Nanocluster discovery will protect precious metals

Date:
August 17, 2021
Source:
University of Nottingham
Summary:
Scientists have created a new type of catalyst that will lead to
new, sustainable ways of making and using molecules and protect
the supply of precious metals.



FULL STORY ========================================================================== Scientists have created a new type of catalyst that will lead to new, sustainable ways of making and using molecules and protect the supply
of precious metals.


==========================================================================
A research team from the University of Nottingham have designed a new
type of catalyst that combines features that are previously thought to
be mutually exclusive and developed a process to fabricate nanoclusters
of metals on a mass scale.

In their new research, published today in Nature Communications, they demonstrate that the behaviour of nanoclusters of palladium do not
conform to the orthodox characteristics that define catalysts as either homogeneous or heterogenous.

Traditionally, catalysts are divided into homogeneous, when catalytic
centres are intimately mixed with reactant molecules, and heterogenous,
where reactions take place on surface of a catalyst. Usually, chemists
must make compromises when choosing one type or another, as homogeneous catalysts are more selective and active, and heterogenous catalysts are
more durable and reusable. However, the nanoclusters of palladium atoms
appear to defy the traditional categories, as demonstrated by studying
their catalytic behaviour in the reaction of cyclopropanation of styrene.

Catalysts enable nearly 80 per cent of industrial chemical processes
that deliver the most vital ingredients of our economy, from materials
(such as polymers) and pharmaceuticals right through to agrochemicals
including fertilisers and crop protection. The high demand for catalysts
means that global supplies of many useful metals, including gold, platinum
and palladium, are become rapidly depleted. The challenge is to utilise each-and-every atom to its maximum potential. Exploitation of metals
in the form of nanoclusters is one of the most powerful strategies for increasing the active surface area available for catalysis. Moreover,
when the dimensions of nanoclusters break through the nanometre scale,
the properties of the metal can change drastically, leading to new
phenomena otherwise inaccessible at the macroscale.

The research team used analytical and imaging techniques to probe the structure, dynamics, and chemical properties of the nanoclusters, to
reveal the inner workings of this unusual catalyst at the atomic level.



==========================================================================
The team's discovery holds the key to unlock full potential of catalysis
in chemistry, leading to new ways of making and using molecules in the
most atom- efficient and energy-resilient ways.

The research was led by Dr Jesum Alves Fernandes, Propulsion Futures
Beacon Nottingham Research Fellow from the School of Chemistry, he said:
"We use the most direct way to make nanoclusters, by simply kicking out
the atoms from bulk metal by a beam of fast ions of argon -- a method
called magnetron sputtering.

Usually, this method is used for making coatings or films, but we tuned it
to produce metal nanoclusters that can be deposited on almost any surface.

Importantly, the nanocluster size can be controlled precisely by
experimental parameters, from single atom to a few nanometres, so that an
array of uniform nanoclusters can be generated on demand within seconds."
Dr Andreas Weilhard, a Green Chemicals Beacon postdoc researcher in
the team added: "Metal clusters surfaces produced by this method are
completely 'naked', and thus highly active and accessible for chemical reactions leading to high catalytic activity." Professor Peter Licence, director of the GSK Carbon Neutral Laboratory at the University of
Nottingham added: "This method of catalyst fabrication is important
not only because it allows the most economical use of rare metals,
but it does it the cleanest way, without any need for solvents or
chemical reagents, thus generating very low levels of waste, which
is an increasingly important factor for green chemical technologies."
The University is set to embark on a large-scale project to expand on
this work with research which will lead to the protection of endangered elements. 'Metal Atoms on Surfaces & Interfaces (MASI) for Sustainable
Future' is funded by the Engineering & Physical Sciences Research Council (EPSRC) and will be launched at four UK universities (Nottingham, Cardiff, Cambridge, Birmingham).

Professor Andrei Khlobystov, principal investigator of MASI, said:
"Our project is set to revolutionise the ways metals are used in a
broad range of technologies, and to break our dependence on critically endangered elements.

Specifically, MASI will make advances in: the reduction of carbon dioxide
(CO2) emissions and its valorisation into useful chemicals; the production
of 'green' ammonia (NH3) as an alternative zero-emission fuel and a new
vector for hydrogen storage; and the provision of more sustainable fuel
cells and electrolyser technologies." Metal nanoclusters are activated
for reactions with molecules, that can be driven by heat, light or
electric potential, while tuneable interactions with support materials
provide durability and reusability of catalysts. In particular, MASI
catalysts will be applied for the activation of hard-to-crack molecules
(e.g. N2, H2 and CO2) in reactions that constitute the backbone of the
chemical industry, such as the Haber-Bosch process.

========================================================================== Story Source: Materials provided by University_of_Nottingham. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Israel Cano, Andreas Weilhard, Carmen Martin, Jose Pinto, Rhys
W. Lodge,
Ana R. Santos, Graham A. Rance, Elina Harriet AAhlgren,
Erlendur Jo'nsson, Jun Yuan, Ziyou Y. Li, Peter Licence, Andrei
N. Khlobystov, Jesum Alves Fernandes. Blurring the boundary between
homogenous and heterogeneous catalysis using palladium nanoclusters
with dynamic surfaces. Nature Communications, 2021; 12 (1) DOI:
10.1038/s41467-021- 25263-6 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210817084631.htm

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