Corrosion news

Noble Metal Clusters Can Enhance Performance of Catalysts and Save Resources

Billions of noble metal catalysts are used worldwide for the production of chemicals, energy generation, or cleaning the air. However, the resources required for this purpose are expensive and their availability is limited. To optimize the use of resources, catalysts based on single metal atoms have been developed. A research team of Karlsruhe Institute of Technology (KIT) demonstrated that noble metal atoms may assemble to form clusters under certain conditions. These clusters are more reactive than the single atoms and, hence, exhaust gases can be much better removed. The results are reported in Nature Catalysis (https://doi.org/10.1038/s41929-020-00508-7).

Fig.: Schematic representation of a noble metal catalyst with inactive single atoms (left) and active clusters (right; noble metal: white; carrier metal: yellow; oxygen: red). (Graphics: Florian Maurer, KIT)

Noble metal catalysts are used for a wide range of reactions. Among others, they are applied in nearly all combustion processes to reduce pollutant emissions. Often, they consist of very small particles of the active component, such as a noble metal, which are applied to a carrier material. These so-called nanoparticles are composed of several thousands of metal atoms. “But only atoms on the outside are active in the reaction, while most atoms remain unused,” explains Professor Jan-Dierk Grunwaldt from KIT's Institute for Chemical Technology and Polymer Chemistry (ITCP). By changing operation conditions, the structure of such a catalyst and, hence, its activity may be changed. “At high temperatures in the exhaust gas system of a car, which are reached during a longer drive on a motorway, for instance, interaction between the noble metal and carrier may lead to the formation of single atoms, i.e. isolated, separate metal atoms on the carrier,” Grunwaldt says. “Such single-atom catalysts might be expected to reach a very high utilization rate of the noble metal components, because all atoms can theoretically participate in the reaction.” Contrary to this expectation, however, the team of Grunwaldt, in cooperation with professors Christof Wöll from the Institute of Functional Interfaces of KIT and Felix Studt from KIT's Institute of Catalysis Research and Technology, has found that these atoms first have to form noble metal clusters under reaction conditions to become active.

The researchers specifically induced the formation of single atoms and examined their structure thoroughly during the reaction. With the help of highly specialized spectroscopy and theoretical calculations, which were used for the first time ever for this class of catalysts, the team succeeded in explaining why platinum atoms frequently have a low activity. “To convert pollutants, they usually have to react with oxygen in the catalyst. For this, both components must be available at the same time and place, which cannot be achieved for isolated platinum atoms, as the oxygen for the required reaction is much too strongly bound to the carrier component – in our case cerium oxide,” says Florian Maurer from ITCP, one of the main authors of the study. “After breaking the platinum-cerium oxide bonds, platinum atoms can move across the carrier surface. In a next step, these platinum atoms form small platinum clusters, on which the reaction takes place much faster than on single atoms.”

29^th Topical Meeting of the International Society of ElectrochemistryEnergy and water: electrochem-istry in securing the sustainable society development

April 18 – 21, 2021, Mikulov (Czech Republic)

As the main conference motto indicates, energy and the environment probably represent the two most important challenges currently facing mankind. At the same time, although they may sound heterogeneous and wide-ranging, these topics are closely interconnected by numerous aspects and they form a unique research and development field. Electrochemistry can make a significant contribution to this important complex topic in a number of unique ways. The main obstacle to the broad application of electrochemical techniques for water treatment technology is the accessibility of an affordable and, preferentially, environmentally neutral source of electrical energy. On other hand, this is closely connected with the availability of energy conversion and storage technology, enabling efficient exploitation of renewable energy sources which are characterised by intermittent supply. In certain cases, pollution treatment can be directly connected with electrical energy production, e.g. in biological fuel cells or in the reverse electrodialysis process using concentrate streams from reverse electroosmosis, among other processes. Electrochemistry also provides unique opportunities for monitoring both the pollution level and the operation of the technologies involved, as well as the development of new, related, and ideally pollution-free technologies. The combination of basic electrochemical research, electrochemical process engineering and environmental protection with renewable energy offers new and efficient approaches to a more sustainable development for the benefit of society.

For more information, please contact: International Society of Electrochemistry, [email protected], www.topical29.ise-online.org –CCE3320

Advances in Corrosion Protection by Organic Coatings

September 5 – 9, 2021, Cambridge (United Kingdom)

For more information, please contact: Stuart Lyon, AkzoNobel Professor of Corrosion Control, University of Manchester, [email protected], www.acpocconference.org –CCE3420

European NDT&CM2021

October 4 – 8, 2021, Prague (Czech Republic)

The 2^nd European NDT & CM Days in Prague will consist of – 11^th workshop NDT in Progress, International conference NDE & CM for Safety, 51^st annual CNDT conference Defektoskopie 2021 and NDT & CM Expo. During these days you can visit four different events at the Cubex centre Prague. It will be an exceptional opportunity to meet people interested in research & development, as well as in practice, standardization and the application of all NDT/NDE, CM and SHM methods with an emphasis on areas of modern Industry.

These “Days” will be one of the most important NDT, CM, SHM and related branches European events in 2021. We hope that the 2^nd European NDT&CM Days 2021 will not only be an opportune time for exchanging research findings but also an occasion for strengthening existing contacts and establishing new ones for all participants. Naturally, seminars, workshops, excursions and other social events will be organized.