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Energy

Acid coating converts regular electrolyzers to split seawater

By Loz Blain
February 02, 2023
Acid coating converts regular electrolyzers to split seawater
A simple acid layer on a catalyst can convert regular commercial electrolyzers to produce hydrogen from seawater, says an international research team
A simple acid layer on a catalyst can convert regular commercial electrolyzers to produce hydrogen from seawater, says an international research team
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A simple acid layer on a catalyst can convert regular commercial electrolyzers to produce hydrogen from seawater, says an international research team
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A simple acid layer on a catalyst can convert regular commercial electrolyzers to produce hydrogen from seawater, says an international research team

Green hydrogen is going to demand a lot of water for electrolysis – nine liters of pure water for every kilogram of hydrogen. Researchers say they've found a simple way to use seawater in standard electrolyzers, and that's big news for clean energy.

An international team from the University of Adelaide, Australia, Tianjin and Nankai Universities in China and Kent State University in the US has published new research claiming that a simple, cheap acid layer over the catalyst in an electrolyzer allows it to split seawater with "nearly 100 per cent efficiency," without any pre-treatment other than filtering.

A typical electrolyzer catalyst, says the team, might be made from cobalt oxide, with chromium oxide on its surface. Seawater would generally ruin these catalysts via severe erosion due to chlorine ions, or gunk them up with insoluble precipitations of magnesium and calcium, which build up and block the electrodes.

But the addition of a Lewis acid layer on the catalyst, it seems, was able to capture enough negatively charged hydroxyl anions from the seawater to generate a powerfully alkaline environment with a pH of 14 around the catalyst, stopping both chloride attacks on the catalyst and the formation of precipitates on the electrodes.

“We have split natural seawater into oxygen and hydrogen with nearly 100 per cent efficiency, to produce green hydrogen by electrolysis, using a non-precious and cheap catalyst in a commercial electrolyzer,” said Professor Shizhang Qiao.

"The performance of a commercial electrolyzer with our catalysts running in seawater is close to the performance of platinum/iridium catalysts running in a feedstock of highly purified deionized water," added Associate Professor Yau Zheng.

Two things seem clear looking at the decades ahead: there's going to be a lot of demand for green hydrogen, and the water shortages that are projected to impact two-thirds of the world's population by 2025 are going to get worse.

But if green hydrogen can be made in bulk using seawater, then anywhere it's used, either in a fuel cell or in a combustion process, it'll end up being combined with oxygen and released back into the environment as fresh water – a desalination process with a clean energy bonus, if you will.

The team says it's working to scale up its system for commercial-scale electrolyzers, and looking for industrial partners to take it into production.

The paper is available in the journal Nature Energy.

Sources: University of Adelaide, South China Morning Post

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EnergyElectrolysisUniversity of AdelaideHydrogenKent State University
10 comments
Loz Blain
Loz Blain
Loz has been one of our most versatile contributors since 2007, and has since proven himself as a photographer, videographer, presenter, producer and podcast engineer, as well as a senior features writer. Joining the team as a motorcycle specialist, he's covered just about everything for New Atlas, concentrating lately on clean energy, AI, humanoid robotics, next-gen aircraft, and the odd bit of music and automotive. In February 2024, he stepped up to lead New Atlas as Editorial Director, and he's as curious as anyone to see how that pans out.

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Joy Parr
Another major advance, this is very heartening.
Claudio
it seems almost too good to be true... let's hope it works as they claim and it's scalable and economically sustainable
Brian M
Hydrogen could really be the best solution for future energy, its production starts solving some of the storage issues of non-continuous green energy production from solar, wind etc. Advances like this help taker it closer to a reality.
Lawrence Smith
The combustion process does not turn it back into water. It converts it to energy and a tiny fraction of it to water. We will have a worldwide water shortage if it is used for combustion.
eMacPaul
@Lawrence, combustion is a chemical process, not a nuclear process. No atoms are are lost, it all converts back into water.
DaveWesely
Oh my, @Lawrence, that makes my head hurt. H2O (water) + energy in <=> H2 (hydrogen) + O (oxygen) + energy out. There's a bit more to it than that, but atoms are not destroyed in the combustion, electrolysis, or fuel cell process. There are many downsides to hydrogen as an energy storage medium. The loss of matter is not one of them.
drzarkov99
Hydrogen production isn't the problem. Transport and storage is challenging, due to the small size of the hydrogen atom, which leaks from standard transport pipes, and reacts with many metals to cause hydrogen embrittlement.
Daniel Caon
It would be interesting to see in the decades ahead, if hydrogen use becomes entrenched, that rather than deal with smog, cities will contend with higher humidity...
Aermaco
There seems to be little doubt that H2 from Solar will continue to head toward being the dominant "fuel" in the future, with its rate of progress found in the rate of demand for its clean use.
meofbillions
I agree with Aermaco. Current CO2 production by the US is a little under 5 GT and the 2022 energy report by the US EIA projects that by 2050 it will be a little under 4 GT. We are supposed to be in a Green Energy Transition with net-zero by 2050???

My view is that the projection is off the mark so much because planners are not considering Hydrogen enough. My prediction is that sometime before 2030, when enough s**t hits the fan, there will be a mad scramble for the only technically feasible solution: hydrogen.

By my calculations, a 100% hydrogen economy for the US (not considering nonfuel petrochemicals) will require about 3.8 gallons of water per citizen per day for all the electrolysis required. We get back about 2.4 gallons per citizen per day from the Utility and Transportation fuel cells. That's a net of about 17 billion gallons a year required.