At Hamburg's PETRA III X-ray source, a platinum surface was caught aging in real time—atoms oxidizing under electrical voltage as researchers watched the precise moment a catalyst began losing its power.
This discovery matters because platinum catalysts are the workhorses of two technologies essential to the energy transition: electrolysers, which produce hydrogen from water, and fuel cells, which generate electricity from hydrogen. Both offer proven solutions for storing and transporting renewable energy. But there's a persistent problem. Under the high voltages these devices require to operate, platinum catalysts gradually degrade—their performance declining as if they're slowly wearing out. The faster this degradation happens, the more expensive these hydrogen technologies become, and the less viable they are as alternatives to fossil fuels.
For the first time, an international research team led by scientists at DESY has directly observed how this degradation occurs. Using advanced X-ray techniques at PETRA III, researchers including Leon Jacobse, Andreas Stierle, and Vedran Vonk watched as a thin oxide layer formed on a platinum surface under realistic operating conditions. The team combined three complementary X-ray methods simultaneously—measuring the atomic structure of the platinum surface, the thickness of the oxide layer, and its chemical composition all at once. This combination allowed them to track changes happening at the atomic scale while the chemical reaction was actively taking place, rather than examining an inert sample afterward.
The findings, published in Nature Communications, reveal a troubling trade-off. The oxide layer that forms actually protects the platinum from further material loss, which sounds beneficial. But this same layer makes the catalyst less efficient at its job. "We are seeing a balancing act between stability and activity," explains Andreas Stierle, a leading scientist at DESY and professor at the University of Hamburg. "Oxidation partially protects the platinum surface from further material loss, but at the same time makes the catalyst less efficient."
The researchers discovered that the oxidation process happens layer by layer, and at high voltages creates a disordered platinum oxide layer that compromises catalytic activity. Understanding exactly what happens at the atomic level is crucial for developing strategies to slow or prevent this degradation. As Vedran Vonk notes, "Only by understanding the tiny processes occurring at the level of platinum atoms can researchers develop new strategies to counteract degradation."
The implications extend beyond hydrogen technology. Similar aging effects plague battery technologies and other electrochemical processes, meaning these findings could help improve multiple clean energy systems simultaneously. In future work, the research team plans to investigate how catalyst materials closer to real-world applications—such as platinum nanoparticles rather than flat surfaces—change during actual operation.
By developing more durable catalysts, researchers could create electrolysers and fuel cells that last longer and cost less, removing a significant barrier to hydrogen's role in the global energy transition. This atomic-scale understanding is the foundation for building the more efficient, economically viable hydrogen technologies the world needs.