Electrocatalysis under the atomic force microscope

Date:
March 9, 2023
Source:
Helmholtz-Zentrum Berlin fu"r Materialien und Energie
Summary:
A further development in atomic force microscopy now makes
it possible to simultaneously image the height profile of
nanometer-fine structures as well as the electric current and the
frictional force at solid-liquid interfaces. A team has succeeded
in analyzing electrocatalytically active materials and gaining
insights that will help optimize catalysts. The method is also
potentially suitable for studying processes on battery electrodes,
in photocatalysis or on active biomaterials.


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FULL STORY ==========================================================================
A further development in atomic force microscopy now makes it possible to simultaneously image the height profile of nanometre-fine structures as
well as the electric current and the frictional force at solid-liquid interfaces. A team from the Helmholtz-Zentrum Berlin (HZB) and the
Fritz Haber Institute (FHI) of the Max Planck Society has succeeded in analysing electrocatalytically active materials and gaining insights that
will help optimise catalysts. The method is also potentially suitable
for studying processes on battery electrodes, in photocatalysis or on
active biomaterials.


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To manage the energy transition, it will also be important to
rapidly develop cheap and efficient materials that can be used to
split water or CO2 by electrocatalysis. In this process, part of the
electrical energy is stored in the chemical reaction products. The
efficiency of such electrocatalysts depends largely on the nature of
the electrode-electrolyte interfaces, i.e. the interfaces between the
solid electrodes and the typically aqueous electrolyte.

However, spatially resolved physical studies of such solid-liquid
interfaces are still relatively scarce.

More insights with AFM Dr Christopher S. Kley and his team have now
developed a new approach to correlative atomic force microscopy
(AFM). An extremely sharp tip is scanned across the surface and
its height profile is recorded. By attaching the tip to the end of a miniaturised cantilever, the force interactions between the tip and the
sample surface, including frictional forces, can be measured with high sensitivity. In addition, the electrical current flowing through the
mechanical contact can be measured, provided a voltage is applied. "This allowed us to simultaneously determine the electrical conductivity, the mechanical-chemical friction and the morphological properties in situ
(i.e. under the relevant liquid-phase conditions rather than in vacuum
or in air)," emphasises Kley.

Copper-gold electrocatalyst Using this method, the scientists now
studied a nanostructured and bimetallic copper-gold electrocatalyst,
in collaboration with Prof. Beatriz Rolda'n Cuenya from the Fritz-Haber-Institute (FHI). Among others, such materials are used in
the electrocatalytic conversion of CO2 into energy carriers. "We were
able to clearly identify islands of copper oxide with higher electrical resistance, but also grain boundaries and low-conductivity regions in
the hydration layer where the catalyst surface comes into contact with
the aqueous electrolyte," says Dr Martin Munz, first author of the study.

Such results on catalyst-electrolyte interfaces help to optimise them
in a targeted manner. "We can now observe how local electrochemical environments influence charge transfer at the interface," says Kley.

Focus on solid-liquid interfaces "However, our results are also of general interest to energy research, especially for the study of electrochemical conversion processes, which also play a role in battery systems." Insights
into solid-liquid interfaces can also be useful in completely different
areas of research, such as understanding corrosion processes, nanosensor systems, and possibly addressing scientific queries in fluidics and environmental sciences, such as dissolution or deposition processes on
metal surfaces exposed to water.

This work was carried out within the framework of the CatLab project,
where researchers from the HZB and the FHI of the MPG are working
together, to develop thin-film catalysts for the energy transition.

* RELATED_TOPICS
o Matter_&_Energy
# Energy_Technology # Energy_and_Resources #
Fuel_Cells # Nature_of_Water # Spintronics # Graphene #
Materials_Science # Physics
* RELATED_TERMS
o Friction o Battery_electric_vehicle o Ampere o
Potential_energy o Torque o Energy o Propellant o Magnetic_field

========================================================================== Story Source: Materials provided by Helmholtz-Zentrum_Berlin_fu"r_Materialien_und_Energie.

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Martin Munz, Jeffrey Poon, Wiebke Frandsen, Beatriz Roldan Cuenya,
Christopher S. Kley. Nanoscale Electron Transfer Variations
at Electrocatalyst-Electrolyte Interfaces Resolved by in Situ
Conductive Atomic Force Microscopy. Journal of the American Chemical
Society, 2023; 145 (9): 5242 DOI: 10.1021/jacs.2c12617 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/03/230309124941.htm

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