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Electrolysis is a key component of the cost of green hydrogen, and a Korean team says it's made a huge breakthrough with an anion exchange membrane that's not only much cheaper than current proton exchange tech, but offers some 20 percent better performance.

Electrolysis is the process of splitting water into hydrogen and oxygen, and when powered by renewable energy, it's shaping up to be a key step in the production of green hydrogen. Green hydrogen is set to play a substantial role in the race to zero emissions, offering a high energy density that makes it an attractive option in several hard-to-decarbonize activities where batteries just don't make sense.

Typically, electrolyzers use proton exchange membranes (PEMs), in which an anode and a cathode in an electrolyte material are separated by a membrane designed to allow positively-charged hydrogen ions to pass through as they're attracted by the cathode. Here they combine with electrons to form hydrogen gas, which is collected, and oxygen is released at the anode.

The problem here is materials; the acidic environment required by PEMs generally necessitates expensive metals like platinum, ruthenium or iridium in their electrodes, as well as titanium in their separator plates.

One alternative electrolysis technology being researched is anion exchange membranes (AEMs), in which the separating membrane allows negatively-charged OH- ions to pass through instead. These are attracted to the anode, where they combine to form oxygen and water molecules, as the hydrogen atoms gravitate to the cathode for collection as H2 gas.

AEMs can operate under alkaline conditions, so they don't need fancy noble metals – the materials involved are thus some 3,000 times less expensive. A relatively young technology, AEMs have not found commercial success in hydrogen electrolysis because they don't perform as well and they don't last as long.

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