Scientists from Leiden University and the SLAC National Laboratory have finally uncovered why platinum electrodes corrode under certain conditions, a problem that has puzzled researchers for decades.
This discovery could lead to more efficient green hydrogen production and better electrochemical sensors.
The study was published in Nature Materials.
Platinum is often used in electrolyzers and other electrochemical devices due to its durability and stability.
These devices rely on platinum electrodes that are negatively polarized and submerged in an electrolyte, a saltwater-like solution.
However, despite its reputation as a stable metal, platinum can corrode rapidly in this environment, raising questions about what causes this breakdown.
“Even though platinum is quite stable, it can still degrade significantly,” explains Dimosthenis Sokaras, a senior scientist at SLAC.
Under very negative conditions, a piece of platinum can dissolve in just minutes. This poses a major challenge for industries that rely on platinum-based devices.
Two main theories have been proposed over the years:
- Sodium ions from the electrolyte: Some researchers believed these ions pushed into the platinum’s atomic structure, forming “platinides” (platinum atoms attached to sodium ions) that caused corrosion.
- Sodium and hydrogen ions working together: Others suggested that hydrogen ions, or protons, combined with sodium ions to produce “platinum hydrides,” which destabilize the electrode.
To solve this mystery, the researchers needed to watch platinum corrode in real-time while it was submerged in an electrolyte and producing hydrogen. Using the Stanford Synchrotron Radiation Lightsource (SSRL) at SLAC, they developed advanced X-ray spectroscopy techniques to observe these changes at the atomic level.
The team also created a specialized pump and “flow cell” to remove hydrogen bubbles that could interfere with their experiments. This allowed them to track subtle changes on the surface of the platinum electrode as it corroded.
After years of work, the team confirmed that platinum hydrides—structures formed when hydrogen ions penetrate the platinum lattice—are responsible for the corrosion. They used computational models to simulate the X-ray spectra of platinum hydrides and platinides, comparing these to their experimental data. Only platinum hydrides matched the results.
This discovery not only explains why platinum corrodes but also opens the door to designing better materials and devices. “This project shows how important it is to combine expertise from different fields,” says Marc Koper, a professor at Leiden University.
By understanding the cause of platinum corrosion, scientists can now work on solutions to improve the reliability and efficiency of technologies like electrolyzers, paving the way for more sustainable energy systems.
