The Experts below are selected from a list of 56073 Experts worldwide ranked by ideXlab platform
Guozhong Cao - One of the best experts on this subject based on the ideXlab platform.
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phosphorus sulfur co doped Porous Carbon with enhanced specific capacitance for supercapacitor and improved catalytic activity for oxygen reduction reaction
Journal of Power Sources, 2016Co-Authors: Yao Zhou, Stephanie L Candelaria, Qian Liu, Evan Uchaker, Guozhong Cao, Jiacheng Wang, Yongfang ChenAbstract:Abstract Phosphorus (P)/sulfur (S) co-doped Porous Carbon derived from resorcinol and furaldehyde are synthesized through one-step sol-gel processing with the addition of phosphorus pentasulfide as P and S source followed with freeze-drying and pyrolysis in nitrogen. The P/S co-doping strategy facilitates the pore size widening both in micropore and mesopore regions, together with the positive effect on the degree of graphitization of Porous Carbon through elimination of amorphous Carbon through the formation and evaporation of Carbon disulfide. As an electrode for supercapacitor application, P/S co-doped Porous Carbon demonstrates 43.5% improvement on specific capacitance of the single electrode compared to pristine Porous Carbon in organic electrolyte at a current of 0.5 mA due to the P-induced pseudocapacitive reactions. As for electrocatalytic use, promoted electrocatalytic activity and high resistance to crossover effects of oxygen reduction reaction (ORR) in alkaline media are observed after the introduction of P and S into Porous Carbon. After air activation, the specific capacitance of the single electrode of sample PS-pC reaches up to 103.5 F g−1 and an improved oxygen reduction current density.
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Porous Carbon with high capacitance and graphitization through controlled addition and removal of sulfur containing compounds
Nano Energy, 2015Co-Authors: Yao Zhou, Stephanie L Candelaria, Qian Liu, Evan Uchaker, Guozhong CaoAbstract:Abstract Highly Porous Carbon with high degree of graphitization was synthesized through the addition of sulfur containing precursors during the sol–gel processing and subsequent removal of sulfur oxide during activation processes. This Porous Carbon was subjected to activation in air for different periods of time; the sample with 1.5 h air activation demonstrated a specific capacitance of the single electrode of 120.4 F/g in organic electrolyte at a current of 0.5 A. The retention of capacitance was more than 94.0% after 2000 charge–discharge cycles. The effects of controlled air activation on the evolution of Porous structure and an improved degree of graphitization are discussed and used to explain the improved electrochemical properties including both specific capacitance and cyclic stability of the resulting Porous Carbon.
Weikun Wang - One of the best experts on this subject based on the ideXlab platform.
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hierarchical Porous Carbon obtained from animal bone and evaluation in electric double layer capacitors
Carbon, 2011Co-Authors: Wentao Huang, Yaqin Huang, Weikun WangAbstract:Abstract Animal bone, an abundant biomass source and high volume food waste, had been converted into a hierarchical Porous Carbon in a simple two-step sustainable manner to yield a highly textured material. The structures were characterized by nitrogen sorption at 77 K, scanning electron microscopy and X-ray diffraction. The electrochemical measurement in 7 M KOH electrolyte showed that the Porous Carbon had excellent capacitive performances, which can be attributed to the unique hierarchical Porous structure (abundant micropores with the size of 0.5–0.8 and 1–2 nm, mesopores and macropores with the size of 2–10 and 10–100 nm), high surface area ( S BET = 2157 m 2 /g) and high total pore volume ( V t = 2.26 cm 3 /g). Its specific capacitance was 185 F/g at a current density of 0.05 A/g. Of special interest was the fact that the Porous Carbon still maintained 130 F/g even at a high current density of 100 A/g.
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A fish scale based hierarchical lamellar Porous Carbon material obtained using a natural template for high performance electrochemical capacitors
Journal of Materials Chemistry, 2010Co-Authors: Weixin Chen, Yaqin Huang, Hao Zhang, Weikun WangAbstract:A hierarchical lamellar Porous Carbon material was prepared with fish scale using a natural template. Electric double layer capacitors electrodes prepared from this kind of Porous Carbon exhibited exceptional ration ability which demonstrated that fish scale is a promising candidate precursor to prepare low cost but high performance Porous Carbon material.
Wenzhong Shen - One of the best experts on this subject based on the ideXlab platform.
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nitrogen doped asphaltene based Porous Carbon fibers as supercapacitor electrode material with high specific capacitance
Electrochimica Acta, 2020Co-Authors: Fangfang Qin, Zhongya Guo, Jiashi Wang, Wenzhong ShenAbstract:Abstract Porous Carbon fibers with developed micro-mesopore structure, oxygen and nitrogen co-doping were synthesized from asphaltene, and were selected as electrode material for high performance supercapacitor. In three-electrode system, the original Porous Carbon fiber exhibited high specific capacitance of 301 and 482 F/g at 1 A/g in 6 M KOH and 1 M H2SO4, respectively. While the ammoniated Porous Carbon fiber showed good rate capability retention in KOH electrolyte (76.9%, 0.5–50 A/g) and H2SO4 electrolyte (66%, 1–50 A/g). Based on the relationship between the capacity and square-root of discharge time, the diffusion control capacitance of Porous Carbon fibers in H2SO4 electrolyte were significantly higher than that in KOH electrolyte. In two-electrode system (1 M KOH), the samples showed the specific capacitance of 201, 209 and 225 F/g for original, ammoniated and in-situ nitrogen-doped Porous Carbon fiber at 1 A/g and excellent cycling stability with 96.3%, 95.8% and 94.3% capacity retention after 10,000 cycles. The superior capacitance performance of Porous Carbon fibers was resulted from the synergistic effects of high specific surface area with abundant narrow micropores for charge storage, the unique open-framework structure on fibers providing short diffusion path for electrolyte ion and heteroatoms incorporation improving its wettability.
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Asphaltene-Based Porous Carbon Nanosheet as Electrode for Supercapacitor
2018Co-Authors: Fangfang Qin, Xiaodong Tian, Zhongya Guo, Wenzhong ShenAbstract:Asphaltene with high aromaticity derived from coal direct liquefaction residue is a favorable precursor to prepare new Carbon materials because it is easy to polymerize or cross link. Here, asphaltene was used as a Carbon precursor for synthesis of Porous Carbon nanosheets via an in situ sheet-structure-directing agent from urea thermal polymerization. The Porous Carbon nanosheet with controllable thickness and a graphitized-like ribbon structure was obtained after KOH activation. As supercapacitor electrode materials, the as-prepared Porous Carbon nanosheets demonstrated a specific capacitance of 282.9 F/g even at 100 A/g in a three-electrode test and 186.7 F/g at 20 A/g in a two-electrode test. The electrolyte was a KOH aqueous solution in both tests; the specific capacitance of the device retained 89.6% after 10,000 cycles showing a good lifetime and durability. The specific capacitance of the device was 135.4 and 119.1F/g at 1 A/g, respectively, in ionic liquid and organic electrolyte; its highest energy density reached 53.5 Wh/kg (at 159.9 W/kg) and 35.9 Wh/kg (at 134.9 W/kg), respectively. The synergism of high specific surface area to volume ratio developed micromesoPorous structure, graphitized-like conduction paths, resulting in excellent specific capacitance and outstanding cycle life and rate performance capability of the prepared Porous Carbon nanosheets as supercapacitor electrodes
Jianming Jiang - One of the best experts on this subject based on the ideXlab platform.
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microwave absorption enhancement of Porous Carbon fibers compared with Carbon nanofibers
Journal of Physical Chemistry C, 2012Co-Authors: Tianshi Xie, Shenglin Yang, Junhong Jin, Jianming JiangAbstract:Porous Carbon fibers (pores of: 0.1–3 μm in diameter) and Carbon nanofibers (∼100 nm in diameter) were prepared from polyacrylonitrile/polymethyl methacrylate (PAN/PMMA) blend fibers with 70/30 and 30/70 weight ratio, respectively, as precursors. The composites containing 2–6 wt % Porous Carbon fibers or Carbon nanofibers as microwave absorbents were fabricated. The complex permittivity of these composites was measured, and the microwave absorption properties were stimulated based on a model for a single-layer plane wave absorber. We found that composites filled with the Porous Carbon fibers exhibited a much better performance in microwave absorption than those containing the Carbon nanofibers. Composites containing 6 wt % Porous Carbon fibers or Carbon nanofibers showed the lowest reflection loss of −31 dB at 9.7 GHz and −12.2 dB at 10.7 GHz, respectively. The bandwidth with reflection loss below −5 dB covered the whole X band (4.2 GHz) in the former case, whereas it was only 2.6 GHz in the latter case, ...
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microwave absorption enhancement of Porous Carbon fibers compared with Carbon nanofibers
Journal of Physical Chemistry C, 2012Co-Authors: Tianshi Xie, Shenglin Yang, Junhong Jin, Jianming JiangAbstract:Porous Carbon fibers (pores of: 0.1–3 μm in diameter) and Carbon nanofibers (∼100 nm in diameter) were prepared from polyacrylonitrile/polymethyl methacrylate (PAN/PMMA) blend fibers with 70/30 and...
Jing Wang - One of the best experts on this subject based on the ideXlab platform.
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nitrogen doped hierarchically Porous Carbon spheres for low concentration co2 capture
Journal of Energy Chemistry, 2021Co-Authors: Jing Wang, Sisi Fan, Fanan Wang, Zheng Shen, Hongmin Duan, Yanqiang HuangAbstract:Abstract Synthesis of spherical Carbon beads with effective CO2 capture capability is highly desirable for large scale application of CO2 sorption, but remains challenging. Herein, a facile and efficient strategy to prepare nitrogen-doped hierarchically Porous Carbon spheres was developed via co-pyrolyzation of poly(vinylidene chloride) and melamine in alginate gel beads. In this approach, melamine not only serves as the nitrogen precursor, but also acts as a template for the macropores structures. The nitrogen contents in the hierarchically Porous Carbon spheres reach a high level, ranging from 11.8 wt% to 14.7 wt%, as the melamine amount increases. Owing to the enriched nitrogen functionalities and the special hierarchical Porous structure, the Carbon spheres exhibit an outstanding CO2 capture performance, with the dynamic capacity of as much as about 7 wt% and a separation factor about 49 at 25 °C in a gas mixture of CO2/N2 (0.5:99.5, v/v).
