Tens of thousands of potential stimuli in the diameter of a single hair

When looking for catalysts for energy transition, materials consisting of at least five elements are considered very promising. But there are millions in theory – how do we define the strongest one?

A Bochum-based research team led by Prof. Alfred Ludwig, Head of the Department of Materials Discovery and Interfaces (MDI), has succeeded in putting all possible combinations of five elements on Transporter in one step. In addition, the researchers developed a method for analyzing the electrocatalytic potential of each of the combinations in this fine material library in high throughput.

This is how they hope to greatly speed up the search for potential triggers. The Ruhr University Bochum team published their findings in the journal Advanced materials.

A complete five-element material system on a single conveyor

To produce libraries of materials for so-called high-entropy alloys, the Bochum researchers use the spraying process. In this process, all starting materials are simultaneously applied to a conveyor from different directions.

Starting materials with different mixing ratios are deposited on each portion of the carrier. “In the current project, we have optimized this process by using perforations in such a way that each mixture of materials is deposited only in a small spot of about 100 micrometers in diameter on the conveyor,” says Alfred Ludwig. This is roughly equivalent to the diameter of a human hair.

“By miniaturizing material libraries, we are now able to accommodate a complete five-component system on a single conveyor – this is a huge advance,” says Dr. Lars Panko of MDI.

Search using suspended drops

To study materials created with this technique, researchers use what is known as scanning electron microscopy (SECCM). This involves measuring the electrochemical properties of a material at a point via a nanoelectrode suspended from an electrolyte one-thousandth of a hair’s diameter.

“This means that we can use high-throughput methods to identify candidates with the highest catalytic activity, where a more detailed analysis would seem advantageous,” says Prof. Wolfgang Schumann, Head of the Department of Analytical Chemistry at the Ruhr-University Bochum.

Using these methods, researchers hope to efficiently search through a large number of possibilities Materials for novel catalysts in order to identify particularly active candidates as catalysts. Catalysts are needed, for example, for energy conversion processes that could enable us to widely use green hydrogen as an environmentally friendly energy carrier.