Introduction
Green hydrogen is considered one of the most important technologies for decarbonising industries such as steel, chemicals, shipping and heavy transport. Produced by splitting water using renewable electricity, green hydrogen offers a pathway towards cleaner fuels without direct carbon emissions.
However, scaling green hydrogen has a major challenge: the equipment required to produce it is expensive.
Electrolysers, which split water into hydrogen and oxygen, operate under highly demanding conditions involving high electrical potential, reactive chemicals and corrosion risks. Materials such as titanium, often coated with precious metals like platinum or gold, are used because conventional steel cannot survive these harsh environments.
Researchers at the University of Hong Kong (HKU) have developed a new stainless steel called SS-H₂ that could potentially replace expensive titanium components and significantly reduce the cost of hydrogen production systems.
Why Materials Matter in Hydrogen Production
At the heart of a hydrogen electrolyser is a simple reaction: electricity splits water molecules into hydrogen and oxygen.
However, the operating environment is far from simple. Components must withstand:
- High electrical voltages
- Oxygen-rich conditions
- Corrosive environments
- Long operating hours
In seawater-based electrolysis, the challenge becomes even greater because chloride ions can attack protective layers on metals and accelerate corrosion.
Today, expensive materials such as titanium are used because they can survive these conditions. But these materials increase the capital cost of electrolyser systems and make large-scale hydrogen production more difficult.
The Science Behind SS-H₂: A Self-Protecting Steel
The breakthrough from HKU comes from redesigning stainless steel at the atomic level.
Traditional stainless steel relies mainly on a chromium oxide layer that protects the surface from corrosion. However, this protective layer can fail at the high electrical potentials required for water oxidation.
The HKU researchers developed a sequential dual-passivation strategy. The new SS-H₂ material forms an additional protective manganese-based layer over the traditional chromium layer.
This dual protection allows the steel to survive electrochemical conditions up to around 1,700 millivolts, significantly beyond the limits of conventional stainless steel.
Why This Could Transform Green Hydrogen Economics
The cost of hydrogen electrolysers is not only determined by electricity and catalysts. Structural materials also contribute significantly to overall system costs.
According to researchers, replacing titanium-based structural components with SS-H₂ could reduce structural material costs by approximately 40 times.
Lower-cost materials could enable:
- Cheaper electrolyser manufacturing
- Greater adoption of seawater electrolysis
- Reduced dependence on expensive metals
- Faster deployment of green hydrogen projects
Could Seawater Become the Future Source of Hydrogen?
Most current green hydrogen systems use purified water because impurities in seawater can damage electrolyser components.
If corrosion-resistant materials like SS-H₂ become commercially available, direct seawater electrolysis could become more practical, especially in coastal regions with abundant renewable energy resources.
This could be particularly valuable for countries with large coastlines, including India, Australia and Middle Eastern nations investing heavily in renewable hydrogen.
Challenges Before Commercial Deployment
Although the discovery is promising, moving from laboratory success to industrial deployment will require further work.
Key challenges include:
- Testing long-term durability under commercial operating conditions
- Manufacturing SS-H₂ components at large scale
- Producing specialised forms such as meshes and foams used in electrolysers
- Ensuring cost advantages remain after industrial production
The researchers have already moved towards industrialisation, including producing SS-H₂-based wire with manufacturing partners.
What Investors Should Watch
The hydrogen economy will not only be built by hydrogen producers. It will depend on an ecosystem of advanced materials, manufacturing technologies and engineering solutions.
Investors should track opportunities in:
- Electrolyser manufacturing
- Advanced alloys and coatings
- Hydrogen storage systems
- Renewable energy integration
- Industrial decarbonisation technologies
The next breakthrough in clean energy may come not from a new fuel, but from a better material that makes existing technologies affordable.
The Future of Green Hydrogen
Green hydrogen has often been described as a technology waiting for cost reductions. Innovations like SS-H₂ show that reducing costs may require breakthroughs across the entire value chain, from electricity generation to catalysts, membranes and structural materials.
A stronger, cheaper steel may seem like a small engineering improvement, but it could become an important building block in making clean hydrogen a global reality.
References for further reading
- Economic Times — HKU scientists create steel that survives 1,700 mV in seawater for green hydrogen
- University of Hong Kong — Research on Stainless Steel for Hydrogen (SS-H₂)
- Materials Today — A sequential dual-passivation strategy for designing stainless steel used above water oxidation
- International Energy Agency (IEA) — Global Hydrogen Review
- International Renewable Energy Agency (IRENA) — Green Hydrogen Technology Reports
- Hydrogen Council — Hydrogen industry developments and investment trends
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