Featured Research

from universities, journals, and other organizations

Artificial photosynthesis: Key intermediate steps in artificial photosynthesis reaction identified

Date:
March 4, 2014
Source:
DOE/Lawrence Berkeley National Laboratory
Summary:
The first direct, temporally resolved observations of intermediate steps in water oxidation using cobalt oxide, an Earth-abundant solid catalyst, revealed kinetic bottlenecks whose elimination would help boost the efficiency of artificial photosynthesis systems.

Nano-sized crystals of cobalt oxide, an Earth-abundant catalyst, have been shown to be able to effectively carry out the critical photosynthetic reaction of splitting water molecules.
Credit: Roy Kaltschmidt

Artificial photosynthesis, in which we emulate the process used by nature to capture energy from the sun and convert it into electrochemical energy, is expected to be a major asset in any sustainable energy portfolio for the future. Artificial photosynthesis offers the promise of producing liquid fuels that are renewable and can be used without exacerbating global climate change. A key to realizing commercial-scale artificial photosynthesis technology is the development of electrocatalysts that can efficiently and economically carry out water oxidation reaction that is critical to the process. Heinz Frei, a chemist with Berkeley Lab's Physical Biosciences Division, has been at the forefront of this research effort. His latest results represent an important step forward.

"The oxidation of water to molecular oxygen is a four-electron process involving multiple steps," Frei says. "We've obtained the first direct, temporally resolved observation of two intermediate steps in water oxidation using an Earth-abundant solid catalyst, cobalt oxide, that allowed us to identify the kinetic bottlenecks. With this knowledge, we can devise and design improvements on the cobalt oxide catalyst and its support environment to partially or completely remove these bottlenecks and improve the efficiency of water oxidation."

In an artificial photosynthetic system, the oxidation of water molecules into oxygen, electrons and protons (hydrogen ions) provides the electrons needed to produce liquid fuels from carbon dioxide and water. This requires a catalyst that is both efficient in its use of solar photons and fast enough to keep up with solar flux in order to avoid wasting those photons. It should also be robust and affordable on a large-scale. Five years ago, a study led by Frei identified cobalt oxide in the form of single crystal nanoparticles as an excellent candidate for meeting the challenge. However, realizing the full catalytic potential of cobalt oxide nanocrystals requires a better understanding of the individual events in the four-electron cycle of water oxidation.

To provide this understanding, Frei, working with Miao Zhang and Moreno de Respinis, used a spectroscopic technique known as rapid-scan Fourier transform infrared (FTIR) spectroscopy.

"Prior to our study, it was not known whether the catalysis, which takes place on the surface of the cobalt oxide crystallites, happens at every cobalt center on the surface at the same speed, or whether a subset of cobalt sites does most of the work while other subsets are slow or merely spectators, Frei says. "Our results show that there is a subset of fast sites where a considerable fraction of the catalysis takes place, and a subset of sites where the catalysis proceeds considerably more slowly. This discovery of these fast and slow sites and the proposed structural difference between two provides the basis for designing cobalt oxide surfaces with higher concentrations of fast sites."

Frei, Zhang and de Respinis have reported their findings in the journal Nature Chemistry in a paper titled "Time-resolved observations of water oxidation intermediates on a cobalt oxide nanoparticle catalyst."

This research was supported by the U.S. Department of Energy'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. Miao Zhang, Moreno de Respinis, Heinz Frei. Time-resolved observations of water oxidation intermediates on a cobalt oxide nanoparticle catalyst. Nature Chemistry, 2014; DOI: 10.1038/nchem.1874

Cite This Page:

DOE/Lawrence Berkeley National Laboratory. "Artificial photosynthesis: Key intermediate steps in artificial photosynthesis reaction identified." ScienceDaily. ScienceDaily, 4 March 2014. <www.sciencedaily.com/releases/2014/03/140304095025.htm>.
DOE/Lawrence Berkeley National Laboratory. (2014, March 4). Artificial photosynthesis: Key intermediate steps in artificial photosynthesis reaction identified. ScienceDaily. Retrieved July 30, 2014 from www.sciencedaily.com/releases/2014/03/140304095025.htm
DOE/Lawrence Berkeley National Laboratory. "Artificial photosynthesis: Key intermediate steps in artificial photosynthesis reaction identified." ScienceDaily. www.sciencedaily.com/releases/2014/03/140304095025.htm (accessed July 30, 2014).

Share This




More Matter & Energy News

Wednesday, July 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Climate Change Could Cost Billions, According To White House

Climate Change Could Cost Billions, According To White House

Newsy (July 29, 2014) A report from the White House warns not curbing greenhouse gas emissions could cost the U.S. billions. Video provided by Newsy
Powered by NewsLook.com
Stranded Whale Watching Boat Returns to Boston

Stranded Whale Watching Boat Returns to Boston

Reuters - US Online Video (July 29, 2014) Passengers stuck overnight on a whale watching boat return safely to Boston. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Baluchistan Mining Eyes an Uncertain Future

Baluchistan Mining Eyes an Uncertain Future

AFP (July 29, 2014) Coal mining is one of the major industries in Baluchistan but a lack of infrastructure and frequent accidents mean that the area has yet to hit its potential. Duration: 01:58 Video provided by AFP
Powered by NewsLook.com
Easier Nuclear Construction Promises Fall Short

Easier Nuclear Construction Promises Fall Short

AP (July 29, 2014) The U.S. nuclear industry started building its first new plants using prefabricated Lego-like blocks meant to save time and prevent the cost overruns that crippled the sector decades ago. So far, it's not working. (July 29) Video provided by AP
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:
from the past week

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