Carbon Nanotube Research in Its 30th Year

Establishment and application of a screening method for α-glucosidase inhibitors based on dual sensing and affinity chromatography

α-Glucosidase plays a direct role in the metabolic pathways of starch and glycogen, any dysfunction in its activity could result in metabolic disease. Concurrently, this enzyme serves as a target for diverse drugs and inhibitors, contributing to the regulation of glucose metabolism in the human body. Here, an integrated analytical method was established to screen inhibitors of α-glucosidase. This step-by-step screening model was accomplished through the biosensing and affinity chromatography techniques. The newly proposed sensing program had a good linear relationship within the enzyme activity range of 0.25 U mL-1 to 1.25 U mL-1, which can quickly identify active ingredients in complex samples. Then the potential active ingredients can be captured, separated, and identified by an affinity chromatography model. The combination of the two parts was achieved by an immobilized enzyme technology and a microdevice for reaction, and the combination not only ensured efficiency and accuracy for inhibitor screening but also eliminated the occurrence of false positive results in the past. The emodin, with a notable inhibitory effect on α-glucosidase, was successfully screened from five traditional Chinese medicines using this method. The molecular docking results also demonstrated that emodin was well embedded into the active pocket of α-glucosidase. In summary, the strategy provided an efficient method for developing new enzyme inhibitors from natural products.

Modulation of Carbon Nanotube Electronic Structure by Grain Boundary Defects in RbI on Au(111)

The electronic properties of single-walled carbon nanotubes (SWCNTs) are known to be highly sensitive to environmental effects. Here, we use scanning tunneling microscopy and spectroscopy to investigate the electronic properties of SWCNTs deposited on RbI monolayer films grown on Au(111). We find that grain boundary defects in RbI monolayers cause the appearance of spatially confined localized states in the SWCNTs. Our density functional theory calculations show that grain boundary defects in RbI/Au(111) produce a stabilizing electrostatic potential caused by reduced coordination of iodine atoms at the RbI grain boundary. The presented results may offer insights into the performance of devices involving transport through SWCNTs subjected to external electrostatic disorder.

Recent Advances in Rolling 2D TMDs Nanosheets into 1D TMDs Nanotubes/Nanoscrolls

Transition metal dichalcogenides (TMDs) van der Waals (vdW) 1D heterostructures are recently synthesized from 2D nanosheets, which open up new opportunities for potential applications in electronic and optoelectronic devices. The most recent and promising strategies in regards to forming 1D TMDs nanotubes (NTs) or nanoscrolls (NSs) in this review article as well as their heterostructures that are produced from 2D TMDs are summarized. In order to improve the functionality of ultrathin 1D TMDs that are coaxially combined with boron nitride nanotubes and single-walled carbon nanotubes. 1D heterostructured devices perform better than 2D TMD nanosheets when the two devices are compared. The photovoltaic effect in WS₂ or MoS₂ NTs without a junction may exceed the Shockley-Queisser limit for the above-band-gap photovoltage generation. Photoelectrochemical hydrogen evolution is accelerated when monolayer WS₂ or MoS₂ NSs are incorporated into a heterojunction. In addition, the photovoltaic performance of the WSe₂ /MoS₂  NSs junction is superior to that of the performance of MoS₂ NSs. The summary of the current research about 1D TMDs can be used in a variety of ways, which assists in the development of new types of nanoscale optoelectronic devices. Finally, it also summarizes the current challenges and prospects.

A solvent-compatible filter-transfer method of semi-transparent carbon-nanotube electrodes stacked with silver nanowires

Low-density films of single-walled carbon nanotubes (SWNTs) can be used as a semi-transparent top electrode for all-solution-processed film devices; however, their semiconductor characteristics vary depending on the experimental factors in their dispersion into solvents, and the sublayers are damaged as a result of solvent incompatibility. In this study, we report a solvent-compatible filter-transfer method for SWNT films stacked with silver nanowires (AgNWs), and evaluate the semiconductor characteristics through the p/n heterojunction with a Si wafer (SWNT/Si). AgNWs and SWNTs were successively filtered through their aqueous dispersion solutions using a membrane filter. The stacked semi-transparent films (AgNW/SWNT films with controlled densities) were successfully transferred onto glass plates and Si wafers. The transmittance at 550 nm revealed a window between 60% and 80% with a narrow sheet resistance range between 11 and 23 Ω □^-1. The power conversion efficiency (PCE) of SWNT/Si was improved to 11.2% in a junction area of 0.031 cm² through the use of spin-coated Nafion resins; however, the accumulated resistance of SWNTs drastically reduced the PCE to 2% as the area increased to ≥0.5 cm². AgNWs maintained the PCE within a range of 10.7% to 8.6% for an area ranging from 0.031 cm² to 1.13 cm². All of the photovoltaic parameters were dependent on the junction areas, suggesting that AgNWs function as an effective current-collector layer on the semiconductor layer of SWNTs without direct contact of AgNWs with the Si surface. In addition, we report a solvent-compatible experiment for transferring AgNW/SWNT films onto a solvent-sensitive perovskite material (CH₃NH₃PbI₃).

Catalytic Conversion of Hydrocarbons and Formation of Carbon Nanofilaments in Porous Pellets

Catalytic conversion of hydrocarbons occurring at metal nanoparticles in porous pellets is often accompanied by the formation of coke in the form of growing heterogeneous film-like aggregates or carbon nanofilaments. The latter processes result in deactivation of metal nanoparticles. The corresponding kinetic models imply the formation and growth of film-like coke aggregates. Herein, I present an alternative generic kinetic model focused on the formation and growth of carbon nanofilaments. These processes are considered to deactivate metal nanoparticles and reduce the rate of reactant diffusion in pores. In this framework, the kinetically limited reaction regime is described by simple analytical expressions. The diffusion-limited regime can be described as well but only numerically. The model presented can be used for interpretation of experimental results.

Graphical Abstract