“Cannot be explained” – New super steel stuns scientists

A team of researchers at the University of Hong Kong has created a new form of stainless steel called stainless steel for hydrogen (SS-H2). This innovative material is designed to resist corrosion in conditions that typical stainless steel cannot withstand. The development stems from Professor Mingxin Huang's Super Steel Project, which has previously produced stainless steel with anti-COVID properties, and exceptionally strong and tough variants.

SS-H2's standout feature is its resistance to corrosion under high electrical potentials, making it particularly useful for systems that produce green hydrogen. Green hydrogen is produced through electrolysis, a process that splits water into hydrogen and oxygen using electricity. When the electricity comes from renewable sources, the resulting hydrogen is considered "green."

However, the equipment used for electrolysis must be able to withstand harsh chemical and electrical conditions, especially when salt is involved. Conventional stainless steel often fails to meet these demands. The SS-H2 material, however, offers performance comparable to titanium structural components used in hydrogen production from desalinated seawater or acidic solutions.

The key distinction is its significantly lower cost. The findings were published in Materials Today in a study titled "A sequential dual-passivation strategy for designing stainless steel used above water oxidation." The research team has applied for patents for this technology in several countries, with two patents already authorized.

Stainless steel has been widely used for a century due to its corrosion resistance, largely attributed to chromium. However, the protective chromium oxide layer can degrade under certain conditions, particularly under high electrical potentials. This degradation hinders the use of conventional stainless steel in some high-voltage electrochemical applications, like water oxidation during electrolysis.

SS-H2 addresses this limitation through a unique dual-passivation strategy. This involves the formation of an additional protective layer based on manganese, which begins developing at around 720 mV. Together, the chromium and manganese layers allow SS-H2 to resist corrosion at potentials reaching 1700 mV, far beyond conventional stainless steel's capabilities.

The researchers' discovery of the manganese-based passivation is particularly noteworthy, as manganese has traditionally been considered detrimental to stainless steel's corrosion resistance. The breakthrough, which took nearly six years to achieve, represents a significant advancement over conventional stainless steel, especially in resisting corrosion at high electrical potentials.

Huang's team emphasizes the potential economic benefits of SS-H2, noting that traditional electrolyzers using desalinated seawater or acidic solutions require expensive titanium components. These components, coated with gold or platinum, can account for a significant portion of the cost of an electrolysis system. SS-H2 could drastically reduce these material costs.