Featured Research

from universities, journals, and other organizations

Evolution of a bimetallic nanocatalyst

Date:
June 6, 2014
Source:
DOE/Lawrence Berkeley National Laboratory
Summary:
Atomic-scale snapshots of a bimetallic nanoparticle catalyst in action have provided insights that could help improve the industrial process by which fuels and chemicals are synthesized from natural gas, coal or plant biomass.

TEM image of platinum/cobalt bimetallic nanoparticle catalyst in action shows that during the oxidation reaction, cobalt atoms migrate to the surface of the particle, forming a cobalt oxide epitaxial film, like water on oil.
Credit: Image courtesy of DOE/Lawrence Berkeley National Laboratory

Atomic-scale snapshots of a bimetallic nanoparticle catalyst in action have provided insights that could help improve the industrial process by which fuels and chemicals are synthesized from natural gas, coal or plant biomass. A multi-national lab collaboration led by researchers with the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) has taken the most detailed look ever at the evolution of platinum/cobalt bimetallic nanoparticles during reactions in oxygen and hydrogen gases.

"Using in situ aberration-corrected transmission electron microscopy (TEM), we found that during the oxidation reaction, cobalt atoms migrate to the nanoparticle surface, forming a cobalt oxide epitaxial film, like water on oil," says Haimei Zheng, a staff scientist in Berkeley Lab's Materials Sciences Division who led this study. "During the hydrogen reduction reaction, cobalt atoms migrate back into the bulk, leaving a monolayer of platinum on the surface. This atomic information provides an important reference point for designing and engineering better bimetallic catalysts in the future."

Bimetallic catalysts are drawing considerable attention from the chemical industry these days because in many cases they offer superior performances to their monometallic counterparts. There is also the possibility of tuning their catalytic performances to meet specific needs. A bimetallic catalyst of particular interest entails the pairing of platinum, the gold standard of monometallic catalysts, with cobalt, a lesser catalyst but one that is dramatically cheaper than platinum. The platinum/cobalt catalyst is not only considered a model system for the study of other bimetallic nanocatalysts, it is also an excellent promoter of the widely used Fischer-Tropsch process, in which mixtures of hydrogen and carbon monoxide are converted into long-chain carbons for use as fuels or in low-temperature fuel cells.

"While there have been many studies on platinum/cobalt and other bimetallic catalysts, information on how reactions proceed atomically and what the morphology looks like has been missing," Zheng says. "To acquire this information it was necessary to map the atomic structures in reactive environments in situ, which we did using specially equipped TEMs."

The in situ environmental TEM experiments were carried out at both the Environmental Molecular Sciences Laboratory, which is located at PNNL, and at BNL's Center for Functional Nanomaterials. Ex situ aberration-corrected TEM imaging was done at Berkeley Lab's National Center for Electron Microscopy using TEAM 0.5, the world's most powerful TEM.

"This work is an excellent example of collaborative team-work among multiple institutes," Zheng says. "Having access to such high-end resources and being able to form such close team collaborations strengthens our ability to tackle challenging scientific problems."

The in situ aberration corrected TEM studies of Zheng and her colleagues revealed that because of a size mismatch between the lattices of the cobalt oxide epitaxial film and the platinum surface, the cobalt oxide lattice is compressively strained at the interface to fit on the platinum lattice. As the strain energy relaxes, the cobalt oxide film starts breaking up to form distinct molecular islands on the platinum surface. This reduces the effective reaction surface area per volume and creates catalytic voids, both of which impact overall catalytic performance.

"By taking this segregation of the platinum and cobalt atoms into consideration, the interfacial strain that arises during oxidation can be predicted," Zheng says. "We can then design nanoparticle catalysts to ensure that during reactions the material with higher catalytic performance will be on surface of the nanoparticles."

Zheng adds that the ability to observe atomic scale details of the evolution of the structure of nanoparticles in their reactive environments not only opens the way to a deeper understanding of bimetallic nanoparticle catalysis, it also allows for the study of a wider variety of nanoparticle systems where reaction pathways remain elusive.

This research was supported by the DOE Office of Science. It made use of the resources at the Environmental Molecular Sciences Laboratory, the Center for Functional Nanomaterials, and the National Center for Electron Microscope, user facilities supported by DOE's Office of Science.


Story Source:

The above story is based on materials provided by DOE/Lawrence Berkeley National Laboratory. Note: Materials may be edited for content and length.


Journal Reference:

  1. Huolin L. Xin, Selim Alayoglu, Runzhe Tao, Arda Genc, Chong-Min Wang, Libor Kovarik, Eric A. Stach, Lin-Wang Wang, Miquel Salmeron, Gabor A. Somorjai, Haimei Zheng. Revealing the Atomic Restructuring of Pt–Co Nanoparticles. Nano Letters, 2014; 140519100039000 DOI: 10.1021/nl500553a

Cite This Page:

DOE/Lawrence Berkeley National Laboratory. "Evolution of a bimetallic nanocatalyst." ScienceDaily. ScienceDaily, 6 June 2014. <www.sciencedaily.com/releases/2014/06/140606131457.htm>.
DOE/Lawrence Berkeley National Laboratory. (2014, June 6). Evolution of a bimetallic nanocatalyst. ScienceDaily. Retrieved September 30, 2014 from www.sciencedaily.com/releases/2014/06/140606131457.htm
DOE/Lawrence Berkeley National Laboratory. "Evolution of a bimetallic nanocatalyst." ScienceDaily. www.sciencedaily.com/releases/2014/06/140606131457.htm (accessed September 30, 2014).

Share This



More Matter & Energy News

Tuesday, September 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Do Video Games Trump Brain Training For Cognitive Boosts?

Do Video Games Trump Brain Training For Cognitive Boosts?

Newsy (Sep. 29, 2014) More and more studies are showing positive benefits to playing video games, but the jury is still out on brain training programs. Video provided by Newsy
Powered by NewsLook.com
CERN Celebrates 60 Years of Science

CERN Celebrates 60 Years of Science

Reuters - Business Video Online (Sep. 29, 2014) CERN, the European Organisation for Nuclear Research, celebrates 60 years of bringing nations together through science. As Joanna Partridge reports from inside the famous science centre it's also planning to turn the Large Hadron Collider particle accelerator back on after an upgrade. Video provided by Reuters
Powered by NewsLook.com
This 'Invisibility Cloak' Is Simpler Than Most

This 'Invisibility Cloak' Is Simpler Than Most

Newsy (Sep. 28, 2014) Researchers from the University of Rochester have created a type of invisibility cloak with simple focal lenses. Video provided by Newsy
Powered by NewsLook.com
New Corvette Can Secretly Record Convos And Get You Arrested

New Corvette Can Secretly Record Convos And Get You Arrested

Newsy (Sep. 28, 2014) The 2015 Corvette features valet mode – which allows the owner to secretly record audio and video – but in many states that practice is illegal. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins