{"id":255492,"date":"2021-05-21T14:32:47","date_gmt":"2021-05-21T11:32:47","guid":{"rendered":"https:\/\/en.buradabiliyorum.com\/the-complex-rhythm-of-chemistry\/"},"modified":"2021-05-21T14:32:47","modified_gmt":"2021-05-21T11:32:47","slug":"the-complex-rhythm-of-chemistry","status":"publish","type":"post","link":"https:\/\/buradabiliyorum.com\/en\/the-complex-rhythm-of-chemistry\/","title":{"rendered":"#The complex rhythm of chemistry"},"content":{"rendered":"

“#The complex rhythm of chemistry<\/strong>”<\/p>\n

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\"Nanoparticles:
\n (a) Modern cataylsts constist of nanoparticles; (b) A Rhodium tip as a model for a nanoparticle; (c) Tracing a chemical reaction in real time with a field emission microscope (d) At low temperatures, different facets oscillate in sync (e) At higher temperatures, synchronicity is broken. Credit: Vienna University of Technology<\/a>
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Most commercial chemicals are produced using catalysts. Usually, these catalysts consist of tiny metal nanoparticles that are placed on an oxidic support. Similar to a cut diamond, whose surface consists of facets oriented in different directions, a catalytic nanoparticle also possesses crystallographically different facets\u2014and these facets can have different chemical properties.<\/p>\n


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Until now, these differences have often remained unconsidered in catalysis research because it is very difficult to simultaneously obtain information about the chemical reaction itself and about the surface structure of the catalyst. At TU Wien (Vienna), this has now been achieved by combining different microscopic methods: With the help of field electron microscopy and field ion microscopy, it became possible to visualize the oxidation of hydrogen on a single rhodium nanoparticle in real time at nanometer resolution. This revealed surprising effects that will have to be taken into account in the search for better catalysts in the future. The results have now been presented in the scientific journal Science<\/a><\/i>.<\/p>\n

The rhythm of chemical reactions<\/b><\/p>\n

“In certain chemical reactions, a catalyst can periodically switch back and forth between an active and an inactive state,” says Prof. G\u00fcnther Rupprechter from the Institute of Materials Chemistry at TU Wien. “Self-sustaining chemical oscillations can occur between the two states\u2014the chemist Gerhard Ertl received the Nobel Prize in Chemistry for this discovery in 2007.”<\/p>\n

This is also the case with rhodium nanoparticles, which are used as a catalyst for hydrogen oxidation\u2014the basis of every fuel cell. Under certain conditions, the nanoparticles can oscillate between a state in which oxygen molecules dissociate on the surface of the particle and a state in which hydrogen is bound.<\/p>\n

Incorporated oxygen changes the surface behavior<\/b><\/p>\n

“When a rhodium particle is exposed to an atmosphere of oxygen and hydrogen, the oxygen molecules are split into individual atoms at the rhodium surface. These oxygen atoms can then migrate below the uppermost rhodium layer and accumulate as the subsurface oxygen there,” explains Prof. Yuri Suchorski, the first author of the study.<\/p>\n

Through interaction with hydrogen, these stored oxygen atoms can then be brought out again and react with hydrogen atoms. Then, there is again room for more oxygen atoms inside the rhodium particle and the cycle starts again. “This feedback mechanism controls the frequency of the oscillations,” says Yuri Suchorski.<\/p>\n


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