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  • richardmitnick 5:00 pm on January 16, 2022 Permalink | Reply
    Tags: "A treasure map for the realm of electrocatalysts", , , , , High entropy alloys (HEAs) are chemically complex materials made up of mixtures of five or more elements., , Millions of high-entropy systems are possible and each system involves tens of thousands of different compositions., The Ruhr-Universität Bochum (DE)   

    From The Ruhr-Universität Bochum (DE): “A treasure map for the realm of electrocatalysts” 

    From The Ruhr-Universität Bochum (DE)

    13 January 2022

    By
    Meike Drießen (md)
    Translated by
    Donata Zuber

    1
    A view of the sputtering machine used to produce the material library counters. © Christian Nielinger.

    Research into promising materials is hampered by the sheer number of possible candidates. A German-Danish team has developed an efficient method to solve this problem.

    Efficient electrocatalysts, which are needed for the production of green hydrogen, for example, are hidden in materials composed of five or more elements. A team from Ruhr-Universität Bochum (RUB) and The University of Copenhagen [Københavns Universitet](DK) has developed an efficient method for identifying promising candidates in the myriad of possible materials. To this end, the researchers combined experiments and simulation. They published their report in the journal Advanced Energy Materials from 5 January 2022.

    Millions of systems are conceivable

    High entropy alloys (HEAs) are chemically complex materials made up of mixtures of five or more elements. What’s interesting about them is that they offer completely new possibilities for the development of electrocatalysts. Such catalysts are urgently needed to make energy conversion processes more efficient, for example for the production and use of green hydrogen. “The problem with HEAs is that, in principle, millions of high-entropy systems are possible and each system involves tens of thousands of different compositions,” explains Professor Alfred Ludwig, who heads the Materials Discovery and Interfaces Chair at RUB. It is almost impossible to tackle such complexity using conventional methods and traditional high-throughput procedures.

    Five sources, six constellations

    The researchers describe a new method in their paper that should help to find promising high entropy alloys for electrocatalysis. In the first step, the team developed a way to produce as many potential compositions as possible. For this purpose, they used a sputtering system that simultaneously applies the five base materials to a carrier. “You can imagine this as five spray cans directed at one point on the target,” explains RUB researcher Dr. Lars Banko. This produces a very specific composition of the five source materials on each point of the carrier, so-called materials libraries. Since this composition is also affected by the position of the sources of the source materials, the research team modified them in the experiment. The materials libraries from the manufacturing processes with six different constellations of the sources were subsequently characterized using high-throughput measurements.

    The RUB electrochemistry team then examined the materials libraries in this manner for their electrocatalytic activity.” This enables us to identify trends where possible promising candidates are located,” explains Dr. Olga Krysiak, who with Lars Banko is a lead author of the paper. The team matched this data from the experiment with a large simulation data set provided by the researchers at the University of Copenhagen in order to understand the composition of the materials in greater detail. The comparison between simulation and experiment enables the researchers to explore the atomic scale of electrocatalysts, to estimate the statistical arrangement of atoms on the material surface and to determine their influence on the catalytic activity.

    See the full article here.

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    The Ruhr-Universität Bochum (DE) is a public university located in the southern hills of the central Ruhr area in Bochum. It was founded in 1962 as the first new public university in Germany after World War II. Instruction began in 1965.

    The Ruhr-University Bochum is one of the largest universities in Germany and part of the Deutsche Forschungsgemeinschaft, the most important German research funding organization.

    The RUB was very successful in the Excellence Initiative of the German Federal and State Governments (2007), a competition between Germany’s most prestigious universities. It was one of the few institutions left competing for the title of an “elite university”, but did not succeed in the last round of the competition. There are currently nine universities in Germany that hold this title.

    The University of Bochum was one of the first universities in Germany to introduce international bachelor’s and master’s degrees, which replaced the traditional German Diplom and Magister. Except for a few special cases (for example in Law) these degrees are offered by all faculties of the Ruhr-University. Currently, the university offers a total of 184 different study programs from all academic fields represented at the university.

     
  • richardmitnick 2:51 pm on January 11, 2022 Permalink | Reply
    Tags: "Catalyst surface analysed at atomic resolution", , Atomic Probe Tomography, , , , , , The Ruhr-Universität Bochum (DE)   

    From The Ruhr-Universität Bochum (DE): “Catalyst surface analysed at atomic resolution” 

    From The Ruhr-Universität Bochum (DE)

    1

    Members of the Bochum-based research team in the lab: Weikai Xiang, Chenglong Luan and Tong Li (from left to right) © Privat.

    Catalyst surfaces have rarely been imaged in such detail before. And yet, every single atom can play a decisive role in catalytic activity.

    A German-Chinese research team has visualised the three-dimensional structure of the surface of catalyst nanoparticles at atomic resolution. This structure plays a decisive role in the activity and stability of the particles. The detailed insights were achieved with a combination of atom probe tomography, spectroscopy and electron microscopy. Nanoparticle catalysts can be used, for example, in the production of hydrogen for the chemical industry. To optimise the performance of future catalysts, it is essential to understand how it is affected by the three-dimensional structure.

    Researchers from the Ruhr-Universität Bochum, The University of Duisburg-Essen [Universität Duisburg-Essen](DE) and The MPG Institute for Chemical Energy Conversion [Max-Planck-Institut für chemische Energieumwandlung](DE) cooperated on the project as part of the Collaborative Research Centre “Heterogeneous oxidation catalysis in the liquid phase”.

    At RUB, a team headed by Weikai Xiang and Professor Tong Li from Atomic-scale Characterisation worked together with the Chair of Electrochemistry and Nanoscale Materials and the Chair of Industrial Chemistry. Institutes in Shanghai, China, and Didcot, UK, were also involved. The team presents their findings in the journal Nature Communications, published online on 10 January 2022.

    Particles observed during the catalysis process

    The researchers studied two different types of nanoparticles made of cobalt iron oxide that were around ten nanometres. They analysed the particles during the catalysis of the so-called oxygen evolution reaction. This is a half reaction that occurs during water splitting for hydrogen production: hydrogen can be obtained by splitting water using electrical energy; hydrogen and oxygen are produced in the process. The bottleneck in the development of more efficient production processes is the partial reaction in which oxygen is formed, i.e. the oxygen evolution reaction. This reaction changes the catalyst surface that becomes inactive over time. The structural and compositional changes on the surface play a decisive role in the activity and stability of the electrocatalysts.

    For small nanoparticles with a size around ten nanometres, achieving detailed information about what happens on the catalyst surface during the reaction remains a challenge. Using atom probe tomography, the group successfully visualised the distribution of the different types of atoms in the cobalt iron oxide catalysts in three dimensions. By combining it with other methods, they showed how the structure and composition of the surface changed during the catalysis process – and how this change affected the catalytic performance.

    “Atom probe tomography has enormous potential to provide atomic insights into the compositional changes on the surface of catalyst nanoparticles during important catalytic reactions such as oxygen evolution reaction for hydrogen production or CO2 reduction,” concludes Tong Li.

    See the full article here.

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    The Ruhr-Universität Bochum (DE) is a public university located in the southern hills of the central Ruhr area in Bochum. It was founded in 1962 as the first new public university in Germany after World War II. Instruction began in 1965.

    The Ruhr-University Bochum is one of the largest universities in Germany and part of the Deutsche Forschungsgemeinschaft, the most important German research funding organization.

    The RUB was very successful in the Excellence Initiative of the German Federal and State Governments (2007), a competition between Germany’s most prestigious universities. It was one of the few institutions left competing for the title of an “elite university”, but did not succeed in the last round of the competition. There are currently nine universities in Germany that hold this title.

    The University of Bochum was one of the first universities in Germany to introduce international bachelor’s and master’s degrees, which replaced the traditional German Diplom and Magister. Except for a few special cases (for example in Law) these degrees are offered by all faculties of the Ruhr-University. Currently, the university offers a total of 184 different study programs from all academic fields represented at the university.

     
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