Researchers have figured out how to produce hydrogen fuel using seawater. (Image Credit: Sarah Brown/Unsplash)
Researchers at the University of Adelaide have discovered a new way to extract seawater and use it to produce hydrogen fuel without pre-treatment. This solution could lead to more affordable green energy production in coastal regions. The team used a cheap and non-precious catalyst in an electrolyzer for this process, splitting seawater into oxygen and hydrogen.
“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 Shizhang Qiao, the team’s co-lead.
The team layered a hard Lewis acid substance atop cobalt oxide catalysts, splitting water molecules. As a result, the device performed similarly to a traditional process involving platinum and iridium catalysts with purified and deionized water. “We used seawater as a feedstock without the need for any pre-treatment processes like reverse osmosis desolation, purification, or alkalisation,” said Associate Professor Yao Zheng. “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 deionised water.”
Although it sounds exciting, there are still obstacles to commercialization. "Direct seawater electrolysis without the purification process and chemical additives is highly attractive and has been investigated for about 40 years, but the key challenges of this technology remain in both catalyst engineering and device design,” the team wrote in the paper.
According to the researchers, seawater is nearly infinite and serves as a natural feedstock electrolyte. So it’s more suitable for long coastline regions with plenty of sunlight. On the other hand, it’s simply not practical in regions that have scarce seawater.
Compared to pure water electrolysis, seawater electrolysis is still under development due to electrode side reactions and corrosion from using seawater. “It is always necessary to treat impure water to a level of water purity for conventional electrolyzers including desalination and deionisation, which increases the operation and maintenance cost of the processes. 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,” said Zheng.
The team is exploring ways to upscale their technology by using a larger electrolyzer, allowing it to be used in commercial processes, including hydrogen production for fuel cells and ammonia synthesis.
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