Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Mysterious catalyst explained: How tiny gold particles aid the production of plastic components

Gold/titanium dioxide catalyst in action: At the interface between a gold particle (Au, gold) and the titanium dioxide surface (TiO2, red and light blue), an oxygen molecule (O2, dark blue spheres) is activated by a charge transfer and becomes catalytically active. Thus, methanol (CH3OH) can be efficiently and selectively oxidized to formaldehyde (CH2O); water (H2O) is produced as well. The researchers made the charge transfer visible using vibrational spectroscopy of adsorbed carbon monoxide (CO; middle of the figure): In the presence of oxygen, a new band (CO@Au(delta+)O2(delta-) appears in the spectrum.
Gold/titanium dioxide catalyst in action: At the interface between a gold particle (Au, gold) and the titanium dioxide surface (TiO2, red and light blue), an oxygen molecule (O2, dark blue spheres) is activated by a charge transfer and becomes catalytically active. Thus, methanol (CH3OH) can be efficiently and selectively oxidized to formaldehyde (CH2O); water (H2O) is produced as well. The researchers made the charge transfer visible using vibrational spectroscopy of adsorbed carbon monoxide (CO; middle of the figure): In the presence of oxygen, a new band (CO@Au(delta+)O2(delta-) appears in the spectrum.

Abstract:
From methanol to formaldehyde - this reaction is the starting point for the synthesis of many everyday plastics. Using catalysts made of gold particles, formaldehyde could be produced without the environmentally hazardous waste generated in conventional methods. Just how the mysterious gold catalyst works has been found out by theoretical and experimental researchers at the Ruhr-Universitšt Bochum in a cooperation project. In the international edition of the journal "Angewandte Chemie" they report in detail on what happens on the gold surface during the chemical reaction.

Mysterious catalyst explained: How tiny gold particles aid the production of plastic components

Bochum, Germany | Posted on April 30th, 2013

"Gold should not really be suitable as a catalyst."

"That nanoparticles of gold actually selectively transform methanol into formaldehyde is remarkable", says Prof. Dr. Martin Muhler of the Laboratory of Industrial Chemistry at the RUB. "As a stable precious metal, gold should not really be suitable as a catalyst." However, gold particles of a few nanometres in size, anchored to a titanium dioxide surface, fulfil their purpose. You only need oxygen to set the reaction in motion, and the only waste product is water. How this is achieved is examined by Muhler's team together with the groups of Prof. Dr. Dominik Marx of the Chair of Theoretical Chemistry and Dr. Yuemin Wang of the Department of Physical Chemistry I.

Oxygen binds at the interface between gold and titanium dioxide

The chemists identified the active site of the catalyst, i.e. the point at which the oxygen and methanol bind and are converted to water and formaldehyde. Elaborate calculations by Dr. Matteo Farnesi Camellone showed that oxygen binds at the interface between titanium dioxide and gold particles. Since titanium dioxide is a semiconductor, and thus electrically conductive, a charge exchange between oxygen, gold particles and titanium dioxide is possible here. Oxygen vacancies in the titanium dioxide further favour this charge transfer. Electrons transitionally transfer from the catalyst to the oxygen molecule. This allows the methanol to bind to the gold particles. In several further reaction steps, formaldehyde and water form. The solid, which consists of gold and titanium dioxide, is in the same state at the end of the reaction cycle as at the beginning, and is thus not consumed.

Experiment and theory: only the combination makes it possible

The RUB team clarified the individual reaction steps in detail. The researchers used computer simulations, so-called density functional calculations, and various spectroscopic techniques, namely, vibrational spectroscopy (HREELS method) and thermal desorption spectroscopy. In his model calculations, Dr. Farnesi quantified the charge exchange taking place during catalysis. Extremely sensitive vibrational spectroscopic measurements by Dr. Wang's group confirmed the consequences of the charge transfer in the real system. "Through an intensive cooperation between theory and experiment, we have been able to qualitatively and quantitatively explore the active site and the entire reaction mechanism of this complex catalyst", stresses Prof. Marx.

###

Funding

The study originates from the Collaborative Research Centre 558 "Metal-substrate interactions in heterogeneous catalysis", which ended mid-2012. "The results are, so to speak, the crowning glory of the SFB works on alcohol oxidation", Muhler sums up. The project was further actively funded by the Cluster of Excellence "Ruhr Explores Solvation" RESOLV (EXC 1069), approved by the German Research Foundation (DFG) in 2012, in which researchers investigate the selective oxidation of alcohols in the liquid phase.

Bibliographic record

M. Farnesi Camellone, J. Zhao, L. Jin, Y. Wang, M. Muhler, D. Marx (2013): Molecular understanding of reactivity and selectivity for methanol oxidation at the Au/TiO2 interface, Angewandte Chemie International Edition, DOI: 10.1002/anie.201301868

Editor: Dr. Julia Weiler

####

For more information, please click here

Contacts:
Prof. Dr. Martin Muhler
Laboratory of Industrial Chemistry
Faculty of Chemistry and Biochemistry at the Ruhr-Universitšt
44780 Bochum, Germany
Tel. +49-234-32-28754
E-mail:

Prof. Dr. Dominik Marx
Chair of Theoretical Chemistry
Faculty of Chemistry and Biochemistry at the Ruhr-Universitšt
44780 Bochum, Germany

Copyright © Ruhr-University Bochum

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

Further press releases on this topic:

Related News Press

News and information

Sol-gel capacitor dielectric offers record-high energy storage July 30th, 2015

Controlling Dynamic Behavior of Carbon Nanosheets in Structures Made Possible July 30th, 2015

Newly-Developed Polymers Control Size of Nanoparticles during Production Process July 30th, 2015

Detecting small metallic contaminants in food via magnetization: A practical metallic-contaminant detecting system using three high-Tc RF superconducting quantum interference devices (SQUIDs) July 29th, 2015

Controlling phase changes in solids: Controlling phase changes in solids July 29th, 2015

Chemistry

March 2016; 6th Int'l Conference on Nanostructures in Iran July 29th, 2015

Meet the high-performance single-molecule diode: Major milestone in molecular electronics scored by Berkeley Lab and Columbia University team July 29th, 2015

Discoveries

Sol-gel capacitor dielectric offers record-high energy storage July 30th, 2015

Controlling Dynamic Behavior of Carbon Nanosheets in Structures Made Possible July 30th, 2015

Newly-Developed Polymers Control Size of Nanoparticles during Production Process July 30th, 2015

Non-Enzyme Sensor Determines Level of Blood Sugar July 29th, 2015

Announcements

Sol-gel capacitor dielectric offers record-high energy storage July 30th, 2015

Controlling Dynamic Behavior of Carbon Nanosheets in Structures Made Possible July 30th, 2015

Newly-Developed Polymers Control Size of Nanoparticles during Production Process July 30th, 2015

Detecting small metallic contaminants in food via magnetization: A practical metallic-contaminant detecting system using three high-Tc RF superconducting quantum interference devices (SQUIDs) July 29th, 2015

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

Sol-gel capacitor dielectric offers record-high energy storage July 30th, 2015

Controlling Dynamic Behavior of Carbon Nanosheets in Structures Made Possible July 30th, 2015

Newly-Developed Polymers Control Size of Nanoparticles during Production Process July 30th, 2015

Meet the high-performance single-molecule diode: Major milestone in molecular electronics scored by Berkeley Lab and Columbia University team July 29th, 2015

Environment

March 2016; 6th Int'l Conference on Nanostructures in Iran July 29th, 2015

Laboratorial Performance of Nanocomposite Membrane Improved in Water Purification July 28th, 2015

Nanosorbents Reduce Amount of Heavy Metals in Petrochemical Wastewater July 23rd, 2015

Nanopaper as an optical sensing platform July 23rd, 2015

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project