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The concept of "internal and external simultaneous decoration" with different valence states of manganese oxides is proved to boost the electrochemical performance of carbon nanofibers. [Display omitted] • The strategy of "internal and external simultaneous development" for carbon fibers was demonstrated. • Simultaneous realization of the full use of carbon fiber structure and the introduction of pseudocapacitance. • The kinetic analysis of the capacity properties of MnO 2 /MnO@CF-90 is carried out. • Ultra-high cyclic stability of 100 % after 10,000 cycles is achieved. Carbon nanofibers (CFs) have been widely applied as electrodes for energy storage devices owing to the features of increased contact area between electrodes and electrolyte, and shortened transmission route of electrons. However, the poor electrochemical activity and severe waste of space hinder their further application as supercapacitors electrodes. In this work, MnO 2−x nanoflowers restricted and epitaxial growth in/out carbon nanofibers (MnO 2 /MnO@CF) were prepared as excellent electrode materials for supercapacitors. With the synergistic effect of uniquely designed structure and the introduction of MnO and MnO 2 nanoflowers, the prepared interconnected MnO 2 /MnO@CF electrodes demonstrated satisfactory electrochemical performance. Furthermore, the MnO 2 /MnO@CF//activated carbon (AC) asymmetric supercapacitor offered an outstanding long-term cycle stability. Besides, kinetic analysis of MnO 2 /MnO@CF-90 was conducted and the diffusion-dominated storage mechanism was well-revealed. This concept of "internal and external simultaneous decoration" with different valence states of manganese oxides was proven to improve the electrochemical performance of carbon nanofibers, which could be generalized to the preparation and performance improvement of other fiber-based electrodes. [ABSTRACT FROM AUTHOR]

Restricted growth of molybdenum carbide nanoparticles in hierarchically porous nitrogen-doped carbon matrix was prepared, which exhibits satisfactory electromagnetic wave absorption properties. This work enriches the variety of EMW absorbers and offers the route to promote the EMW absorption performance, especially large effective absorption bandwidth. [Display omitted] • MO 2 C/NC composites with honeycomb porous structure was synthesized; • This strategy enriches the variety of high-performance absorbers with mass production; • Bandwidth of 9.6 GHz at 3.5 mm was achieved for electromagnetic wave absorber; • Analysis of the absorption mechanism of MO 2 C/NC absorbers was investigated. With the development of electronic science and technology, electromagnetic pollution is becoming increasingly serious, which urgent people to develop wave-absorbing materials with the features of "thin, light, strong and wide". In this paper, restricted growth of molybdenum carbide nanoparticles in hierarchically porous nitrogen-doped carbon matrix (Mo 2 C/NC) was designed and prepared via a salt-assisted template route and carbonization process, whose morphology and the wave-absorbing properties are regulated by changing the content of Mo 2 C/NC nanoparticles. The honeycomb porous Mo 2 C/NC composites with large specific surface area and smooth surface can optimize the impedance matching and allow the entrance, multiple reflections and scattering of incident electromagnetic waves (EMW), which effective enhance the electromagnetic wave consumption. Meanwhile, the honeycomb cross-linked carbon matrix facilitates the construction of the conductive network and enhances its conductive loss. Furthermore, numerous Mo 2 C/NC nanoparticles dispersed restricted growth in carbon matrix induces interfacial polarization. In addition, the heteroatom nitrogen doping acts as dipole centers to induce dipole polarization under electromagnetic field. The uniquely designed Mo 2 C/NC absorbers show satisfactory EMW absorption behaviors of a minimum reflection loss (RL min) of −61.53 dB at 1.5 mm and an effective absorption bandwidth (EAB) of 9.6 GHz at 3.5 mm. This work enriches the variety of EMW absorbers and offers the route to promote the EMW absorption performance, especially large effective absorption bandwidth. [ABSTRACT FROM AUTHOR]

[Display omitted] Multi-dimensional design and the combination of multiple phases can effectively enhance the dielectric loss properties and multiple reflection effects of absorbers. Herein, a novel multi-dimensional microporous nanostructured composite, melamine sponge (MS) loaded puffed-rice biomass carbon (C) together with bimetallic carbide material Ni 3 ZnC 0.7 (Ni 3 ZnC 0.7 -MS/C) was synthesized by simple vacuum filtration and hydrothermal calcination. The result indicates that small Ni 3 ZnC 0.7 particles with little Ni doping uniformly decorated on the surfaces of the three-dimensional (3D) melamine sponge and puffed rice carbons. The Ni 3 ZnC 0.7 -MS/C composite mixed with paraffin (weight ratio of 1:2) exhibited the best electromagnetic wave (EMW) absorption performance, and the minimum reflection loss (RL min) value of the Ni 3 ZnC 0.7 -MS/C composite reaches −107.7 dB with a matching thickness of 2.78 mm and the maximum effective absorption bandwidth for RL below −10 dB (EAB max) is adjusted to 9.2 GHz at a matching thickness of 4.0 mm. The dipole polarization effect of the N doping and the different interfaces provided by the 3D structure of the MS carbon enhance the conduction loss and interface polarization, while the positive effects of eddy current and resonance caused by Ni 3 ZnC 0.7 effectively improve the microwave absorption performances. This melamine sponge–loaded bimetallic carbon composite exhibited a magnetic/dielectric loss combination, resulting in a high-performance absorber with lightweight, cost-effective and efficient properties. [ABSTRACT FROM AUTHOR]

The puffed-rice derived carbon@Ni 3 ZnC 0.7 -400 showed RL min of −39.9 dB and the broadest absorption bandwidth of 9.9 GHz. Moreover, the composite showed good performance stability under 400 °C. [Display omitted] • Various puffed-rice derived carbon@Ni 3 ZnC 0.7 composites were prepared by chemical synthesis and annealing. • The puffed-rice derived carbon@Ni 3 ZnC 0.7 -400 mg showed best electrochemical performance. • It showed RL min of −39.9 dB and the broadest absorption bandwidth of 9.9 GHz. • The composite material can be stable at 400 °C and has good performance stability. With the rapidly development of radar detection technology and the increasingly complex application environment in military field and electromagnetic pollution surrounded by electron devices, increasingly demand is needed for electromagnetic wave absorbent materials with high absorption efficiency and thermal stability. Herein, a novel Ni 3 ZnC 0.7 /Ni loaded puffed-rice derived carbon (RNZC) composites are successfully prepared by vacuum filtration of metal-organic frameworks gel precursor together with layered porous-structure carbon and followed by calcination. The Ni 3 ZnC 0.7 particles uniformly decorate on the surface and pores of puffed-rice derived carbon. The puffed-rice derived carbon@Ni 3 ZnC 0.7 /Ni-400 mg (RNZC-4) sample displayed the best electromagnetic wave absorption (EMA) performances among the samples with different Ni 3 ZnC 0.7 loading. The minimum reflection loss (RL min) of the RNZC-4 composite reaches −39.9 dB at 8.6 GHz, while widest effective absorption bandwidth (EAB) of RNZC-4 for RL < −10 dB can reach 9.9 GHz (8.1–18 GHz, 1.49 mm). High porosity and large specific surface area promote the multiple reflection-absorption effect of the incident electromagnetic waves. The Ni 3 ZnC 0.7 nanoparticles provide a large number of interfaces and dipole factors. Analysis reveals that the RNZC-4 remained general stability under 400 °C with formation of a small amount of NiO and ZnO phases. Surprisingly, at such high temperature, the absorbing properties of the material are improved rather than decreased. Obviously, the material still maintains good electromagnetic wave performance at high temperature, and implies that the absorber shows good performance stability. Therefore, our preparations exhibit potential applications under extreme conditions and a new insight for the design and application of bimetallic carbides. [ABSTRACT FROM AUTHOR]

Three-dimensional network structures of flower-like 1T/2H Molybdenum disulfide nanosheets anchored to carbon fibers were prepared, which exhibited satisfactory electromagnetic wave absorption properties, providing a path for the preparation of electromagnetic wave absorbing materials with wide effective absorption bandwidth. [Display omitted] • 3D 1T/2H MoS 2 /CNFs interconnected network structures were prepared; • Heterogeneous interfaces between CNFs and MoS 2 , 1T and 2H MoS 2 phase was built; • Excellent EM wave absorption with RL min of −42.26 dB and EAB of 6.48 GHz was obtained; • The EM wave absorption performance was proved by radar reflectance cross section simulation. With the wide application of electromagnetic waves in national defense, communication, navigation and home appliances, the electromagnetic pollution problem is becoming more and more prominent. Therefore, high-performance, and low-density composite wave-absorbing materials have attracted much attention. In this paper, three-dimensional (3D) network structures of flower-like 1T/2H Molybdenum disulfide nanosheets anchored to carbon fibers (1T/2H MoS 2 /CNFs) were prepared by electrostatic spinning technique and calcination process. The morphology and electromagnetic wave absorption properties were tuned by changing the content of flower-like MoS 2. The optimized 1T/2H MoS 2 /CNFs composite exhibits superior electromagnetic wave absorption with minimum reflection (RL min) of −42.26 dB and effective absorption bandwidth (EAB) of 6.48 GHz at 2.5 mm. Multi-facts contribute to the super performance. First, the uniquely designed nanosheet and 3D interconnected networks leads to multiple reflection and scattering of electromagnetic waves, which promotes the attenuation of electromagnetic waves. Second, the propriate content of CNFs and MoS 2 with different phase regulates its impedance matching characteristic. Third, Numerous heterogeneous interfaces existed between CNFs and MoS 2 , 1T and 2H MoS 2 phase results in interface polarization. Besides, the 1T/2H MoS 2 rich in defects induces defect polarization, improving the dielectric loss. Furthermore, the electromagnetic wave absorption performance was proved via radar reflectance cross section simulation. This work illustrates 1T/2H MoS 2 /CNFs is a promising material for electromagnetic absorption with wide bandwidth, strong absorption, low density, and high thermal stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • An assisted liquid-phase plasma electrolysis is applied for synthesis of composite. • The synergy of CNFs, NiCo 2 O 4 and NiCo-LDH improves the electrochemical properties. • The specific capacitance of electrode can reach 1534.7 F/g at 1 A/g. • The ASC device has an energy density of 33.8 Wh/kg at 400 W/kg. • Deposition dynamics of NiCo 2 O 4 /NiCo-LDH/CNFs composites is explored. Nickel cobaltate/NiCo-layered double hydroxides (NiCo 2 O 4 /NiCo-LDH) as energy storage materials offer considerable potential for various applications. However, many of current methods for synthesizing NiCo 2 O 4 /NiCo-LDH suffer from long synthesis times, complex preparation process, and high temperatures and high pressures. In this study, we present a green, simple, and efficient approach known as assisted liquid-phase plasma electrolysis, which realizes the rapid fabrication of ultra-fine NiCo 2 O 4 /NiCo-LDH nanoparticle-decorated electrospun carbon nanofibers (NiCo 2 O 4 /NiCo-LDH/CNFs) composites. Ultra-fine NiCo 2 O 4 /NiCo-LDH nanoparticles (<70 nm) are uniformly deposited on the CNF surface. The CNFs are intertwined to form a highly conductive three-dimensional mesh structure, which synergizes the NiCo 2 O 4 /NiCo-LDH nanoparticles with a high specific capacitance in favor of ion/electron transport efficiency. In addition, the cooperative effect between the two phases of NiCo 2 O 4 and NiCo-LDH further improves the electrochemical properties. The NiCo 2 O 4 /NiCo-LDH/CNFs composites exhibit a high specific capacitance of 1534.7 F/g at 1 A/g and a capacitance retention of 93.9 % after 5000 cycles. An assembled asymmetric supercapacitor using activated carbon and NiCo 2 O 4 /NiCo-LDH/CNFs composites achieves an energy density of 33.8 Wh/kg at a power density of 400 W/kg and a capacitance retention of 93.0 % after 5000 cycles. Notably, two series-connected NiCo 2 O 4 /NiCo-LDH/CNFs ASC supercapacitors can light up an LED bulb, which maintains a certain brightness even after 50 min. Hence, this work provides a new and efficient route for synthesizing carbon-based NiCo 2 O 4 /NiCo-LDH composites for use as advanced energy storage materials. [ABSTRACT FROM AUTHOR]

The nickel metal nanoparticles and 3D nitrogen-doped carbon matrix are adopted to embellish nickel oxide via a simplified hard template method. This strategy will shine the route to prepare and ameliorate the electrochemical performance of NiO-based electrodes and other-type electrodes for energy storage. [Display omitted] Tailoring the omnidirectional conductivity networks in nickel oxide-based electrodes is important for ensuring their long lifespan, stability, high capacity, and high-rate capability. In this study, nickel metal nanoparticles and a three-dimensional nitrogen-doped carbon matrix were used to embellish the nickel oxide composite NiO–Ni/N–C via simplified hard templating. When a porous nitrogen-doped carbon matrix is present, a rapid pathway would be established for charging and discharging the electrons and lithium ions in a lithium-ion battery, thereby alleviating the volumetric expansion of the NiO nanoparticles during the operation of the battery. Moreover, the Ni0 ions added to serve as active sites to improve the capacity of the NiO-based electrodes and strengthen their conductivities. The multielement-effects of the optimal NiO–Ni/N–C electrode leads it to exhibit a capacity of 1310.8 mAh g-1 at 0.1 A g-1 for 120 loops and a rate capability of 441.5 mAh g-1 at 20.0 A g-1. Kinetic analysis of the prepared electrodes proved their ultrafast ionic and electronic conductivities. This strategy of hard templating reduces the number of routes required for preparing different types of electrodes, including NiO-based electrodes, and improves their electrochemical performance to enable their use in energy storage applications. [ABSTRACT FROM AUTHOR]

[Display omitted] The lotus seedpod-based activated carbon (LSAC) is derived from pyrolysis of lotus seedpod as biomass carbon precursor, and Co 3 O 4 is then deposited to LSAC by oxidation-precipitation and crystallization process of Co ions from Co(NO 3) 2 solution. The Co 3 O 4 particles uniformly decorate on the surface and/or the inner channels of LSAC. The optimal reflection loss (RL) value of LSAC/Co 3 O 4 -paraffin wax (PW) composite reaches −39.8 dB, and the bandwidth for RL below −10 dB and −20 dB are 10.3 and 3.0 GHz, respectively, much better than that of LSAC-PW composite for the higher magnetic loss. The addition of Co 3 O 4 particles in LSAC-PW composite significantly enhance the RL values in various thicknesses. The channels of the LSAC and decorated Co 3 O 4 can improve the abilities of multiple scattering, dipole polarization, interface polarization and magnetic loss. This composite provides a promising method to construct high performance absorbers by using biomass carbon to tune the dielectric properties of the ferromagnetic materials. [ABSTRACT FROM AUTHOR]