In the PH2OTOGEN project, one of our key focus areas is the optimisation of transparent, porous, conductive photocatalyst supports that electronically couple the hydrogen evolving and oxidizing particles. These fluorine-doped tin oxide coated quartz felts were first developed in an earlier European project Sun-To-X (Adv. Mater. 2023, 35, 2208740). In PH2OTOGEN, we are further developing them to improve their robustness and the scalability of the manufacturing process.
Improving robustness of the porous photocatalyst support
By optimising factors such as loading, density, and annealing temperature, we have substantially improved the mechanical performance of the porous photocatalyst supports.
Key results include:
- The Young’s modulus, which measures the stiffness of the material, has increased from 0.2 GPa to 0.75 GPa.
- The maximum weight a standard test-sized sample of the support can bear has risen dramatically from 25 grams to 135 grams.
These improvements mean the supports are now far more robust and able to withstand the demands of the photocatalyst deposition without compromising their effectiveness.
To achieve this, we optimised key factors such as the density of the material, the amount of photocatalyst loaded onto the support , and the temperature used during heat treatment (annealing). We are also testing additional strategies to make the supports even stronger, including:
- Adding internal or external structural reinforcements.
- Doping the material with specific elements to enhance its properties.
- Combining different types of fibres for added strength and stability.
Scaling Up Production
While developing a durable support is essential, scaling up the production of the support for real-world applications is equally critical. In a collaboration between EPFL and Solaronix, we’ve made significant progress in creating larger-area supports that retain high-performance specifications.
A final step in the support fabrication is the coating with a material called fluorine-doped tin oxide (FTO), which is essential for conducting electricity within the system. Recent achievements include:
- Successfully producing FTO-coated porous supports with a diameter of 7.5 cm, a significant step toward scaling up the technology.
- Achieving a sheet resistivity of 12–15 ohms/sq, which ensures efficient electrical conductivity.
However, challenges remain, particularly in ensuring the coatings are uniform on both sides of the support. Our teams are actively working to address this, refining the production process to achieve consistent quality at larger scales.
What’s Next?
These advancements in robustness and scalability bring us closer to realising PH2OTOGEN’s mission: creating an efficient, durable, and scalable system for green hydrogen production. By improving the strength and size of the photocatalyst supports, we are laying the groundwork for systems that can operate reliably in larger, real-world applications.
As we continue to refine these materials and techniques, we are excited about the potential to contribute to a more sustainable and economically viable hydrogen economy.
Stay tuned for more updates in our upcoming newsletters!
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Kevin Sivula
Professor of Chemical Engineering at EPFL