| Apr 16, 2026 |
A new measurement method for photoelectrochemical cells enables real-time observation of material aging.
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(Nanowerk News) A research team at the Helmholtz-Zentrum Hereon has demonstrated how a classic technique can be repurposed to measure the material degradation of photoelectrodes in real time. This new method enables continuous and precise detection of subtle material losses. The technique can directly determine material degradation rates under realistic operating conditions.
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The researchers presented their innovation in the journal EES Solar (“Operando spectroscopic ellipsometry enables direct quantification of dynamic degradation rates in photoelectrochemical cells “).
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Photoelectrochemical devices can convert sunlight into valuable chemicals such as hydrogen, ethylene, or ammonia. However, their practical application has so far been limited by the fact that the materials used degrade — that is, corrode-during operation. The dynamics of this process are still poorly understood: How quickly does it progress, and what conditions influence it?
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The method of operando spectroscopic ellipsometry now provides a solution to these questions: for the first time, it enables the corrosion of photoelectrodes to be tracked in real time and with high precision. The technique measures minute changes in layer thickness — on the order of just a few nanometers — across the entire electrode surface while the device operates under varying electrochemical conditions and changing illumination.
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| Schematic diagram illustrating the principle of operando spectroscopic ellipsometry used as realtime measurement technique with a photoelectrochemical cell. (Image: Reproduced from DOI:10.1039/D5EL00179J, CC BY)
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Insights into dynamic degradation processes
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To demonstrate how the method detects material degradation in light-driven electrochemical components, the team focused on ultrathin layers of titanium dioxide. This material is widely used in energy technologies, such as in photoelectrodes for hydrogen production, in solar cells, and in photocatalytic systems. The researchers produced these layers with different internal structures and observed how they changed during operation under realistic conditions.
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This allowed them to determine that the material’s internal structure plays a crucial role. Disordered, amorphous layers degraded under sunlight about 14 times faster than well-ordered, crystalline layers, as they transport electrical charges less efficiently. By directly measuring these effects under realistic operating conditions, the measurement technique provides important insights for the development of more resilient systems.
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Satisfied Researchers
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“The ability to observe material changes in real time during operation opens up entirely new avenues for identifying degradation mechanisms before they become a problem,” says Prof Francesca Toma, director of the Hereon Institute of Functional Materials for Sustainability in Teltow, who plays a key role in developing the research concept. “This allows us not only to improve existing materials but also to develop new concepts more quickly that meet the future requirements for sustainable energy systems.”
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The new measurement method can also be applied to many other photoelectrochemical and electrocatalytic materials. Thus, the research makes an important contribution to the further development of sustainable energy technologies and supports the energy transition.
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Dr. Mauricio Schieda, one of the study’s lead authors, adds: “Greater stability means lower material consumption, reduced maintenance requirements, and lower overall costs. All of these are crucial prerequisites for the widespread adoption of light-driven energy conversion technologies.”
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