A team of international chemical engineers, led by the University of Adelaide in Australia, has successfully split seawater to produce green hydrogen without pre-treatment. The researchers were motivated by the fact that the only thing emitted by hydrogen fuel is water.
The team used a non-precious and cheap catalyst in a commercial electrolyzer to split natural seawater into oxygen and hydrogen with nearly 100% efficiency. They did not use any pre-treatment processes such as reverse osmosis desalination, purification, or alkalization.
The team used seawater as a feedstock, which is an almost infinite resource and is considered a natural feedstock electrolyte. This would be very practical for regions with long coastlines and abundant sunlight.
The researchers used catalysts of cobalt oxide and chromium oxide, which provided a performance close to that of expensive platinum/iridium catalysts running in a feedstock of highly purified deionized water.
Associate Professor Yao Zheng, co-author of the study published in the journal Nature Energy, explained that “Increased demand for hydrogen to partially or totally replace energy generated by fossil fuels will significantly increase scarcity of increasingly-limited freshwater resources.” Using seawater eliminates the need to treat impure water, which increases the operation and maintenance cost of the processes.
Seawater electrolysis is still in early development compared with pure water electrolysis due to electrode side reactions, and corrosion arising from the complexities of using seawater. 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.
This development is significant as it provides a solution to directly utilize seawater without pre-treatment systems and alkali addition, showing similar performance to that of existing metal-based mature pure water electrolyzer. As the world looks for greener alternatives to fossil fuels, this research could prove to be a significant step towards a more sustainable future.
