New type of stainless steel pulls hydrogen directly out of seawater

Green hydrogen has long been sold as one of the clean energy economy’s most important tools. It can be made by splitting water with electricity from renewable sources, then used in industries that are hard to clean up, from fertilizer production to steelmaking. The problem is that making it at scale still costs too much, and some of the equipment wears down too fast.

A research team at the University of Hong Kong says it may have found a way around both problems with a new kind of stainless steel designed for hydrogen systems.

Called SS-H2, the material was developed under the leadership of Professor Mingxin Huang. The team says it combines the corrosion resistance needed for harsh electrolysis conditions with a much lower cost than the titanium components commonly used today. If that holds up in wider industrial use, it could reshape a part of the hydrogen business that has quietly held the sector back.

In many proton exchange membrane, or PEM, electrolysis systems, manufacturers rely on titanium coated with precious metals such as gold or platinum. Those materials work, but they make equipment expensive. SS-H2 is aimed squarely at that problem.

The University of Hong Kong team says the new steel can match titanium’s resistance to corrosion while costing far less.

The key to the material is what the researchers describe as a sequential dual-passivation process. In simple terms, the steel protects itself through two defensive layers, one based on chromium and another based on manganese. Together, those layers allow the material to withstand conditions that usually damage ordinary stainless steel.

That matters because electrolysis equipment must operate in tough chemical environments for long periods. Corrosion can shorten the life of critical parts, raise maintenance costs, and make hydrogen production less economical.

Dr. Kaiping Yu, the study’s first author, said even the team had doubts at first because manganese has generally been viewed as harmful to stainless steel’s corrosion resistance.

“The prevailing view is that manganese impairs the corrosion resistance of stainless steel,” he said. “Mn-based passivation is a counter-intuitive discovery, which cannot be explained by current knowledge in corrosion science. However, when numerous atomic-level results were presented, we were convinced. Beyond being surprised, we cannot wait to exploit the mechanism.”

That quote gets at what makes the work stand out. The researchers are not just reporting a better-performing alloy. They are describing a behavior that runs against accepted thinking in corrosion science, particularly the idea that manganese would weaken rather than strengthen protection.

The material also appears to hold up in seawater, a detail that could broaden where hydrogen is produced and how. According to the team, SS-H2 can operate in seawater at voltages up to 1700 millivolts, far above what regular stainless steel can manage.

That raises the possibility of making green hydrogen directly from seawater.

For all the attention hydrogen gets in energy policy and corporate climate plans, the economics remain difficult. A cleaner fuel only goes so far if the machinery needed to produce it remains expensive and hard to maintain.

The Hong Kong team argues that SS-H2 could make a serious dent in those costs. In a standard 10-megawatt PEM electrolysis system, with a price tag of about HK$17.8 million, they estimate material expenses could be reduced by as much as 40 times by using SS-H2.

That is the kind of number that gets industry attention.

Lower-cost materials do more than shave money off equipment bills. They can also change whether a project gets built, how quickly capacity expands, and whether green hydrogen can compete with more carbon-intensive alternatives. In that sense, the significance of SS-H2 goes beyond metallurgy. It touches the larger question of whether hydrogen can move from promising technology to routine industrial practice.

Professor Huang said the work has already moved beyond the lab bench.

“From experimental materials to real products, such as meshes and foams, for water electrolyzers, there are still challenging tasks at hand. Currently, we have made a big step toward industrialization. Tons of SS-H2-based wire has been produced in collaboration with a factory from the Mainland. We are moving forward in applying the more economical SS-H2 in hydrogen production from renewable sources,” he said.

That statement suggests the effort is entering a more practical phase, where success depends not just on scientific performance but on manufacturing, scaling, and product design.

A cheaper, longer-lasting material for green hydrogen production could ripple through a long list of industries that already depend on hydrogen or are expected to use more of it in the future.

Ammonia production is one of the clearest examples. Hydrogen is essential in making ammonia, which is widely used in fertilizers and industrial chemicals. If that hydrogen comes from renewable-powered water splitting instead of fossil fuels, the climate impact changes dramatically.

Oil refining is another major use. Hydrogen helps remove sulfur from fuels, and switching that supply to green hydrogen would reduce emissions tied to the refining process.

Steelmaking is also on the list. Hydrogen-based direct reduction of iron ore is widely seen as one of the more promising routes for cutting emissions in a sector that has been notoriously difficult to decarbonize.

Methanol production could benefit too. Green hydrogen can support lower-emission methanol used in transportation and power generation.

Some major companies are already working hydrogen into their strategies. The source material points to Shell, Linde, and Bloom Energy as examples. Shell is pursuing large-scale green hydrogen projects around the world, while Linde is developing hydrogen technologies across a range of markets.

If a material such as SS-H2 lowers costs enough, those kinds of efforts could become easier to expand.

Stainless steel has depended on chromium for corrosion resistance for a long time, but that protection has limits. In highly oxidative conditions, even advanced grades such as 254SMO can suffer what researchers describe as transpassive corrosion at high potentials.

SS-H2 is presented as a way around that weakness.

The team says its manganese-based layer forms above the chromium layer, helping shield the material in chloride-rich environments that would otherwise speed degradation. That two-layer defense is what gives the new steel its unusual resilience and what makes it especially relevant for harsh electrolysis conditions.

The work also fits a broader pattern in Huang’s research. The source material notes that he previously led work on anti-COVID-19 stainless steel in 2021 and had earlier developed ultra-strong Super Steel. In that sense, SS-H2 is part of a longer push to use materials science to solve practical, large-scale problems.

This time, the target is not public health or structural strength. It is the infrastructure of cleaner energy.

If SS-H2 performs in industry the way it has in development, the biggest effect may be simple: cheaper hydrogen systems that last longer. That could lower maintenance demands, reduce reliance on titanium and precious metal coatings, and make large electrolysis projects easier to justify financially.

The seawater performance is another important piece. A material that can function under those conditions opens room for hydrogen production linked more directly to ocean resources, rather than depending only on freshwater-compatible systems.

For industries like ammonia, refining, steel, and methanol, the value is practical rather than abstract. A better materials platform could help move green hydrogen from a high-cost climate solution toward something closer to routine industrial supply. The research does not solve every challenge tied to hydrogen, but it pushes on one of the most stubborn ones: the hardware itself.