Portuguese 
English 
Spanish 
3 min of reading 
0 comments 
New stainless steel developed by the University of Hong Kong resists seawater corrosion, creates a second protective layer with manganese, and can reduce costs of electrolyzers used in large-scale green hydrogen production.
The University of Hong Kong’s (HKU) stainless steel innovation targets a critical point in green hydrogen: creating electrolyzers capable of resisting seawater without expensive structural materials. The team created SS-H₂, a corrosion-resistant material for aggressive environments.
The discovery was reported in the journal Materials Today, “A sequential dual passivation strategy for the development of stainless steel used above water oxidation.” It also stems from the “Super Steel” project, which produced anti-COVID-19 stainless steel in 2021 and ultra-resistant versions in 2017 and 2020.
Stainless steel can reduce costs
Green hydrogen is obtained using electricity to separate water into hydrogen and oxygen. Seawater is abundant, but salt, chloride ions, side reactions, and corrosion can damage electrolyzer components.
-
Scientists are baffled as to how a giant eruption in Tonga may have destroyed atmospheric methane and revealed an unexpected path to curb part of global warming.
-
Huawei surprises with a luxury smartwatch with 99 diamonds and launches a children’s watch with a camera, powerful battery, and advanced security and health features.
-
Virus alert on the small island: Tristan da Cunha, without an airport and with only 216 residents, now under attention for hantavirus.
-
A public school student creates an “electric defensive” that uses only water, salt, and energy to protect crops without industrial pesticides, wins the Young Scientists Award 2025, and transforms an invisible chemical process into a solution for small farmers.
In saltwater, the team observed performance comparable to titanium-based materials used for hydrogen from desalinated water or acid. The difference lies in the cost, as titanium parts coated with gold or platinum are expensive.
For a 10-megawatt PEM system, the total cost was estimated at HK$ 17.8 million. Structural components accounted for up to 53% of this expense, and replacement with SS-H₂ could reduce this cost by about 40 times.
Why common steel fails
Stainless steel has been used for over a century in corrosive environments due to the self-protection generated by chromium. When chromium oxidizes, it forms a thin passive film, capable of protecting the steel from damage.
This protection has an intrinsic limit. In conventional stainless steel, the chromium oxide layer can break down at high potentials, with Cr₂O₃ oxidizing into soluble Cr(VI) species, causing transpassive corrosion around 1000 mV, below the 1600 mV required for water oxidation.
Even 254SMO, a reference chromium alloy for pitting corrosion resistance in seawater, reaches this high-voltage limit. It works in common marine environments, but hydrogen production creates an extreme electrochemical environment.
Second shield surprised researchers
HKU’s solution was named sequential dual passivation. Instead of relying solely on the Cr₂O₃ barrier, SS-H₂ forms a second protective layer.
First, the Cr₂O₃-based passive film appears. Then, at around 720 mV, a manganese-based layer forms over the chromium layer, protecting the steel in chloride environments up to 1700 mV.
The discovery was surprising because manganese was not seen as an ally for corrosion resistance. Dr. Kaiping Yu, the first author, stated that the team did not believe the results, as the prevailing view was that Mn was detrimental to stainless steel.
Yu stated that Mn-based passivation is counter-intuitive and cannot be explained by current knowledge in corrosion science. The team was convinced after atomic results and began to search for the mechanism.
Six years until industrial application
The breakthrough required almost six years between initial observation, scientific explanation, publication, and potential industrial use. Huang stated that the strategy overcame the fundamental limitation of conventional stainless steel and established a new paradigm for alloys applicable at high potentials.
The achievements have been submitted for patent applications in several countries, and two patents had already been granted at the time of HKU’s announcement. The team reported that tons of SS-H₂-based wire were produced with a factory in mainland China.
Huang acknowledged that transforming experimental materials into real products, such as meshes and foams, still requires challenging tasks. Nevertheless, he stated that the production of the wire represents a significant step towards industrialization and the application of SS-H₂ in renewable hydrogen production.
Advance still depends on engineering
Although the study was published in 2023, the problem remains relevant. Recent research continues to focus on corrosion-resistant materials, durable electrodes, chlorine suppression, and systems capable of operating with real seawater.
SS-H₂ is not yet a ready-made solution for the hydrogen economy. Its potential lies in replacing expensive titanium-based components with high-voltage resistant stainless steel in seawater, paving the way for cheaper and more scalable production.
Be the first to react!