Featured Research

from universities, journals, and other organizations

Activating and deactivating gold nanoparticle catalysts may lead to longer-lasting hydrogen fuel cells

Date:
August 29, 2012
Source:
The Agency for Science, Technology and Research (A*STAR)
Summary:
The latest advance in imaging technology helps optimize catalysts for use in onboard fuel processing. A*STAR researchers have identified the subtle, atomic-scale structural transformations that can activate and de-activate gold nanoparticle catalysts, a finding that may lead to longer-lasting hydrogen fuel cells.

The latest advance in imaging technology helps optimize catalysts for use in onboard fuel processing. A*STAR researchers have identified the subtle, atomic-scale structural transformations that can activate and de-activate gold nanoparticle catalysts, a finding that may lead to longer-lasting hydrogen fuel cells.

The presence of carbon monoxide (CO) impurities in hydrogen gas (H2) can have a detrimental impact on the performance of fuel cells. Recent studies have shown that gold nanoparticles -- particles less than five nanometers wide -- can catalytically remove CO impurities from H2 under mild temperature and pressure conditions. This breakthrough understanding has helped facilitate the development of fuel-cell vehicles that use 'onboard' fuel processing technology. Unfortunately, gold nanoparticles tend to lose their catalytic activity after a few hours of use -- and scientists need to overcome this problem if gold nanoparticles are to be used.

Ziyi Zhong at the A*STAR Institute of Chemical and Engineering Sciences, Ming Lin at the A*STAR Institute of Materials Research and Engineering and co-workers have identified the subtle, atomic-scale structural transformations that can activate and de-activate gold nanoparticle catalysts, a finding that may lead to longer-lasting hydrogen fuel cells.

The researchers set out to design an improved catalyst for so-called preferential oxidation (PROX) reactions. This approach transforms CO impurities into carbon dioxide (CO2) on a ceramic support containing metal catalysts. Previously, the team found that silica-based supports, called SBA-15, could boost CO removal by selectively absorbing the CO2 by-product. The researchers took advantage of another SBA-15 characteristic -- a mesoporous framework decorated by terminal amine groups -- to engineer a novel PROX catalyst.

First, the team used amine modification to disperse a mixture of gold and copper(II) oxide (CuO) precursors evenly over the SBA-15 support. They then used heating treatment to generate gold and CuO nanoparticles on the SBA-15 support. The numerous pores in SBA-15 and the CuO particles work together to hinder agglomeration of gold nanoparticles -- a major cause of catalyst de-activation.

The team then achieved a near-unprecedented chemical feat: localized structural characterization of their catalyst at atomic scale, using high-resolution transmission electron microscopy (HR-TEM) and three-dimensional electron tomography (see movie below). These imaging techniques revealed that the active catalyst sites -- gold or gold-copper alloy nanoparticles in the immediate vicinity of amorphous and crystalline CuO -- remained stable for up to 13 hours. However, the reducing atmosphere eventually transforms CuO into copper(I) oxide and free copper; the latter of which then alloys with the gold nanoparticles and deactivates them. Fortunately, heating to >300C reversed the alloying process and restored the catalyst's activity.

"People working in catalysis are always curious about the 'local structures' of their materials," says Zhong. "Because the Au-CuO/SBA-15 catalyst is active at room temperature, advanced characterization in our state-of-the-art facilities is possible -- though it takes great patience and requires multidisciplinary collaboration."


Story Source:

The above story is based on materials provided by The Agency for Science, Technology and Research (A*STAR). Note: Materials may be edited for content and length.


Journal Reference:

  1. Xu Li, Stella See Soon Fang, Jaclyn Teo, Yong Lim Foo, Armando Borgna, Ming Lin, Ziyi Zhong. Activation and Deactivation of Au–Cu/SBA-15 Catalyst for Preferential Oxidation of CO in H2-Rich Gas. ACS Catalysis, 2012; 2 (3): 360 DOI: 10.1021/cs200536a

Cite This Page:

The Agency for Science, Technology and Research (A*STAR). "Activating and deactivating gold nanoparticle catalysts may lead to longer-lasting hydrogen fuel cells." ScienceDaily. ScienceDaily, 29 August 2012. <www.sciencedaily.com/releases/2012/08/120829112222.htm>.
The Agency for Science, Technology and Research (A*STAR). (2012, August 29). Activating and deactivating gold nanoparticle catalysts may lead to longer-lasting hydrogen fuel cells. ScienceDaily. Retrieved October 21, 2014 from www.sciencedaily.com/releases/2012/08/120829112222.htm
The Agency for Science, Technology and Research (A*STAR). "Activating and deactivating gold nanoparticle catalysts may lead to longer-lasting hydrogen fuel cells." ScienceDaily. www.sciencedaily.com/releases/2012/08/120829112222.htm (accessed October 21, 2014).

Share This



More Matter & Energy News

Tuesday, October 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Thanks, Marty McFly! Hoverboards Could Be Coming In 2015

Thanks, Marty McFly! Hoverboards Could Be Coming In 2015

Newsy (Oct. 21, 2014) If you've ever watched "Back to the Future Part II" and wanted to get your hands on a hoverboard, well, you might soon be in luck. Video provided by Newsy
Powered by NewsLook.com
Robots to Fly Planes Where Humans Can't

Robots to Fly Planes Where Humans Can't

Reuters - Innovations Video Online (Oct. 21, 2014) Researchers in South Korea are developing a robotic pilot that could potentially replace humans in the cockpit. Unlike drones and autopilot programs which are configured for specific aircraft, the robots' humanoid design will allow it to fly any type of plane with no additional sensors. Ben Gruber reports. Video provided by Reuters
Powered by NewsLook.com
Graphene Paint Offers Rust-Free Future

Graphene Paint Offers Rust-Free Future

Reuters - Innovations Video Online (Oct. 21, 2014) British scientists have developed a prototype graphene paint that can make coatings which are resistant to liquids, gases, and chemicals. The team says the paint could have a variety of uses, from stopping ships rusting to keeping food fresher for longer. Jim Drury reports. Video provided by Reuters
Powered by NewsLook.com
Portable Breathalyzer Gets You Home Safely

Portable Breathalyzer Gets You Home Safely

Buzz60 (Oct. 21, 2014) Breeze, a portable breathalyzer, gets you home safely by instantly showing your blood alcohol content, and with one tap, lets you call an Uber, a cab or a friend from your contact list to pick you up. Sean Dowling (@SeanDowlingTV) has the details. Video provided by Buzz60
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