, reaction thermodynamics and kinetics, and interface strengthening mechanisms were analyzed and discussed. Several preferential epitaxial relationships of the Mg/CaCO3 interface were revealed, which are conducive to minimize the interfacial energy, stabilize and strengthen the interface. Moreover, strong ionic bond of graphite/CaCO3 interface was demonstrated. The strong chemical interface bonding of graphite-Mg via in situ interface modification facilitates both the interfacial cohesion and interfacial thermal conduction, which endows the graphite/Mg composites with superior strength-thermal conductivity synergy.

Reversible Dual-Covalent Molecular Locking of the 14-3-3/ERRγ Protein-Protein Interaction as a Molecular Glue Drug Discovery Approach.

Molecules that stabilize protein-protein interactions (PPIs) are invaluable as tool compounds for biophysics and (structural) biology, and as starting points for molecular glue drug discovery. However, identifying initial starting points for PPI stabilizing matter is highly challenging, and chemical optimization is labor-intensive. Inspired by chemical crosslinking and reversible covalent fragment-based drug discovery, we developed an approach that we term "molecular locks" to rapidly access molecular glue-like tool compounds. These dual-covalent small molecules reversibly react with a nucleophilic amino acid on each of the partner proteins to dynamically crosslink the protein complex. The PPI between the hub protein 14-3-3 and estrogen-related receptor γ (ERRγ) was used as a pharmacologically relevant case study. Based on a focused library of dual-reactive small molecules, a molecular glue tool compound was rapidly developed. Biochemical assays and X-ray crystallographic studies validated the ternary covalent complex formation and overall PPI stabilization via dynamic covalent crosslinking. The molecular lock approach is highly selective for the specific 14-3-3/ERRγ complex, over other 14-3-3 complexes. This selectivity is driven by the interplay of molecular reactivity and molecular recognition of the composite PPI binding interface. The long lifetime of the dual-covalent locks enabled the selective stabilization of the 14-3-3/ERRγ complex even in the presence of several other competing 14-3-3 clients with higher intrinsic binding affinities. The molecular lock approach enables systematic, selective, and potent stabilization of protein complexes to support molecular glue drug discovery.

Structural modification of TA2/Q355B composite interface and study of TiC stability mechanism

Constructing different titanium/steel composite interface structures and stabilising the TiC layer at 950°C through structural modification, the coexistence of multiple brittle phases at the composite interface was reduced and discussed the formation mechanism. Through structure modulation, the organisation of the bonding interface near the Ti side transformed into α-Ti, and the bond strength significantly increased to 290 MPa. Break through the rolling temperature should be limited to below 850°C, and the rolling temperature increases to 950°C. The bonding interface is transformed from discontinuous TiC and aggregated Fe2Ti particles to a uniform and continuous TiC layer at 850 and 900°C. Achieving a regulated TiC layer thickness of 180–190 nm inhibited Fe2Ti and FeTi production.

On the application of strong thermoplastic–thermoset interactions for developing advanced aerospace-composite joints

In this study, an aerospace thermosetting composite was co-curing joined by Polyether-ether-ketone (PEEK) and Polyethylenimine (PEI) films, with an aim of developing advanced composite joints. The semi-crystalline PEEK films were surface activated upon a UV-irradiation technique to obtain a strong film–composite interface, while the amorphous PEI films could be directly used. The fracture behaviour of the composite joints was evaluated and compared with benchmark aerospace adhesive joints. The experimental results proved remarkable mode-I and mode-II fracture resistance of the PEEK co-cured joints at 22 °C and 130 °C, while the PEI co-cured joints exhibited excellent mode-I fracture resistance at 22 °C and mode-II fracture resistance in both testing temperature cases. Extensive elongation, tearing and fracture of the PEEK/PEI plastics were proved to be the main mechanisms for toughness enhancement. Overall, this work had successfully demonstrated the effectiveness of developing advanced composite joints via a co-curing process using high-performance thermoplastic films.

An innovative design of integrative polyaniline/carbon foam flexible electrode material with improved electrochemical performance

The core task of high performance flexible supercapacitor is to generate flexible electrode material with high performance, light weight, and easy machining. Supercritical fluid technology is introduced, going beyond electrochemical deposition method, to solve the problems of low specific capacity and poor interface compatibility. An integrated polyaniline/carbon foam electrode material with improved electrochemical performance is constructed, by using supercritical fluid with high diffusivity, strong permeability, and superior solvation ability, to realize the controllable construction of composite microstructure and active interface regulation. The specific capacitance reaches 856.07 F/g at 1 A/g and high specific energy density of 96.3 Wh/kg at a power density of 3600 W/kg. This work makes possible the innovative experiment design of polymer and carbon-based materials integration with higher specific capacity and better interface compatibility. Therefore, the flexible electrode with high specific and high stability can be constructed by using the high diffusivity, strong permeability, and superior solvation ability of supercritical fluid.

In-situ growth of Z-Scheme Ag/PPy/BiVO4 core–shell structure for efficient CO2 photoreduction into hydrocarbon fuels

Photocatalytic reduction of CO2 to hydrocarbons (e.g., CH4) or CO under mild conditions, providing a feasible and promising method for the environmental remediation and utilization of carbon resources. However, since CO2-to-CO is a two–electron process, and even CO2-to-CH4 is an eight-electron reaction, it is a challenging task to achieve CO2 activation with an extremely short effective charge lifetime. In this paper, a synergistic effect strategy is used to prepare Ag nanoparticles modified PPy/BiVO4 Z-Scheme composites for synergizing the charge separation and surface catalytic processes in CO2 reduction reaction. With the joint efforts of synergy, the optimal photocatalyst achieves an efficient CO2 reduction yield (5.92 μmol·g−1·h−1) with an exceptionally high CO selectivity of 85.8% and the corresponding O2 evolution. Based on the result analysis, it can be clearly proved that the excellent CO2 reduction performance relies on the Z–Scheme charge transfer mechanism between PPy/BiVO4 composites interface and the strong catalytic effect of Ag nanoparticles on CO2. Furthermore, the detailed processes of deoxygenation and proton acquisition during CO2 reduction is revealed by in-situ DRIFTS and NAP-XPS. This paper demonstrates a strategy for designing efficient photocatalysts toward reduction of CO2 to higher value-added chemicals, and highlights the importance of catalysis and charge separation to the synergy of key steps in catalytic reactions.

Impact of interfacial compositional diffusion on interfacial phonon scattering and transmission in GaN/AlN heterostructure

Compositional diffusion at interfaces often occurs during the synthesis of heterostructures, which poses a significant challenge to the reliability and performance of heterostructure-based electronic devices. In this study, the effect of interfacial compositional diffusion on the interfacial phonon transport in GaN/AlN heterostructures has been explored using molecular dynamics and phonon dynamics simulations. It is found the compositional diffusion results in a remarkable reduction in the interfacial thermal conductance (ITC) of the heterostructures, which can be modulated by tuning the compositional diffusion thickness. Phonon wave packet simulations further revealed that the energy transmission coefficient across the interface is strongly phonon frequency-dependent and interfacial morphology-dependent, which is consistent well with the calculated ITC of the structures. The phonon mode conversion and phonon localization are observed at the region of interfaces. Furthermore, it is found that the longitudinal acoustic phonons are more sensitive to the compositional diffusion interface than transverse-acoustic phonons do. However, it is interesting to find that the energy transmission coefficients of transverse-acoustic phonons with a high frequency (above 3.6 THz) across the compositional interface are abnormally higher than those across the sharp interface due to the stronger phonon mode conversion in the compositional diffusion region, which provides additional pathways for energy transmission. Our findings provide a deeper insight into the interfacial phonon scattering and transmission under the coupling effect of interfacial morphology and compositional diffusion.

An efficient and durable bifunctional electrocatalyst based on PdO and Co2FeO4 for HER and OER

The adoption of effective, minimal, and versatile electrocatalysts for water splitting to generate hydrogen fuels is of critical importance. The bulk of newly described materials have considerable onset potential, but their electrocatalytic activity is limited by weak electrical conductivity and a limited range of catalytic sites. The combination of a few precious metals added with transition metal-based compounds is a novel and captivating approach. Herein, cobalt ferrite oxide (Co2FeO4) @ palladium oxide (PdO) nanostructures have been prepared through the combined use of hydrothermal and ultraviolet (UV) irradiation techniques. For hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) kinetics, the modified composition offers a high concentration of active sites, improved electrical conductivity, and stability. The Co, Fe, and Pd ions at the composite system's interface may affect the adsorption energy of reaction intermediates synergistically, enabling the process to continue with less potential. The electrocatalyst Co2FeO4@PdO demonstrates an excellent bifunctional approach to electrochemical water splitting (EWS) for HER and OER in alkaline medium. As-prepared electrocatalyst shows an overpotential value of 269 and 259 mV for HER and OER at 10 and 20 mA/cm2 current densities respectively. The low charge transfer resistance values such as 72.2 and 62.4 Ω and durability for 48 h has been observed toward HER and OER, support this material as an efficient and durable electrocatalyst for energy conversion systems.

Effect of WC Content on Microstructure and Element Diffusion of Nano WC-Co-TiC/304 Stainless Steel Composites for Micro Drill

In this study, WC-Co-TiC/304 stainless steel composites were successfully prepared by compression at room temperature and vacuum sintering in a special mold. Through analysis and comparison of the microstructure, density, and particle size of WC-Co-TiC/304 stainless steel composite, the effects of different WC contents on the structure and properties of WC-Co-TiC were studied. The results show that among different WC contents when the WC content is 60%, the distribution of each structure is relatively uniform and fine, and the agglomeration of each structure is not obvious. The bonding effect of WC-Co-TiC cemented carbide and 304 stainless steel composite interface is the best. With the increase of WC content, the side defects of WC-Co-TiC cemented carbide increase gradually. When WC content is 60%, the best ratio is 1:1 of Co/TiC, as the density is 94.45%, the particle size of 0.2–0.3 μm is 38.9%, and the highest hardness of WC-Co-TiC cemented carbide side is 1370 HV0.1, but it is better when the ratio of Co/TiC is 3:2 at the composite interface, as the hardness value is 852 HV0.1 and the diffusion of Cr element is more uniform, while other elements have little difference.

Interface Calculation of In Situ Micro-Nano TaC/NbC Ceramic Particle Composites.

Traditional experiments are difficult to accurately and quantitatively measure the interfacial properties of composites, such as interfacial bonding strength, interfacial microelectronic structure, and other information. It is particularly necessary to carry out theoretical research for guiding the interface regulation of Fe/MCs composites. In this research, the first-principles calculation method is used to systematically study the interface bonding work; however, in order to simplify the first-principle calculation of the model, dislocation is not considered in this paper, including interface bonding characteristics and electronic properties of α-Fe- and NaCl-type transition metal carbides (Niobium Carbide (NbC) and Tantalum Carbide (TaC)). The interface energy is related to the bond energy between the interface Fe atoms, C atoms and metal M atoms, and the interface energy Fe/TaC < Fe/NbC. The bonding strength of the composite interface system is accurately measured, and the interface strengthening mechanism is analyzed from the perspectives of atomic bonding and electronic structure, which provides a scientific guiding ideology for regulating the interface structure of composite materials.

Numerical simulation of an entangled wire-silicone rubber continuous interpenetration structure based on domain meshing superposition method

The entangled metal wire/silicone rubber continuous interpenetrated phase composite (EMW-SRC) is a high-performance damping material with silicone rubber as matrix and metal wire turns as the reinforcement skeleton. EMW-SRC has good damping characteristics and significant load-bearing stiffness. This work first characterizes the fine interface morphology and macroscopic mechanical characteristics of the EMW-SRC and adopts a computer-aided preparation technology to accurately reconstruct the complex structure of the spatially random distribution of the entangled metal wire material. It develops a finite element model of the EMW-SRC with high-quality structured mesh based on the domain mesh superposition method cohesive cells to share and embed the surface nodes at the interface. Moreover, the composite interface bonding performance between metal wire and silicone rubber is investigated, the interfacial bonding parameters are determined, and the reliability of the mesh model is assessed by comparing the results of a single wire pull-out test and simulation analysis. Based on this, quasi-static compression test and simulation of the material are further performed, with the simulation results matching well with the experimental ones. The mesoscale simulation results show that the metal wire inside the EMW-SRC can overcome the silicone rubber restriction on micro-slip during the load-bearing process. The metal wire micro-element is subjected to torsional load. Under a compression displacement of 0.7 mm, the composite interface bonding remains intact without damage. In conclusion, the developed model can provide a prior guidance on the preparation and use conditions of the proposed material and offers an effective way to investigate the fine-mechanics of such materials with high damping and high load-bearing characteristics.