Researchers in Australia, an island nation, have successfully split seawater to produce green hydrogen without pre-treatment.
An international chemical engineering team, led by the University of Adelaide’s Professor Shizhang Qiao and Associate Professor Yao Zheng, were motivated by the fact that the only thing emitted by hydrogen fuel is water.
“We have split natural seawater into oxygen and hydrogen with nearly 100 percent efficiency, to produce green hydrogen by electrolysis, using a non-precious and cheap catalyst in a commercial electrolyzer,” said Professor Qiao.
“We used seawater as a feedstock without the need for any pre-treatment processes like reverse osmosis desolation, purification, or alkalization,” said Associate Professor Zheng.
The team reports that the performance of their seawater with catalysts of cobalt oxide and chromium oxide is close to the performance of expensive platinum/iridium catalysts running in a feedstock of highly purified deionized water.
“Increased demand for hydrogen to partially or totally replace energy generated by fossil fuels will significantly increase scarcity of increasingly-limited freshwater resources,” explained Zheng.
Seawater is an almost infinite resource and is considered a natural feedstock electrolyte, which would be very practical for regions with long coastlines and abundant sunlight.
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 electrolyzers including desalination and deionization, which increases the operation and maintenance cost of the processes,” said Associate Professor Zheng, co-author of the study published in the journal Nature Energy.
“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 electrolyzer.”
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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