Researchers at the University of Southampton have transformed optical fibers into photocatalytic microreactors that convert water into hydrogen fuel using solar energy. The technology combines, for the first time, microstructured optical fiber technology with photocatalysis, creating a photocatalytic microreactor coated with TiO₂, decorated with palladium nanoparticles. The microstructured optical fiber canes (MOFCs) with photocatalyst generate hydrogen that could power a wide range of sustainable applications.

The researchers have published their proof-of-concept in ACS Photonics and will now establish wider studies that demonstrate the scalability of the platform.

Computerized tomography of a MOFC, showing buildup of TiO₂ (light blue particles) in the triangular channels. Zepler Institute, University of Southampton.

The MOFCs have been developed as high pressure microfluidic reactors by each housing multiple capillaries that pass a chemical reaction along the length of the cane.

Alongside hydrogen generation from water, the multi-disciplinary research team is investigating photochemical conversion of carbon dioxide into synthetic fuel. The unique methodology presents a potentially feasible solution for renewable energy, the elimination of greenhouse gases and sustainable chemical production.

Being able to combine light-activated chemical processes with the excellent light propagation properties of optical fibers has huge potential. In this work our unique photoreactor shows significant improvements in activity compared to existing systems. This as an ideal example of chemical engineering for a 21^st century green technology.

—Dr Matthew Potter, Chemistry Research Fellow and lead author

Advances in optical fiber technology have played a major role in telecommunications, data storage and networking potential in recent years. This latest research involves experts from Southampton’s Optoelectronics Research Centre (ORC), part of the Zepler Institute for Photonics and Nanoelectronics, to tap into the fibers’ unprecedented control of light propagation.

The scientists coat the fibers with titanium oxide, decorated with palladium nanoparticles. This approach allows the coated canes to simultaneously serve as both host and catalyst for the continuous indirect water splitting, with methanol as a sacrificial reagent.

Optical fibers form the physical layer of the remarkable four billion kilometer long global telecommunications network, currently bifurcating and expanding at a rate of over Mach 20, i.e. over 14,000 ft/sec. For this project, we repurposed this extraordinary manufacturing capability using facilities here at the ORC, to fabricate highly scalable microreactors made from pure silica glass with ideal optical transparency properties for solar photocatalysis.

—Dr Pier Sazio, study co-author from the Zepler Institute

The research builds upon findings from the Engineering and Physical Sciences Research Council (EPRC)-funded Photonic fiber technologies for solar fuels catalysis (EP/N013883/1).

Resources

• Matthew E. Potter, Daniel J. Stewart, Alice E. Oakley, Richard P. Boardman, Tom Bradley, Pier J. A. Sazio, Robert Raja (2020) “Combining Photocatalysis and Optical Fiber Technology toward Improved Microreactor Design for Hydrogen Generation with Metallic Nanoparticles”, ACS Photonics doi: 10.1021/acsphotonics.9b01577