Green hydrogen is a type of energy that's produced when you split water into hydrogen and oxygen using renewable energy through a process called electrolysis. It's widely considered to be the future of the energy sector. Some countries are already betting their future on green hydrogen, although more research is needed so that large-scale production of this type of energy is sustainable.
When it comes to research on this particular topic, Japan has a head start.
A bit of context. In recent years, PEM electrolyzers, which use a proton exchange membrane as an electrolyte, have become more popular among hydrogen producers due to their higher efficiency and ability to respond quickly to intermittent power sources.
However, the challenge with PEM electrolyzers is their high cost. They require efficient catalysts that are resistant to corrosion in acid, which is why they utilize rare and expensive metals like platinum or iridium.
In search of a cheap catalyst. Iridium catalysts prolong the oxygen evolution reaction and allow for larger volumes of hydrogen production. However, is there any low-cost material out there that would be as effective?
Recently, researchers at the RIKEN Institute in Japan seem to have found a cheap and efficient alternative to iridium catalysts. During their tests, they used manganese, a common metal, and modified its three-dimensional structure to achieve the first efficient and durable PEM electrolyzer that doesn't require rare metals.
The secret lies in 3D structure of Manganese Oxide. Japanese scientists developed a manganese oxide (MnO2) catalyst by manipulating the material’s lattice structure so that it forms stronger bonds with oxygen atoms.
The improved MnO2 is much more stable than other non-noble metal catalysts and can maintain the reaction with water for much longer.
10 times more hydrogen. A recent study published in Nature Catalysis found that MnO2 can improve the lifetime and stability of other cheap catalysts by 4,000%. This material is more resistant to dissolving in acid and can produce more hydrogen than other materials.
In laboratory tests, the catalyst produced 10 times more hydrogen than other materials and operated for over 1,000 hours at 200 mA/cm².
This is just the beginning. While further work is needed to make this material work in industrial electrolyzers, researchers believe that this finding will be a significant step toward sustainable hydrogen production.
They also suggest that future modifications to the manganese structure could increase the current density supported by the material and the lifetime of the catalyst. The long-term goal is to make water electrolysis iridium-free.
Image | RIKEN Center for Sustainable Resource Science
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