Palladium, meet copper: Skoltech researchers use machine learning to improve catalysts

November 17, 2020

Researchers from Skoltech and their colleagues from Germany and the US have studied the properties and behavior of a palladium-copper alloy under changing temperatures and hydrogen concentrations, with highly relevant implications of this research for catalyst design. The paper was published in the Journal of Applied Physics.

Transition metal-alloy materials can have catalytic properties and are widely used in facilitating various chemical reactions such as CO2 hydrogenation, a process that turns carbon dioxide into methanol. Using an alloy of a more expensive reactive element with another one that is cheaper and more inert makes these catalysts highly efficient. One example of such a catalyst would be an alloy of palladium (Pd) and copper (Cu), where isolated atoms of Pd are positioned in the Cu lattice.

Zhong-Kang Han, Debalaya Sarker and Sergey Levchenko of the Skoltech Center for Energy Science and Technology (CEST) and their colleagues modeled the properties of a Pd/Cu alloy, using a machine-learning model to predict the distribution of Pd atoms on a Cu surface as a function of hydrogen partial pressure and temperature. "Only Pd atoms at the surface provide catalytically active sites. Therefore, it is important to know how many of these atoms can be found at the surface at relevant temperatures and hydrogen partial pressures," Levchenko says.

He says that evaluating the energies of many atomic configurations of Pd within the Cu lattice requires a lot of computational resources, so the researchers chose a surrogate cluster expansion model that is easier to handle. "This model allows us to evaluate the energy of millions of configurations in seconds. In this study, we had a system that is more complex than the ones typically studied using cluster expansion: a surface of an alloy where the stability of various atomic configurations is influenced by adsorbates from the gas phase. Therefore, we applied the machine-learning approach based on compressed sensing (a method widely used to compress images) to develop a very accurate and predictive surrogate model," Levchenko notes.

The team found that hydrogen adsorption indeed has a strong effect on the concentration of Pd atoms in the top layer of Cu (111) surface. "While at low hydrogen partial pressures and higher temperatures Pd prefers to stay at the surface, at higher pressures and lower temperatures hydrogen adsorption drives Pd away from the surface," Levchenko explains.

The authors hope that their findings can open the door for designing metal alloys with better catalytic properties by taking into account dynamic changes in the composition and structure of materials at realistic operational conditions.
-end-
Other organizations involved in this research include Humboldt-Universität zu Berlin and the University of Pittsburg.

Skolkovo Institute of Science and Technology (Skoltech)

Related Atoms Articles from Brightsurf:

How to gently caress atoms
It is extremely difficult to study oxygen molecules on the metal oxide surface without altering them.

'Hot and messy' entanglement of 15 trillion atoms
In a study published in Nature Communications, ICFO, HDU and UPV researchers report the production of a giant entangled state that may help medical researchers detect extremely faint magnetic signals from the brain.

Exciting apparatus helps atoms see the light
Researchers in the Light-Matter Interactions for Quantum Technologies Unit at the Okinawa Institute of Science and Technology Graduate University (OIST) have generated Rydberg atoms - unusually large excited atoms - near nanometer-thin optical fibers.

Manipulating atoms to make better superconductors
A new study by University of Illinois at Chicago researchers published in the journal Nature Communications shows that it is possible to manipulate individual atoms so that they begin working in a collective pattern that has the potential to become superconducting at higher temperatures.

Grabbing atoms
In a first for quantum physics, University of Otago researchers have 'held' individual atoms in place and observed previously unseen complex atomic interactions.

Chemists allow boron atoms to migrate
Organic molecules with atoms of the semi-metal boron are important building blocks for synthesis products to produce drugs and agricultural chemicals.

2D materials: arrangement of atoms measured in silicene
Silicene consists of a single layer of silicon atoms. In contrast to the ultra-flat material graphene, which is made of carbon, silicene shows surface irregularities that influence its electronic properties.

Atoms don't like jumping rope
Nanooptical traps are a promising building block for quantum technologies.

2000 atoms in two places at once
The quantum superposition principle has been tested on a scale as never before in a new study by scientists at the University of Vienna.

Single atoms as catalysts
Only the outermost layer of a catalyst can play a role in chemical reactions.

Read More: Atoms News and Atoms Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.