Scientists from Leiden University and the Department of Energy's SLAC National Laboratory have discovered the unexplained source of platinum electrode corrosion, according to a study published in Nature Materials. This achievement paves the way for more cost-effective green hydrogen production and more dependable electrochemical sensors.
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Most metals are negatively polarised, which protects against corrosion. However, platinum electrodes degrade quickly under these conditions.
Electrolyzers and other electrochemical devices frequently rely on negatively polarized platinum electrodes submerged in an electrolyte, which is typically saltwater. Although platinum is an expensive but robust and typically stable material, it is not impervious to degradation in certain settings.
Being quite stable does not mean it does not degrade at all.
Dimosthenis Sokaras, Study Principal Investigator and Senior Scientist, SLAC National Accelerator Laboratory
What Compounds Are to Blame?
If you take a piece of platinum and you apply a very negative potential, you can dissolve your platinum in a matter of minutes.
Marc Koper, Study Principal Investigator and Professor, Leiden University
Two well-known ideas have attempted to explain this mechanism. Some researchers believed that the electrolyte solution's sodium ions were the cause. According to the theory, these ions forced their way into the atomic lattice of platinum, forming platinizes, which are platinum atoms that drag positively charged sodium ions around and then peel away. Others proposed a similar mechanism, but they blamed the production of platinum hydrides on the cooperation of sodium and hydrogen ions, or protons.
Observing Platinum Corrosion In Action
Since platinum was corroding an electrolyte and producing a lot of hydrogen, the study team understood they would need to detect it somehow. To do this, the scientists used the Stanford Synchrotron Radiation Lightsource at SLAC.
To focus on minute changes in the platinum electrode in operando or during operation, SLAC researchers have created high-energy-resolution X-ray spectroscopy techniques that penetrate the electrolyte and filter out extraneous effects.
For us, high-energy-resolution X-ray absorption spectroscopy was the only technique we could come up with that could sort of deal with the experimental conditions.
Thom Hersbach, Scientist, SLAC National Accelerator Laboratory
According to Sokaras, the group created a unique pump and “flow cell" that might eliminate hydrogen bubbles that emerge when the electrode is in use and obstruct the X-ray experiment.
Platinum Hydrides are the Culprit Behind the Corrosion
By combining those skills, the scientists recorded X-ray spectra from the surface of the negatively polarized electrode and made the first-ever observations of platinum actively corroding.
Before experimenting, the researchers suspected that hydrides caused the corrosion, but it took them years to analyze the data and validate this theory.
“It just took loads and loads of different iterations of trying to figure out “how do we accurately capture what's going on?” Hersbach added.
The researchers calculated the spectra they would anticipate seeing from each structure under the SSRL's X-ray beam using computer models of platinum hydrides and platinides. It was determined that only platinum hydride could have achieved their results by comparing the many simulated spectra with the outcomes of their experiment.
“By advancing the frontiers of X-ray science, SSRL has developed operando methods that, combined with modern supercomputing, now allow us to tackle decades-old scientific questions,” Sokaras added.
The team’s results can now be used to create solutions for platinum corrosion in electrolyzers and other electrochemical devices.
The project, Koper added, “shows how important in science it is to put a lot of expertise together.”
Journal Reference:
Hersbach, T. J. P., et al. (2025) Platinum hydride formation during cathodic corrosion in aqueous solutions. Nature Materials. doi.org/10.1038/s41563-024-02080-y.