Fabrication of Cu/Al/Cu Laminated Composites Reinforced with Graphene by Hot Pressing and Evaluation of Their Electrical Conductivity

Metal laminated composites are widely used in industrial and commercial applications due to their excellent overall performance. In this study, the copper/graphene-aluminum-copper/graphene (Cu/Gr-Al-Cu/Gr) laminated composites were prepared by ingenious hot pressing design. Raman, optical microscope (OM), scanning electron microscope (SEM), van der Pauw (vdP), and X-Ray Diffractometer (XRD) were used to investigate the graphene status, interface bonding, diffusion layer thickness, electrical conductivity, Miller indices and secondary phases, respectively. The results demonstrate that the Cu-Al interfaces in the Cu/Gr-Al-Cu/Gr composites were free of pores, cracks and other defects and bonded well. The number of graphene layers was varied by regulating the thickness of the Cu/Gr layer, with the Cu/Gr foils fabricated by chemical vapor deposition (CVD). The electrical conductivity of the composite was significantly improved by the induced high-quality interfaces Cu/Gr structure. The increased number of graphene layers is beneficial for enhancing the electrical conductivity of the Cu/Gr-Al-Cu/Gr composite, and the highest conductivity improved by 20.5% compared to that of raw Al

Design strategy to simultaneously enhance electrical conductivity and strength: Cold-drawn copper-based composite wire with in-situ graphene

We proposed a unique wire-production process by rolling up and drawing chemical vapor deposition copper/graphene (Cu/Gr) foils, and a good strength-conductivity trade-off was achieved originating from the dispersed Gr in Cu matrix and the high-quality heterointerfaces. The 1.14 mm cold-drawn composite wire exhibited a tensile strength of 455 ± 5 MPa and a conductivity of 98.18 ± 0.16 % of the International Annealed Copper Standard (IACS), and the tensile strength was 250 ± 2 MPa with a satisfied electrical conductivity of 101.68 ± 0.52 % IACS upon annealing. The microstructure involution during the preparing process was revealed, and the reinforcement mechanisms in the yield strength and conductivity due to the introduced Gr were clarified. The results indicated that the Gr plays a role in pinning dislocations and preventing grain boundary movement during deformation and the subsequent annealing, thereby enhancing the strength of the Cu matrix. Meanwhile, the Cu-Gr coupling interfaces exhibited an electronic doping effect, enhancing the conductive properties. Our work presented a feasible method for preparing Cu/Gr composite wire with comprehensive electrical conductivity and strength optimization

Optical fibres with embedded two-dimensional materials for ultrahigh nonlinearity

| openaire: EC/H2020/834742/EU//ATOP | openaire: EC/H2020/820423/EU//S2QUIPNonlinear optical fibres have been employed for a vast number of applications, including optical frequency conversion, ultrafast laser and optical communication1–4. In current manufacturing technologies, nonlinearity is realized by the injection of nonlinear materials into fibres5–7 or the fabrication of microstructured fibres8–10. Both strategies, however, suffer from either low optical nonlinearity or poor design flexibility. Here, we report the direct growth of MoS2, a highly nonlinear two-dimensional material11, onto the internal walls of a SiO2 optical fibre. This growth is realized via a two-step chemical vapour deposition method, where a solid precursor is pre-deposited to guarantee a homogeneous feedstock before achieving uniform two-dimensional material growth along the entire fibre walls. By using the as-fabricated 25-cm-long fibre, both second- and third-harmonic generation could be enhanced by ~300 times compared with monolayer MoS2/silica. Propagation losses remain at ~0.1 dB cm–1 for a wide frequency range. In addition, we demonstrate an all-fibre mode-locked laser (~6 mW output, ~500 fs pulse width and ~41 MHz repetition rate) by integrating the two-dimensional-material-embedded optical fibre as a saturable absorber. Initial tests show that our fabrication strategy is amenable to other transition metal dichalcogenides, making these embedded fibres versatile for several all-fibre nonlinear optics and optoelectronics applications.Peer reviewe

PECAM-1 drives β-catenin-mediated EndMT via internalization in colon cancer with diabetes mellitus

Abstract Background Diabetes mellitus (DM) is considered to be a risk factor in carcinogenesis and progression, although the biological mechanisms are not well understood. Here we demonstrate that platelet-endothelial cell adhesion molecule 1 (PECAM-1) internalization drives β-catenin-mediated endothelial-mesenchymal transition (EndMT) to link DM to cancer. Methods The tumor microenvironment (TME) was investigated for differences between colon cancer with and without DM by mRNA-microarray analysis. The effect of DM on colon cancer was determined in clinical patients and animal models. Furthermore, EndMT, PECAM-1 and Akt/GSK-3β/β-catenin signaling were analyzed under high glucose (HG) and human colon cancer cell (HCCC) supernatant (SN) or coculture conditions by western and immunofluorescence tests. Results DM promoted the progression and EndMT occurrence of colon cancer (CC). Regarding the mechanism, DM induced PECAM-1 defection from the cytomembrane, internalization and subsequent accumulation around the cell nucleus in endothelial cells, which promoted β-catenin entry into the nucleus, leading to EndMT occurrence in CC with DM. Additionally, Akt/GSK-3β signaling was enhanced to inhibit the degradation of β-catenin, which regulates the process of EndMT. Conclusions PECAM-1 defects and/or internalization are key events for β-catenin-mediated EndMT, which is significantly boosted by enhanced Akt/GSK-3β signaling in the DM-associated TME. This contributes to the mechanism by which DM promotes the carcinogenesis and progression of CC. Graphical Abstract Video Abstrac

Kinetic modulation of graphene growth by fluorine through spatially confined decomposition of metal fluorides

Two-dimensional materials show a variety of promising properties, and controlling their growth is an important aspect for practical applications. To this end, active species such as hydrogen and oxygen are commonly introduced into reactors to promote the synthesis of two-dimensional materials with specific characteristics. Here, we demonstrate that fluorine can play a crucial role in tuning the growth kinetics of three representative two-dimensional materials (graphene, hexagonal boron nitride and WS2). When growing graphene by chemical vapour deposition on a copper foil, fluorine released from the decomposition of a metal fluoride placed near the copper foil greatly accelerates the growth of the graphene (up to a rate of ~200?????m???s???1). Theoretical calculations show that it does so by promoting decomposition of the methane feedstock, which converts the endothermic growth process to an exothermic one. We further show that the presence of fluorine also accelerates the growth of two-dimensional hexagonal boron nitride and WS2

Measurement of complex optical susceptibility for individual carbon nanotubes by elliptically polarized light excitation

The complex optical susceptibility is the most fundamental parameter characterizing light-matter interactions and determining optical applications in any material. In one-dimensional (1D) materials, all conventional techniques to measure the complex susceptibility become invalid. Here we report a methodology to measure the complex optical susceptibility of individual 1D materials by an elliptical-polarization-based optical homodyne detection. This method is based on the accurate manipulation of interference between incident left- (right-) handed elliptically polarized light and the scattering light, which results in the opposite (same) contribution of the real and imaginary susceptibility in two sets of spectra. We successfully demonstrate its application in determining complex susceptibility of individual chirality-defined carbon nanotubes in a broad optical spectral range (1.6–2.7 eV) and under different environments (suspended and in device). This full characterization of the complex optical responses should accelerate applications of various 1D nanomaterials in future photonic, optoelectronic, photovoltaic, and bio-imaging devices.Peer reviewe

Robust synthesis of two-dimensional metal dichalcogenides and their alloys by active chalcogen monomer supply

Two-dimensional (2D) transition metal dichalcogenides (TMDs), with their atomic thicknesses, high carrier mobility, fast charge transfer, and intrinsic spin-valley couplings, have been demonstrated one of the most appealing candidates for next-generation electronic and optoelectronic devices. The synthesis of TMDs with well-controlled crystallinity, quality and composition is essential to fully realize their promising applications. Similar to that in III-V semiconductor synthesis, the precise precursor supply is a precondition for controllable growth of TMDs. Although great efforts have been devoted to modulate the transition metal supply, few effective methods of chalcogen feeding control were developed. Herein we report a strategy of using active chalcogen monomer supply to grow TMDs and their alloys in a robust and controllable manner. It is found that at a high temperature, the active chalcogen monomers (such as S, Se, Te atoms or their mixtures) can be controllably released from metal chalcogenides and, thus, enable the synthesis of TMDs (MX2, M = Mo, W; X = S, Se, Te) with very high quality, e.g., MoS2 monolayers exhibit photoluminescent circular helicity of ~92%, comparable to the best exfoliated single-crystal flakes and close to the theoretical limit of unity. More intriguingly, a uniform quaternary TMD alloy with three different anions, i.e., MoS2(1-x-y)Se2xTe2y, was accomplished for the first time. Our mechanism study revealed that the active chalcogen monomers can bind and diffuse freely on a TMD surface, which enables the effective nucleation and reaction, quick chalcogen vacancy healing, and alloy formation during the growth. The chalcogen monomer supply strategy offers more degrees of freedom for the controllable synthesis of 2D compounds and their alloys, which will greatly benefit the development of high-end devices with desired 2D materials