Chemists uncover the true active surface of nickel catalysts

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Researchers at Ulm University found that nickel dioxide, rather than nickel oxyhydroxide, forms the active surface of nickel electrodes during alkaline water electrolysis. The finding revises a long-standing assumption and could inform development of catalysts for producing low-carbon hydrogen.

Nickel is a promising, cost-effective and robust catalyst for alkaline water electrolysis—a key technology for the climate-neutral production of hydrogen. However, the actual structure of the active surface of such nickel electrodes under reaction conditions had not yet been conclusively determined. A research team at Ulm University has now refuted a decades-old assumption: The catalytically active surface does not consist of nickel oxyhydroxide (NiOOH), as was previously widely assumed, but is nickel dioxide (NiO₂). The findings have been published in the journal Nature Catalysis.