University of Adelaide’s Professor Shizhang Qiao and Associate Professor Yao Zheng from the School of Chemical Engineering led an international team that successfully split seawater without pre-treatment to produce green hydrogen.
Professor Qiao said, “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.”
The team published their research in the journal Nature Energy.
A typical non-precious catalyst is cobalt oxide with chromium oxide on its surface.
Associate Professor Zheng explained, “We used seawater as a feedstock without the need for any pre-treatment processes like reverse osmosis desolation, purification, or alkalization. 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 deionized water.
Professor Zheng added, “Current electrolysers are operated with highly purified water electrolyte. Increased demand for hydrogen to partially or totally replace energy generated by fossil fuels will significantly increase scarcity of increasingly limited freshwater resources.”
Seawater is an almost infinite resource and is considered a natural feedstock electrolyte. This is more practical for regions with long coastlines and abundant sunlight. However, it isn’t practical for regions where seawater is scarce.
Seawater electrolysis is still in early development compared with pure water electrolysis because of electrode side reactions, and corrosion arising from the complexities of using seawater.
“It is always necessary to treat impure water to a level of water purity for conventional electrolysers including desalination and deionization, which increases the operation and maintenance cost of the processes,” noted Zheng. “Our work provides a solution to directly utilize seawater without pre-treatment systems and alkali addition, which shows similar performance as that of existing metal-based mature pure water electrolyser.”
The team will work on scaling up the system by using a larger electrolyzer so that it can be used in commercial processes such as hydrogen generation for fuel cells and ammonia synthesis.
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Should this work get replication with similar success it will be a breakthrough. No expensive precious metals involved. But cobalt while not so rare isn’t abundant by any means and is often sourced from ore gathering by small children. That makes the future of cobalt very much up in the air for assessment. Should this research prove up, the cobalt demands would sky rocket and get way more expensive. There is cobalt to be had, its just buried under ‘not in my backyard’ and the environmental green groups’ lawyer barriers, which plug up the politics quite severely.
The second matter is that the power source isn’t discussed. While the energy input is definitely electric and the claim is near 100% efficiency, the input vs product calculation isn’t shown or discussed.
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Yet the prospect of a greatly reduced water source cost, plus not using precious metals is cause for a lot of anticipation. Congratulations to the team is in order. Lets hope the next steps are solvable by low costs and not requiring decades of political maneuvering to get the jobs done.
By Brian Westenhaus via New Energy and Fuel
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