Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Carving up water

05.07.2010
Single water molecules can now be sliced into different atomic components, thanks to the electronic properties of ultrathin oxide films

In its bulk state, magnesium oxide (MgO) is a chalky white, rather unreactive mineral that is best known as an ingredient in antacid medication. But when this compound is formed into nanoscale films, only a few atoms deep, things begin to change. While bulk MgO is an insulator, ultrathin MgO can transfer small amounts of charge to substances, such as metal catalysts, adsorbed on its surface—giving these films the ability to tune chemical reactivity and unlock new reaction routes.

Now, researchers led by Yousoo Kim and Maki Kawai at the RIKEN Advanced Science Institute in Wako have used MgO films to establish unprecedented control over bond-breaking pathways at the single molecule level. The team reports that water molecules adsorbed onto ultrathin MgO can be selectively split apart using the sharp tip of a scanning tunneling microscope (STM)1.

According to lead author Hyung-Joon Shin, understanding the activity of MgO films required a detailed study with a well-known compound. “The atomic-scale picture of a single water molecule on the MgO surface has been [in] demand for a long time,” says Shin. “And, we expected to see interesting dynamics from the water molecules.”

In their STM experiment, the researchers worked at temperatures close to absolute zero to produce stable images of water molecules adsorbed on ultrathin MgO. By injecting small amounts of tunneling current with the STM tip, they could make the water molecules ‘hop’ laterally around the surface—but only at applied voltages corresponding to the vibrational frequencies of hydrogen–oxygen bonds. Excitations beyond these vibrational thresholds caused a chemical reaction: the water molecules dissociated into a new species, which STM images and theoretical analysis revealed was a hydroxyl group.

Because the energy required to split water on the MgO film was much lower than the hydrogen–oxygen bond energy, the researchers theorized that ultrathin MgO traps tunneling electrons in the molecule—generating a resonance-enhanced vibration that shakes the molecule apart. “The vibrationally induced dissociation of single water molecules has never been observed before,” says Shin.

The team’s experiment yielded a third discovery about the MgO surface. By injecting tunneling electrons at voltages close to the hydrogen–oxygen bond energy, STM images showed that another chemical transformation occurred: this time, water molecules split into atomic oxygen. Having two selectable water dissociation pathways—one vibrational, one electronic—has potent implications for ‘green’ energy research, because water splitting is one of the simplest way to produce clean hydrogen fuel.

The corresponding author for this highlight is based at the Surface and Interface Science Laboratory, RIKEN Advanced Science Institute


Journal information
1. Shin, H.-J., Jung, J., Motobayashi, K., Yanagisawa, S., Morikawa, Y., Kim, Y. & Kawai, M. State-selective dissociation of a single water molecule on an ultrathin MgO film. Nature Materials 9, 442–447 (2010)

gro-pr | Research asia research news
Further information:
http://www.riken.jp
http://www.researchsea.com

More articles from Life Sciences:

nachricht Scientists unlock ability to generate new sensory hair cells
22.02.2017 | Brigham and Women's Hospital

nachricht New insights into the information processing of motor neurons
22.02.2017 | Max Planck Florida Institute for Neuroscience

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Microhotplates for a smart gas sensor

22.02.2017 | Power and Electrical Engineering

Scientists unlock ability to generate new sensory hair cells

22.02.2017 | Life Sciences

Prediction: More gas-giants will be found orbiting Sun-like stars

22.02.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>