Co-recrystallization induced self-catalytic Li2S cathode fully interfaced with sulfide catalyst toward a high-performance lithium-free sulfur battery

Lithium sulfide(Li_(2)S)is a promising cathode for a practical lithium-sulfur battery as it can be coupled with various safe lithium-free anodes.However,the high activation potential(>3.5 V)together with the shuttling of lithium polysulfides(LiPSs)bottleneck its practical uses.We are trying to present a catalysis solution to solve both problems simultaneously,specially with twinborn heterostructure to shoot off the trouble in interfacial contact between two solids,catalyst and Li_(2)S.As a typical example,a Co9S8/Li_(2)S heterostructure is reported here as a novel self-catalytic cathode through a co-recrystallization followed by a one-step carbothermic conversion.Co9S8 as the catalyst effectively lowers the Li_(2)S activation potential(<2.4 V)due to fully integrated and contacted interfaces and consistently promotes the conversion of LiPSs to suppress the shuttling.The obtained freestanding cathode of Co9S8/Li_(2)S heterostructures encapsulated in three-dimensional graphene shows a high capacity,reaching 92.6%of Li_(2)S theoretical capacity,high rate performance(739 mAh g1 at 2 C),and a low capacity fading(0.039%per cycle at 1 C over 900 cycles).Even under a high Li_(2)S loading of 12 mg cm^(-2)and a low E/S ratio of 5μL mgLi_(2)S^(-1),86%of theoretical capacity can be utilized.

Self-catalytic degradation of iron-bearing chemical conversion coating on magnesium alloys — Influence of Fe content

A number of industrial and biomedical fields,such as hydraulic fracturing balls for gas and petroleum exploitation and implant materials,require Mg alloys with rapid dissolution.An iron-bearing phosphate chemical conversion(PCC)coating with self-catalytic degradation function was fabricated on the Mg alloy AZ31.Surface morphologies,chemical compositions and degradation behaviors of the PCC coating were investigated through FE-SEM,XPS,XRD,FTIR,electrochemical and hydrogen evolution tests.Results indicated that the PCC coating was characterized by iron,its phosphates and hydroxides,amorphous Mg(OH)2 and Mg3-n(HnPO4)2.The self-catalytic degradation effects were predominately concerned with the Fe concentration,chemical composition and microstructure of the PCC coating,which were ascribed to the galvanic corrosion between Fe in the PCC coating and the Mg substrate.The coating with higher Fe content and porous microstructure exhibited a higher degradation rate than that of the AZ31 substrate,while the coating with a trace of Fe and compact surface disclosed a slightly enhanced corrosion resistance for the AZ31 substrate.

Augmenting Intrinsic Fenton-Like Activities of MOF-Derived Catalysts via N-Molecule-Assisted Self-catalyzed Carbonization

To overcome the ever-growing organic pollutions in the water system,abundant efforts have been dedicated to fabricating efficient Fenton-like carbon catalysts.However,the rational design of carbon catalysts with high intrinsic activity remains a long-term goal.Herein,we report a new N-molecule-assisted self-catalytic carbonization process in augmenting the intrinsic Fenton-like activity of metal-organic-framework-derived carbon hybrids.During carbonization,the N-molecules provide alkane/ammonia gases and the formed iron nanocrystals act as the in situ catalysts,which result in the elaborated formation of carbon nanotubes(in situ chemical vapor deposition from alkane/iron catalysts)and micro-/meso-porous structures(ammonia gas etching).The obtained catalysts exhibited with abundant Fe/Fe-Nx/pyridinic-N active species,micro-/meso-porous structures,and conductive carbon nanotubes.Consequently,the catalysts exhibit high efficiency toward the degradation of different organic pollutions,such as bisphenol A,methylene blue,and tetracycline.This study not only creates a new pathway for achieving highly active Fenton-like carbon catalysts but also takes a step toward the customized production of advanced carbon hybrids for diverse energy and environmental applications.

Hierarchically Structured Three-Dimensional Carbon-Based Integrated Electrodes with Enhanced Pseudocapacitance and Deformability

Compressible supercapacitors play an increasingly significant role in flexible sensors and wearable electronic devices.However,the integration of mechanical compressibility and excellent electrochemical performance into a single device remains a challenge.Herein,we demonstrate a compressible and high-performance supercapacitor based on an N-doped carbon foam elastomer with hierarchical carbon nanotubes.Hierarchically structured Fe3C@N-doped carbon nanotubes/N-doped carbon foam and Ni@N-doped carbon nanotubes/N-doped carbon foam have been synthesized via a simple and universal self-catalytic strategy.The hierarchical structural features of self-catalytic N-doped carbon nanotubes serve as a cushion when the composite is subjected to an external force,exhibiting excellent mechanical properties with a maximum compressive strain of 80%and fatigue resistance of 1000 cycles.Moreover,the different electroactive potentials of the transition-metal species in the composites provide the assembly with a maximum operating voltage of 1.4 V,which shows a maximum energy density of∼10.74 Wh kg^(−1)(0.084 mWh cm^(−3))at the power density of∼179.2 W kg^(−1)(1.4 mWh cm^(−3)),and retains 88.4%of the original capacitance after 20,000 charge–discharge cycles,even at a strain of 80%.This work paves the way for controllable fabrication of compressible electrodes and supercapacitors.