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The practical application of Li−S batteries is still limited by the fundamental problems of the insulation properties of sublimed S and the "shuttle effect" of polysulfides. S‐doped porous carbon cage (SPCC) obtained by the catalytic guidance methodology is employed as a highly efficient S host material for Li−S batteries, which presents the cage‐like morphology coupled with abundant pore channels. Compared to the undoped PCC, SPCC exhibits higher electrical conductivity. The composite of sublimed S and SPCC (S@SPCC) employed as cathode for Li−S batteries possesses a higher reversible capacity, superior rate capability and better durability in comparison with that of S@PCC cathode. The synergistic effect of robust matrix associated with good electrical conductivity and abundant pore channels of SPCC is beneficial for the fast electron transport and shorten the Li‐ion diffusion distance. Besides, S doping possesses the positive function to attract Li‐polysulfides, inhibiting the shuttle of Li‐polysulfides and contributing to the superior electrode behavior of the S@SPCC cathode. [ABSTRACT FROM AUTHOR]

It is a serious challenge to develop photoanodes with fast charge separation efficiency and surface reaction kinetics. Herein, the N doped carbon dot modified WO3 nanoflake (NCDs/WO3) is constructed by impregnation method. The resulting NCDs/WO3 exhibits an excellent photocurrent density of 1.42 mA cm−2 (1.0 V vs saturated calomel electrode, SCE) in 1 m H2SO4 solution under AM 1.5 G irradiation, which is 2.25 times higher than that of the pristine WO3. In addition, the onset potential of NCDs/WO3 photoanode represents a cathodic shift of 70 mV, indicating the charge separation and transfer process are both promoted. These results demonstrate N doped CD modified WO3 can further enhance the conductivity and electrochemical activity surface area, which contributes to the higher photoelectrochemical (PEC) performance. This work provides an efficient strategy for the development of doping carbon material with heteroatoms to increase the charge transfer and charge separation efficiency in PEC water oxidation. Nitrogen doped carbon dots modified WO3 nanoflakes are studied to strengthen the light absorption and to accelerate the charge separation and transfer efficiency of WO3 nanoflakes. Nitrogen doping improves the electrical conductivity and electrochemical activity surface area of carbon dots, which is beneficial for promoting the photoelectrochemical performance of WO3. [ABSTRACT FROM AUTHOR]

An increasing energy storage property with high rate capability during fast charging at the high current density has been a long-standing challenge for supercapacitors. In this work, a novel nitrogen-enriched graphitized hierarchical porous carbon (NGHPC) was synthesized by a convenient one-step carbonization process from melamine(M)-resorcinol(R)-formaldehyde(F) co-polymeric microspheres using nano γ-Fe 2 O 3 as template, graphitized catalyst precursor and activation promoting agent coupled with ZnCl 2 activation. The nano-sized γ-Fe 2 O 3 was reduced to Fe metal and other Fe-containing species in the carbonization process, and Fe served as catalyst to generate perfectly graphitized carbon skeleton, and other nanoparticles acted as the template of macropores. Meanwhile, CO 2 which generated from the oxidation reactions of CO and γ-Fe 2 O 3 reacted with carbon to bring the in situ CO 2 physical activation, resulting in the promotive tailoring in microporosity. Interestingly, the morphology of the obtaining NGHPC materials could be controlled from spherical aspect to the structure of sphere coated by thin sheet by varying the M/R mass ratio. As supercapacitor electrodes materials, the optimal material achieved an outstanding specific capacitance of 417.5 F g −1 at 0.5 A g −1 in 6 M KOH electrolyte. More importantly, a superb rate capability was also exhibited, and a capacitance of 296.4 F g −1 was still retained at an ultrahigh current density of 100 A g −1 . Besides, the assembled symmetric supercapacitor with the optimal material displayed a high integrated energy density of 33.9 Wh kg −1 at a power density of 809.9 W kg −1 within a voltage range of 0–1.8 V in 0.5 M Na 2 SO 4 natural electrolyte and an approximate 84.8% capacitance retention after consecutive 10,000 cycles at 5 A g −1 . [ABSTRACT FROM AUTHOR]

Many novel two-dimensional (2D) allotropes of carbon have been predicted to be (meta)stable at 0 K, however, their thermal stability and mechanical properties at finite temperatures remain unclear. In this study, the mechanical properties and fracture behaviors of five newly predicted monatomic thick carbon sheets (C 31 , C 33 , δ-graphyne (GY), γ-GY, C 63 , and graphene) are investigated using molecular simulations. The δ-GY, γ-GY, and graphene show brittle fractures in uniaxial tension testing at temperatures from 1 to 1200 K. The first signs of fracture in these brittle carbon sheets indicate that the C C bonds linking the benzene rings and linear acetylenic carbons break with strong directional preference, whereby the direction of the breaking C C bonds is parallel to the direction of tensile stress. A brittle-to-ductile transition is identified in the C 31 , C 33 , and C 63 sheets at high temperatures, which corresponds to the breakages of the C C bonds in the triangular carbon rings. Global and local order-order structural transitions as well as order-disorder transitions are obtained in different ductile carbon sheets, and are found in the same carbon sheet under tensile stress along different directions. These results suggest a strong correlation between the structure and the failure mechanism in 2D carbon sheets, which is of great importance in the future design, synthesis and application of novel 2D materials. [ABSTRACT FROM AUTHOR]