An international team of scientists in the University of Adelaide have split naturally occurring seawater into hydrogen and oxygen with an efficiency of almost 100% using the simple process of electrolysis.
The team which was headed by Professor Shizhang Qiao and Associate Professor Yao Zheng from the School of Chemical Engineering used completely natural seawater as a feedstock and did not subject it to any kind of pre-treatment processes like purification, alkalisation or desolation by reverse osmosis. In addition to this they achieved this feat using a cheap, non-precious catalyst such as cobalt oxide with chromium oxide on its surface, and a commercial electrolyser.
They achieved this feat using a cheap, non-precious catalyst such as cobalt oxide with chromium oxide.”
Despite the simplicity of their methods, the electrolyser achieved an efficiency close to that of running highly deionised pure water as feedstock and using a rare platinum or iridium as the catalyst.
The reason seawater electrolysis has been very underdeveloped in comparison to pure water electrolysis is due to the complications caused by corrosion and electrode side reactions. It has also a lot more expensive to convert seawater to pure water through desalination and deionisation which is a problem that has now been solved.
“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.” says Assistant Professor Zhang.
If the team can scale up their system by using a larger electrolyser and utilize this method in commercial processes such as hydrogen generation for fuel cells and the synthesis of ammonia it would significantly reduce the intense pressure on highly limited pure water resources. Seawater, being a virtually infinite resource, is a much more sustainable alternative that can act as a natural feedstock electrolyte.
Seawater, being a virtually infinite resource, is a much more sustainable alternative.”
“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,” said Associate Professor Zheng.
The only limitation of this system is that unlike pure water, this practice would be regionally limited to places with a proximity to seawater as it would not be practical in an area without long coastlines or abundant sunlight.