The results of their findings identify a clear trend in the behavior of extended and nanoscale surfaces of platinum-bimetallic alloy. Additionally, the techniques and concepts derived from the research program are expected to make overarching contributions to other areas of science well beyond the focus on electrocatalysis.
The Argonne researchers, Nenad Markovic and Vojislav Stamenkovic, published related results last month in Science and this month in Nature Materials on the behavior of single crystal and polycrystalline platinum alloy surfaces. The researchers discovered that the nanosegregated platinum-nickel alloy surface has unique catalytic properties, opening up important new directions for the development of active and stable practical cathode catalysts in fuel cells.
These scientific accomplishments together provide a solid foundation for the development of hydrogen-powered vehicles, as basic research brings value of society today by helping to lay the foundation for tomorrow's technological breakthroughs. "Understanding catalysis is a grand challenge of nanoscience that is now coming within reach," said George Crabtree, director of Argonne's Materials Science Division. "The systematic work that Voya and Nenad are doing is a major step toward transforming catalysis from an empirical art to a fundamental science."
Their experiments and approach sought to substantially improve and reduce platinum loading as the oxygen-reduction catalyst. The research identified a fundamental relationship in electrocatalytic trends on surfaces between the experimentally determined surface electronic structure (the d -band centre) and activity for the oxygen-reduction reaction. This relationship exhibits "volcano-type" behavior, where the maximum catalytic activity is governed by a balance between adsorption energies of reactive intermediates and surface coverage by spectator (blocking) species.
The electrocatalytic trends established for extended surfaces explain the activity pattern of nanocatalysts and provide a fundamental basis for the enhancement of cathode catalysts. By combining experiments with simulations in the quest for surfaces with desired activity, the researchers developed an advanced concept in nanoscale catalyst engineering.
"In the past, theoretical connections have been suggested between electronic behavior and catalytic activity," explained Markovic. "Our work represents the first time that the connections have been identified experimentally. For us, this development constitutes the beginning of more breakthrough advances in nanocatalysts."
According to Stamenkovic, "Our study demonstrates the potential of new analytical tools for characterizing nanoscale surfaces in order to fine tune their properties in a desired direction. We have identified a cathode surface that is capable of achieving and even exceeding the target for catalytic activity with improved stability. This discovery sets a new bar for catalytic activity of the cathodic reaction in fuel cells."
Through continued research combining nanoscale fabrication, electrochemical characterization and numerical simulation a new generation of multi-metallic systems with engineered nanoscale surfaces is on the horizon. Argonne's Center for Nanoscale Materials, Advanced Photon Source and Electron Microscopy Center will enable some of this research.
"We have got crucial support from Argonne management to set up the new labs and launch research directions, which would establish Argonne as a leading center in basic sciences related to energy conversion." said Stamenkovic.
Their lab includes a custom built three-chamber UHV system equipped with the state-of-the-art surface sensitive tools, including Low Energy Ion Scattering Spectroscopy (LEISS), Auger Electron Spectroscopy (AES), angle resolved X-ray photoemission spectroscopy (XPS with monochromator), ultraviolet photoelectron spectroscopy
(UPS), Low Energy Electron Diffraction (LEED) optics, sputtering guns, thermal evaporators, dual hemispherical analyzers, and chamber with scanning tunneling microscopy (STM) and atomic force microscopy AFM. All three chambers are connected to each other but they can also work as independent chambers, making it possible to transfer samples from one to the other unit in order to get detailed surface characterization or to make desirable surface modification.
"We hope that this research program will lead the nation to more secure energy independence and a cleaner environment for future generations," Markovic said.
Collaborators on the research were Bongjin Mun and Philip Ross at DOE's Lawrence Berkeley National Laboratory, Matthias Arenz and Karl Mayrhofer from Technical University of Munich, Christopher Lucas from the University of Liverpool and Guofeng Wang from the University of South Carolina.
This research was funded by DOE's Office of Basic Energy Sciences and by General Motors. The Nature Materials report is on-line at www.nature.com/nmat/journal/vaop/ncurrent/index.html. The Science paper published in January is online at www.sciencemag.org/content/vol315/issue5811/index.dtl.
The nation's first national laboratory, Argonne National Laboratory conducts basic and applied scientific research across a wide spectrum of disciplines, ranging from high-energy physics to climatology and biotechnology. Since 1990, Argonne has worked with more than 600 companies and numerous federal agencies and other organizations to help advance America's scientific leadership and prepare the nation for the future. Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy's Office of Science.
For more information, please contact Sylvia Carson (630/252-5510 or firstname.lastname@example.org) at Argonne.
Sylvia Carson | EurekAlert!
Two intelligent vehicles are better than one
04.10.2017 | Ecole Polytechnique Fédérale de Lausanne
The Future of Mobility: tomorrow’s ways of getting from A to B
07.09.2017 | Fraunhofer-Institut für Angewandte Informationstechnik FIT
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
It's possible to produce hydrogen to power fuel cells by extracting the gas from seawater, but the electricity required to do it makes the process costly. UCF...
Mercury, our smallest planetary neighbor, has very little to call an atmosphere, but it does have a strange weather pattern: morning micro-meteor showers.
Recent modeling along with previously published results from NASA's MESSENGER spacecraft -- short for Mercury Surface, Space Environment, Geochemistry and...
10.10.2017 | Event News
10.10.2017 | Event News
28.09.2017 | Event News
16.10.2017 | Physics and Astronomy
16.10.2017 | Earth Sciences
16.10.2017 | Physics and Astronomy