Multidimensional hollow SiO_(2)/C nanofibers modified by magnetic nanocrystals for electromagnetic energy conversion and lithium battery storage

Multifunctional materials are powerful tools to support the advancement of energy conversion devices.Materials with prominent electromagnetic and electrochemical properties can realize the conversion of electromagnetic energy and solve the subsequent storage issues.Herein,an electrospinning-thermal reduction method is employed to construct ultrafine nickel nanoparticle modified porous SiO_(2)/C(Ni-SiO_(2)/C)hollow nanofibers as promising materials for applications in both electromagnetic wave absorption(EMA)and lithium-ion storage.Impressively,when used as an EMA material,the reflection loss(RL)of Ni-SiO_(2)/C can reach−47.8 dB at 15.8 GHz with a matching thickness of 2.2 mm.Its excellent microwave absorption performance can be attributed to the enhanced conduction loss,polarization relaxation,synergistic magnetic loss,and preferred impedance matching,which result from multi-component magnetic/dielectric synergy and the unique interconnected multidimensional hollow structure.Furthermore,the electronic conductivity and electrochemical activity of the samples are significantly enhanced due to the uniform distribution of ultrafine Ni nanoparticles in the amorphous SiO_(2)/C matrix.Meanwhile,the hierarchical hollow porous structure provides sufficient free space for volume change during lithiation/delithiation cycles.Accordingly,the Ni-SiO_(2)/C nanocomposite exhibits a high reversible capacity of 917.6 mAh·g^(−1)at 0.1 A·g^(−1).At a high current density of 2 A·g^(−1),a capacity of 563.9 mAh·g^(−1)can be maintained after 300 cycles.An energy conversion-storage device is designed to store waste electromagnetic energy in the form of useful electrical energy.This work inspires the development of high-performance bifunctional materials.

Multidimensional network of polypyrrole nanotubes loaded with ZIF-67 to construct multiple proton transport channels in composite proton exchange membranes for fuel cells

Due to the designability of their proton transport channels,high-performance long-lasting composite proton exchange membranes(PEMs)are currently the subject of extensive research.However,the compatibility and channel order of the internal components of the composite membranes are still challenging.In this work,hollow polypyrrole(PPy)nanotube structures were obtained to provide a nitrogen source and to act as a skeleton to confine and separate cobalt nanoparticles on the surface of PPy nanotubes.Finally,zeolitic imidazolate framework material-67(ZIF-67)was attached to the surface.By using this method,PPy@ZIF-67 filler can minimize the particle size and inhibit Co^(2+)ions from aggregating,thus constructing a reasonably distributed transport channel and improving the proton transport capacity.As a result,the synthesized polymer nanotubes loaded metal-organic framework(MOF)nanofiber network can enhance the physicochemical properties and stability of the membrane by providing a more extensive interfacial interaction.In addition,the composite membrane has excellent ionic conductivity and power density,reaching 233.7 mS cm^(–1) and 837 mW cm^(–2) at 80℃ and 100%humidity.It indicates that the nanofibrous MOF structure not only improves the compatibility with the substrate but also provides sufficient leap points for proton transport via the interfacial conduction pathway between the PPy@ZIF-67 filler and the substrate,thus allowing the resulting composite membrane to facilitate proton transfer via the Vehicle and Grotthuss mechanisms synergistically.

Recent Progress of the Active Materials with Various Micro‑structures for Flexible Textile‑Based Supercapacitors

Flexible textile-based supercapacitors have exhibited great potential for use in e-textile systems due to their high flexibility,light weight and ease of integration into the textile materials.The capacitance and energy density of current textile-based supercapacitors,however,are insufficient to meet the high demands of wearable electronics and smart textiles.This review summarizes the recent progress of enhancement methods regarding textile-based supercapacitors,including the multidimen-sional nanostructure of active materials,the structural designs of textile substrates and the wearable softness.Furthermore,the remaining challenges and future prospects of constructing high-performance flexible textile-based supercapacitors for smart textiles and wearable electronics are also proposed.