The functional design of separators has been proved to be one of the most efficient methods to improve the electrochemical performance of lithium–sulfur batteries. In this work, a multifunctional separator with gradual changes to four aspects was constructed by integrating a PVDF-HFP/h-BN membrane with a Co-doped carbon nanofiber. The architecture has four gradations, which offers multifold advantages. First, in terms of density, there is a transition from loose to dense, which results in a higher electrolyte uptake rate, reduces the amount of free electrolyte and further suppresses the shuttle effect. Additionally, in terms of composition, a transition from inorganic to organic is designed, which allows the inorganic and organic components to bind closely and reduces the interfacial resistance. Meanwhile, there is a transition from high electronic conductivity to insulation. The change in electronic conductivity leads to effective conversion of the polysulfide. Finally, in terms of ionic conductivity, there is a transition from low to high, which gives the separator better ability to conduct lithium ions. As a consequence, a battery with the as-constructed multifunctional separator performs with good capacity stability, which demonstrates a new concept for high-performance lithium–sulfur battery design.
Li Zhang,Ming Yin,Xiuxia Wei,Yiwei Sun,Yuting Luo,Huaqing Lin,Ruxin Shu,Dongpo Xu
Fe-Co@CNF was synthesized by electrospinning technology, and AuNPs was loaded onto Fe-Co@CNF by in-situ reduction to obtain Fe-Co@CNF@AuNPs composite material, which was used as the working electrode based on Au-S bond cooperation. The tetracycline electrochemical sensing interface Fe-Co@CNF@AuNPs@Apt was constructed by connecting mercaptoylated tetracycline (TC) aptamers on Fe-Co@CNF@AuNPs surface. The morphology and composition of Fe-Co@CNF@AuNPs composites were characterized by SEM, TEM, EDS, XRD and XPS, and the electrochemical properties of tetracycline were evaluated by CV and DPV. The results showed that the addition of Fe and Co did not destroy the structure of the original carbon nanofibers, and their synergistic effect enhanced the electrocatalytic performance, effective electrode area and electron transfer ability of carbon nanofibers. AuNPs are evenly distributed over the fibers, which effectively improves the electrical conductivity of the material. Under the optimal conditions, the theoretical detection limit of tetracycline was 0.213 nM, and the linear detection range was 5.12–10 mM, which could successfully detect tetracycline in milk.
Difficulties in mineralizing organic dyes and antibiotics have been bottlenecks limiting wastewater treatment technology development. Electrocatalytic advanced oxidation through selective two-electron oxygen reduction on cathodes is a promising method of mineralizing organic wastewater. However, most developed cathodes cannot efficiently synthesize H 2 O 2 in situ via 2e − pathways and their durability cannot be guaranteed due to Fe 2+ leaching. Therefore, the electrospun cathode (MOFs (2Fe/Co)/CNF) with both photocatalytic and electrocatalytic functions was ingeniously fabricated for efficient degradation of dyes and antibiotics through graphene template effect, carbonization and in-situ growing strategies. On the cathode surface , H 2 O 2 was continuously generated in situ via 2e − reduction reactions, activating Fenton-like reactions. In addition, the developed cathode (MOFs (2Fe/Co)/CNF) had a low band gap (1.32 eV), which enhanced visible light response and improved catalytic active sites of the cathode. Degradation experiments of methylene blue and erythromycin solution indicate that the developed cathode showed excellent synergistic photoelectrocatalysis performance. In a photo-electro-Fenton system (PEF), the mineralization rate of methylene blue and erythromycin reached 86.5% and 90.2% within 10 and 30 min, respectively. The cathode in this research is expected to have great potential to efficiently mineralize wastewater via PEF.
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