Binders play an important role in battery systems. The lithium-sulfur (Li-S) batteries have poor cycling performance owing to large volume alteration of sulfur and shuttle effect. Herein, a novel water-soluble functional binder (named GN-BA) is prepared by the cross-linking effect between gelatin and boric acid. The excellent binder can effectively maintain the integrated electrode stable, buffer the volume changes, prevent active materials exfoliation from current collectors, and anchor polysulfides by chemical bonding. Sulfur electrodes in this binder also exhibit a loosely stacked porous structure, which is advantageous to the electrolyte permeation and fast ion diffusion. X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy, and density functional theory calculations further verified that the binder can anchor polysulfides by forming BOLi, COLi, and CNLi chemical bonds. At 0.5 C, a high initial capacity of 980 mA h g −1 can be obtained, which is higher than those sulfur cathodes with traditional poly(vinylidene fluoride) binder. When the sulfur loading is up to 5.0 mg cm −2 , a high areal specific capacity of 5.7 mA h cm −2 and excellent cycling stability are achieved. This study proposes an economical and environmentally friendly strategy for the construction of advanced binders and promotes the practical application of high-energy Li-S batteries.
Particular N, S co-doped graphene/Fe3O4 hybrids have been successfully synthesized by the combination of a simple hydrothermal process and a subsequent carbonization heat treatment. The nanostructures exhibit a unique composite architecture, with uniformly dispersed Fe3O4 nanoparticles and N, S co-doped graphene encapsulant. The particular porous characteristics with many meso/micro holes/pores, the highly conductive N, S co-doped graphene, as well as the encapsulating N, S co-doped graphene with the high-level nitrogen and sulfur doping, lead to excellent electrochemical performance of the electrode. The N-S-G/Fe3O4 composite electrode exhibits a high initial reversible capacity of 1362.2 mAhg−1, a high reversible specific capacity of 1055.20 mAhg−1 after 100 cycles, and excellent cycling stability and rate capability, with specific capacity of 556.69 mAhg−1 when cycled at the current density of 1000 mAg−1, indicating that the N-S-G/Fe3O4 composite is a promising anode candidate for Li-ion batteries.
A simple and no-drug resistance antibacterial
method was developed
by the synthesis of heat-stable and pH-tolerant nisin-loaded iron
oxide nanoparticles polydopamine (IONPs@pDA) composites. The composites
had a crystal structure and diameters of 25 ± 3 nm, with a saturation
magnetization (M
s) of 43.7995 emu g–1. Nisin was successfully conjugated onto the IONPs@pDA
nanoparticles, as evinced by Fourier transform infrared spectroscopy
and X-ray photoelectron spectroscopy analyses. The novel synthesized
material showed good performance in reducing Alicyclobacillus
acidoterrestris, a common food spoilage bacterium
that represents a significant problem for the food industry. Treatment
of A. acidoterrestris cells with composites
resulted in membrane damage, as observed by live/dead staining and
scanning electron microscopy and transmission electron microscopy
analyses. Further, the composites exhibited highly efficient antibacterial
activity against cells in only 5 min. Transcriptomic sequencing of
culture RNA pools after exposure to composites resulted in a total
of 334 differentially expressed genes that were primarily associated
with transcriptional regulation, energy metabolism, membrane transporters,
membrane and cell wall syntheses, and cell motility. Thus, these results
suggested that changes in transcriptional regulation caused by aggregated
composites on target cells led to major changes in homeostasis that
manifested by decreased energy metabolism, pore formation in the membrane,
and repressed cell wall synthesis. Concomitantly, cell motility and
sporulation activities were both repressed, and finally, intracellular
substances flowed out of leaky cells. The proposed biocontrol method
represents a novel means to control microorganisms without inducing
drug resistance. Further, these results provide novel insights into
the molecular mechanisms underlying the antibacterial activity of
composites against microorganisms.
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