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.
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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.
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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.
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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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