Showing papers by "Mao-Sheng Cao published in 2020"

Assembling Nano–Microarchitecture for Electromagnetic Absorbers and Smart Devices

Abstract: Smart devices, nowadays, are inspiring the infinite vitality and possibilities of intelligent life, such as self-power electromagnetic (EM) nanogenerator and microsensor, smart window, thermally-driven EM absorber, interstellar energy deliverer, and so on. Herein, the latest and most impressive works of 3D nano-micro architectures and their smart EM devices are highly focused on. The most key information, including assembly strategy and mechanism, EM response, and approach-structure-function relationship, is extracted and well-organized with profundity and easy-to-understand approach. The merit and demerit are revealed by comparison. What's more, the brightest and most cutting-edge smart EM devices constructed by 3D nano-micro architectures are reported as highlights, and the device principles are deeply dissected. Finally, a profound and top comment on the fast-growing field as well as challenges are proposed, and the future directions are predicted intelligently.

Variable-Temperature Electron Transport and Dipole Polarization Turning Flexible Multifunctional Microsensor beyond Electrical and Optical Energy.

Abstract: Humans are undergoing a fateful transformation focusing on artificial intelligence, quantum information technology, virtual reality, etc., which is inseparable from intelligent nano-micro devices. However, the booming of "Big Data" brings about an even greater challenge by growing electromagnetic radiation. Herein, an innovative flexible multifunctional microsensor is proposed, opening up a new horizon for intelligent devices. It integrates "non-crosstalk" multiple perception and green electromagnetic interference shielding only in one pixel, with satisfactory sensitivity and fast information feedback. Importantly, beneficial by deep insight into the variable-temperature electromagnetic response, the microsensor tactfully transforms the urgent threat of electromagnetic radiation into "wealth," further integrating self-power. This result will refresh researchers' realization of next-generation devices, ushering in a new direction for aerospace engineering, remote sensing, communications, medical treatment, biomimetic robot, prosthetics, etc.

Synergetic dielectric loss and magnetic loss towards superior microwave absorption through hybridization of few-layer WS2 nanosheets with NiO nanoparticles

Abstract: WS2 nanomaterials have attracted great attention in the field of electromagnetic wave absorption due to their high specific surface area, layered structure, and peculiar electronic properties. However, further improvements on their limited electromagnetic absorbing (EMA) capacity and bandwidth are urgently required for their practical application as EMA absorbents. In this work, WS2/NiO hybrids with heterostructures are prepared by a hydrothermal method and developed into EMA absorbents. The maximum reflection loss of the hybrids with 20% NiO loading could reach −53.31 dB at a thickness of 4.30 mm; the bandwidth with a reflection loss value of less than −10 dB is determined to be 13.46 GHz (4.54–18 GHz) when the thickness of the absorbent is between 3.5 and 5.5 mm. It is found that the enhanced EMA performance of WS2/NiO hybrids is caused by the addition of magnetic NiO, which could result in the interfaces between WS2 and NiO being responsible for the synergetic magnetic loss and dielectric loss in the hybrids. This work provides a new approach for the design of excellent EMA materials for practical applications.

Customizing coaxial stacking VS2 nanosheets for dual-band microwave absorption with superior performance in the C- and Ku-bands

Abstract: Engineering microwave absorption materials with absorption in multiple bands and strong absorption performance in the C-band remains challenging to date. Herein, coaxial stacking VS2 nanosheets (CSVNs) were customized via a facile one-step hydrothermal route for the first time and their microwave absorption (MA) properties were systematically investigated. The complex permittivity and conductivity of CSVNs could be tuned by regulating the hydrothermal reduction temperature. When the reaction temperature was 190 °C, the VS2 nanosheets exhibited unique dual-band absorption characteristics in the C-band and Ku-band. A minimum reflection loss value of −57 dB and an average absorption intensity exceeding 15 dB in both the C (4–8 GHz) and Ku (12–18 GHz) bands were obtained. For the optimized CSVNs, the qualified bandwidth with reflection loss less than −10 dB reached up to 7 GHz, which almost covered the whole measured range of the C- and Ku-bands. Notably, this desirable microwave absorption performance, which probably results from the good conductivity of the 1T-phase CSVNs in the 2H phase, the well-matched impedance and the multiple reflections induced by their distinctive stacking structure, demonstrates that CSVNs are potential outstanding absorbers. More importantly, this study provides an effective strategy to tune the microwave performance of CSVNs by tailoring their structures.

Confinedly growing and tailoring of Co3O4 clusters-WS2 nanosheets for highly efficient microwave absorption

Abstract: Electromagnetic (EM) wave absorbing materials have been a research hotspot in materials science and related technical fields in recent years. Finding lightweight, efficient, and broadband electromagnetic wave absorbing materials has always been a very challenging subject. Herein, we successfully prepared Co3O4-WS2 hybrid nanosheets with heterostructures, which excellent combine the advantages of magnetic property of Co3O4 and dielectric property of WS2. By the electromagnetic synergy effect, maximum RL is up to -61.1 dB at 1.9 mm, and the bandwidth exceeds 5 GHz. Such highly efficient microwave absorption is attributed to not only the electromagnetic synergy effect, but the dipole polarization as well as conduction loss. These results show that the obtained Co3O4-WS2 is an excellent EM wave absorbing material and can be used as a candidate for advanced EM wave absorbing materials in the fields such as commerce, military and aerospace in future.

Hollow nanoparticle-assembled hierarchical NiCo2O4 nanofibers with enhanced electrochemical performance for lithium-ion batteries

Abstract: Significant capacity degradation and a dramatic volume change call for effective strategies to address the intrinsic issues of transition metal oxide anodes of lithium-ion batteries. Rational nanostructural design has shown great promise in improving structural stability and electrochemical performance. We here report the fabrication of hollow nanoparticle-assembled hierarchical NiCo2O4 nanofibers via a facile electrospining technique and annealing process. A set of control experiments and systematic characterization demonstrate that the presence of polymers and an appropriate annealing procedure are key to form a novel nanostructured anode. The hollow nanostructure and abundant mesopores centered at about 20 nm in the nanofibers could effectively suppress severe volume variations in the lithiation/delithiation process. Furthermore, the novel nanoparticle-nanofiber hierarchical architecture could shorten the lithium diffusion length, increase the contact areas between the electrode and electrolyte, and accordingly promote fast electron/charge transfer. As expected, the optimized hierarchical NiCo2O4 nanofibers exhibit excellent performance for Li-ion batteries, delivering a capacity of 926.2 mA h g−1 at 0.1 A g−1 and 687 mA h g−1 at a high current density of 2 A g−1. This work may provide an attractive and promising strategy for advancing transition metal oxide anodes.

A study of the microwave actuation of a liquid crystalline elastomer

Abstract: We present a method for actuating LCE materials by microwave radiation. The microwave actuation performance of a polysiloxane-based nematic liquid crystalline elastomer (LCE) was investigated. The microwave–material interaction caused a dipolar loss, which created a heating effect to trigger the nematic–isotropic transition of the LCE matrix, thus leading to the deformation actuation of the LCE material. This energy conversion from radiant energy to thermal energy provided a contactless pathway to actuate the LCE material without the aid of other components acting as energy converters. The LCE demonstrated rapid maximum contraction upon microwave irradiation, and this microwave-stimulated response was fully reversible when the microwave irradiation was switched off. More importantly, the microwave actuation exhibited superiority relative to photo-actuation, which is the usual method of contactless actuation. The microwaves can penetrate the opaque thick barriers to effectively actuate the LCE due to their strong penetrability; they can also penetrate multiple LCE samples and actuate them almost simultaneously. By taking advantage of the salient features of microwave actuation, a microwave detector system, implementing the LCE as an actuator material, was fabricated. This demonstrated the performance of monitoring microwave irradiation intensities with good sensitivity and convenient manipulation.