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Abstract: Electrospun porous carbon nanofibers fabricated by electrospinning and steam activation were functionalized by spontaneous grafting of phenylsulfonic acid (PSA) groups. SEM and Raman observation suggested that modified electrospun nanofibers did not exhibit distinct changes of surface morphology and intrinsic graphitic structure. Nitrogen adsorption showed decrease in surface area and pore volume of modified carbon nanofibers. XPS and elementary analysis were conducted to characterize the surface chemistry of carbon nanofibers. The hydrophilic character was measured by the contact angles and static adsorption isotherms of water. The adsorption isotherms of benzene and butanone showed that the increasing hydrophilicity led to enhancement of adsorption performance for butanone on carbon nanofibers, indicating that the adsorption selectivity to hydrophilic organic compounds was improved. [Copyright &y& Elsevier]

The pore microstructures in two viscouse rayon-based ACF samples were characterized by nitrogen adsorption and HRTEM. For TEM, a two-dimensional fast Fourier transform (FFT) of the original TEM images was performed, and pores in different size ranges were extracted by the inverse FFT (IFFT) operation. The surface fractal dimensions of the samples were evaluated by using both N2 adsorption and TEM image analysis. The results show that TEM can portray the shapes of the pore, and it can give a quantitative evaluation of surface irregularity that is consistent with nitrogen adsorption results. [Copyright &y& Elsevier]

We report a one-step method for fabricating uniform and hierarchical porous HCNSs directly from raw biomass, in which HCNSs were obtained by just thermal treatment of raw biomass in the presence of polytetrafluoroethylene (PTFE). The as-fabricated HCNSs show combined advantages of uniform and hollow spherical architecture, high surface area, abundant accessible/open micropores and reasonable mesopores, so the HCNS-based electrode delivers high electrochemical capacitance. Hierarchical porous hollow carbon nanospheres (HCNSs) were fabricated directly from raw biomass via a one-step method, in which HCNSs were obtained by thermal treatment of raw biomass in the presence of polytetrafluoroethylene (PTFE). The HCNSs possess coupling merits of uniformly distributed hollow spherical architectures, and high specific surface area, abundant accessible/open micropores and reasonable mesopores, the HCNS-based electrodes deliver high electrochemical capacitance. The formation mechanisms of pores and hollow core-shell structures were explored thoroughly, it is found that the key to the formation of hollow core-shell structure is the onset-pyrolysis temperature difference between raw biomass and PTFE. Moreover, the content of silica had significant effects on the textures of HCNSs, and HCNS with the largest SSA of 1984 m2/g was obtained. Accordingly, a possible mechanism of HCNSs formation was proposed here, where PTFE acted as the pore creation and nucleation agents and raw biomasses were the primary carbon precursors. [ABSTRACT FROM AUTHOR]

Facial expression : G@PE40-MC700 fabricated by low temperature carbonization at 700 °C are shown to be capable work at 4 V in symmetric supercapacitors with high power density and energy density. We report a successful design and synthesis method for developing a graphene/mesoporous carbon (G@PE40-MC700) electrode materials from upcycled waste polyethylene (PE) plastic combined with graphene oxide (GO) and flame retardant by low-temperature carbonization at 700 °C. The G@PE40-MC700 exhibits a high surface area (1175 m2 g−1) and a considerable amount of mesopores (2.30 cm3 g−1), thus improved electrochemical performance in both symmetric and hybrid supercapacitors with wide voltage windows. The hybrid supercapacitor assembled from G@PE40-MC700 as anode and LiMn 2 O 4 as cathode operating at 2.0 V in 0.5 M Li 2 SO 4 was investigated. The hybrid supercapacitor delivers an energy density of 47.8 Wh kg−1 at a power density of 250 W kg−1, as well as high cycling stability of 83.8 % after 5000 cycles. Furthermore, the much higher energy density of 63.3 Wh kg−1 by using G@PE40-MC700 as electrode material was achieved in high-voltage (4.0 V) symmetric supercapacitors using 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF 4) as the electrolyte with enhanced cycling stability of 89.3% after 5000 cycles. The high capacitance and rate capability of G@PE40-MC700 can be attributed to the synergistic effect of graphene and the mesoporous carbon composites. Our work not only offers a sustainable approach to turn waste plastic into valuable carbon materials but also an opportunity for its applications in "gold capacitors." [ABSTRACT FROM AUTHOR]

Although various anode materials have been reported, graphite is still a commercial anode material for lithium-ion batteries. In this study, nitrogen-doped carbon-coating graphite anode material with hollow structure is designed and fabricated through a facile and scalable process. This hollow structure constituted of graphite flakelets with disordered orientation inside can promote the penetration of electrolyte and shorten path of Li+ diffusion. The uniform N-doped carbon coating layer of NHG@C can significantly limit the side reaction between the organic electrolyte and superfine graphite inside and keep the electrode structure stability during charge and discharge. The obtained NHG@C anode material exhibits excellent rate capability in different current densities and displays a high reversible capacity of 304 ​mAh g−1 at a current density of 1A g−1 after 500 cycles. The excellent properties indicate that such a graphite-based anode material has a good prospect in the practical application of LIBs. [Display omitted] • The hollow structure facilitates the penetration of electrolyte. • Carbon coating layer reduces the occurrence of side reactions. • Nitrogen-doped atoms could regulate the electron-donating capability of materials. • The material has an excellent performance at high rate and long-term cycles. [ABSTRACT FROM AUTHOR]