Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Carving out a golden opportunity

04.12.2014

Upsetting the stability of super-small gold clusters generates multifaceted nanocrystals with potent catalytic properties

A*STAR researchers have devised a way to destabilize gold nanoclusters so that they form tiny atomic nuclei that then grow together into perfectly proportioned, 12-sided dodecahedron crystals[1]. These unique polyhedra have energy-rich surfaces that can boost the catalytic efficiency of important chemical reactions and serve as potential adsorption sites for targeted sensor devices.


Extraordinary 12-sided gold nanocrystals can now be synthesized from gold nanoclusters using a destabilization technique based on hydrogen peroxide.

Modified, with permission, from Ref. 1 © 2014 Wiley-VCH

Typically, gold nanoclusters are prepared by chemically reducing a gold–sulfur precursor in the presence of an organic stabilizing agent. This procedure creates a symmetric core of gold atoms protected by a thin layer of surface groups known as thiolates. Researchers have developed many techniques for varying the size of the nanoclusters to tune their chemical and physical properties. But destabilizing gold-thiolate bonds to enable further transformations into polyhedral crystals has proved more challenging.

To tackle this issue, an interdisciplinary team led by Yong-Wei Zhang from the Institute of High Performance Computing and Ming-Yong Han from the Institute of Materials Research and Engineering at A*STAR in Singapore investigated strategies to destabilize gold clusters by oxidizing the surface-protecting thiolates. While promising, this approach has its risks: previous attempts using ozone destabilization agents produced uncontrolled aggregation of gold atoms into macroscopic precipitates.

The researchers examined if switching to a milder hydrogen peroxide destabilization agent would give more favorable results. They first synthesized a solution of 25-atom gold clusters stabilized by outer layers of bovine serum albumin (BSA). When hydrogen peroxide was added to the mixture, the team’s mass spectrometry instruments showed that covalent gold–sulfur bonds slowly ruptured.

This peroxide-based destabilization initially produced smaller 11-atom gold clusters. But after sitting for nearly a week at room temperature, these clusters transformed into remarkable dodecahedron shapes (see image).

High-resolution scanning electron microscopy revealed that every facet on the dodecahedra had identical crystallographic orientations — a rare distribution of gold atoms known as a [110] facet. Density functional theory calculations initiated by co-author Guijian Guan showed that these unusual structures arise when amino acids liberated from BSA during the destabilization reaction attach to the nanoparticles and promote growth in every crystal direction except the [110] orientation.

Guan explains that because [110] facets have the highest surface energies among standard gold facets, they present strong attractive forces to incoming molecules — a phenomenon that improves the catalytic capacity due to a stronger binding affinity to target molecules. “For example, we observed a four-fold enhancement in catalytic ability for our dodecahedra compared to gold nanoparticles during the reduction of 4-nitrophenol to 4-aminophenol,” he notes.

The A*STAR-affiliated researchers contributing to this research are from the Institute of High Performance Computing and the Institute of Materials Research and Engineering. More information about the group’s research can be found on the Engineering Mechanics webpage.

Reference:
[1] Guan, G., Liu, S., Cai, Y., Low, M., Bharathi, M. S. et al. Destabilization of gold clusters for controlled nanosynthesis: From clusters to polyhedra. Advanced Materials 26, 3427–3432 (2014).

A*STAR Research | ResearchSEA
Further information:
http://www.research.a-star.edu.sg/research/7118
http://www.researchsea.com

More articles from Materials Sciences:

nachricht Getting closer to porous, light-responsive materials
26.07.2017 | Kyoto University

nachricht Multitasking monolayers
25.07.2017 | Vanderbilt University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

 
Latest News

CCNY physicists master unexplored electron property

26.07.2017 | Physics and Astronomy

Molecular microscopy illuminates molecular motor motion

26.07.2017 | Life Sciences

Large-Mouthed Fish Was Top Predator After Mass Extinction

26.07.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>