Search

Nowadays, one of the design direction of bio‐derived and biodegradable polymer foams with multi‐functionalization is how to attain superior electromagnetic interference (EMI) shielding property, which has become a hot topic. Herein, bio‐based poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) foams filled with carbon nanotubes (CNTs) and/or graphene nanoplatelets (GNPs) were fabricated by supercritical carbon dioxide. As observed by optical microscope and scanning electron microscope, the CNTs and GNPs in PHBV matrix might gradually construct three kinds of network structures (CNTs‐CNTs, GNPs‐GNPs and GNPs‐CNTs network structures), which would improve the melt viscoelasticity, crystallization, electrical, dielectric and EMI shielding properties of PHBV. The complex viscosity and storage modulus of PHBV nanocomposites with the ratio of CNTs/GNPs as 1:1 rose nearly three orders of magnitudes than those of pure PHBV, in addition, its crystallization temperature and crystallinity increased remarkably to 122°C and 62%, individually. When the CNTs/GNPs ratio was 1:1 at a low total content of 3 wt%, PHBV nanocomposite and its foam implemented the high dielectric properties. Furthermore, the EMI specific shielding effectiveness of obtained PHBV was blend with 1.5 wt% CNTs and 1.5 wt% GNPs nanocomposite foam was the highest, reaching 19.3 dB cm3/g. This work paved a feasible way to the production of eco‐friendly PHBV nanocomposite foams for the application of electronics and aerospace industries. Highlights: PHBV/CNTs/GNPs foams were prepared using a scCO2‐assisted foaming method.Dispersion of carbon fillers in PHBV was the best as CNTs/GNPs ratio was 1:1.G' of PHBV/C1.5/G1.5 specimens were increased by three orders of magnitude.EMI specific shielding effectiveness of PHBV/C1.5/G1.5 nanocomposite foam could reach 19.3 dB cm3/g. [ABSTRACT FROM AUTHOR]

The atmospheric fluorocarbon plasma is widely used in surface modification of polymers. Recently, the pulsed microwave Ar/CF4 plasma jet is proved to be a promising atmospheric fluorocarbon plasma source with good performance. In this paper, the discharge characteristics of the pulsed microwave Ar/CF4 plasma jet are studied systematically. The discharge morphologies, ionization processes, optical emission spectra, and electron densities are obtained by a digital camera, an intensified charge coupled device, a fiber spectrometer, and a home-made microwave Rayleigh scattering device, respectively. The influences of the plasma operation parameters on the discharge characteristics are investigated, and the microwave input power and CF4 volume fraction are optimized. The results provide a basis for the generation and surface modification application of high-performance atmospheric fluorocarbon plasma. [ABSTRACT FROM AUTHOR]

Room-temperature sodium–sulfur batteries (RT-Na/S batteries) with high reversible capacity (1675 mA h g−1) and excellent energy density (1274 W h kg−1) based on abundant resources of the metal Na have become a research hotspot recently. However, the intermediate product sodium polysulfides (NaPSs) generated during the charge–discharge process are easily dissolved in the ether electrolyte and transferred from the sulfur cathode to the metallic sodium surface, resulting in rapid capacity decay (shuttle effect), which seriously affects the practical application of RT-Na/S batteries. Herein, the mechanism and recent research progress in suppressing the shuttle effect of the sulfur cathode in RT-Na/S batteries are summarized. Strategies such as carbon-based materials physically fixing NaPSs, polar materials absorbing NaPSs to reduce their dissolution, and catalytic materials accelerating the transformation of NaPSs into final products are provided. Challenges and insights into high-performance sulfur electrodes for optimizing RT-Na/S batteries are discussed. [ABSTRACT FROM AUTHOR]

SnSe 2 with high theoretical capacity has been identified as an emerging anode candidate for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). However, the rate performance and cycling performance of this material in practical applications are still limited by unavoidable volume expansion and low conductivity. In this work, we designed and synthesized nitrogen-doped carbon-coated SnSe 2 /C-N composites using 2-aminoterephthalic acid (C 8 H 7 NO 4 ) as a nitrogen-containing compound for modification by hydrothermal and vacuum calcination methods to achieve efficient utilization of active sites and optimization of the electronic structure. The carbon skeleton inherited from the Sn-MOF precursor can effectively improve the electronic conduction properties of SnSe 2 . N-doping in the Sn-MOF can increase the positive and negative electrostatic potential energy regions on the molecular surface to further improve the electrical conductivity, and effectively reduce the binding energy with Li + /Na + which was determined by Density Functional Theory (DFT) methods. In addition, the N-doped carbon skeleton also introduces a larger space for Li + /Na + intercalation and enhances the mechanical properties. In particular, the post-synthetically modified MOF-derived SnSe 2 /C-N materials exhibit excellent cyclability, with a reversible capacity of 695 mA h g -1 for LIBs and 259 mA h g -1 for SIBs after 100 cycles at 100 mA g -1 .

Room-temperature sodium-sulfur batteries (RT-Na/S batteries) with high reversible capacity (1675 mA h g -1 ) and excellent energy density (1274 W h kg -1 ) based on abundant resources of the metal Na have become a research hotspot recently. However, the intermediate product sodium polysulfides (NaPSs) generated during the charge-discharge process are easily dissolved in the ether electrolyte and transferred from the sulfur cathode to the metallic sodium surface, resulting in rapid capacity decay (shuttle effect), which seriously affects the practical application of RT-Na/S batteries. Herein, the mechanism and recent research progress in suppressing the shuttle effect of the sulfur cathode in RT-Na/S batteries are summarized. Strategies such as carbon-based materials physically fixing NaPSs, polar materials absorbing NaPSs to reduce their dissolution, and catalytic materials accelerating the transformation of NaPSs into final products are provided. Challenges and insights into high-performance sulfur electrodes for optimizing RT-Na/S batteries are discussed.

This work using the density functional theory simulates the strong potential of the CuO-decorated PtSe 2 (CuO-PtSe 2 ) monolayer as a recycle use C 2 H 2 and C 2 H 4 sensor in order to realize the arc discharge monitoring based on the nano-sensing method. Results indicate that CuO decoration causes strong n-type doping for the PtSe 2 monolayer with a binding force ( E b ) of -2.49 eV, and the CuO-PtSe 2 monolayer exhibits strong chemisorption and electron-accepting properties in the two gas systems, with the adsorption energy ( E ad ) and charge transfer ( Q T ) obtained as -1.19 eV and 0.040 e for the C 2 H 2 system and as -1.24 eV and 0.011 e for the C 2 H 4 system, respectively. The density of states reveals the deformed electronic property of the CuO-PtSe 2 monolayer in gas adsorptions, and its sensing mechanism based on the change of electrical conductivity and the work function are uncovered. This work sheds light on the metal-oxide-decorated transition-metal dichalcogenides for gas sensor applications and would provide the guidance to explore novel sensing materials in many other fields as well., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)