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Comment by digikata | Hacker News Reader

From the article: "Using nickel and iron, which are cheap materials, we were able to make the electrocatalysts active enough to split water at room temperature with a single 1.5-volt battery. This is the first time anyone has used non-precious metal catalysts to split water at a voltage that low. It's quite remarkable, because normally you need expensive metals, like platinum or iridium, to achieve that voltage."

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They're overselling the science. This is certainly not the first time anyone has used non-precious metals to split water at low voltages. Both Ni oxide and Ni-Fe oxide systems that they use in their paper are well known in the literature. Ni oxides have been published back in the 1950s while Ni-Fe oxide catalysts were introduced in the 1980s. However, they do claim that their NiO/Ni/CNT system is novel, which may be true.

In their experimental setup, they target 20 mA/cm2 current density. To achieve that, they can just increase the amount of catalyst they use. The geometric area (cm2) will remain the same, but the surface area will increase which will correspondingly raise current density. For example, one can stack sheets of carbon aerogel to achieve the same current density.

But it really isn't. The only thing of minor note here is room temperature vs doing it at 60 deg C.

At scale, that's a good bit of energy, I would assume. But I had the same reaction as you did. "My 7th grade science class did that..."

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