A study published in the journal Nature Energy
Professor Shizhang Chao from the Australian University of Adelaide 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. The team published their research in the journal Nature Energy.
"We split natural seawater into oxygen and hydrogen with nearly 100 percent efficiency to produce environmentally friendly hydrogen by electrolysis, using a non-precious and inexpensive catalyst in a commercial electrolyzer," said Professor Chao.
Seawater is an almost infinite resource
A typical non-noble catalyst is cobalt oxide with chromium oxide on the surface.
– We used seawater as raw material without the need for any pre-treatment processes, such as reverse osmosis desalination, purification or alkalization. The performance of a commercial electrolyzer with our catalysts operating in seawater is close to that of platinum/iridium catalysts operating in highly purified deionized water feedstock – Professor Zheng explained.
She added that current electrolyzers work with highly purified water electrolyte. The increased demand for hydrogen that would partially or fully replace energy produced by fossil fuels will significantly increase the scarcity of increasingly limited fresh water resources.
Seawater is an almost infinite resource and is considered a natural source of electrolytes. This is more practical for regions with long coastlines and lots of sunlight. However, it is not practical for regions where there is not enough seawater.
Seawater electrolysis is still in its infancy compared to pure water electrolysis, due to electrode side reactions and corrosion resulting from the complexity of using seawater.
– It is always necessary to treat the impure water to the level of water purity for conventional electrolyzers, including desalination and deionization, which increases the operation and maintenance costs of the process. Our work provides a solution for the direct use of seawater without a pre-treatment system and alkali addition, which shows similar performance to the existing metal-based mature pure water electrolyzer - Zheng points out.
Demand for cobalt would increase
The team will work to scale the system, using a larger electrolyser, so that it can be used in commercial processes such as hydrogen production for fuel cells and ammonia synthesis.
If this work is repeated with similar success, it will be a major advance. We are not talking about expensive precious metals. But cobalt, although not so rare, is by no means abundant. Therefore, the future of cobalt is very doubtful to assess. If this research proves correct, the demand for cobalt would increase and become significantly more expensive.
Another thing is not to argue about the source of energy. Although the input power is definitely electrical and the efficiency is claimed to be close to 100 percent, the calculation of input versus output is not shown or discussed. However, the possibility of significantly reduced costs for water sources, with the non-use of precious metals, is the reason for many expectations, "Oilprice.com" reports.
