Showing papers by "Yi Huang published in 2021"

A Review on Metal-Organic Framework-Derived Porous Carbon-Based Novel Microwave Absorption Materials.

Abstract: The development of microwave absorption materials (MAMs) is a considerable important topic because our living space is crowed with electromagnetic wave which threatens human’s health. And MAMs are also used in radar stealth for protecting the weapons from being detected. Many nanomaterials were studied as MAMs, but not all of them have the satisfactory performance. Recently, metal–organic frameworks (MOFs) have attracted tremendous attention owing to their tunable chemical structures, diverse properties, large specific surface area and uniform pore distribution. MOF can transform to porous carbon (PC) which is decorated with metal species at appropriate pyrolysis temperature. However, the loss mechanism of pure MOF-derived PC is often relatively simple. In order to further improve the MA performance, the MOFs coupled with other loss materials are a widely studied method. In this review, we summarize the theories of MA, the progress of different MOF-derived PC‑based MAMs, tunable chemical structures incorporated with dielectric loss or magnetic loss materials. The different MA performance and mechanisms are discussed in detail. Finally, the shortcomings, challenges and perspectives of MOF-derived PC‑based MAMs are also presented. We hope this review could provide a new insight to design and fabricate MOF-derived PC-based MAMs with better fundamental understanding and practical application.

3D Ultralight Hollow NiCo Compound@MXene Composites for Tunable and High-Efficient Microwave Absorption

Abstract: The 3D hollow hierarchical architectures tend to be designed for inhibiting stack of MXene flakes to obtain satisfactory lightweight, high-efficient and broadband absorbers. Herein, the hollow NiCo compound@MXene networks were prepared by etching the ZIF 67 template and subsequently anchoring the Ti3C2Tx nanosheets through electrostatic self-assembly. The electromagnetic parameters and microwave absorption property can be distinctly or slightly regulated by adjusting the filler loading and decoration of Ti3C2Tx nanoflakes. Based on the synergistic effects of multi-components and special well-constructed structure, NiCo layered double hydroxides@Ti3C2Tx (LDHT-9) absorber remarkably achieves unexpected effective absorption bandwidth (EAB) of 6.72 GHz with a thickness of 2.10 mm, covering the entire Ku-band. After calcination, transition metal oxide@Ti3C2Tx (TMOT-21) absorber near the percolation threshold possesses minimum reflection loss (RLmin) value of − 67.22 dB at 1.70 mm within a filler loading of only 5 wt%. This work enlightens a simple strategy for constructing MXene-based composites to achieve high-efficient microwave absorbents with lightweight and tunable EAB. Highlights: 1 Ultralight 3D NiCo compound@MXene nanocomposites that inherited hollow polyhedral skeleton and excellent conductive network were fabricated.2 Excellent electromagnetic absorption performance was achieved with optimal RLmin value of − 67.22 dB and ultra-wide EAB of 6.72 GHz under the low filler loading.3 Electromagnetic parameters and microwave absorption property can be distinctly or slightly regulated by adjusting the filler loading and decoration of Ti3C2Tx nanoflakes.

Highly Stretchable Carbon Nanotubes/Polymer Thermoelectric Fibers.

Abstract: Thermoelectric (TE) technology provides a new way to directly harvest and convert the heat continuously released from the human body. The greatest challenge for TE materials applied in wearable TE generators is compatible with the constantly changing morphology of the human body while offering a continuous and stable power output. Here, a stretchable carboxylic single-walled carbon nanotube (SWNT)-based TE fiber is prepared by an improved wet-spinning method. The stable Seebeck coefficient of the annealed carboxylic SWNT-based TE fiber is 44 μV/K even under the tensile strain of ∼30%. Experimental results show that the fiber can continue to generate constant TE potential when it is changed to various shapes. The new stretchable TE fiber has a larger Seebeck coefficient and more stretchability than existing TE fibers based on the Seebeck effect, opening a path to using the technology for a variety of practical applications.

Synergistically Assembled Cobalt-Telluride/Graphene Foam with High-Performance Electromagnetic Wave Absorption in Both Gigahertz and Terahertz Band Ranges.

Abstract: Electromagnetic wave (EMW)-absorbing materials have a great impact on civil use and national defense. In this paper, a novel composite, RGO@6CoTe2-300 (the mass ratio of reduced graphene oxide to CoTe2 is 1:6, annealed at 300 °C), has been obtained through a facile melt-diffusion method and solvothermal method. The as-prepared samples have shown excellent reflection losses (RL) and effective adsorption bandwidth (EAB) by controlling the loading of CoTe2 and the annealing temperature. The sample has exhibited a RL of -62.2 dB at 13.04 GHz with the matching thickness of 3.53 mm, and the EAB reaches 8.2 GHz at 2-18 GHz. Moreover, excellent terahertz (THz) absorption property is also obtained at 0.2-2.0 THz. A RL of 54.07 dB is acquired, and the EAB covers 100% of the entire measured bandwidth. Thus, RGO@6CoTe2-300 can be considered as a promising EMW absorption material in both gigahertz and terahertz band ranges.

Electrostatic Actuating Double‐Unit Electrocaloric Cooling Device with High Efficiency

Abstract: DOI: 10.1002/aenm.202003771 of chip operating temperature to avoid overheating is an important guarantee to maintain the normal operation of electronic devices. The traditional refrigeration technology based on the vapor compression cycle is difficult to meet the refrigeration requirements of highly integrated microelectronic devices due to the existence of the compressor.[2] Moreover, the extensive use of chlorofluorocarbons and other refrigerants bring about new problems such as ozone layer destruction and greenhouse effect, and the relatively low coefficient of performance (COP) also limits its application in cooling systems for electronic devices.[3] Therefore, it is necessary to develop a new type of refrigeration technology that can be miniaturized, high efficiency, and environment-friendly. Solid-state refrigeration technology as an alternative has the properties of no heat transfer media of liquid refrigerants, rapid cooling, safety, and environmental protection.[2] The existing solid-state refrigeration technologies include thermoelectric, magnetocaloric, elastocaloric, and electrocaloric (EC) refrigeration technologies. Thermoelectric refrigerators fabricated by bismuth antimony telluride ceramics have a variety of applications.[4–6] However, their COP is lower than that of vapor compression coolers.[7] Magnetocaloric and elastocaloric coolers require a strong magnetic field and high load to achieve the entropy change of the refrigeration material, respectively, which limits their miniaturization.[8,9] The EC cooling technology has been considered to be a more effective alternative and can also be used to realize compact and low-profile devices. The EC effect is the change of internal polarization state caused by the change of external electric field under adiabatic condition, which leads to the change of entropy and temperature.[10] The current generated in the cooling process is quite small and energy consumption is very low due to the insulation of materials. Therefore, compared with other solid-state refrigeration technologies, EC refrigeration is not only environmentally friendly and efficient, but also has an important application prospect in the temperature regulation of microelectronic devices. Current EC materials of relaxor ferroelectric ceramics have promising performance. However, EC refrigeration devices based on ferroelectric ceramics are limited by the inherent Compact solid-state refrigeration systems that offer a high specific cooling power and a high coefficient of performance (COP) are desirable in a wide range of applications where efficient and localized heat transfer is required. Here, a double-unit electrocaloric (EC) polymer-based refrigeration device with high intrinsic thermodynamic efficiency is demonstrated using a flexible EC polymer film with improved performance by doping plasticizer and an electrostatic actuation mechanism. The double-unit refrigeration device achieves a large temperature span of 4.8 K, which is 71% higher than that of the single-unit device. A specific cooling power of 3.6 W g−1 and a maximum COP of 8.3 for the cooling device are produced. The surface temperature of a central processing unit (CPU) cooled by an active EC device is 22.4 K lower than that of the CPU cooled in air. The highly efficient and compact EC cooling device demonstrated here not only leapfrogs the performance of existing solid-state cooling technologies, but also brings solid state cooling closer to reality for a variety of practical applications that require compact or mechanically flexible refrigeration.

Highly Stretchable Shape Memory Self-Soldering Conductive Tape with Reversible Adhesion Switched by Temperature.

Abstract: With practical interest in the future applications of next-generation electronic devices, it is imperative to develop new conductive interconnecting materials appropriate for modern electronic devices to replace traditional rigid solder tin and silver paste of high melting temperature or corrosive solvent requirements. Herein, we design highly stretchable shape memory self-soldering conductive (SMSC) tape with reversible adhesion switched by temperature, which is composed of silver particles encapsulated by shape memory polymer. SMSC tape has perfect shape and conductivity memory property and anti-fatigue ability even under the strain of 90%. It also exhibits an initial conductivity of 2772 S cm−1 and a maximum tensile strain of ~ 100%. The maximum conductivity could be increased to 5446 S cm−1 by decreasing the strain to 17%. Meanwhile, SMSC tape can easily realize a heating induced reversible strong-to-weak adhesion transition for self-soldering circuit. The combination of stable conductivity, excellent shape memory performance, and temperature-switching reversible adhesion enables SMSC tape to serve two functions of electrode and solder simultaneously. This provides a new way for conductive interconnecting materials to meet requirements of modern electronic devices in the future.