Bimetallic ZIFs-derived electrospun carbon nanofiber membrane as bifunctional oxygen electrocatalyst for rechargeable zinc-air battery

The recharged zinc-air battery(ZAB) has drawn significant attention owing to increasing requirement for energy conversion and storage devices.Fabricating the efficient bifunctional oxygen catalyst using a convenient strategy is vitally important for the rechargeable ZAB.In this study,the bimetallic ZIFs-containing electrospun(ES) carbon nanofibers membrane with hierarchically porous structure was prepared by coaxial electrospinning and carbonization process,which was expected to be a bifunctional electrocatalyst for ZABs.Owing to the formed dual single-atomic sites of Co-N_(4) and Zn-N_(4),the obtained ES-Co/ZnCNZIFexhibited the preferable performance toward oxygen reduction reaction(ORR) with E1/2of 0.857 V and JLof 5.52 mA cm^(-2),which were more than Pt/C.Meanwhile,it exhibited a marked oxygen evolution reaction(OER) property with overpotential of 462 mV due to the agglomerated metallic Co nanoparticles.Furthermore,the ZAB based on the ES-Co/Zn-CNZIFcarbon nanofibers membranes delivered peak power density of 215 mW cm^(-2),specific capacity of 802.6 mA h g^(-1),and exceptional cycling stability,far larger than Pt/C+RuO_(2)-based ZABs.A solid-state ZAB based on ES-Co/Zn-CNZIFshowed better flexibility and stability with different bending angles.

High-performance all-solid-state polymer electrolyte with fast conductivity pathway formed by hierarchical structure polyamide 6 nanofiber for lithium metal battery

The utilization of all-solid-state electrolytes is considered to be an effective way to enhance the safety performance of lithium metal batteries.However,the low ionic conductivity and poor interface compatibility greatly restrict the development of all-solid-state battery.In this study,a composite electrolyte combining the electrospun polyamide 6(PA6)nanofiber membrane with hierarchical structure and the polyethylene oxide(PEO)polymer is investigated.The introduction of PA6 nanofiber membrane can effectively reduce the crystallinity of the polymer,so that the ionic conductivity of the electrolyte can be enhanced.Moreover,it is found that the presence of finely branched fibers in the hierarchical structure PA6 membrane allows the polar functional groups(C=O and N-H bonds)to be fully exposed,which provides sufficient functional sites for lithium ion transport and helps to regulate the uniform deposition of lithium metal.Moreover,the hierarchical structure can enhance the mechanical strength(9.2 MPa)of the electrolyte,thereby effectively improving the safety and cycle stability of the battery.The prepared Li/Li symmetric battery can be stably cycled for 1500 h under 0.3 mA cm^(-2) and 60℃.This study demonstrates that the prepared electrolyte has excellent application prospects in the next generation all-solid-state lithium metal batteries.

“Zincophilic‑Hydrophobic”PAN/PMMA Nanofiber Membrane Toward High‑Rate Dendrite‑Free Zn Anode

Uncontrollable Zn dendrites and side reactions seriously downgrade the cycling stability of the Zn anode,and restrict the commercialization of aqueous zinc ion batteries.Here,PAN-based(PAN,PAN/PMMA)nanofiber membranes with uniform“zincophilic-hydrophobic”sites have been in-situ electrospun on Zn to effectively prevent harmful side reactions and control Zn plating/stripping behavior.The abundant highly-negative functional groups(C≡N and C=O)of PAN/PMMA have strong coordination interactions with Zn2+,which can accelerate Zn2+desolvation and increase the Zn2+migration number.Furthermore,the even distribution of zincophilic sites can help create a uniform Zn deposition environment and enable horizontal Zn deposition.Simultaneously,the inherent“hydrophobicity”of the nonpolar carbon skeleton in PAN/PMMA can prevent Zn corrosion and hydrogen evolution reaction(HER)side reactions,thus improving the cycling stability of the Zn anode.As a result,PAN/PMMA@Zn symmetric cells demonstrated remarkable rate performance and long cycling stability,sustaining efficient operation for over 2000 cycles at 10 mA cm^(−2)with a low polarization voltage below 65 mV.This Zn anode modification strategy by in-situ constructed PAN-based nanofiber membrane has the advantages of simple-preparation,one-step membrane construction,binder-free,uniform distribution of functionalized units,which not only provides a specific scheme for developing advanced Zn anode but also lays a certain research foundation for developing“separator-anode”integrated Zn-based batteries.

A TEMPOL and rapamycin loaded nanofiber-covered stent favors endothelialization and mitigates neointimal hyperplasia and local inflammation

An increased level of reactive oxygen species(ROS)plays a major role in endothelial dysfunction and vascular smooth muscle cell(VSMC)proliferation during in-stent thrombosis and restenosis after coronary artery stenting.Herein,we report an electrospun core-shell nanofiber coloaded with 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl(TEMPOL)and rapamycin(RAPA)that correspondingly serves as an ROS scavenger and VSMC inhibitor.This system has the potential to improve the biocompatibility of current drug-eluting stent(DES)coatings with the long-term and continuous release of TEMPOL and rapamycin.Moreover,the RAPA/TEMPOL-loaded membrane selectively inhibited the proliferation of VSMCs while sparing endothelial cells(ECs).This membrane demonstrated superior ROS-scavenging,anti-inflammatory and antithrombogenic effects in ECs.In addition,the membrane could maintain the contractile phenotype and mitigate platelet-derived growth factor BB(PDGF-BB)-induced proliferation of VSMCs.In vivo results further revealed that the RAPA/TEMPOL-loaded covered stents promoted rapid restoration of vascular endothelium compared with DES and persistently impeded inflammation and neointimal hyperplasia in porcine models.