Oregon State University research into the design of catalysts has shown that
hydrogen can be cleanly produced with much greater efficiency and at a lower
cost than is possible with current commercially available catalysts.
A catalyst is a substance that increases the rate of a chemical reaction
without itself undergoing any permanent chemical change.
The findings are significant because the production of hydrogen is important
for “many aspects of our life, such as fuel cells for cars and the
manufacture of many useful chemicals such as ammonia,” said the OSU College
of Engineering’s Zhenxing Feng, a chemical engineering professor who led the
research. “It’s also used in the refining of metals, for producing man-made
materials such as plastics and for a range of other purposes.”
Producing hydrogen by splitting water via an electrochemical catalytic
process is cleaner and more sustainable than the conventional method of
deriving hydrogen from natural gas via a carbon-dioxide-producing process
known as methane-steam reforming, Feng said. But the cost of the greener
technique has been a barrier in the marketplace.
The new findings, which describe ways to design catalysts that can greatly
improve the efficiency of the clean hydrogen production process, were
published in Science Advances and JACS Au.
In facilitating reaction processes, catalysts often experience structural
changes, Feng said. Sometimes the changes are reversible, other times
irreversible, and irreversible restructuring is believed to degrade a
catalyst’s stability, leading to a loss of catalytic activity that lowers
reaction efficiency.
Feng, OSU Ph.D. student Maoyu Wang and collaborators studied the
restructuring of catalysts in reaction and then manipulated their surface
structure and composition at the atomic scale to achieve a highly efficient
catalytic process for producing hydrogen.
An active phase of a catalyst based on amorphous iridium hydroxide exhibited
efficiency 150 times that of its original perovskite structure and close to
three orders of magnitude better than the common commercial catalyst,
iridium oxide.
“We found at least two groups of materials that undergo irreversible changes
that turned out to be significantly better catalysts for hydrogen
production,” Feng said. “This can help us produce hydrogen at $2 per
kilogram and eventually $1 per kilogram. That’s less expensive than the
polluting process in current industries and will help achieve the United
States’ goal of zero emissions by 2030.”
Feng notes that the U.S. Department of Energy Hydrogen and Fuel Cell
Technologies Office has established benchmarks of technologies that can
produce clean hydrogen at $2 per kilogram by 2025 and $1 per kilogram by
2030 as part of the Hydrogen Energy Earthshot target of cutting the cost of
clean hydrogen by 80%, from $5 to $1 per kilogram, in one decade.
The water electrolysis technology for clean hydrogen production that Feng’s
group is focused on uses electricity from renewable sources to split water
to make clean hydrogen. However, the efficiency of water splitting is low,
he said, mainly due to the high overpotential - the difference between the
actual potential and the theoretical potential of an electrochemical
reaction - of one key half-reaction in the process, the oxygen evolution
reaction or OER.
“Catalysts are critical to promoting the water-splitting reaction by
lowering the overpotential, and thus lowering the total cost for hydrogen
production,” Feng said. “Our first study in JACS Au laid the foundation for
us, and as demonstrated in our Science Advances article we now can better
manipulate atoms on surface to design catalysts with the desired structure
and composition.”
References:
“Lattice site-dependent metal leaching in perovskites toward a
honeycomb-like water oxidation catalyst” by Yubo Chen, Yuanmiao Sun, Maoyu
Wang, Jingxian Wang, Haiyan Li, Shibo Xi, Chao Wei, Pinxian Xi, George E.
Sterbinsky, John W. Freeland, Adrian C. Fisher, Joel W. Ager, Zhenxing Feng
and Zhichuan J. Xu, 10 December 2021, Science Advances.
DOI: 10.1126/sciadv.abk1788
“The Restructuring-Induced CoOx Catalyst for Electrochemical Water
Splitting” by Maoyu Wang, Qingbo Wa, Xiaowan Bai, Zuyun He, Widitha S.
Samarakoon, Qing Ma, Yingge Du, Yan Chen, Hua Zhou, Yuanyue Liu, Xinwei Wang
and Zhenxing Feng, 2 November 2021, JACS Au.
DOI: 10.1021/jacsau.1c00346
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Chemistry