• Carbon-coated nickel enables fuel cell f

    From ScienceDaily@1:317/3 to All on Thursday, March 24, 2022 22:30:44
    Carbon-coated nickel enables fuel cell free of precious metals

    Date:
    March 24, 2022
    Source:
    Cornell University
    Summary:
    A nitrogen doped carbon-coated nickel anode can catalyze an
    essential reaction in hydrogen fuel cells at a fraction of the
    cost of the precious metals currently used, researchers have found.



    FULL STORY ==========================================================================
    A nitrogen doped carbon-coated nickel anode can catalyze an essential
    reaction in hydrogen fuel cells at a fraction of the cost of the precious metals currently used, Cornell University researchers have found.


    ==========================================================================
    The new discovery could accelerate the widespread use of hydrogen fuel
    cells, which hold great promise as efficient, clean energy sources for
    vehicles and other applications.

    It's one of a string of discoveries for the He'ctor D. Abrun~a lab in
    their ongoing search for active, inexpensive, durable catalysts for use
    in alkaline fuel cells.

    "This finding makes progress toward using efficient, clean hydrogen
    fuel cells in place of fossil fuels," said Abrun~a, professor in the
    department of chemistry and chemical biology at Cornell University.

    The results published March 21 in "A Completely Precious-Metal-Free
    Alkaline Fuel Cell With Enhanced Performance Using a Carbon-Coated Nickel Anode," in the Proceedings of the National Academy of Sciences.

    Expensive precious metals, such as platinum, are currently required in
    hydrogen fuel cells to efficiently catalyze the reactions they employ
    to produce electricity. Although alkaline polymer electrolyte membrane
    fuel cells (APEMFCs) enable the use nonprecious metal electrocatalysts,
    they lack the necessary performance and durability to replace precious metal-based systems.



    ==========================================================================
    A fuel cell produces electricity through the hydrogen oxidation reaction
    (HOR) and an oxygen reduction reaction (OOR). Platinum, in particular, is
    a model catalyst for both reactions because it catalyzes them efficiently,
    and is durable in the acidic environment of a PEM fuel cell, Abrun~a said.

    But what about other materials? Recent experiments with nonprecious-metal
    HOR electrocatalysts needed to overcome two major challenges, the
    researchers wrote: low intrinsic activity from too strong a hydrogen
    binding energy, and poor durability due to rapid passivation from metal
    oxide formation.

    To overcome these challenges, the researchers designed a nickel-based electrocatalyst with a 2 nanometer shell made of nitrogen-doped carbon.

    Their hydrogen fuel cell has an anode (where hydrogen is oxidized)
    catalyst consisting of a solid nickel core surrounded by the carbon
    shell. When paired with a cobalt-manganese cathode (where oxygen is
    reduced), the resulting completely precious-metal-free hydrogen fuel
    cell outputs more than 200 milliwatts per square centimeter.



    ==========================================================================
    The presence of nickel oxide species on the surface of the nickel
    electrode slows the hydrogen oxidation reaction dramatically, Abrun~a
    said. The nitrogen- doped carbon coating serves as a protection layer
    and enhances the HOR kinetics, making the reaction quicker and much
    more efficient.

    In addition, the presence of the graphene coating on the nickel electrode prevents the formation of nickel oxides -- resulting in electrodes with dramatically enhanced lifetimes. These electrodes are also much more
    tolerant to carbon monoxide, which rapidly poisons platinum.

    "The use of this novel anode would dramatically lower prices enabling
    the application of alkaline fuel cells in a wide variety of areas,"
    Abrun~a said.

    In February, Abrun~a and colleagues found that a cobalt nitride catalyst
    is nearly as efficient as platinum in catalyzing the oxygen reduction
    reaction.

    Funding for this research was provided by the Center for Alkaline-Based
    Energy Solutions, an Energy Frontier Research Center funded by the
    U.S. Department of Energy, Office of Science, Basic Energy Sciences,
    and the Zhuang research group at Wuhan University, China, supported by
    the National Natural Science Foundation of China.


    ========================================================================== Story Source: Materials provided by Cornell_University. Original written
    by Kate Blackwood, courtesy of the Cornell Chronicle. Note: Content may
    be edited for style and length.


    ========================================================================== Journal Reference:
    1. Yunfei Gao, Yao Yang, Roberto Schimmenti, Ellen Murray, Hanqing
    Peng,
    Yingming Wang, Chuangxin Ge, Wenyong Jiang, Gongwei Wang, Francis J.

    DiSalvo, David A. Muller, Manos Mavrikakis, Li Xiao, He'ctor
    D. Abrun~a, Lin Zhuang. A completely precious metal-free alkaline
    fuel cell with enhanced performance using a carbon-coated nickel
    anode. Proceedings of the National Academy of Sciences, 2022; 119
    (13) DOI: 10.1073/ pnas.2119883119 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/03/220324184546.htm

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