Saving Platinum in Hydrogen Production

Saving Platinum in Hydrogen Production

Hydrogen is expected to become an important energy carrier of the future, particularly for industrial applications. But this requires climate-friendly technologies that split water into hydrogen and oxygen. One major challenge is cost: PEM water electrolysis requires components that can withstand highly corrosive conditions. Some of these components are coated with platinum.

Experiments at TU Wien have now taken a closer look at the electrochemical processes occurring in such platinum coatings. The results show that, if the coating is designed correctly, significantly less platinum is needed than is commonly used today. This could make electrolysis noticeably less expensive.

Splitting Water with Electricity

The basic principle of water electrolysis is simple: electrical current is used to split water molecules. At one electrode, oxygen molecules (O₂), positively charged hydrogen ions (protons), and electrons are produced. The protons migrate through a membrane to the second electrode, where they combine with electrons to form hydrogen molecules (H₂).

The technical implementation, however, is more complicated. "Electrolysis creates a chemical environment that is damaging to many metallic components. Metal can dissolve, while oxide layers can form at the same time and impede the flow of electric current," explains Helmut Riedl-Tragenreif from the Institute of Materials Science and Technology at TU Wien. "If the system is to remain operational for a long time, the different components have to be carefully matched to one another. Bipolar plates play a particularly important role here, accounting for up to 30 percent of total system costs."

These plates perform several functions at once: They provide mechanical stability, conduct electric current, and enable the transport of water and gases. Titanium is well suited for this purpose because it is highly resistant to corrosion even under aggressive conditions. However, an oxide layer forms on the titanium surface, and this layer impedes the flow of current.

For this reason, such bipolar plates are coated with a thin layer of platinum. The platinum conducts electricity, is corrosion-resistant, and protects the titanium underneath. Until now, however, one important question remained open: How thick does this platinum layer actually need to be?

This was systematically investigated at TU Wien. The result is surprising: Under the conditions studied, a platinum layer just 24 nanometers thick proved sufficient. At a thickness of eight nanometers, by contrast, clear problems occurred.

Compared with a 200-nanometer coating of the kind currently used in industry, this means that around 88 percent of the platinum used for the protective layer could potentially be saved. "Today, platinum coatings several hundred nanometers thick are often used. Our results show just how large the potential for savings is," says Riedl-Tragenreif. Platin sparen

A Self-Destructive Vicious Cycle

To demonstrate this, it is not enough simply to produce a coating that initially works. It is also necessary to investigate how resistant it remains under aggressive operating conditions. "We analyzed the coatings before and after electrochemical stress using high-resolution methods," says Riedl-Tragenreif. "One particularly important question is whether microscopic defects develop in the coating."

Such defects can trigger a vicious cycle: If the protective platinum layer is damaged at one point, the titanium underneath can be attacked. The titanium oxidizes, and small oxygen bubbles may also form at the interface. This can generate mechanical stresses and further damage the platinum coating. Larger sections of the coating may detach, exposing even more titanium - and the process accelerates.

For the eight-nanometer platinum layer, the researchers indeed found clear indications of such damage: After electrochemical stress, the coating showed larger defects, while significantly more titanium and platinum ions were released into the electrolyte.

The 24-nanometer coating, by contrast, remained largely intact under the conditions studied and retained its good electrical conductivity. The release of metal ions could be kept at a very low level.

"Which coating thickness is truly optimal depends on many factors, including the manufacturing technique and the uniformity of the coating. But what we have clearly shown is that there is considerable potential to reduce platinum consumption in electrolyzers. From a materials-science perspective, the coating thicknesses commonly used today are not necessarily required," says Riedl-Tragenreif.

Original publication

A. Glitschthaler et al., Toward Low-Pt PEMWE Components: Determining the Minimum Thickness of Pt Protection Coatings on Titanium BPP, ACS Applied Materials & Interfaces, 18,33 (2026)., opens an external URL in a new window

Contact

Prof. Helmut Riedl-Tragenreif
Institute of Materials Science and Technology
TU Wien
+43 1 58801 30865
helmut.riedl@tuwien.ac.at