The importance of good neighbors in catalysis

Date:
November 3, 2020
Source:
Chalmers University of Technology
Summary:
Are you affected by your neighbors? So are nanoparticles in
catalysts.

New research reveals how the nearest neighbors determine how well
nanoparticles work in a catalyst.



FULL STORY ==========================================================================
Are you affected by your neighbours? So are nanoparticles in
catalysts. New research from Chalmers University of Technology, Sweden, published in the journals Science Advances and Nature Communications,
reveals how the nearest neighbours determine how well nanoparticles work
in a catalyst.


==========================================================================
"The long-term goal of the research is to be able to identify 'super- particles', to contribute to more efficient catalysts in the future. To
utilise the resources better than today, we also want as many particles
as possible to be actively participating in the catalytic reaction at the
same time," says research leader Christoph Langhammer at the Department
of Physics at Chalmers University of Technology.

Imagine a large group of neighbours gathered together to clean a communal courtyard. They set about their work, each contributing to the group
effort.

The only problem is that not everyone is equally active. While some
work hard and efficiently, others stroll around, chatting and drinking
coffee. If you only looked at the end result, it would be difficult to
know who worked the most, and who simply relaxed. To determine that,
you would need to monitor each person throughout the day. The same
applies to the activity of metallic nanoparticles in a catalyst.

The hunt for more effective catalysts through neighbourly cooperation
Inside a catalyst several particles affect how effective the reactions
are.

Some of the particles in the crowd are effective, while others are
inactive.

But the particles are often hidden within different 'pores', much like
in a sponge, and are therefore difficult to study.

To be able to see what is really happening inside a catalyst pore, the researchers from Chalmers University of Technology isolated a handful
of copper particles in a transparent glass nanotube. When several are
gathered together in the small gas-filled pipe, it becomes possible to
study which particles do what, and when, in real conditions.

What happens in the tube is that the particles come into contact with
an inflowing gas mixture of oxygen and carbon monoxide. When these
substances react with each other on the surface of the copper particles,
carbon dioxide is formed. It is the same reaction that happens when
exhaust gases are purified in a car's catalytic converter, except there particles of platinum, palladium and rhodium are often used to break
down toxic carbon monoxide, instead of copper.

But these metals are expensive and scarce, so researchers are looking
for more resource-efficient alternatives.

"Copper can be an interesting candidate for oxidising carbon monoxide. The challenge is that copper has a tendency to change itself during the
reaction, and we need to be able to measure what oxidation state a
copper particle has when it is most active inside the catalyst. With
our nanoreactor, which mimics a pore inside a real catalyst, this will
now be possible," says David Albinsson, Postdoctoral researcher at the Department of Physics at Chalmers and first author of two scientific
articles recently published in Science Advances and Nature Communications.

Anyone who has seen an old copper rooftop or statue will recognise how
the reddish-brown metal soon turns green after contact with the air
and pollutants.

A similar thing happens with the copper particles in the catalysts. It
is therefore important to get them to work together in an effective way.

"What we have shown now is that the oxidation state of a particle can be dynamically affected by its nearest neighbours during the reaction. The
hope therefore is that eventually we can save resources with the help
of optimised neighbourly cooperation in a catalyst," says Christoph
Langhammer, Professor at the Department of Physics at Chalmers.


========================================================================== Story Source: Materials provided by
Chalmers_University_of_Technology. Original written by Mia Hallero"d
Palmgren and Joshua Worth. Note: Content may be edited for style and
length.


========================================================================== Journal Reference:
1. David Albinsson, Astrid Boje, Sara Nilsson, Christopher Tiburski,
Anders
Hellman, Henrik Stro"m, Christoph Langhammer. Copper catalysis at
operando conditions--bridging the gap between single nanoparticle
probing and catalyst-bed-averaging. Nature Communications, 2020;
11 (1) DOI: 10.1038/s41467-020-18623-1 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/11/201103075524.htm

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