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This study employed novel joint treatments to strengthen the carbon fiber reinforced polymer (CFRP) composites. Vertically aligned carbon nanotubes (VACNTs) were prepared in situ on the catalyst-treated CF surface via the chemical vapor deposition (CVD) method, intertwining into three-dimensional fiber-nets and fully surrounding CF to form an integrated structure. The resin pre-coating (RPC) technique was further used to guide diluted epoxy resin (without hardener) to flow into nanoscale and submicron spaces to eliminate void defects at the root of VACNTs. Three-point bending testing results showed the “growing CNTs and RPC”-treated CFRP composites yielded the best flexural strength, a 27.1% improvement over the specimens without treatment, while the failure modes indicated that the original delamination failure was changed into “flexural failure” with through-the-thickness crack propagation. In brief, growing VACNTs and RPC on the CF surface enabled toughening of the epoxy adhesive layer, reducing potential void defects and constructing the integrated quasi-Z-directional fiber bridging at the CF/epoxy interface for stronger CFRP composites. Therefore, the joint treatments of growing VACNTs in situ via the CVD method and RPC technique are very effective and have great potential in manufacturing high-strength CFRP composites for aerospace applications.

Vertically aligned carbon nanotubes arrays (VACNTs) are a promising candidate for the thermal interface material (TIM) of next-generation electronic devices due to their attractive thermal and mechanical properties. However, the environment required for synthesizing VACNTs is harsh and severely incompatible with standard device packaging processes. VACNTs’ extremely low in-plane thermal conductivity also limits its performance for cooling hot spots. Here, using a transfer-and-encapsulate strategy, a two-step soldering method is developed to cap both ends of the VACNTs with copper microfoils, forming a standalone Cu-VACNTs-Cu sandwich TIM and avoiding the need to directly grow VACNTs on chip die. This new TIM is fully compatible with standard packaging, with excellent flexibility and high thermal conductivities in both in-plane and through-plane directions. The mechanical compliance behavior and mechanism, which are critical for TIM applications, are investigated in depth using in situ nanoindentation. The thermal performance is further verified in an actual light emitting diode (LED) cooling experiment, demonstrating low thermal resistance, good reliability, and achieving a 17 °C temperature reduction compared with state-of-the-art commercial TIMs. This study provides a viable solution to VACNTs’ longstanding problem in device integration and free-end contact resistance, bringing it much closer to application and solving the critical thermal bottleneck in next-generation electronics.

Nanoscale materials are gaining massive attention in recent years due to their potential to alleviate the present electrochemical electrode constraints. Possessing high conductivity (both thermally and electrically), high chemical and electrochemical stability, exceptional mechanical strength and flexibility, high specific surface area, large charge storage capacity, and excellent ion-adsorption, carbon nanotubes (CNTs) remain one of the most researched of other nanoscale materials for electrochemical energy storage. Rather than having them packed at random, CNTs perform better when packed/grown to order, vertically or horizontally aligned to a substrate. This study presents an overview of the impact of CNT alignment on the electrochemical performance of lithium-ion batteries (LIBs). The unique properties of vertically aligned CNTs (VACNTs) for LIB application were discussed. Furthermore, the mechanisms of charge storage and electrochemical performances in VACNT-based (pristine and composites) anodes and cathodes of LIBs were succinctly reviewed. In the end, the existing challenges and future directions in the field were also briefly discussed.

A three-dimensional (3D) hybrid nanostructure of Fe3O4 nanoparticles uniformly anchored on vertically-aligned carbon nanotubes (VACNTs) was fabricated by a facile two-step method. Assisted by supercritical carbon dioxide (SCCO2), the Fe precursor was firstly absorbed on CNT surface and then transformed into Fe3O4 nanoparticles by vacuum thermal annealing. Owing to the synergetic effects of well-distributed Fe3O4 nanoparticles (~7 nm) and highly conductive VACNTs, the hybrid electrode exhibits a high specific capacitance of 364.2 F g−1 at 0.5 A g−1 within the potential range from −0.9 to +0.1 V in Na2SO3 electrolyte and an excellent cycling stability of 84.8% capacitance retention after 2000 cycles at a current density of 4 A/g. This 3D hybrid architecture consisting of aligned CNTs and pseudocapacitive metal oxide may be a promising electrode for high-performance supercapacitors.

A cost-effective, point of care (POC) device based on highly oriented CNT arrays was developed as an electrochemical assay for real-time and sensitive detection of glucose in complex samples. A low-cost, microcontroller-based potentiostat consisting of Arduino Due and LMP9100-EVM was developed to perform electrochemical measurements such as cyclic voltammetry (CV) and amperometry. A syringe pump based on open-source electronics was designed to direct the flow through a microfluidic chip. Vertically aligned carbon nanotube (VACNT) sensor arrays, in combination with the miniature potentiostat and the syringe pumps, were utilized as a POC device for the rapid and accurate detection of glucose. The structure and morphology of samples were characterized by field emission scanning electron microscopy (FESEM) and attenuated total reflectance Fourier transform infrared spectrometry (ATR-FTIR). CV as well as electrochemical impedance spectroscopy (EIS) was performed to investigate the electrochemical behavior of the electrode with respect to different diffusion regimes. The mediator-less biosensor had a limit of detection of 23 μM and sensitivity of 1462 μA mM−1 cm−2 and 1050 μA mM−1 cm−2 at the linear range of 1.2–7.8 mM and 7.8–11.2 mM, respectively. The presence of other biological compounds such as uric acid (UA) and ascorbic acid (AA) did not interfere with the detection of glucose. Finally, the designed POC device was successfully applied for the determination of glucose in human blood plasma samples.

Vertically Aligned Carbon Nanotubes (VACNTs)-coated flexible aluminium (Al) foil is studied as an electrode for supercapacitor applications. VACNTs are grown on Al foil inside thermal Chemical Vapor Deposition (CVD) reactor. 20 nm thick layer of Fe is used as a catalyst while Ar, H 2 and C 2 H 2 are used as precursor gases. The effect of growth temperature on the structure of CNTs is studied by varying the temperature of CVD reactor from 550 °C to 625 °C. Better alignment of VACNTs arrays on Al foil is recorded at 600 °C growth temperature in comparison to other processing temperatures. Cyclic voltammetry results shows that VACNTs-coated Al foil has a specific capacitance of ~ 3.01 F/g at a scan rate of 50 mV/s. The direct growth of VACNT array results in better contact with Al foil and thus low ESR values observed in impedance spectroscopy analysis. This leads to a fast charge–discharge cycle as well as a very high value of power density (187.79 kW/kg) suitable for high power applications. Moreover, wettability study shows that the fabricated VACNT electrode has a contact angle of more than 152° which signifies that it is a superhydrophobic surface and hence shows lower specific capacitance in comparison to reported values for VACNT array. Therefore, it is necessary to develop suitable post-processing strategies to make VACNTs hydrophilic to realize their full potential in supercapacitor applications.

Copper-filled vertically aligned carbon nanotubes (Cu@VACNTs) were grown directly on Cu foil substrates of 0.1 mm thicknesses at different temperatures via plasma-enhanced chemical vapor deposition (PECVD). By circumventing the need for additional catalyst layers or intensive substrate treatments, our in-situ technique offers a simplified and potentially scalable route for fabricating Cu@VACNTs with enhanced electrical and thermal properties on thin Cu foils. Comprehensive analysis using field emission scanning microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) mappings, and X-ray diffraction (XRD) revealed uniform Cu filling within the VACNTs across a range of synthesis temperatures (650 °C, 700 °C, and 760 °C). Field emission (FE) measurements of the sample synthesized at 700 °C (S700) showed low turn-on and threshold fields of 2.33 V/μm and 3.29 V/μm, respectively. The findings demonstrate the viability of thin Cu substrates in creating dense and highly conductive Cu-filled VACNT arrays for advanced electronic and nanoelectronics applications.

The design and construction of microstructures and nanostructures are crucial for regulating and enhancing phonon transport. Optimizing the heat dissipation and reducing the phonon scattering of hierarchical carbon-based anisotropic building blocks in the in-plane and/or through-plane directions is challenging. In this study, two types of multilayer interwoven order-structured carbon-based building blocks (DD/SDS) were fabricated using the ordered assembly of single/double-layer vertically arranged carbon nanotube arrays and flexible graphite paper (GP). The results show that the design and construction of multilayer order-structured are crucial for regulating in-plane and through-plane heat conduction. The different interlayer interwoven structures of DD and SDS generated two dominant modes of through-plane and in-plane heat conduction, respectively; these modes can be regulated within the 16.6 to 35.1 W/mK and 164.4 to 300.0 W/mK ranges. SDS exhibited tensile (5.4 MPa) and bending (30.0 MPa) strengths that were higher than those of DD (tensile strength of 3.8 MPa and bending strength of 28.0 MPa) because of the combined effect of the high strength of its three-layer GP and its interwoven nanotubes. These carbon-based building blocks as versatile heat dissipation boards the efficient heat dissipation requirements of point heat sources across varying power densities owing to their diverse and controllable heat conduction modes. They can also be applied in the cooling field of high-power light-emitting diode chips and alumina ceramic heating elements. Results showed that the cooling efficiency of SDS and DD is 33% and 72% higher than that of Si 3 N 4 , respectively. Graphical abstract

This study reports a binder-free, catalyst-free method for fabricating vertically aligned carbon nanotubes (VACNTs) directly on copper (Cu) foil using plasma-enhanced chemical vapor deposition (PECVD) for electrochemical double-layer capacitor (EDLC) applications. This approach eliminates the need for catalyst layers, polymeric binders, or substrate pre-treatments, simplifying electrode design and enhancing electrical integration. The resulting VACNTs form a dense, uniform, and porous array with strong adhesion to the Cu substrate, minimizing contact resistance and improving conductivity. Electrochemical analysis shows gravimetric specific capacitance (Cgrav) and areal specific capacitance (Careal) of 8 F g−1 and 3.5 mF cm−2 at a scan rate of 5 mV/s, with low equivalent series resistance (3.70 Ω) and charge transfer resistance (0.48 Ω), enabling efficient electron transport and rapid ion diffusion. The electrode demonstrates excellent rate capability and retains 92% of its initial specific capacitance after 3000 charge–discharge cycles, indicating strong cycling stability. These results demonstrate the potential of directly grown VACNT-based electrodes for high-performance EDLCs, particularly in applications requiring rapid charge–discharge cycles and sustained energy delivery.

The incorporation of vertically aligned carbon nanotubes (VACNTs) between composites plies has been said to enhance the through-thickness strength, and it can also decrease the risk of interply delamination and reduce crack initiation. Thanks to these high mechanical performances, nano-engineered hybrid composites are seen as promising for highly demanding structural reinforcement applications. This paper is part of a study that focuses specifically on the methodology for transferring VACNTs onto a prepreg surface while maintaining their initial vertically aligned morphology. The chosen method involved bonding the VACNTs’ forest through capillary impregnation of the forest by the prepreg’s resin. Key parameters for an effective transfer and to achieve a partial capillary rise of the resin into the VACNTs will be discussed here.