Single-walled carbon nanotubes (SWNTs) have been regarded as one of the most promising candidates to supplement or even replace silicon in the post-Moore era. The requirement is to prepare the horizontally aligned SWNTs arrays (HASAs) with multiple indicators, including high density, high semiconducting purity, and wafer-scale uniformity. However, after all the fevered works being done in controlled synthesis, we still have a long way to go before realizing the application of SWNTs in highly performed electronic devices. The methods of batch production and high-throughput characterization techniques of the HASAs are the two main challenges. In this outlook, we first summarized the progresses in synthesis of HASAs with either high density or high semiconducting purity. Then the methods adopted in characterizing SWNTs and HASAs were discussed according to the different principles of characterization techniques. Afterwards, the development of carbon nanotube based electronic devices, specifically, the field effect transistors (FETs), was reviewed from three perspectives. The problems involved in electronic applications bring forward the higher request to the HASAs itself. Therefore, in the end of this outlook, we prospected the future of the synthesis and corresponding characterization of HASAs, and tried to provide our ideas about how to pave the way to the batch production of HASAs for carbon based electronic devices.

Heterocyclic aramid fibers, a typical kind of high-performance fibers, have been widely used in aerospace and protection fields because of their excellent mechanical properties. However, the application of heterocyclic aramid fibers as a reinforcement is hindered by the weak interfacial combination with matrix materials, especially epoxy. Traditional strategies enhancing the interfacial shear strength (IFSS) usually decrease the tensile strength. Therefore, simultaneous enhancement of both mechanical properties remains a challenge. Herein, we report a novel heterocyclic aramid fiber with high interfacial shear strength (49.3 MPa) and tensile strength (6.27 GPa), in which 4,4′-diamino-2′-chlorobenzanilide (DABA-Cl) and a small amount of graphene oxide (GO) are introduced through in-situ polymerization. Hydrogen bonds and π–π interaction between GO and polymer chains trigger the enhancement in crystallinity, orientation, and lateral interaction of the fibers, thus improving the tensile strength and interfacial shear strength of the fibers. Moreover, the interfacial interaction between fiber and epoxy is enhanced due to the improvement of the surface polarity of the fibers caused by DABA-Cl. Therefore, a method to improve both tensile strength and interfacial shear strength of heterocyclic aramid fibers was found by introducing GO and DABA-Cl, which may provide guidance for the design and preparation of other high-performance fibers.

The chirality structure of a single-walled carbon nanotube (SWNT) strongly depends on the composition of catalyst used in the chemical vapor deposition process. In this study, we develop a porous magnesia supported manganese-rhenium (MnRe/MgO) catalyst for chirality-selective synthesis of SWNTs. Detailed characterizations reveal that (6,5) tubes with a selectivity higher than 70% are grown from the Re-rich MnRe/MgO catalyst. By comparing the SWNT growth results with those of monometallic Mn or Re, the formation of sigma phase, an intermetallic compound occurring in transition-metal alloy systems, is revealed to be crucial for the dominant synthesis of (6,5) SWNTs. This work not only extends the application of sigma phase alloy for catalytic synthesis of SWNTs, but also sheds lights on the growth of SWNTs with a high chirality selectivity.

Graphene nanoribbons (GNRs) are regarded as an ideal candidate for beyond-silicon electronics. However, synthesis of aligned GNR arrays on insulating substrates with high efficiency is challenging. In this work, we develop a facile strategy, involving KOH pre-treatment and high-temperature annealing, to construct parallel steps on the two-fold symmetry a-plane sapphire substrate. Horizontal GNRs as narrow as 15.1 nm with global alignment across a region of 20 mm² are then grown on the step edge-enriched substrate through plasma enhanced chemical vapor deposition (PECVD) method. GNRs align well along the atomic steps on sapphire ([ $1\overline{1}00$] direction) with their widths and densities swiftly adjustable by step morphology modification on substrate surface. A step-edge confined growth mechanism is proposed, attributing the constraint on the nanoribbon broadening to a relatively low growth temperature in PECVD, which restrains the activation energy to suppress GNRs across step edges on sapphire and prevents detrimental nanoribbon widening. The results provide a new perspective for scalable synthesizing well aligned nanoribbons of other two-dimensional materials.

Bulk synthesis of single-walled carbon nanotubes (SWNTs) using solid catalyst has been challenging, despite of recent breakthrough in the chirality-specific growth on the flat substrate surface. In this work, we propose a porous magnesia support rhenium catalyst for bulk synthesis of SWNTs. It is found that the well-dispersed catalyst with a high melting point and the optimal chemical vapor deposition reaction conditions account for the growth of SWNTs. Detailed characterizations reveal the produced SWNTs are dominant in (n, n − 1) and (n, n − 2) species. Furthermore, by using a multicolumn chromatography post-growth separation method, SWNTs with three defined diameter ranges were obtained. This work guides the design of porous oxide supported catalyst for bulk synthesis and diameter-dependent sorting of SWNTs, which will ultimately help harness the extraordinary properties of SWNTs.

The abuse of conventional antibiotics leads to increasing bacterial resistance. Nanozyme is a new kind of ultra-efficient and safe nanomaterial with intrinsic enzyme-like activities, showing remarkable potential as a next generation nanobactericide. Graphdiyne (GDY) is a burgeoning two-dimensional (2D) carbon allotrope with intriguing physicochemical properties, holding a great promise as a metal-free nanozyme. In this study, a boron doped GDY nanosheet (B-GDY) was constructed to simulate the performance of peroxidase (POD). By promoting the decomposition of H₂O₂ to produce reactive oxygen species (ROS), the bactericidal efficacies against both Gram-positive and Gram-negative bacteria were substantially enhanced attributed to the extremely high catalytic activity of B-GDY. In-depth density functional theory (DFT) calculations illuminate that doping of boron can introduce more active B-defect sites as well as lower Gibbs free energy during the H₂O₂ decomposition reaction. Notably, B-GDY contributes to significant wound healing and excellent biocompatibility, reducing the biological burden. The design of this nanozyme opens a new avenue for the development of alternative antibiotics.

The development of rechargeable lithium-ion batteries (LIBs) is being driven by the ever-increasing demand for high energy density and excellent rate performance. Charge transfer kinetics and polarization theory, considered as basic principles for charge regulation in the LIBs, indicate that the rapid transfer of both electrons and ions is vital to the electrochemical reaction process. Graphene, a promising candidate for charge regulation in high-performance LIBs, has received extensive investigations due to its excellent carrier mobility, large specific surface area and structure tunability, etc. Recent progresses on the structural design and interfacial modification of graphene to regulate the charge transport in LIBs have been summarized. Besides, the structure- performance relationships between the structure of the graphene and its dedicated applications for LIBs have also been clarified in detail. Taking graphene as a typical example to explore the mechanism of charge regulation will outline ways to further understand and improve carbon-based nanomaterials towards the next generation of electrochemical energy storage devices.

Mixed dimensional van der Waals (vdW) heterostructures constructed by one-dimensional (1D) and two-dimensional (2D) materials exhibit extra degree of freedom to modulate the electronic and optical properties due to the combination of different dimensionalities. The charge transfer at the interface between 1D and 2D materials plays a crucial role in the optoelectronic properties and performance of the heterostructure-based devices. Here, we stacked single-walled carbon nanotubes (SWNTs) on monolayer WS₂ for a mixed dimensional vdW heterostructure, and investigated the local modulation of excitions and trions in WS₂ by SWNTs. Different directions of charge transfer between SWNTs and WS₂ are evidenced by the photoluminescence (PL) spectra of WS₂. The PL intensity can be either enhanced or weakened by individual SWNTs. In our work, the PL intensity of WS₂ is enhanced and the exciton peak position heterostructure is red-shifted about 3 meV due to the charge transfer from WS₂ to an individual SWNT (SWNT#1). The change of PL by another SWNT (SWNT#2) can not be well-resolved in far-field, but scanning near-field optical microscope (SNOM) measurements show that the PL intensity of WS₂ is weakened by the SWNT. The peak position of exciton is blue-shifted by ~ 1 meV while that of trion is redshifted by ~ 1 meV due to the charge transfer from the SWNT to WS₂. These results give insight into the charge transfer at the interface of SWNT/WS₂ heterostructure, and can be useful for design of optoelectronic devices based on mixed dimensional vdW heterostructures.

Manipulating the polarization of light at the nanoscale is essential for the development of nano-optical devices. Owing to its corrugated honeycomb structure, two-dimensional (2D) layered black phosphorus (BP) exhibits outstanding in-plane optical anisotropy with distinct linear dichroism and optical birefringence in the visible region, which are superior characteristics for ultrathin polarizing optics. Herein, taking advantage of polarized Raman spectroscopy, we demonstrate that layered BP with a nanometer thickness can remarkably alter the polarization state of a linearly-polarized laser and behave as an ultrathin optical polarization element in a BP-Bi₂Se₃ stacking structure by inducing the exceptionally polarized Raman scattering of isotropic Bi₂Se₃. Our findings provide a promising alternative for designing novel polarization optics based on 2D anisotropic materials, which can be easily integrated in microsized all-optical and optoelectronic devices.