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The lithium storage performance and bioimaging of metal sulfides are restricted by their intrinsic poor conductivity, large volumetric expansion and toxicity. Here we report a new strategy to solve these problems by coating pyrrhotite (Fe1−xS) (FS) nanoparticles with N-doped hard carbon ultrathin film (N-HCUF). The porous nanocomposites with multilevel structures have been synthesized by using petrochemical waste water (PWW) as the organic ligands of iron metal-organic frameworks (Fe-MOFs) precursor and the sources of sulfur, nitrogen and carbon. We have clarified the formation mechanism and the influences of wash and calcination temperature on the structural composition, electrochemical and luminescence properties of the nanocomposites. As a novel anode for lithium ion batteries (LIBs), the FS/N-HCUF-700S exhibits high initial discharge capacity of 1542.08 mAh g−1 at a current density of 0.1 A g−1 and the discharge specific capacity becomes stable at 632.16 mAh g−1 after 200 cycles; Meanwhile, the Li+ storage mechanism in the as-prepared samples has also been investigated. More importantly, FS/N-HCUF-700S exhibits strong yellow-fluorescent emission at 614 nm, which is particularly important for bioimaging. Last, the removal efficiency of chemical oxygen demand of PWW is up to 80.7% during the synthesis process. [ABSTRACT FROM AUTHOR]

Using polypyrrole (PPy) nanotubes as the substrate, the layered molybdenum disulfide (MoS) nanosheets were wrapped on PPy nanotubes to form MoS/PPy nanocomposites by a hydrothermal reaction. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed that MoS nanosheets coated uniformly on the surface of PPy nanotubes owing to the electrostatic force. The specific capacitance of the MoS/PPy nanocomposites was high up to 307.5 F g, much higher than that of the pure PPy with specific capacitance of 106.3 F g and MoS with specific capacitance of 138.5 F g at a current density of 1.0 A g in 1 M KCl electrolyte. And the special structure of MoS/PPy nanocomposites electrode reduces the deformation during the charge-discharge process and thus improves the rate stability and electrochemical cycling stability of the electrode significantly. The specific capacitance retains 96.47 % after 1000 charge-discharge processes which provides potential as supercapacitors. [ABSTRACT FROM AUTHOR]