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This study reports the fabrication of mixed matrix membranes (MMMs) using immersion precipitation phase inversion for promising application in desalination of dye solutions. Aromatic poly(m-phenylene isophthalamide) is used as the polymer material, and the metal−organic framework MIL-53(Al) is added to develop integrally skinned asymmetric membranes. Successful dispersion of MIL-53(Al) particles into the membrane-separating layer is confirmed by scanning electron microscopy. The optimum performance of the membranes is obtained at 0.5 wt % MIL-53(Al) concentration. In particular, the M-0.5 membrane is planned for use in separating dye/salt aqueous mixtures. It is observed that the M-0.5 membrane has a rejection for NaCl and Na 2 SO 4 below 11% and 37%, respectively, in mixed salt/ dye solutions. Additionally, the M-0.5 membrane is found to have a rejection rate of 83.9%, 98.3%, and 99.8% for nitroso-R salt, xylenol orange, and ponceau S, respectively, in mixed Na 2 SO 4 /dye solutions. The rejection rate for Na 2 SO 4 is lower than that of some commercial nanofiltration membranes (NF90, NF270, and DK). The membrane is promising for dye desalination in industrial-scale applications.

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Li2S-based Li–S batteries are taken as promising energy storage systems due to the high theoretical specific capacity/energy density and nature of a matching Li-metal-free anode. However, the cyclic stability of the Li2S-based Li–S battery is seriously prevented by the shuttle effect of lithium polysulfides (LiPSs). Meanwhile, due to the poor electrical conductivity of Li2S, the Li–S battery displays slow reaction kinetics. In this work, we design 3D-porous carbon (PC) architecture as a host for inhabiting the LiPS shuttle based on physical capture. Furthermore, this porous carbon architecture is modified by introducing two kinds of heteroatoms (N and S) to form dual active sites (named as NSPC) for chemically binding LiPSs and accelerating their conversion. The polyvinyl pyrrolidone-coated Li2SO4·H2O is embedded in the NSPC skeleton and further forms the Li2S/NSPC cathode via a carbothermal reduction process. In consequence, the NSPC architecture possesses continuous electron/ion channels and abundant active sites, which are beneficial to the fast diffusion of Li+ and timely conversion of sulfur species. As a result, the as-prepared Li2S/NSPC cathode exhibits a high initial discharge capacity of 690 mAh g–1 at a high rate of 1C and keeps a capacity of 587 mAh g–1 after 200 cycles with a good capacity retention rate of 85% and low fading rate of 0.075% per cycle. Therefore, this work offers a brand-new platform to understand the synergistic effects of promoting reaction kinetics for Li2S-based Li–S batteries.

Nowadays, Li−S batteries are facing many thorny challenges like volume expansion and lithium dendrites on the road to commercialization. Due to the peculiarity of complete lithiation and the capability to match non-lithium anodes, Li 2 S-based Li−S batteries have attracted more and more attention. Nevertheless, the same notorious shuttle effect of polysulfides as in traditional Li−S batteries and the poor conductivity of Li 2 S lead to sluggish conversion reaction kinetics, poor Coulombic efficiency, and cycling performance. Herein, we propose the interconnected porous carbon skeleton as the host, which is modified by an atomically dispersed Mn catalyst as well as O, N atoms (named as ON-MnPC) via the melt salt method, and introduce the Li 2 S nanosheet into the carbon host with poly(vinyl pyrrolidone) ethanol solution. It has been found that the introduction of O, N to bind with Mn atoms can endow the nonpolar carbon surface with ample unsaturated coordination active sites, restrain the shuttle effect, and enhance the diffusion of Li + and accelerate the conversion reaction kinetics. Besides, due to the ultra-high catalyst activity of atomically dispersed Mn catalysts, the Li 2 S/ON-MnPC cathode shows good electrochemical performance, e.g., an initial capacity of 534 mAh g −1 , a capacity of 514.18 mAh g −1 after 100 cycles, a high retention rate of 96.23%, and a decay rate of 0.04% per cycle. Hence, use of atomically dispersed Mn catalysts to catalyze the chemical conversion reactions of polysulfides from multiple dimensions is a significant exploration, and it can provide a brand-new train of thought for the development and commercialization of the economical, high-performance Li 2 S-based Li−S batteries.

Lithium-sulfur (Li-S) batteries are considered a prospective energy storage system because of their high theoretical specific capacity and high energy density, whereas Li-S batteries still face many serious challenges on the road to commercialization, including the shuttle effect of lithium polysulfides (LiPSs), their insulating nature, the volume change of the active materials during the charge−discharge process, and the tardy sulfur redox kinetics. In this work, double transition metal oxide TiNb 2 O 7 (TNO) nanometer particles are tactfully deposited on the surface of an activated carbon cloth (ACC), activating the surface through a hydrothermal reaction and high-temperature calcination and finally forming the flexible self-supporting architecture as an effective catalyst for sulfur conversion reaction. It has been found that ACC@TNO possesses many catalytic activity sites, which can inhibit the shuttle effect of LiPSs and increase the Coulombic efficiency by boosting the redox reaction kinetics of LiPS transformation reaction. As a consequence, the ACC@TNO/S cathode exhibits an impressive electrochemical performance, including a high initial discharge capacity of 885 mAh g −1 at a high rate of 1 C, a high discharge specific capacity of 825 mAh g −1 after 200 cycles with a prominent capacity retention rate of 93%, and a small decay rate of 0.034% per cycle. Although TNO is extensively used in the fields of lithium ion batteries and other rechargeable batteries, it is first introduced as sulfur host materials to boost the redox reaction kinetics of the LiPS transformation reaction and increase the electrochemical performance of Li-S batteries. Therefore, studies of the synergistic effect on the chemical absorption and catalytic conversion effect of TNO for LiPSs of Li-S batteries provide a good strategy for boosting further the comprehensive electrochemical performances of Li-S batteries.