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Zhenyu Yang - One of the best experts on this subject based on the ideXlab platform.

  • manganese monoxide biomass inherited porous Carbon Nanostructure composite based on the high water absorbent agaric for asymmetric supercapacitor
    ACS Sustainable Chemistry & Engineering, 2019
    Co-Authors: Hai Zhang, Ze Zhang, Jianxin Cai, Zhenyu Yang
    Abstract:

    Biomass-inherited metal oxide/Carbon composites have been utilized as competitive materials of supercapacitor electrodes owing to the hierarchical structures, fast regeneration rate, and easy synth...

  • Manganese Monoxide/Biomass-Inherited Porous Carbon Nanostructure Composite Based on the High Water-Absorbent Agaric for Asymmetric Supercapacitor
    2019
    Co-Authors: Hai Zhang, Ze Zhang, Jianxin Cai, Zhenyu Yang
    Abstract:

    Biomass-inherited metal oxide/Carbon composites have been utilized as competitive materials of supercapacitor electrodes owing to the hierarchical structures, fast regeneration rate, and easy synthesis. However, the low content and agglomeration of metal oxides are the contradictory issues to be addressed for their practical applications. In this work, manganese monoxide/biomass-inherited porous Carbon (MnO/BPC) Nanostructure composites with high MnO content (∼75%) and uniform distribution have been prepared through a simple immersion-calcination process by high water-absorbent agaric. The superhigh Mn2+ solution absorption of agaric ensures the high MnO content in MnO/BPC composite, and the abundant internal chitin with hydrogel and hot-melting property enables the uniform dispersion of MnO in Carbon matrix. The Carbon Nanostructure endows the composite with high specific surface area, efficient electron/ion transportation, and better electrolyte wettability. As expected, the MnO/BPC composite materials realizes high capacitance of ∼735 mF cm–2 (∼637 F g–1) at 3 mA cm–2, good rate performance (∼608 mF cm–2 at 10 mA cm–2), and excellent cycling performance (capacity retention of ∼91% at 10 mA cm–2, 5000 cycles). In addition, this work presents a facile and productive strategy to obtain metal-based composites with high metal-oxide content and homogeneous distribution by adopting the edible and worldwide abundant agaric

Kyungwon Park - One of the best experts on this subject based on the ideXlab platform.

  • enhanced oxygen reduction reaction of pt deposited fe n doped bimodal porous Carbon Nanostructure catalysts
    Journal of Catalysis, 2018
    Co-Authors: Jinyoung Park, Dahee Kwak, Sangbeom Han, Geun Seok Chai, Sangkyung Kim, Donghyun Peck, Changsoo Kim, Anthony Kucernak, Kyungwon Park
    Abstract:

    Abstract For commercialization of proton exchange membrane fuel cells (PEMFCs), the loading amount of Pt-based cathode catalysts for oxygen reduction reaction (ORR) needs be significantly reduced. In this study, we propose Pt catalysts supported by an iron/nitrogen-doped porous Carbon (FeNC) Nanostructure having a catalytic activity for ORR in order to significantly reduce the utilization of Pt. The FeNC Nanostructure was prepared using a template method with 50 and 500 nm SiO2 beads and phthalocyanine as a dopant and Carbon source. The nanosized Pt catalysts with different loading weights (5, 10, 20, 30 wt%) were uniformly deposited on the FeNC with a bimodal porous crystalline doped Carbon Nanostructure using an electron beam radiation method. In particular, the cathode catalyst having 5 wt% Pt on FeNC (Pt5/FeNC) exhibited enhanced ORR mass activities of 2.19 and 2.58 A mgPt−1 at 0.9 V measured by electrochemical half cells in acidic and alkaline media, respectively, compared to a commercial Pt(20 wt%)/C (Pt20/C). Furthermore, Pt5/FeNC showed a higher mass activity of 18.76 A mgPt−1 at 0.6 V as a unit cell performance than that of the commercial catalyst. The improved ORR activity of Pt/FeNC might be synergistically attributed to the homogeneous dispersion of Pt nanoparticles on the bimodal porous doped Carbon Nanostructure, the interaction (electronic effect) between the metallic catalyst and the doped support, and the dual catalytic effect of both Pt and the doped Carbon Nanostructure.

  • fe n s doped mesoporous Carbon Nanostructures as electrocatalysts for oxygen reduction reaction in acid medium
    Applied Catalysis B-environmental, 2017
    Co-Authors: Dahee Kwak, Sangbeom Han, Youngwoo Lee, Hyunsuk Park, Inae Choi, Mincheol Kim, Sijin Kim, Dohyoung Kim, Junginn Sohn, Kyungwon Park
    Abstract:

    Abstract Many alternatives to typical Pt-based catalysts have been developed to enhance oxygen reduction reaction (ORR) performance in acid medium due to their scarcity and high activation loss during the ORR. We synthesized mesoporous Carbon Nanostructures with multi-dopants such as iron, nitrogen, and sulfur as a cathode catalyst using the ordered silica templates and porphyrinic iron. The co-doped mesoporous Carbon cathode catalysts exhibited a high ORR performance in an acid medium, i.e. complete ORR process and improved durability. The enhanced ORR properties of the catalysts might be ascribed to iron-containing catalytic active sites surrounded by nitrogen/sulfur species and a well-defined mesoporous Carbon Nanostructure.

  • in situ synthesis and characterization of ge embedded electrospun Carbon Nanostructures as high performance anode material for lithium ion batteries
    ACS Applied Materials & Interfaces, 2016
    Co-Authors: Youngwoo Lee, Mincheol Kim, Sijin Kim, Junginn Sohn, Dami Kim, Huiseon Choe, Kyuho Lee, Seungnam Cha, Jong Min Kim, Kyungwon Park
    Abstract:

    While active materials based on germanium (Ge) are considered as a promising alternative anodic electrode due to their relatively high reversible capacity and excellent lithium-ion diffusivity, the quite unstable structural/electrochemical stability and severe volume expansion or pulverization problems of Ge electrodes remain a considerable challenge in lithium ion batteries (LIBs). Here, we present the development of Ge embedded in one-dimensional Carbon Nanostructures (Ge/CNs) synthesized by the modified in situ electrospinning technique using a mixed electrospun solution consisting of a Ge precursor as an active material source and polyacrylonitrile (PAN) as a Carbon source. The as-prepared Ge/CNs exhibit superior lithium ion behavior properties, i.e., highly reversible specific capacity, rate performance, Li ion diffusion coefficient, and superior cyclic stability (capacity retention: 85% at 200 mA g(-1)) during Li alloying/dealloying processes. These properties are due to the high electrical conductivity and unique structures containing well-embedded Ge nanoparticles (NPs) and a one-dimensional Carbon Nanostructure as a buffer medium, which is related to the volume expansion of Ge NPs. Thus, it is expected that the Ge/CNs can be utilized as a promising alternative anodic material in LIBs.

Yi Zhao - One of the best experts on this subject based on the ideXlab platform.

Gabor Csanyi - One of the best experts on this subject based on the ideXlab platform.

  • growth mechanism and origin of high sp3 content in tetrahedral amorphous Carbon
    Physical Review Letters, 2018
    Co-Authors: Miguel A Caro, Jari Koskinen, Tomi Laurila, Volker L Deringer, Gabor Csanyi
    Abstract:

    We study the deposition of tetrahedral amorphous Carbon (ta-C) films from molecular dynamics simulations based on a machine-learned interatomic potential trained from density-functional theory data. For the first time, the high sp^{3} fractions in excess of 85% observed experimentally are reproduced by means of computational simulation, and the deposition energy dependence of the film's characteristics is also accurately described. High confidence in the potential and direct access to the atomic interactions allow us to infer the microscopic growth mechanism in this material. While the widespread view is that ta-C grows by "subplantation," we show that the so-called "peening" model is actually the dominant mechanism responsible for the high sp^{3} content. We show that pressure waves lead to bond rearrangement away from the impact site of the incident ion, and high sp^{3} fractions arise from a delicate balance of transitions between three- and fourfold coordinated Carbon atoms. These results open the door for a microscopic understanding of Carbon Nanostructure formation with an unprecedented level of predictive power.

  • growth mechanism and origin of high sp 3 content in tetrahedral amorphous Carbon
    Physical Review Letters, 2018
    Co-Authors: Miguel A Caro, Jari Koskinen, Tomi Laurila, Volker L Deringer, Gabor Csanyi
    Abstract:

    We study the deposition of tetrahedral amorphous Carbon (ta-C) films from molecular dynamics simulations based on a machine-learned interatomic potential trained from density-functional theory data. For the first time, the high sp^{3} fractions in excess of 85% observed experimentally are reproduced by means of computational simulation, and the deposition energy dependence of the film's characteristics is also accurately described. High confidence in the potential and direct access to the atomic interactions allow us to infer the microscopic growth mechanism in this material. While the widespread view is that ta-C grows by "subplantation," we show that the so-called "peening" model is actually the dominant mechanism responsible for the high sp^{3} content. We show that pressure waves lead to bond rearrangement away from the impact site of the incident ion, and high sp^{3} fractions arise from a delicate balance of transitions between three- and fourfold coordinated Carbon atoms. These results open the door for a microscopic understanding of Carbon Nanostructure formation with an unprecedented level of predictive power.

Lunhui Guan - One of the best experts on this subject based on the ideXlab platform.