Scientists from Leiden University and the Department of Energy’s SLAC National Laboratory have revealed the mysterious cause behind the rapid corrosion of platinum electrodes, a problem that has perplexed researchers for decades. Published in the journal Nature Materials, the research paves the way for more affordable and reliable green hydrogen production and more effective electrochemical sensors, offering a solution to a long-standing challenge in material science.
The Mystery of Platinum Corrosion
Platinum, known for its exceptional durability and resistance to corrosion, is frequently used in electrolyzers and other electrochemical devices, often in the form of electrodes submerged in an electrolyte—a solution, often saltwater, that facilitates electrochemical reactions. While platinum is typically resistant to degradation, it has been a paradox for scientists: when negatively polarized, platinum electrodes can undergo rapid breakdown. This is a perplexing phenomenon, as for most metals, negative polarization is a protective measure against corrosion.
Dimosthenis Sokaras, a senior scientist at SLAC and the principal investigator for the SLAC team, explains that while platinum is quite stable, this does not mean it is impervious to degradation in these environments. In fact, prolonged exposure to certain conditions, particularly the negative polarization applied in devices like electrolyzers, accelerates the breakdown of the metal.
What Was Causing the Breakdown?
For years, researchers struggled to identify the precise cause of this rapid corrosion. Two leading theories dominated the conversation. One theory proposed that sodium ions from the electrolyte solution played a central role. According to this idea, sodium ions infiltrate platinum’s atomic lattice, forming compounds called platinides—platinum atoms carrying sodium ions. Over time, this interaction weakens the structure, causing platinum to peel away.
An alternative hypothesis focused on a similar process but with an added complexity: the interaction of hydrogen ions (protons) along with sodium ions. This theory suggested that the combination of these two types of ions created platinum hydrides, which may be the culprit behind the corrosion of the platinum electrodes.
Innovative Techniques to Observe Platinum Corrosion
In order to resolve the mystery, the research team needed a way to directly observe the platinum electrode during the electrochemical process, as it corroded and made hydrogen. This required advanced technology and a new experimental approach.
To tackle this, the team turned to the Stanford Synchrotron Radiation Lightsource (SSRL) at SLAC, which offers high-energy-resolution X-ray spectroscopy techniques. These techniques were key because they allowed the scientists to observe the platinum electrodes in operando—meaning during operation. This real-time observation of the platinum electrode, submerged in an electrolyte, was crucial for understanding the corrosion process.
SLAC scientist Thom Hersbach emphasized that high-energy-resolution X-ray absorption spectroscopy was the only viable method to analyze the platinum’s behavior under these specific experimental conditions. The team also developed a special pump and flow cell system that could clear the hydrogen bubbles that form during the reaction. These bubbles would otherwise obstruct the X-ray experiment by blocking the view of the platinum’s surface.
The Culprit: Platinum Hydrides
The results of the experiments confirmed the team’s hunch that platinum hydrides were indeed the cause of the corrosion. These platinum-hydrogen compounds, which form when platinum is exposed to a negative polarization in an electrolyte, contribute to the breakdown of the electrode. By closely examining the X-ray spectra from the platinum electrode’s surface, the team could track the structural changes in the platinum as it corroded.
Although the researchers had suspected hydrides to be responsible for the corrosion, it took several years of data analysis to definitively prove their hypothesis. As Hersbach put it, “It just took loads and loads of different iterations of trying to figure out ‘how do we accurately capture what’s going on?'”
Using computational models, the team simulated the expected X-ray spectra from both platinum hydrides and platinides under the same conditions. By comparing these simulations with the experimental results, they found that only platinum hydride could have produced the observed X-ray signatures.
A Major Scientific Breakthrough
This breakthrough in understanding platinum corrosion is significant not only for advancing materials science but also for improving the efficiency and longevity of electrochemical devices. Sokaras praised the importance of the SSRL’s advancements in X-ray science, stating, “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.”
The findings of this research offer valuable insights into how platinum corrosion occurs in electrolyzers, which are used in the production of green hydrogen—a sustainable energy source. The corrosion of platinum electrodes has been a significant barrier to making hydrogen production more cost-effective. By understanding the mechanisms at play, researchers can now work toward developing solutions to mitigate platinum degradation, leading to more reliable and affordable hydrogen production methods.
Moreover, these insights could also lead to the development of more durable platinum electrodes for other electrochemical devices, including sensors and batteries, which rely on similar materials. These devices are vital for various applications, from environmental monitoring to medical diagnostics, and improving their reliability and efficiency would have broad-reaching implications across multiple industries.
Collaboration and Expertise in Science
The success of this research highlights the importance of collaboration and interdisciplinary expertise. Marc Koper, Professor of Catalysis and Surface Chemistry at Leiden University, and the principal investigator for the Leiden team, emphasized the value of pooling knowledge from various fields of science. “This project shows how important it is in science to put a lot of expertise together,” he said.
By combining advanced spectroscopy techniques with computational modeling, the teams from SLAC and Leiden University were able to address a scientific puzzle that had remained unsolved for decades. The combination of experimental research, computational simulation, and cutting-edge X-ray technology proved to be the key to understanding the corrosion process.
Implications for the Future
The implications of this discovery extend far beyond the immediate issue of platinum corrosion in electrolyzers. Understanding the mechanisms behind this degradation opens up new avenues for improving the durability of platinum and other precious metals used in electrochemical applications. This could lead to cheaper, more efficient green hydrogen production technologies, which are crucial for achieving global sustainability goals and transitioning to cleaner energy sources.
The ability to extend the lifespan of electrochemical devices would also have a profound impact on a variety of industries. From sensors used in environmental monitoring to batteries that power everything from smartphones to electric vehicles, more reliable electrodes would increase the performance and affordability of these devices, driving innovation and making sustainable technologies more accessible to a wider population.
Conclusion
The recent research into platinum corrosion by scientists from Leiden University and SLAC National Laboratory represents a major step forward in the field of electrochemistry. By using high-energy-resolution X-ray spectroscopy to directly observe the corrosion process in real-time, they have uncovered the critical role of platinum hydrides in the degradation of platinum electrodes. This discovery not only sheds light on a decades-old mystery but also offers practical solutions for improving the efficiency and durability of electrochemical devices, including those used in green hydrogen production. With further development and refinement, this research holds the potential to revolutionize the way we produce and use energy, bringing us closer to a sustainable future.
Reference: Thomas J. P. Hersbach et al, Platinum hydride formation during cathodic corrosion in aqueous solutions, Nature Materials (2025). DOI: 10.1038/s41563-024-02080-y