A new super-porous and compact nanomaterial enables efficient electrochemical reactions. The material may represent an important step in the cost-efficient production of hydrogen using electrolysis.
The nanomaterial was developed by researchers at imec and KU Leuven, who are partners within EnergyVille. This is a collaboration between Belgian research partners KU Leuven, VITO, imec and UHasselt for research on renewable energy and intelligent energy systems.
Important role for hydrogen
Green hydrogen and other green molecules are expected to play a vital role in achieving the climate goals set by the European Union (EU) and others. For example, there is as yet no alternative to hydrogen for the decarbonisation of the steel and cement industries as well as the carbon-free production of fertilisers. Hydrogen can also play a major role in sectors that are difficult to electrify. Think of long-distance transport.
Although we are using more and more hydrogen, the share of green hydrogen is limited. Green hydrogen is hydrogen produced using renewable energy sources. In practice, this means that the electricity used in electrolysis comes from renewable energy sources, such as solar or wind power. If this is not the case, we speak of grey hydrogen. Large-scale and cost-efficient production of green hydrogen presents technological challenges.
Decomposing water into hydrogen and oxygen
Electrolysis is a chemical reaction in which compound substances are decomposed under the influence of electric currents. In the case of hydrogen, this means that electrolysis decomposes water into water and oxygen. The reaction in the electrolyser that plays a crucial role in this process takes place on the surface of the electrodes. The more porous the electrode material, the more efficiently hydrogen gas can be carried away from reaction surfaces.
In recent years, Imec and KU Leuven developed a new material that is both highly porous and has an exceptionally large reactive surface area compressed into a small volume (26 m²/cm³). The material is composed of wires 40 nanometres thin, equivalent to one thousandth of a hair. Under an electron microscope, the material looks like a three-dimensional chicken wire.
Non-porous carrier presents obstacles
The material is not new. However, until recently, the nanomaterial had to be supported by a non-porous carrier. This provides the required robustness, but at the same time hinders the inflow of reagents and the outflow of hydrogen gas. imec reports that this left the "enormous potential of the nanomaterial" untapped.
This carrier has now been completely opened up by the researchers with a porous structure accessible from all sides. Based on this, the researchers developed a nickel electrode. With this, they show that almost the entire theoretical surface area is also effectively utilised during electrochemical reactions.
More power leads to more hydrogen AND higher losses
The more current you send through an electrolysis cell, the more hydrogen is formed. At the same time, however, energy efficiency losses also increase. The nanomaterial offers a solution to this. Compared to conventional nickel electrodes, they can handle tens of times higher current densities with the same energy efficiency. The nanomaterial thus provides higher efficiency than common porous alternatives.
"To produce gigawatt-scale green hydrogen at offshore wind farms, where every square metre matters, you need compact electrolysers with high efficiency. This new electrode represents a promising component in the development of such electrolysers. We are continuing the development of these electrolysis components within the company Hyve, in collaboration with VITO, DEME, John Cockerill, Colruyt and Bekaert," explains Bart Onsia, business development manager at imec/EnergyVille.
'Industrial applications are fast approaching'
Philippe Vereecken, imec fellow and part-time professor at KU Leuven, added: "Thanks to our rapid progression in research, industrial applications of our nanomaterial are rapidly approaching. The technology does not rely on rare resources and relies on widely available production technologies that are easy to scale up. Moreover, within imec, together with VITO, we are also investigating how to use these materials for CO2 reduction."
Nina Planckensteiner, Marie-Curie postdoc at imec: "That's immediately the beauty of these nanostructures: you can create them in just about any metal, enabling a range of sustainable applications: nickel in electrolysis reactions, silver and copper for CO2 reduction, platinum for catalysts, and so on."
Further information is available in *Materials Today Energy*, where the researchers have published their findings.
Author: Wouter Hoeffnagel
Image: Rony Michaud via Pixabay
