BEIJING, China – A research team in China has developed a device to split salty seawater to produce hydrogen directly. The device, a membrane-based seawater electrolyzer, helps address the side-reaction and corrosion problems of traditional methods.
The team led by Zongping Shao, a chemical engineering professor at China’s Nanjing Tech University, has published their study in the journal Nature and claimed that their model “ran for over 3,200 hours under practical application conditions without failure”.
Most hydrogen produced today is from fossil fuel sources which can significantly add to the carbon footprint. “Electrochemical saline water electrolysis using renewable energy as input is a highly desirable and sustainable method for the mass production of green hydrogen, said a release.
However, there is a problem. The properties of salt water results in the corrosion of electrodes used in various systems, often making them unviable. The use of polyanion coatings to resist corrosion by chloride ions or highly selective electrocatalysts has not helped enough for practical applications.
A desalination process can solve the issue, “but it requires additional energy input, making it economically less attractive.” The size of the equipment involved in the desalination process also makes such solutions less flexible.
An electrolyzer typically consists of two electrodes coated with catalysts, and a membrane separates the constituent components – hydrogen and oxygen. The formation of the highly corrosive chlorine gas in the process leads to catalysts and electrodes degrading faster. Magnesium and calcium ions in seawater can also block the membranes. These factors decrease the overall efficiency and life of such devices.
“Our strategy realizes efficient, size-flexible, and scalable direct seawater electrolysis in a way similar to freshwater splitting without a notable increase in operation cost,” Shao told IEEE Spectrum.
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