The two key problems for the industrialization of Li−S batteries are the dendrite growth of lithium anode and the shuttle effect of lithium polysulfides (LiPSs). Herein, we report the Janus separator prepared by coating anionic Bio-MOF-100 and its derived single-atom zinc catalyst on each side of the Celgard separator. The anionic metal−organic framework (MOF) coating induces the uniform and rapid deposition of lithium ions, while its derived single-atom zinc catalyzes the rapid transformation of LiPSs, thus inhibiting the lithium dendrite and shuttle effect simultaneously. Consequently, compared with other reported Li−S batteries assembled with single-atomic catalysts as separator coatings, our SAZ-AF Janus separator showed stable cyclic performance (0.05% capacity decay rate at 2 C with 1000 cycles), outstanding performance in protecting lithium anode (steady cycle 2800 h at 10 mAh cm −2 ), and equally excellent cycling performance in Li−SeS 2 or Li−Se batteries. Our work provides an effective separator coating design to inhibit shuttle effect and lithium dendrite.

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Detection of hydrogen peroxide (H2O2) produced by living cells is very significant to fully understand its roles in cellular physiology, as well as providing reliable diagnosis of pathological conditions. However, in situ detection of H2O2 released from adherent cells in cellular culture medium is still insufficiently achieved. Here, we report an electrochemical platform for in situ detection of H2O2 produced by adherent cells in cellular culture medium. It is based on the use of organic electrochemical transistor (OECT) fabricated on a flexible poly­(ethylene terephthalate) substrate and Transwell support. A screen-printed carbon paste electrode was modified with carbon nanotubes and platinum nanoparticles and served as the gate of the device. Under optimal conditions, this device exhibits good modulation and sensitivity. It works in the 0.5 μM to 0.1 mM H2O2 concentration range and has a 0.2 μM detection limit. The cells were seeded and grew on the Transwell membrane. Upon being stimulated by N-formylmethionyl-leucyl-phenylalanine peptide, H2O2 produced by the adherent cells diffused into the bottom chamber of the Transwell and was in situ detected by OECT. Moreover, evaluating in vitro cytotoxicity of the nanomaterial using the OECT-Transwell platform was realized. This simple electrochemical platform would be of great interest for in vitro cytotoxicity, cellular physiology study, and diagnosis of pathological conditions.

The lithium–sulfur (Li–S) battery has drawn tremendous interest because of its superior theoretical specific capacity, while the shuttle effect of lithium polysulfides (LPSs) has greatly hindered its application. Herein, MOF-derived Fe3C compounded with the nitrogen-doped graphene-like carbon nanosheet, Fe3C/NG, was prepared and applied to realize a stable long cycle of Li–S batteries. With the catalytic and conductive Fe3C nanoparticles distributed on the conductive nitrogen-doped graphene-like carbon nanosheets, the Fe3C/NG composite could quickly adsorb and catalyze LPSs under a high current density or large sulfur loading, thus achieving high rate performance for the cell. Even at a current density of 6 C, the Li–S cell with the Fe3C/NG-coated separator can still have a specific capacity of 954.5 mA h/g at the first cycle, and maintain 439.9 mA h/g after 500 stable cycles. Meanwhile, when the cell has a high sulfur loading of 6.5 mg/cm2, a stable specific capacity of 6.0 mA h/cm2 could still be maintained at 0.1 C. Such a lightweight separator coating with excellent catalytic performance and conductivity can provide a good example for the search of catalytic coatings for the high-performance Li–S battery.

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