Catalysts accelerate chemical reactions, but the widely used metal platinum is scarce and expensive.

Researchers have now developed an alternative with a 20x higher activity, a catalyst with hollow nanocages of an alloy of nickel and platinum.

By 2050, the national government aims to get almost all of the Netherlands’ energy requirements from sustainable sources, such as the sun or the wind.

Because these energy sources are not available at all times, it is important to be able to store the generated energy. Given their low energy density, batteries are not suitable for storing very large amounts of energy.

A better solution is chemical bonds, with hydrogen as the most obvious choice of gas.

Using water, an electrolyzer converts (an excess of) electrical energy into hydrogen, which can be stored. At a later stage, a fuel cell does the opposite, converting the stored hydrogen back into electrical energy. Both technologies require a catalyst to drive the process.

The catalyst that helps with these conversions is due to its high activity mostly made of platinum. But platinum is very expensive and relatively scarce; a problem if we want to use electrolyzers and fuel cells on a large scale.

In addition to the other choice of metal, the researchers were also able to make significant changes to the morphology.

The atoms in the catalyst have to bond with the water and/or oxygen molecules to be able to convert them. More binding sites will therefore lead to a higher activity.

The developed hollow nanocages can be accessed from the outside as well as from the inside. This creates a large surface area, allowing more material to react at the same time.

After calculations in Hensen’s model, it turns out that the activity of both solutions combined is 20 times higher than that of the current platinum catalysts. The researchers have also found this result in experimental tests in a fuel cell.

An important criticism of a lot of fundamental work is that it does its thing in the lab, but when someone puts it in a real device, it often doesn’t work. We have shown that this new catalysts works in a real application.

The stability of a catalyst must be such that it can continue to work in a hydrogen car or house for years to come.

The researchers therefore tested the catalyst for 50,000 ‘laps’ in the fuel cell, and saw a negligible decrease in activity.

The possibilities for this new catalyst are manifold. Both in the form of the fuel cell and the reverse reaction in an electrolyzer. For example, fuel cells are used in hydrogen-powered cars while some hospitals already have emergency generators with hydrogen-powered fuel cells.

The underground gas pipelines will transport hydrogen in future, and the domestic central heating boiler will be replaced by a fuel cell, the latter converting the stored hydrogen back into electricity. That’s how we can make the most of the sun.

But for this to happen, the electrolyzer still needs to undergo considerable development. Together with other researchers and industrial partners from the Brabant region.

The aim is to scale up the current commercial electrolyzers to a refrigerator-size electrolyzer of about 10 megawatts.