Bioinspired urchin-like murray carbon nanostructure with protection shell for advanced lithium-sulfur batteries

Commercial application of lithium-sulfur(Li-S) batteries is hindered by the insulating nature of sulfur and the dissolution of polysulfides. Here, a bioinspired 3D urchin-like N-doped Murray's carbon nanostructure(N-MCN) with interconnected micro-meso-macroporous structure and a polydopamine protection shell has been designed as an effective sulfur host for high-performance Li-S batteries. The advanced 3D hierarchically porous framework with the characteristics of the generalized Murray's law largely improves electrolyte diffusion, facilitates electrons/ions transfer and provides strong chemisorption for active species, leading to the synergistic structural and chemical confinement of polysulfides. As a result,the obtained P@S/N-MCN electrode with high areal sulfur loading demonstrates high capacity at high current densities after long cycles. This work reveals that following the generalized Murray's law is feasible to design high-performance sulfur cathode materials for potentially practical Li-S battery applications.

Embedding tin disulfide nanoparticles in twodimensional porous carbon nanosheet interlayers for fast-charging lithium-sulfur batteries

Lithium-sulfur(Li-S)batteries have attracted significant attention for their high specific capacity,non-toxic and harmless advantages.However,the shuttle effect limits their development.In this work,small-sized tin disulfide(SnS_(2))nanoparticles are embedded between interlayers of twodimensional porous carbon nanosheets(PCNs),forming a multi-functional nanocomposite(PCN-SnS_(2))as a cathode carrier for Li-S batteries.The graphitized carbon nanosheets improve the overall conductivity of the electrode,and the abundant pores not only facilitate ion transfer and electrolyte permeation,but also buffer the volume change during the charge and discharge process to ensure the integrity of the electrode material.More importantly,the physical confinement of PCN,as well as the strong chemical adsorption and catalytic reaction of small SnS_(2)nanoparticles,synergistically reduce the shuttle effect of polysulfides.The interaction between a porous layered structure and physical-chemical confinement gives the PCN-SnS_(2)-S electrode high electrochemical performance.Even at a high rate of 2 C,a discharge capacity of 650 mA h g^(-1)is maintained after 150 cycles,underscoring the positive results of SnS_(2)-based materials for Li-S batteries.The galvanostatic intermittent titration technique results further confirm that the PCN-SnS_(2)-S electrode has a high Li+transmission rate,which reduces the activation barrier and improves the electrochemical reaction kinetics.This work provides strong evidence that reducing the size of SnS_(2)nanostructures is beneficial for capturing and reacting with polysulfides to alleviate their shuttle effect in Li-S batteries.

Phase-junction Ag/TiO_(2)nanocomposite as photocathode for H_(2)generation

Developing anatase/rutile phase-junction in Ti O_(2)to construct Z-scheme system is quite effective to improve its photoelectrochemical activity.In this work,the anatase/rutile phase-junction Ag/Ti O_(2)nanocomposites are developed as photocathodes for hydrogen production.The optimized Ag/Ti O_(2)nanocomposite achieves a high current density of 1.28 m A cm-2,an incident photon-to-current conversion efficiency(IPCE)of 10.8%,an applied bias photon-to-current efficiency(ABPE)of 0.32 at 390 nm and a charge carriers’lifetime up to 2000 s.Such enhancement on photoelectrochemical activity can be attributed to:(ⅰ)the generated Z-scheme system in the anatase/rutile phase-junction Ag/Ti O_(2)photocathode enhances the separation,diffusion and transformation of electron/hole pairs inside the structure,(ⅱ)Ag nanodots modification in the anatase/rutile phases leading to the tuned band gap with enhanced light absorption and(ⅲ)the formed Schottky barrier after Ag nanodots surface modification provides enough electron traps to avoid the recombination of photogenerated electrons and holes.Our results here suggest that developing phase-junction nanocomposite as photocathode will provide a new vision for their enhanced photoelectrochemical generation of hydrogen.