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Abstract: Activated carbon nanofibers (ACNFs) were firstly fabricated by stabilizing, carbonizing and activating electrospun-derived polyacrylonitrile (PAN) nanofibers. Then the graphite carbon nanofibers (GPNF-1900, GPNF-2400) were achieved by graphitization at 1900°C and 2400°C. The GPNFs and ACNFs were characterized by SEM, FTIR, Raman and nitrogen adsorption at 77K. The adsorption and oxidation of NO at room temperature (30°C) were investigated. The results showed that GPNF with porous graphitic structure can improve dramatically the catalytic oxidation of NO at room temperature. The steady conversion ratio of NO to NO2 over the ACNFs, GPNF-1900 and GPNF-2400 was 11%, 38%, 45%, respectively, which revealed that GPNFs would be promising catalysts in catalytic oxidation of NO at room temperature. [Copyright &y& Elsevier]

Abstract: A novel hierarchical carbon nanotube/bamboo charcoal (CNT/BC) composite material was prepared by growing CNTs onto low-cost bamboo charcoal (BC) with the CVD method. Adsorption of Pb2+ in aqueous solution with a CNT/BC composite was investigated. The results showed that the CNT/BC composite exhibited higher adsorption capacity and faster uptake rate towards aqueous Pb2+ than the pristine BC. The isotherms and kinetics of adsorption can be well described by the Langmuir and pseudo-second-order models, respectively. The CNT/BC composite prepared possesses much better performance for Pb2+ adsorption, higher capacity and rate of adsorption, than other carbon adsorbents, such as activated carbons and CNTs. [Copyright &y& Elsevier]

Abstract: The adsorption of dimethyl sulfide from an aqueous solution by a cost-effective bamboo charcoal from Dendrocalamus was studied in comparison with other carbon adsorbents. The bamboo charcoal exhibited superior adsorption on dimethyl sulfide compared with powdered activated carbons at different adsorbent dosages. The adsorption characteristics of dimethyl sulfide onto bamboo charcoal were investigated under varying experimental conditions such as particle size, contact time, initial concentration and adsorbent dosage. The dimethyl sulfide removal was enhanced from 31 to 63% as the particle size was decreased from 24–40 to >300 mesh for the bamboo charcoal. The removal efficiency increased with increasing the adsorbent dosage from 0.5 to 10mg, and reached 70% removal efficiency at 10mg adsorbed. The adsorption capacity (μg/g) increased with increasing concentration of dimethyl sulfide while the removal efficiency decreased. The adsorption process conforms well to a pseudo-second-order kinetics model. The adsorption of dimethyl sulfide is more appropriately described by the Freundlich isotherm (R 2, 0.9926) than by the Langmuir isotherm (R 2, 0.8685). Bamboo charcoal was characterized by various analytical methods to understand the adsorption mechanism. Bamboo charcoal is abundant in acidic and alcohol functional groups normally not observed in PAC. A distinct difference is that the superior mineral composition of Fe (0.4wt%) and Mn (0.6wt%) was detected in bamboo charcoal—elements not found in PAC. Acidic functional group and specific adsorption sites would be responsible for the strong adsorption of dimethyl sulfide onto bamboo charcoal of Dendrocalamus origin. [Copyright &y& Elsevier]

Abstract: Photoactive TiO2 was homogeneously mounted on PAN-based activated carbon cloths (ACCs) by a process of dip-coating and subsequent annealing in nitrogen atmosphere. The crystallinity of TiO2 and pore structure of hybrids was characterized by XRD and N2 adsorption. The adsorption and photocatalytic activity for TiO2-mounted ACC towards methylene blue (MB) solution was investigated. The results showed that the coating of TiO2 gel resulted in a marked decrease in specific surface area and pore volume from the pristine ACC, which was recovered gradually with increasing treatment temperature. Besides crystallinity of TiO2 can be modified by heat treatment, its pore structure can be postulated by adding different amount of polyethylene glycol (PEG). Both pore structure of hybrids and crystallinity of TiO2 as well as the carbon residue produced by PEG pyrolysis had effects on their adsorptive and photocatalytic performances of TiO2-mounted ACCs. It would be a promising technology to integrate adsorption and photocatalysis for TiO2-mounted ACCs. [Copyright &y& Elsevier]

Supercritical water (SCW) has been employed as an efficient activating agent for the preparation of activated carbon microspheres (P-ACS) with developed mesopores from phenolic-resin. Several processing factors that influenced the activation reaction, including activation temperature, activation duration, supercritical pressure and water flow rate were investigated. Increasing activation temperature and duration lead to larger porosity and higher specific surface area as demonstrated in the samples. Supercritical pressure change has little effect on the activation; however, there are indications that a slight increase in mesoporosity can be obtained when the pressure was raised to 36 MPa or higher. Higher water flow rate slightly enhanced the development of microporosity but had little effect on the mesoporosity. Compared with the traditional steam activation, SCW activation can produce P-ACS with more mesoporosity and higher mechanical strength. [Copyright &y& Elsevier]

The breakthrough of low concentration methyethylketone (MEK) and benzene vapors in beds packed with rayon-based activated carbon fiber (ACF) with different surface areas was investigated. The breakthrough characteristics depend on the properties of the ACF and the vapors, as well as on the adsorption conditions. The results of dynamic adsorption in an ACF bed were consistent with those of equilibrium adsorption by gravimetric methods. The breakthrough adsorption indicates that ACF, with an appropriate surface area, could be utilized in controlling volatile organic compounds (VOCs) in indoor air. [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]

Lithium-ion hybrid capacitors (LICs) are regarded as one of the most promising next generation energy storage devices. Commercial activated carbon materials with low cost and excellent cycling stability are widely used as cathode materials for LICs, however, their low energy density remains a significant challenge for the practical applications of LICs. Herein, Na0.76V6O15 nanobelts (NaVO) were prepared and combined with commercial activated carbon YP50D to form hybrid cathode materials. Credit to the synergism of its capacitive effect and diffusion-controlled faradaic effect, NaVO/C hybrid cathode displays both superior cyclability and enhanced capacity. LICs were assembled with the as-prepared NaVO/C hybrid cathode and artificial graphite anode which was pre-lithiated. Furthermore, 10-NaVO/C//AG LIC delivers a high energy density of 118.9 Wh kg−1 at a power density of 220.6 W kg−1 and retains 43.7 Wh kg−1 even at a high power density of 21,793.0 W kg−1. The LIC can also maintain long-term cycling stability with capacitance retention of approximately 70% after 5000 cycles at 1 A g−1. Accordingly, hybrid cathodes composed of commercial activated carbon and a small amount of high energy battery-type materials are expected to be a candidate for low-cost advanced LICs with both high energy density and power density. [ABSTRACT FROM AUTHOR]

Abstract: Porous carbon was prepared from deoiled asphalt by conventional NaOH activation process and by the combination of nano-sized MgO template method and NaOH activation process. The electrochemical properties used as supercapacitors electrode material were evaluated in 7M KOH aqueous solution. Porous carbon sample obtained by NaOH activation possessed more micropores and higher specific surface area, resulting in a higher specific capacitance of 235Fg−1 at low charge–discharge current of 50mAg−1. For the combination method, the resultant carbons possessed higher capacitance and good capacitance maintaining at high current, with a capacitance of nearly twice as that of the former at current density of 10Ag−1, due to their abundant mesopores. [Copyright &y& Elsevier]

The traditional air cathode in microbial fuel cell (MFC) usually consists of catalyst layer (CL), supporting layer (SL) and conductive gas diffusion layer (GDL), the overall MFC performance is inevitably affected by the additional and expensive adhesives and conductive agents. Here, we developed an integrated air cathode in MFC without any additional SL, GDL or adhesives. The integrated air cathode was self-supporting nitrogen-doped reduced graphene oxide@carbon nanofiber (N-rGO@CNF) hybrid membranes fabricated by electrospinning with subsequent heat-treatment under ammonia atmosphere. The as-fabricated N-rGO@CNFs possessed far superior MFC performance and oxygen reduction reaction (ORR) activity to the pristine nitrogen-doped carbon nanofibers (NCNF) and commercial activated carbon (CAC). The amount of rGO embedded into CNF had prominent influence on their ORR activities and MFC performances. N-5-rGO@CNF had the lowest resistance and the maximal exchange current density, exhibiting desirable oxygen reduction performance via a four-electron pathway. The maximum power density of N-5-rGO@CNF can reach 826 mW m−2 in MFC, which is approximately 9, 2.53 and 1.82 times of pristine NCNF, CAC and Pt/C with values of 91, 327 and 454 mW m−2. The outstanding performance of the integrated air-cathodes originates from the integrality, brevity and hybrid composition of the electrospun nanofiber membrane. The appropriate embedded rGO not only improves the bulk conductivity of the rGO@CNF to promote ion adsorption, but also provides vacancies to accommodate ions, the doped nitrogen atoms facilitate O 2 adsorption and/or subsequent O–O bond breaking, thus improving the electrochemical performance of N-rGO@CNF in MFC. [Display omitted] • An integrated N-rGO@CNF air cathodes with high-efficiency were developed via electrospinning. • The integrated air cathodes showed excellent catalytic performance in Microbial Fuel Cells. • The optimal air cathode (N-5-rGO@CNF) had maximum power density of 20650 mW m−3. • N-5-rGO@CNF exhibited ideal oxygen reduction reaction via a four-electron pathway. [ABSTRACT FROM AUTHOR]

Nitrogen-doped carbon nanofibers (NCNFs) were prepared by activating electrospun carbon nanofibers using NH 3 as activating agent at different temperatures. NCNFs with various contents of nitrogen were used as adsorbents and catalysts for low-concentration NO removal at room temperature. The NO removal efficiency over NCNFs was far above that over porous carbon nanofibers obtained by steam-activation, suggesting that NCNFs are efficient catalysts for low-concentration NO removal at room temperature. A maximum of 64.5% removal efficiency for NO was acquired at NO initial concentration of 20 ppm and 21 vol.% of O 2 at room temperature. [ABSTRACT FROM AUTHOR]

Nitrogen-doped hollow activated carbon nanofibers (HACNFs) have been prepared by the concentric electrospinning and the following NH 3 activation. The as-obtained samples were directly used as supercapacitor electrode without binders and conductive additives. Owing to the unique hollow architecture and high N-doping level (8.2%), the HACNFs exhibit a high specific capacitance of 197 F g −1 at 0.2 A g −1 , which is 1.33 times than that of the solid electrospun nanofibers activated in the same condition. The samples also possess a superior rate capability of 72.1% (143 F g −1 ) at 20 A g −1 and long-term cycling stability with a retention of 98.6% after 1000 cycles at 5 A g −1 in 6 M KOH. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nitrogen-doped carbon nanofibers (NCNFs) were prepared by ammonia activation. • NCNFs possess ultra-thin fibers and large specific surface area of 2369 m2/g. • NCNFs have superior adsorption capacity for 4-chlorophenol and fast rate. • NCNFs adsorption follow Liu isotherm and pseudo-second-order kinetic model. • The mechanism of NCNFs adsorption 4-chlorophenol were proposed. Porous and Ultrafine Nitrogen-doped carbon nanofibers (NCNFs) were successfully obtained from bacterial cellulose (BC) by carbonization/activation in NH 3 /N 2 atmosphere at higher temperatures. Thanks to the ammonia treatment, the as-obtained NCNFs have nanoarchitectures constructed of one-dimensional (1-D) nanofiber with ultrafine fibers, hierarchically porous structures, abundant nitrogen functionalities leading to the basic and hydrophobic surface, which render them as excellent adsorbents for the adsorption removal of organic pollutants from aqueous solutions. Their adsorption performance for low-concentration 4-chlorophenol (4-CP) were investigated systematically under different conditions. In comparison with the carbon nanofibers (CNFs) without ammonia treatment and commercial activated carbon (CAC), NCNFs displayed greatly enhanced adsorption capacity, short equilibrium time and wide pH range. NCNF-1000 prepared at 1000 °C had adsorption capacity of 4-CP up to 604.1 mg/g for the initial low-concentration of 100 mg/L, which was superior to the previously reported adsorbents. Analyses of the equilibrium adsorption and kinetic data revealed that the adsorption process of 4-CP onto NCNFs were fitted well with the Liu isotherm and pseudo-second-order kinetic models. The thermodynamic parameters (ΔH°, ΔS°, ΔG°) for 4-CP adsorption onto NCNFs confirmed that the essence of 4-CP adsorption was exothermic, feasible and spontaneous. The possible adsorption mechanism of 4-CP on NCNFs was proposed. The excellent adsorption performance of NCNFs for 4-CP were mainly ascribed to their maximum effective surface area, short mass transfer path and hydrophobic surface, which resulted from their nanoarchitectures with many exposed, shallow and accessible pores and a great deal of nitrogen functionalities. [ABSTRACT FROM AUTHOR]

Due to its excellent power performance and high cycling stability, activated carbon is widely used as the cathode in Li-ion hybrid capacitors. However, it remains challenging to improve its energy density. In this article, we report a composite cathode material composed of iron vanadate (Fe 5 V 15 O 39 (OH) 9 ·9H 2 O) (FeVO) particles and commercial activated carbon (YP50D), synthesized by a facile wet-chemical approach. The successful combination of the two materials results in the simultaneous action of electric-double-layer capacitive effects and a diffusion-controlled faradaic process during the charging-discharging cycles, enabling improved energy. LIC devices are fabricated using 10-FeVO@C as the cathode and pre-lithiated artificial graphite as the anode. Compared to pure YP50D, the 10-FeVO@C//AG LIC device delivers a much higher energy density of 117.9 W h kg−1 at a power density of 237.6 W kg−1 and retains 27.3 W h kg−1 at 20008.7 W kg−1. A reasonable cycling stability is achieved as well, with a capacitance retention of 70.7% after 1000 cycles. This work proves the great potential of composite cathodes, with the combination of a battery material and activated carbon, for high-performance lithium-ion hybrid capacitors. • FeVO@C composites are synthesized by a facile wet-chemical approach with a high yield. • LIC devices are assembled combining FeVO@C composite cathode and artificial graphite anode. • The energy density, power density and cycle life of hybrid LIC devices were studied. • Composite cathodes show great potential for high-performance hybrid LIC devices. [ABSTRACT FROM AUTHOR]