Noble metal-free catalyst system as active as platinum
by Staff Writers
Bochum, Germany (SPX) Oct 24, 2018
The industry has been traditionally deploying platinum alloys as catalysts for oxygen reduction, which is for example essential in fuel cells or metal-air batteries. Expensive and rare, that metal imposes strict restrictions on manufacture.
Researchers at Ruhr-Universitat Bochum (RUB) and Max-Planck-Institut fur Eisenforschung have discovered an alloy made up of five elements that is noble metal-free and as active as platinum. They published their paper in the journal Advanced Energy Materials on october 21, 2018.
The catalytic properties of non-noble elements and their alloys are usually rather poor. To the researchers' surprise, one alloy made up of five almost equally balanced components offer much better properties. This is because of the so-called high entropy effect. It causes multinary alloys to maintain a simple crystal structure.
"Through the interaction of different neighbouring elements, new active centres are formed that present entirely new properties and are therefore no longer bound to the limited properties of the individual elements," explains Tobias Loffler, PhD student at the RUB Chair of Analytical Chemistry - Center for Electrochemical Sciences headed by Professor Wolfgang Schuhmann.
"Our research has demonstrated that this alloy might be relevant for catalysis."
Generating alloy nanoparticle libraries
If the nanoparticles are located in the vicinity of the respective atom source, the percentage of atoms from that source is higher in the respective particle. In the centre of the carrier, all five elements are present in more or less equal quantities. "This combinatorial process enables us to precisely control the composition of the alloy nanoparticles anywhere in the material library," says Alfred Ludwig.
In the process, they identified a system made of up five elements where the high entropy effect results in catalytic activity for an oxygen reduction that is similar to that of platinum. By optimising the composition further, they successfully improved the overall activity.
Far-reaching consequences for electrocatalysis
The researchers are hoping to adapt the properties for any required reactions by taking advantage of the almost infinite number of possible combinations of the elements and modifications of their composition. "Accordingly, the application will not necessarily be limited to oxygen reduction," says Ludwig. The research team has already applied for a patent.
However, as the interplay of the elements is not fully understood, the researchers cannot develop any specific catalysts as yet. "This research project lays the foundation for further studies to gain a better understanding of the process, and it introduces high-entropy alloys made up of multiple elements as a new catalyst category," point out the researchers.
Use of raw materials to double by 2060: OECD
Paris (AFP) Oct 22, 2018
Global use of raw materials is expected to double by 2060, "placing twice the pressure on the environment" than at present, according to an OECD study released on Monday. The study "sees global materials use rising to 167 gigatonnes in 2060 from 90 gigatonnes today," the Organisation for Economic Cooperation and Development, a group of advanced economies, said. It gave increases in population, economic activity and living standards around the world as key reasons for the rise, and underscored th ... read more
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