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Seawater split to produce green hydrogen
https://www.adelaide.edu.au/newsroom/news/list/2023/01/30/seawater-split-to-produce-green-hydrogenSeawater split to produce green hydrogen
Posted on Feb 1 2023 by Jessica Stanley
[...]
“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 electrolyser,” said Professor Qiao.
A typical non-precious catalyst is cobalt oxide with chromium oxide on its surface.
“We used seawater as a feedstock without the need for any pre-treatment processes like reverse osmosis desolation, purification, or alkalisation,” said Associate Professor Zheng.
“The performance of a commercial electrolyser with our catalysts running in seawater is close to the performance of platinum/iridium catalysts running in a feedstock of highly purified deionised water.
[...]
Posted on Feb 1 2023 by Jessica Stanley
[...]
“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 electrolyser,” said Professor Qiao.
A typical non-precious catalyst is cobalt oxide with chromium oxide on its surface.
“We used seawater as a feedstock without the need for any pre-treatment processes like reverse osmosis desolation, purification, or alkalisation,” said Associate Professor Zheng.
“The performance of a commercial electrolyser with our catalysts running in seawater is close to the performance of platinum/iridium catalysts running in a feedstock of highly purified deionised water.
[...]
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https://www.nature.com/articles/s41560-023-01195-x
Direct seawater electrolysis by adjusting the local reaction environment of a catalyst
Jiaxin Guo, Yao Zheng, Zhenpeng Hu, Caiyan Zheng, Jing Mao, Kun Du, Mietek Jaroniec, Shi-Zhang Qiao & Tao Ling
Nature Energy (2023)
Abstract
The use of vast amounts of high-purity water for hydrogen production may aggravate the shortage of freshwater resources. Seawater is abundant but must be desalinated before use in typical proton exchange membrane (PEM) electrolysers. Here we report direct electrolysis of real seawater that has not been alkalised nor acidified, achieving long-term stability exceeding 100 h at 500 mA cm−2 and similar performance to a typical PEM electrolyser operating in high-purity water. This is achieved by introducing a Lewis acid layer (for example, Cr2O3) on transition metal oxide catalysts to dynamically split water molecules and capture hydroxyl anions. Such in situ generated local alkalinity facilitates the kinetics of both electrode reactions and avoids chloride attack and precipitate formation on the electrodes. A flow-type natural seawater electrolyser with Lewis acid-modified electrodes (Cr2O3–CoOx) exhibits the industrially required current density of 1.0 A cm−2 at 1.87 V and 60 °C.
Jiaxin Guo, Yao Zheng, Zhenpeng Hu, Caiyan Zheng, Jing Mao, Kun Du, Mietek Jaroniec, Shi-Zhang Qiao & Tao Ling
Nature Energy (2023)
Abstract
The use of vast amounts of high-purity water for hydrogen production may aggravate the shortage of freshwater resources. Seawater is abundant but must be desalinated before use in typical proton exchange membrane (PEM) electrolysers. Here we report direct electrolysis of real seawater that has not been alkalised nor acidified, achieving long-term stability exceeding 100 h at 500 mA cm−2 and similar performance to a typical PEM electrolyser operating in high-purity water. This is achieved by introducing a Lewis acid layer (for example, Cr2O3) on transition metal oxide catalysts to dynamically split water molecules and capture hydroxyl anions. Such in situ generated local alkalinity facilitates the kinetics of both electrode reactions and avoids chloride attack and precipitate formation on the electrodes. A flow-type natural seawater electrolyser with Lewis acid-modified electrodes (Cr2O3–CoOx) exhibits the industrially required current density of 1.0 A cm−2 at 1.87 V and 60 °C.