The shuttle effect and sluggish conversion kinetics of lithium polysulfides (LiPS) hamper the practical application of lithium–sulfur batteries (LSBs). Toward overcoming these limitations, herein an in situ grown C2N@NbSe2 heterostructure is presented with remarkable specific surface area, as a Li–S catalyst and LiPS absorber. Density functional theory (DFT) calculations and experimental results comprehensively demonstrate that C2N@NbSe2 is characterized by a suitable electronic structure and charge rearrangement that strongly accelerates the LiPS electrocatalytic conversion. In addition, heterostructured C2N@NbSe2 strongly interacts with LiPS species, confining them at the cathode. As a result, LSBs cathodes based on C2N@NbSe2/S exhibit a high initial capacity of 1545 mAh g−1 at 0.1 C. Even more excitingly, C2N@NbSe2/S cathodes are characterized by impressive cycling stability with only 0.012% capacity decay per cycle after 2000 cycles at 3 C. Even at a sulfur loading of 5.6 mg cm−2, a high areal capacity of 5.65 mAh cm−2 is delivered. These results demonstrate that C2N@NbSe2 heterostructures can act as multifunctional polysulfide mediators to chemically adsorb LiPS, accelerate Li‐ion diffusion, chemically catalyze LiPS conversion, and lower the energy barrier for Li2S precipitation/decomposition, realizing the “adsorption‐diffusion‐conversion” of polysulfides.

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The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adem.202101804.

W e report on an effort to make narrow, quasi lD, wires in thin epilayers of n*-GaAs, using reactive ion etching (RIE) at accelerating voltages as low as 10 V, We measure depletion widths of the order of 40 nm (while the natural width is about 20 nm). Magnetoresistance measurements on wires with electrical width of 100-300 nm show the phase coherence length of the electrons to be temperature independent below 6 K with a value close to 400 nm. At high magnetic fields (1-6 T) the magnetoresistance exhibits unusual quasi periodic oscillations, the origin of which is unclear.