GoKawiilA stainless steel breakthrough from the University of Hong Kong (HKU) could help solve one of the biggest problems facing green hydrogen: how to build electrolyzers that are tough enough for seawater, yet cheap enough for large scale clean energy.
Led by Professor Mingxin Huang in HKU's Department of Mechanical Engineering, the team developed a special stainless steel for hydrogen production (SS-H 2 ). The material resists corrosion under conditions that normally push stainless steel past its limits, making it a promising candidate for producing hydrogen from seawater and other harsh electrolyzer environments.
The discovery, reported in Materials Today in the study "A sequential dual-passivation strategy for designing stainless steel used above water oxidation," builds on Huang's long running "Super Steel" Project. The same research program previously produced anti-COVID-19 stainless steel in 2021, along with ultra strong and ultra tough Super Steel in 2017 and 2020.
A Cheaper Path Toward Green Hydrogen
Green hydrogen is made by using electricity, ideally from renewable sources, to split water into hydrogen and oxygen. Seawater is an especially tempting feedstock because it is abundant, but it brings a serious materials problem: salt, chloride ions, side reactions, and corrosion can quickly damage electrolyzer components.
Recent reviews of direct seawater electrolysis continue to highlight the same core challenge. The technology could provide a more sustainable route to hydrogen, but corrosion, chlorine related side reactions, catalyst degradation, precipitates, and limited long term durability remain major obstacles to commercial use.
That is where SS-H 2 could matter. In a salt water electrolyzer, the HKU team found that the new steel can perform comparably to the titanium based structural materials used in current industrial practice for hydrogen production from desalted seawater or acid. The difference is cost. Titanium parts coated with precious metals such as gold or platinum are expensive, while stainless steel is far more economical.
For a 10 megawatt PEM electrolysis tank system, the total cost at the time of the HKU report was estimated at about HK$17.8 million, with structural components making up as much as 53% of that expense. According to the team's estimate, replacing those costly structural materials with SS-H 2 could reduce the cost of structural material by about 40 times.
Why Ordinary Stainless Steel Fails
Stainless steel has been used for more than a century in corrosive environments because it protects itself. The key ingredient is chromium. When chromium (Cr) oxidizes, it creates a thin passive film that shields the steel from damage.
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