Green hydrogen: Focus on the catalyst surface

Date:
August 24, 2021
Source:
Karlsruher Institut fu"r Technologie (KIT)
Summary:
Hydrogen produced from renewable energy sources with the help of
electric power is deemed a key to the energy transition: It can
be used to chemically store wind and solar energy in a CO2-neutral
way. Researchers have studied water electrolysis processes on the
surface of an iridium oxide catalyst.



FULL STORY ========================================================================== Hydrogen produced from renewable energy sources with the help of electric
power is deemed a key to the energy transition: It can be used to
chemically store wind and solar energy in a CO2-neutral way. Researchers
have studied water electrolysis processes on the surface of an iridium
oxide catalyst.


========================================================================== Using energy from solar modules and wind turbines, water can be split by electrolysis into its constituents hydrogen and oxygen without producing
any dangerous emissions. As the availability of energy from renewable
sources varies when producing green, i.e. CO2-neutral, hydrogen, it is
very important to know the behavior of the catalysts under high loading
and dynamic conditions. "At high currents, strong oxygen bubble evolution
can be observed on the anode, which aggravates measurement. It has made
it impossible so far to obtain a reliable measurement signal," says the
first author of the study, Dr.

Steffen Czioska from KIT's Institute for Chemical Technology and Polymer Chemistry (ITCP). By combining various techniques, the researchers have
now succeeded in fundamentally investigating the surface of the iridium
oxide catalyst under dynamic operation conditions. "For the first time,
we have studied the behavior of the catalyst on the atomic level in spite
of strong bubble evolution," Czioska says. The American Chemical Society
(ACS) considers the importance of KIT's publication to the international community to be high and recommends it as the ACS Editor's Choice.

X-ray Absorption Spectroscopy with Synchrotron Light For catalysis,
researchers from KIT's ITCP, the Institute of Catalysis Research and Technology, and the Electrochemical Technologies Group of the Institute
for Applied Materials combined X-ray absorption spectroscopy for the
highly precise investigation of modifications on the atomic level with
other analysis methods.

"We have observed regular processes on the catalyst surface during
the reaction, because all irregularities were filtered out -- similar
to slow speed shooting on a road at night -- and we have also pursued
dynamic processes," Czioska says. "Our study reveals highly unexpected structural modifications connected to a stabilization of the catalyst
at high voltages under dynamic loading," the chemist adds. Iridium oxide dissolution is reduced, the material remains stable.

Findings Will Contribute to Better and More Efficient Catalysts
Understanding of the processes on the catalyst surface paves the way to
further investigation of catalysts at high electric potentials and will contribute to the development of improved and more efficient catalysts
meeting the needs of the energy transition, Czioska points out. The study
is part of the "Dynakat" priority program funded by the German Research Foundation. This collaboration of more than 30 research groups from all
over Germany is coordinated by Professor Jan-Dierk Grunwaldt from ITCP.

Green hydrogen is deemed an environmentally compatible chemical energy
storage material and, hence, an important element in the decarbonization
of e.g. steel and chemical industries. According to the National
Hydrogen Strategy adopted by the Federal Government in 2020, reliable, affordable, and sustainable production of hydrogen will be the basis
for its future use.

========================================================================== Story Source: Materials provided by
Karlsruher_Institut_fu"r_Technologie_(KIT). Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Steffen Czioska, Alexey Boubnov, Daniel Escalera-Lo'pez, Janis
Geppert,
Alexandra Zagalskaya, Philipp Ro"se, Erisa Sarac,i, Vitaly
Alexandrov, Ulrike Krewer, Serhiy Cherevko, Jan-Dierk
Grunwaldt. Increased Ir-Ir Interaction in Iridium Oxide during
the Oxygen Evolution Reaction at High Potentials Probed by
Operando Spectroscopy. ACS Catalysis, 2021; 11 (15): 10043 DOI:
10.1021/acscatal.1c02074 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210824135333.htm

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