Melamine-Regulated Ceramic/Polymer Electrolyte Interface Promotes High Stability in Lithium-Metal Battery

With the advantages of organic and inorganic solid electrolytes, composite electrolytes are a promising option for use in all-solid-state Li-metal batteries. However, the considerable disparity in interfacial energy between ceramic and polymer electrolytes results in poor solid-solid contacts and the internal creation of a space charge layer in the composite electrolyte. Here, we report a melamine (MA) transition layer for the sake of strengthening the bond between Li_1.5Al_0.5Ge_1.5(PO₄)₃ (LAGP) and poly(ethylene oxide) (PEO) to enhance physical and electrochemical properties. The MA is absorbed on LAGP by electron transfer from LAGP to MA's triazine ring, resulting in intimate contact and good mechanical stability. Simultaneously, the MA stabilizes the Li-salt anion, reduces its decomposition reactions at the interface between PEO and LAGP in the electrolyte, and promotes free Li⁺ dissociation, resulting in superior ionic conductivity and interfacial stability. Thus, the solid electrolyte film enables symmetric Li/Li batteries to achieve steady Li plating/stripping for more than 1300 h at a current density of 0.25 mA cm^-2. The all-solid-state Li|PEO-MA@LAGP|LFP cell exhibits improved cycling stability. The Li/PEO-MA@LAGP/NCM523 cell shows a cycling life that is a factor of 5 times greater than that of a cell based on PEO-LAGP.

Establishment of Silane/GO Multistage Hybrid Interface Layer to Improve Interfacial and Mechanical Properties of Carbon Fiber Reinforced Poly (phthalazinone ether ketone) Thermoplastic Composites

This study focused on the faint interface bonding between carbon fiber (CF) and poly(phthalazinone ether ketone) (PPEK) thermoplastic, a multistage hybrid interface layer was constructed via the condensation reaction of N-[3-(Trimethoxysilyl)propyl]-N,N,N-trimethylammonium chloride (KHN⁺) and the electrostatic adsorption of graphene oxide (GO). The influence of the contents of GO (0.2 wt%, 0.4 wt%, 0.6 wt%) on the interfacial properties of composites was explored. FTIR, Raman spectra, XPS tests indicated the successful preparation of CF-KHN⁺-GO reinforcements. The multistage hybrid interface layer significantly increased fiber surface roughness without surface microstructure destruction. Simultaneously, polarity and wettability are remarkably improved as evidenced by the dynamic contact angle experiment. The interlaminar shear strength (ILSS) and flexural strength of the CF/PPEK composites with 0.4 wt% GO (CF-KHN⁺-4GO) were 74.57 and 1508 MPa, which was 25.2% and 23.5% higher than that of untreated CF/PPEK composite, respectively. Dynamic mechanical analysis proved that CF/GO/PPEK composites have excellent high-temperature mechanical properties. This study furnishes an unsophisticated and valid strategy to build an interface transition layer with a strong binding force, which would offer a new train of thought in preparing high-performing structural composites.

Tuneable chemistry at the interface and self-healing towards improving structural properties of carbon fiber laminates: a critical review

Carbon fiber reinforced epoxy (CFRE) laminates have become a significant component in aircraft industries over the years due to their superior mechanical and highly tunable properties. However, the interfacial area between the fibers and the matrix continues to pose a significant challenge in debonding and delamination, leading to significant failures in such components. Therefore, since the advent of such laminated structures, researchers have worked on several interfacial modifications to better the mechanical properties and enhance such laminated systems' service life. These methods have primarily consisted of fiber sizing or matrix modifications, while effective fiber surface treatment has utilized the concept of surface energy to form an effective matrix locking mechanism. In recent times, with the advent of self-healing technology, research is being directed towards novel methods of self-healing interfacial modifications, which is a promising arena. In this review, we have provided comprehensive insight into the significance, historical advances, and latest developments of the interface of CFRE laminates. We have analysed the significant research work undertaken in recent years, which has shown a considerable shift in engineering the interface for mechanical property enhancement. Keeping in view the latest developments in self-healing technology, we have discussed reversible interfacial modifications and their impact on future improvements to service life.

Spontaneous formation of multilayer refractory carbide coatings in a molten salt media

Refractory materials hold great promise to develop functional multilayer coating for extreme environments and temperature applications but require high temperature and complex synthesis to overcome their strong atomic bonding and form a multilayer structure. Here, a spontaneous reaction producing sophisticated multilayer refractory carbide coatings on carbon fiber (CF) is reported. This approach utilizes a relatively low-temperature (950 °C) molten-salt process for forming refractory carbides. The reaction of titanium (Ti), chromium (Cr), and CF yields a complex, high-quality multilayer carbide coating composed of 1) Cr carbide (Cr₃C₂), 2) Ti carbide, and 3) Cr₃C₂ layers. The layered sequence arises from a difference in metal dissolutions, reactions, and diffusion rates in the salt media. The multilayer-coated CFs act as a permeable oxidation barrier with no crystalline degradation of the CFs after extreme temperature (1,200 °C) and environment (oxyacetylene flame) exposure. The synthesis of high-quality multilayer refractory coating in a fast, efficient, easy, and clean manner may answer the need for industrial applications that develop cheap and reliable extreme environment protection barriers.

Ultrafast carbon nanotubes growth on recycled carbon fibers and their evaluation on interfacial shear strength in reinforced composites

The global demand for products manufactured with carbon fibers (CFs) has increased in recent years; however, the waste generated at the end of the product lifetime has also increased. In this research, the impact of the addition of carbon nanotubes (CNTs) on the interlaminated resistance of recycled carbon fibers (RCFs) was studied. In this work, a recycling process of the composite material was applied via thermolysis to obtain the CFs, followed by the growth of CNTs on their surface using the Poptube technique. The recycling temperature were 500 °C and 700 °C; and ferrocene and polypyrrole were used to grow CNTs on CFs surface. CNTs were verified by Raman spectroscopy and scanning electron microscopy (SEM). Finally, to determine the interlaminar resistance, a double cantilever beam (DCB) test was performed. The results indicate that with Poptube technique, CNTs can be grown on RCFs using both impregnations. Thermolysis recycling process at 500 °C allowed CFs without resin residues and without visible damage. The DCB tests showed a decrease in the fracture resistance in mode I loading of 34.9% for the polypyrrole samples and 29.3% for the ferrocene samples compared with the virgin carbon fibers (VCFs) samples with a resistance of 1052.5 J/m².

A simple way to synthesize a nano-scale stable epoxy emulsion for sizing CF/epoxy composites

Emulsion prepared with EE-P20 (“lipophilic–hydrophilic–hydrophobic” structure), as the emulsifier can improve the interface performance and moisture resistance of CF.

Chemically Grafting Carbon Nanotubes onto Carbon Fibers for Enhancing Interfacial Properties of Fiber Metal Laminate

This paper primarily investigates the effects of chemically grafted modified carbon fibers on the bonding properties of fiber metal laminates (FMLs). Relative elemental content on the carbon fibers’ surface was performed via X-ray photoelectron spectroscopy (XPS). Scanning electron microscopy (SEM) was utilized to observe the material microstructure. The effect of chemically grafted carbon fibers on the bond strengths of FMLs was experimentally investigated through lap joint testing. The carbon nanotubes (CNTs) grafting concentration and curing conditions of the samples were also investigated. The test results demonstrate that grafting concentrations of 0.1, 0.2, and 0.3 mg/mL CNT solution increased the bond strength of the cured samples under vacuum conditions by 63.51%, 87.16%, and 71.56%, respectively. In addition, the bond strengths of vacuum-cured samples were also increased.

Covalently Conjugated Gold-Porphyrin Nanostructures

Gold nanoparticles show important electronic and optical properties, owing to their size, shape, and electronic structures. Indeed, gold nanoparticles containing no more than 30–40 atoms are only luminescent, while nanometer-sized gold nanoparticles only show surface plasmon resonance. Therefore, it appears that gold nanoparticles can alternatively be luminescent or plasmonic and this represents a severe restriction for their use as optical material. The aim of our study was the fabrication of nanoscale assembly of Au nanoparticles with bi-functional porphyrin molecules that work as bridges between different gold nanoparticles. This functional architecture not only exhibits a strong surface plasmon, due to the Au nanoparticles, but also a strong luminescence signal due to porphyrin molecules, thus, behaving as an artificial organized plasmonic and fluorescent network. Mutual Au nanoparticles–porphyrin interactions tune the Au network size whose dimension can easily be read out, being the position of the surface plasmon resonance strongly indicative of this size. The present system can be used for all the applications requiring plasmonic and luminescent emitters.

Glycine-Induced Electrodeposition of Nanostructured Cobalt Hydroxide: A Bifunctional Catalyst for Overall Water Splitting

Herein, an interconnected α-Co(OH)₂ structure with a network-like architecture was used as a bifunctional electrocatalyst for the overall water splitting reaction in alkaline medium. The complexing ability of glycine with a transition metal was exploited to form [Co(gly)₃ ]^- dispersion at pH 10, which was used for the electrodeposition. High-resolution TEM, UV/Vis-diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy were used to confirm that the as-synthesized materials had an α-Co(OH)₂ phase. The electrocatalytic oxygen and hydrogen evolution activity of the glycine-coordinated α-Co(OH)₂ was found to be approximately 320 and 145 mV, respectively, at 10 mA cm^-2 . The material required approximately 1.60 V (vs. reversible hydrogen electrode; RHE) to achieve the benchmark of 10 mA cm^-2 for overall water splitting with a mass activity of approximately 63.7 A g^-1 at 1.60 V (vs. RHE). The chronoamperometric response was measured to evidence the stability of the material for overall water splitting for up to 24 h. Characterization of the catalyst after the oxygen and hydrogen evolution reactions was performed by XPS and showed the presence of a Co^II /Co^III oxidation state.

Rational functionalization of reduced graphene oxide with an imidazole group for the electrochemical sensing of bisphenol A - an endocrine disruptor

Reduced graphene oxide has been rationally functionalized with histamine for the highly sensitive and selective electrochemical determination of bisphenol A (BPA). Histamine is covalently attached to graphene oxide by amide coupling and the oxygen functionalities of graphene oxide are partially reduced electrochemically. The facilitated electrochemical oxidation of BPA was achieved in neutral pH with functionalized reduced graphene oxide. The pH of the reaction controls the oxidation of BPA. Electrochemical oxidation is not favourable at pH less than the pKa of histamine due to the protonation of the imidazole nitrogen. The electrode is highly sensitive (1727.29 ± 12.48 nA μM-1 cm-2) towards BPA and shows a linear response up to 30 μM of BPA. It could detect as low as 0.03 nM of BPA (S/N = 5). The other coexisting analytes do not interfere with the voltammetric measurement of BPA.