Tens of thousands of feasible catalysts on the diameter of a hair

A complete five-element material system on a single carrier

For the production of material libraries of so-called high entropy alloys, the Bochum researchers employ a sputtering process. In this process, all of the starting materials are simultaneously applied to a carrier from different directions. The starting materials are deposited in different mixing ratios on each part of the carrier. “In the current project, we’ve refined this process by using pinholes in such a way that each material mixture is only deposited in a tiny spot of about 100 micrometres in diameter on the carrier,” describes Alfred Ludwig. This is roughly equivalent to the diameter of a human hair. “By miniaturising the material libraries, we are now able to accommodate a complete five-component system on a single carrier – this constitutes immense progress,” adds Dr. Lars Banko from the MDI Department, who recently became head of the EXIST-funded start-up project xemX.

Research with hanging drops

To study the materials created with this technique, the researchers use what is known as scanning electrochemical cell microscopy (SECCM). This involves measuring the electrochemical properties of the material at a specific point via a hanging nanodroplet of an electrolyte measuring one thousandth the diameter of a hair. “This means we can use high-throughput methods to pinpoint the candidates with the highest catalytic activity, where a more detailed analysis seems worthwhile,” says Professor Wolfgang Schuhmann, head of the Department of Analytical Chemistry at Ruhr University Bochum.

Using these methods, the researchers are hoping to efficiently search through the plethora of possible materials for new catalysts in order to identify candidates that are particularly active as catalysts. Catalysts are needed, for example, for energy conversion processes that could enable us to use green hydrogen on a large scale as an environmentally friendly energy carrier.