Storage of Mechanical Energy Based on Carbon Nanotubes with High Energy Density and Power Density

Fluidization and Application of Carbon Nano Agglomerations

Carbon nanomaterials are unique with excellent functionality and diverse structures. However, agglomerated structures are commonly formed because of small-size effects and surface effects. Their hierarchical assembly into micro particles enables carbon nanomaterials to break the boundaries of classical Geldart particle classification before stable fluidization under gas-solid interactions. Currently, there are few systematic reports regarding the structural evolution and fluidization mechanism of carbon nano agglomerations. Based on existing research on carbon nanomaterials, this article reviews the fluidized structure control and fluidization principles of prototypical carbon nanotubes (CNTs) as well as their nanocomposites. The controlled agglomerate fluidization technology leads to the successful mass production of agglomerated and aligned CNTs. In addition, the self-similar agglomeration of individual ultralong CNTs and nanocomposites with silicon as model systems further exemplify the important role of surface structure and particle-fluid interactions. These emerging nano agglomerations have endowed classical fluidization technology with more innovations in advanced applications like energy storage, biomedical, and electronics. This review aims to provide insights into the connections between fluidization and carbon nanomaterials by highlighting their hierarchical structural evolution and the principle of agglomerated fluidization, expecting to showcase the vitality and connotation of fluidization science and technology in the new era.

Black Liquor and Wood Char-Derived Nitrogen-Doped Carbon Materials for Supercapacitors

Herein, we present a synthesis route for high-efficiency nitrogen-doped carbon materials using kraft pulping residue, black liquor, and wood charcoal as carbon sources. The synthesized nitrogen-doped carbon materials, based on black liquor and its mixture with wood charcoal, exhibited high specific surface areas (SSAs) of 2481 and 2690 m² g^-1, respectively, as well as a high volume of mesopores with an average size of 2.9-4.6 nm. The nitrogen content was approximately 3-4 at% in the synthesized nitrogen-doped carbon materials. A specific capacitance of approximately 81-142 F g^-1 was achieved in a 1 M Na₂SO₄ aqueous solution at a current density of 0.2 A g^-1. In addition, the specific capacitance retention was 99% after 1000 cycles, indicating good electrochemical stability.

Synthesis of Ultralong Carbon Nanotubes with Ultrahigh Yields

Ultralong carbon nanotubes (CNTs) are in huge demand in many cutting-edge fields due to their macroscale lengths, perfect structures, and extraordinary properties, while their practical application is limited by the difficulties in their mass production. Herein, we report the synthesis of ultralong CNTs with a dramatically increased yield by a simple but efficient substrate interception and direction strategy (SIDS), which couples the advantages of floating-catalyst chemical vapor deposition with the flying-kite-like growth mechanism of ultralong CNTs. The SIDS-assisted approach prominently improves the catalyst utilization and significantly increases the yield. The areal density of the ultralong CNT arrays with length of over 1 cm reached a record-breaking value of ∼6700 CNTs mm^-1, which is 2-3 orders of magnitude higher than the previously reported values obtained by traditional methods. The SIDS provides a solution for synthesizing high-quality ultralong CNTs with high yields, laying the foundation for their mass production.

High-Performance Visible-Near-Infrared Single-Walled Carbon Nanotube Photodetectors via Interfacial Charge-Transfer-Induced Improvement by Surface Doping

Single-walled carbon nanotubes (SWCNTs) are considered to be promising candidates for next-generation near-infrared (NIR) photodetectors due to their extraordinary electrical and optical properties. However, the low separation efficiency of photogenerated carriers limits the full utilization of the potential of pristine SWCNTs as photoactive materials. Herein, we report a novel high-performance visible-NIR SWCNT-based photodetector via interfacial charge-transfer-induced improvement by Au nanoparticle (AuNP) surface doping. Under 1064 nm light illumination, the as-fabricated AuNP/SWCNT photodetector exhibits an excellent photoelectrical performance with a responsivity of 2.16 × 10⁵ A/W and a high detectivity of 1.82 × 10¹⁴ Jones, which is three orders of magnitude higher than that of the SWCNT photodetector under the same conditions. Importantly, the interfacial charge transfer between AuNPs and SWCNTs has been first investigated using Raman shift statistics at room temperature. Experimental results indicate that the interfacial charge transfer induced by AuNP doping can reduce the Fermi level of SWCNTs and effectively improve the generation and transport of photogenerated carriers, thereby enhancing the photoelectric performance of SWCNT-based photodetectors. We believe that our results not only demonstrate a facile route to improve the performance of SWCNT-based photodetectors but also provide a novel methodology to characterize the interfacial charge transfer between dopants and SWCNTs.

Wearable Near-Field Communication Sensors for Healthcare: Materials, Fabrication and Application

The wearable device industry is on the rise, with technology applications ranging from wireless communication technologies to the Internet of Things. However, most of the wearable sensors currently on the market are expensive, rigid and bulky, leading to poor data accuracy and uncomfortable wearing experiences. Near-field communication sensors are low-cost, easy-to-manufacture wireless communication technologies that are widely used in many fields, especially in the field of wearable electronic devices. The integration of wireless communication devices and sensors exhibits tremendous potential for these wearable applications by endowing sensors with new features of wireless signal transferring and conferring radio frequency identification or near-field communication devices with a sensing function. Likewise, the development of new materials and intensive research promotes the next generation of ultra-light and soft wearable devices for healthcare. This review begins with an introduction to the different components of near-field communication, with particular emphasis on the antenna design part of near-field communication. We summarize recent advances in different wearable areas of near-field communication sensors, including structural design, material selection, and the state of the art of scenario-based development. The challenges and opportunities relating to wearable near-field communication sensors for healthcare are also discussed.

Intrinsic carbon nanotube liquid crystalline elastomer photoactuators for high-definition biomechanics

Photoresponsive soft actuators with the unique merits of flexibility, contactless operation, and remote control have huge potential in technological applications of bionic robotics and biomedical devices. Herein, a facile strategy was proposed to prepare an intrinsically-photoresponsive elastomer by chemically grafting carbon nanotubes (CNTs) into a thermally-sensitive liquid-crystalline elastomer (LCE) network. Highly effective dispersion and nematic orientation of CNTs in the intrinsic LCE matrix were observed to yield anchoring energies ranging from 1.65 × 10^-5 J m^-2 to 5.49 × 10^-7 J m^-2, which significantly enhanced the mechanical and photothermal properties of the photoresponsive elastomer. When embedding an ultralow loading of CNTs (0.1 wt%), the tensile strength of the LCE increased by 420% to 13.89 MPa (||) and 530% to 3.94 MPa (⊥) and exhibited a stable response to repeated alternating cooling and heating cycles, as well as repeated UV and infrared irradiation. Furthermore, the shape transformation, locomotion, and photo-actuation capabilities allow the CNT/LCE actuator to be applied in high-definition biomechanical applications, such as phototactic flowers, serpentine robots and artificial muscles. This design strategy may provide a promising method to manufacture high-precision, remote-control smart devices.

Applications of Carbon Nanotubes in the Internet of Things Era

The post-Moore's era has boosted the progress in carbon nanotube-based transistors. Indeed, the 5G communication and cloud computing stimulate the research in applications of carbon nanotubes in electronic devices. In this perspective, we deliver the readers with the latest trends in carbon nanotube research, including high-frequency transistors, biomedical sensors and actuators, brain-machine interfaces, and flexible logic devices and energy storages. Future opportunities are given for calling on scientists and engineers into the emerging topics.

Recent progress for silver nanowires conducting film for flexible electronics

Silver nanowires (AgNWs), as one-dimensional nanometallic materials, have attracted wide attention due to the excellent electrical conductivity, transparency and flexibility, especially in flexible and stretchable electronics. However, the microscopic discontinuities require AgNWs be attached to some carrier for practical applications. Relative to the preparation method, how to integrate AgNWs into the flexible matrix is particularly important. In recent years, plenty of papers have been published on the preparation of conductors based on AgNWs, including printing techniques, coating techniques, vacuum filtration techniques, template-assisted assembly techniques, electrospinning techniques and gelating techniques. The aim of this review is to discuss different assembly method of AgNW-based conducting film and their advantages.

GRAPHIC ABSTRACT

Conducting films based on silver nanowires (AgNWs) have been reviewed with a focus on their assembly and their advantages.

High Boron Silicon Nanotubes Combined with Tai Chi Exercise Rehabilitation Therapy in the Treatment of Knee Arthritis Patients

Tai Chi exercise is gentle, convenient, and easy to learn. It is more economical than traditional medical treatments, and it is regarded as the first choice for rehabilitation therapy by patients with knee arthritis. This article aims to study Tai Chi exercise rehabilitation therapy combined with high boron silicon nanotubes to treat knee arthritis patients. This article mainly introduces the treatment of knee arthritis patients with Tai Chi, which is reflected in the improvement of patients’ walking ability and stability, and explores a three-dimensional motion model to provide better help for patients with knee joints. The article uses data mining methods to collect data on the gene expression of human knee joints and analyzes the causes of knee arthritis caused by its internal structure. The experimental results of this paper show that, under Taijiquan exercise rehabilitation treatment, the time needed by knee arthritis patients to get up and run is reduced by 14%, the standing time of one leg is significantly improved, the fall rate is reduced by 13%, and the body’s static balance ability is improved.

Super-durable ultralong carbon nanotubes

Fatigue resistance is a key property of the service lifetime of structural materials. Carbon nanotubes (CNTs) are one of the strongest materials ever discovered, but measuring their fatigue resistance is a challenge because of their size and the lack of effective measurement methods for such small samples. We developed a noncontact acoustic resonance test system for investigating the fatigue behavior of centimeter-long individual CNTs. We found that CNTs have excellent fatigue resistance, which is dependent on temperature, and that the time to fatigue fracture of CNTs is dominated by the time to creation of the first defect.

Construction of Carbon Nanotube Sponges to Have High Optical Antireflection and Mechanical Stability

Antireflective (AR) materials are required to possess high optical antireflection and mechanical stability for their practical applications in optical, opto-electronic, and electron-optical devices. However, the AR materials developed so far can hardly meet these requirements. Here, we report the construction of a highly porous and sponge-like material based on carbon nanotubes (CNTs). This is achieved by continuous winding of a hollow cylindrical CNT assembly and subsequent modification with amorphous carbon (AC). The resultant material is shown to have very low optical reflectance at the visible and infra-red wavelengths over a wide range of incident angles and undergoes little degradation even after long-lasting compressive cycling between 0 and 90% strains or a large change of environmental temperature from -196 to 300 °C. Besides, the AR sponge material can recover fast after bending, stretching, and compression from high elastic strains. Such an excellent combination of broadband and omnidirectional antireflection, mechanical stability, and elastic flexibility results from the strong light absorption by the highly porous CNT structures strengthened by AC deposition on CNT surfaces and junctions, and the new AR material has potential applications in the renewable energy and military fields.

Multifunctional inorganic nanomaterials for energy applications

Our society has been facing more and more serious challenges towards achieving highly efficient utilization of energy. In the field of energy applications, multifunctional nanomaterials have been attracting increasing attention. Various energy applications, such as energy generation, conversion, storage, saving and transmission, are strongly dependent upon the electrical, thermal, mechanical, optical and catalytic functions of materials. In the nanoscale range, thermoelectric, piezoelectric, triboelectric, photovoltaic, catalytic and electrochromic materials have made major contributions to various energy applications. Inorganic nanomaterials' unique properties, such as excellent electrical and thermal conductivity, large surface area and chemical stability, make them highly competitive in energy applications. In this review, the latest research and development of multifunctional inorganic nanomaterials in energy applications were summarized from the perspective of different energy applications. Furthermore, we also illustrated the unique functions of inorganic nanomaterials to improve their performances and the combination of the functions of nanomaterials into a device. However, challenges may be traced back to the limitations set by scaling the relations between multifunctional inorganic nanomaterials and energy devices.