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Owing to their remarkable properties and ordered architecture, vertically aligned CNT forests (VACNT) hold promises for countless applications ranging from energy storage to multifunctional fiber production. Over the last three decades, studies of carbon nanotube (CNT) growth have provided invaluable insight into the CNT nucleation and growth mechanism and enabled critical advancements in nanotechnology. Nevertheless, the ability to fully harness the exceptional VACNT properties in commercial devices is bottlenecked by compatibility of current CNT synthesis processes with large-scale manufacturing. Metal foil substrates present an economic alternative to traditional insulating substrates, like silicon or quartz, and are compatible with both roll-to-roll and automated, large-scale, batch processes. Compared to CNT growth on Si substrates, metal foils present additional challenges, such as increased roughness and reactivity at high temperatures. Nonetheless, many successful VACNT growths on conducting metal foils have been reported, which demonstrate the feasibility of metal substrate use for large-volume production of high-quality CNTs. In this review, we discuss advancements in the field of VACNT growth on metal foil and specifically examine different choices for metal substrates, barrier and catalyst layers, deposition and growth methods, resulting CNT characteristics, and highlight a number of applications that benefit from CNT growth on metal substrates and transition to large-scale manufacturing. [Display omitted] • Exceptional VACNT properties are transformative for many technologies. • Challenges and successes of growing VACNTs on metal foils are described in detail. • Material choice, process conditions, and resulting CNT characteristics are reviewed. • Fundamental investigations and application driven developments are highlighted. • Products based on VACNTs grown on metal supports are at the market horizon. [ABSTRACT FROM AUTHOR]

Smart thermal interface materials must exhibit self-healability and high thermal conductivity (k) and elastic deformation as they can experience repeated compression and undergo sudden damage. However, it remains challenging to ensure high phonon mobility/efficient phonon transfer, self-healing, and good elasticity by optimizing its molecular orientation or cross-links. Herein, a self-healing and elastic polyimide copolymer (EMPI) cross-linked by flexible and rigid segments is uniformly filled into the gaps of a forest of vertically aligned carbon nanotubes (VACNTs). The EMPI@VACNTs composite exhibits a high k value at 10.83 ± 0.22 W m−1 K−1, low interfacial thermal resistance at 6.83 ± 0.15 K mm2 W−1, high elastic compressive deformation (30% at 2.5 MPa), and strong surface adhesion (0.3 MPa). Further, it could recover 90.8% of its elastic modulus and 92% of its thermal resistance after self-healing at 80 °C for 80 h. An EMPI@VACNTs-Cu device exhibits efficient heat conduction not only by recovering after gradient compressive strains of up to 30% but also by self-healing its damage or reforming the interface with Cu. Thus, the thermally conductive, self-healing, and elastic EMPI@VACNTs composite opens new avenues for smart thermal management in various high-power/intelligent devices. Efficient heat conduction across the complex interface between two types of materials is essential for thermal management in advanced systems. The self-healable, elastic EMPI@VACNTs composite opens new avenues for smart thermal management, and it exhibits a high thermal conductivity, low interfacial thermal resistance, high elastic compressive deformation, and strong surface adhesion. [Display omitted] [ABSTRACT FROM AUTHOR]

The one-step aerosol-assisted catalytic chemical vapor deposition (CCVD) process, when operated in a H 2 -based carrier gas, is shown to be effective at an extremely low ferrocene content (0.1 wt% in toluene), which enables to efficiently prepare forests of vertically aligned multiwalled carbon nanotubes (VACNTs) with high purity and good crystalline level. The resulting iron content in VACNT sample is only 0.5 wt% corresponding to a high catalytic yield of 200 while the steady growth rate (20 μm/min) is maintained at a significant value. The iron content in the sample is found proportional to the ferrocene concentration in the precursor, and when it decreases, a noticeable reduction in the iron encapsulation frequency in the nanotube channel is plainly observed. Lowering the ferrocene concentration generates a reduction in the VACNT number density while the growth rate increases and CNT diameters and crystalline structure remain similar. Such significant purity and crystalline levels involves a high oxidation resistance of the VACNT forest. These results, together with the in-situ continuous growth feature of the one-step aerosol assisted CCVD process, open up towards a new VACNT range made of pure and well-crystallized multi-walled carbon nanotubes, which is of interest for industrial production and commercial applications. Image 1 [ABSTRACT FROM AUTHOR]

Gas-phase reactions among carbon precursors could have a significant effect on the catalytic synthesis of vertically aligned (VA-) carbon nanotubes (CNTs). State-of-the-art adjustment of the gas-phase reaction conditions is done ad hoc with low reproducibility, ascribed partly to an incomplete understanding of the mechanism how the gas-phase reaction influences the growth kinetics of VA-CNTs. Here, we investigate this mechanism and propose that in the presence of prominent gas-phase reaction, the growth kinetics characterization shifts from a single rate-limiting reaction to a multi-route reaction with each pathway having its own rate-limiting step. The rate of the gas-phase reaction could be tailored by the partial pressure and thermal history of a carbon feedstock (e.g., acetylene). According to in-situ mass spectrometry and numerical simulation, a rich set of thermally rearranged secondary species (e.g., C 4 H 4 and C 6 H 6 ) are found above the catalyst surface. It appears that these secondary species, along with a chief precursor (C 2 H 2 ), can give variation to a yield of CNTs through various reaction pathways with altering the overall growth rate of VA-CNTs. Our findings would further the current understanding of the VA-CNT growth from thermally rearranged precursors, instrumental to applications such as diameter-controlled growth and CMOS-compatible low-temperature growth. [ABSTRACT FROM AUTHOR]

A unique hierarchical three dimensional (3D) flexible current collector, in which the vertically aligned carbon nanotube (VACNT) array grown directly on carbon cloth (CC), has been developed for flexible lithium ion batteries (LIBs). This novel architecture offers a high surface area, high electronic conductivity and robust structural stability for electrochemical active materials loading. When combined with high capacity Si, the VACNT-Si/CC electrode exhibits high areal capacity together with excellent Li storage performance. Specifically, the electrode could deliver a high reversible areal capacity up to 3.33 mAh/cm 2 (the corresponding specific capacity contribution from Si is as high as 2266 mAh/g) and excellent cycle performance (a capacity retention rate of 94.4% up to 200 cycles) and excellent rate capability (55.3% of the original capacity retained even when the current increased to 25 times of the original). [ABSTRACT FROM AUTHOR]