Nanoparticles on nanosteps

February 29, 2016
Nanoparticles. Credit: SISSA/CNR-IOM

New technologies are starved for efficient and inexpensive catalysts. The best materials are made up of nanoparticles, whose properties are the result of their small size. The single catalyst particles have, however, an ugly tendency to cluster into larger particles, thereby reducing their effectiveness. A group of scientists from the International School of Advanced Studies in Trieste and the DEMOCRITOS centre of the Istituto Officina dei Materiali of the Italian National Research Council (IOM-CNR), with the collaboration of other institutions, have developed a material that maintains the stability of a "dispersed" catalyst, thus maximising the efficiency of the process and decreasing costs and wastage. The study has just been published in Nature Communications.

Platinum is one of the costly metals used as catalysts in new technologies employed for industrial chemical processes, , pollution control and many other purposes. In particular, it is used for fuel cells, devices that turn chemical energy directly into electrical energy, without combustion. Research has shown that the greatest efficiency is achieved when the catalyst is available in the form of nanoparticles (smaller than 10-9 m). Simply put, the greater the dispersion of the material and the smaller the size of the , the more is it available for catalysis. Unfortunately, the laws of thermodynamics cause the particles to "stick" to one another and form larger clusters, which is why the material becomes less effective over time. So what can be done to maintain maximal dispersion of the "nanopowder"?

A group of SISSA/CNR IOM scientists (with the collaboration of the Univerzita Karlova in Prague) has studied a way to produce tiny platinum grains consisting of one atom only and to keep them dispersed in a stable manner, by exploiting the properties of the substrate on which they rest.

"Theoretical work demonstrated that irregularities in the surface known as steps and observed in experiments conducted at the Trieste Synchrotron tend to attract and separate the nanoparticles, causing them to remain literally attached in the form of single atoms", explains Stefano Fabris, CNR-IOM/SISSA research fellow.

"The particles adhering to the steps were no longer visible even using an atomic resolution microscope" explains Nguyen-Dung Tran, a SISSA PhD student. "However, their presence was detected by spectroscopy, so they were indeed there, but they were no longer visible or free to move around". "Our computer simulations solved this dilemma, showing that the particles on the steps are reduced to single atoms" adds Matteo Farnesi Camellone (CNR-IOM), another author of the study.

"If the surface is engineered to contain a large number of these defects, then the force that binds the particles to the substrate effectively offsets the aggregation force", explains Fabris. The theoretical work, led by Fabris, allowed the researchers to develop a "system model" on the computer able predict the behaviour of the material. The model's predictions were confirmed by the experimental measurements. Materials like this can be used for fuel cell electrodes, with far lower costs than the current ones.

"Reducing the amount of platinum used in fuel cell electrodes is a priority, not only to contain costs but also to ensure environmental sustainability, as also indicated by the recent European directives" concludes Fabris. The European project ChipCAT, which funded this research, aims precisely to achieve this goal.

Explore further: Catalysts that produce 'green' fuel

More information: Filip Dvořák et al. Creating single-atom Pt-ceria catalysts by surface step decoration, Nature Communications (2016). DOI: 10.1038/ncomms10801

Related Stories

Catalysts that produce 'green' fuel

March 12, 2013

At the International School for Advanced Studies of Trieste, researchers are studying a way to economically produce a molecule that imitates (and improves) the photosynthesis of plants. It will be used to create solar cells ...

Varying the sliding properties of atoms on a surface

June 22, 2015

It's possible to vary (even dramatically) the sliding properties of atoms on a surface by changing the size and "compression" of their aggregates: an experimental and theoretical study conducted with the collaboration of ...

Platinum and iron oxide working together get the job done

September 16, 2015

Scientists at the Vienna University of Technology (TU Wien) have figured out how a platinum catalyst works. Its remarkable properties are not just due to the platinum, the iron-oxide substrate beneath also plays a role.

Cobalt atoms on graphene a powerful combo

October 21, 2015

Graphene doped with nitrogen and augmented with cobalt atoms has proven to be an effective, durable catalyst for the production of hydrogen from water, according to scientists at Rice University.

Recommended for you

New method developed for producing some metals

August 25, 2016

The MIT researchers were trying to develop a new battery, but it didn't work out that way. Instead, thanks to an unexpected finding in their lab tests, what they discovered was a whole new way of producing the metal antimony—and ...

Force triggers gene expression by stretching chromatin

August 26, 2016

How genes in our DNA are expressed into traits within a cell is a complicated mystery with many players, the main suspects being chemical. However, a new study by University of Illinois researchers and collaborators in China ...

New electrical energy storage material shows its power

August 24, 2016

A powerful new material developed by Northwestern University chemist William Dichtel and his research team could one day speed up the charging process of electric cars and help increase their driving range.

Bio-inspired tire design: Where the rubber meets the road

August 24, 2016

The fascination with the ability of geckos to scamper up smooth walls and hang upside down from improbable surfaces has entranced scientists at least as far back as Aristotle, who noted the reptile's remarkable feats in his ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.