The new catalyst material. Photo: City University of Hong Kong.
The new catalyst material. Photo: City University of Hong Kong.

Storing renewable energy as hydrogen could soon become much easier thanks to a new catalyst based on single atoms of platinum. Designed by researchers at City University of Hong Kong (CityU) and tested by colleagues at Imperial College London in the UK, the new catalyst could be cheaply scaled up for mass use.

“The UK Hydrogen Strategy sets out an ambition to reach 10GW of low-carbon hydrogen production capacity by 2030,” said Anthony Kucernak from the Department of Chemistry at Imperial, who is co-author of a paper on this work in Nature. “To facilitate that goal, we need to ramp up the production of cheap, easy-to-produce and efficient hydrogen storage. The new electrocatalyst could be a major contributor to this, ultimately helping the UK meet its net-zero goals by 2050.”

Renewable energy generation, from sources like wind and solar, is rapidly growing. However, some of the energy generated needs to be stored for when weather conditions are unfavourable for wind and sun. One promising way to do this is to save the energy in the form of hydrogen, which can be stored and transported for later use.

To do this, renewable energy can be used to split water molecules into hydrogen and oxygen, with the energy stored in the hydrogen atoms. This process uses platinum catalysts to spur a reaction that splits the water molecule, known as electrolysis. However, although platinum is an excellent catalyst for this reaction, it is expensive and rare, so minimizing its use is important to reduce system costs and limit platinum extraction.

The researchers have now designed and tested a catalyst that uses as little platinum as possible to produce an efficient but cost-effective platform for water splitting.

“Hydrogen generated by electrocatalytic water splitting is regarded as one of the most promising clean energies for replacing fossil fuels in the near future, reducing environmental pollution and the greenhouse effect,” said lead researcher Zhang Hua from CityU.

The team’s innovation involves dispersing single atoms of platinum on a sheet of molybdenum sulphide (MoS2). This approach uses much less platinum than existing catalysts and even boosts the catalytic performance, as the platinum interacts with the molybdenum to improve the efficiency of the water-splitting reaction.

Growing the thin catalysts on nanosheet supports allowed the CityU team to create high-purity materials. These were then characterized in Kucernak’s lab at Imperial, which has developed methods and models for determining how a catalyst operates.

The Imperial team has the tools for stringent testing because they have developed several technologies that are designed to make use of such catalysts. Kucernak and his colleagues have set up several companies based on these technologies, including RFC Power. This specialises in hydrogen flow batteries, which could be improved by using the new single-atom platinum catalysts.

Once renewable energy is stored as hydrogen, it can be converted back into electricity using fuel cells, which produce just water vapor as a by-product. Recently, Kucernak and colleagues developed a single-atom catalyst for this reaction based on iron, instead of platinum, which will also reduce the cost of this technology.

Bramble Energy, another spinout led by Kucernak, will test this technology in their fuel cells. Both single-atoms catalysts – one helping to turn renewable energy into hydrogen and the other converting that hydrogen into electricity later – thus have the power to bring a hydrogen economy closer to reality.

This story is adapted from material from Imperial College London, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.