- Maximilian Sender University of Ulm ,
- Fabian Huber University of Ulm ,
- Maximilian Moersch University of Ulm ,
- Daniel Kowalczyk University of Ulm ,
- Julian Hniopek Leibniz Institute of Photonic Technology ,
- Sarah Klingler University of Ulm ,
- Michael Schmitt Friedrich Schiller University Jena ,
- Simon Kaufhold University of Ulm ,
- Kevin Siewerth University of Ulm ,
- Jürgen Popp Leibniz Institute of Photonic Technology ,
- Boris Mizaikoff University of Ulm ,
- Dirk Ziegenbalg University of Ulm ,
- Sven Rau University of Ulm
This work elaborates the effect of dynamic irradiation on light-driven molecular water oxidation to counteract catalyst deactivation. It highlights the importance of overall reaction engineering to overcome limiting factors in artificial photosynthesis reactions. Systematic investigation of a homogenous three component ruthenium-based water oxidation system revealed significant potential to enhance the overall catalytic efficiency by synchronizing the timescales of photoreaction and mass transport in a capillary flow reactor. The overall activity could be improved by a factor of more than 10 with respect to the turnover number and a factor of 31 referring to the external energy efficiency by controlling the local availability of photons. Detailed insights into the mechanism of light driven water oxidation could be obtained using complementary methods of investigation like Raman, IR and UV-vis/emission spectroscopy, unraveling the importance of avoiding high concentrations of excited photosensitizers.
The revised version was extended by comprehensive studies on the degradation of the photosensitizer. For this, additional spectroscopic studies, including UV/vis, Raman and IR spectroscopy, were conducted. These results clearly show that the degradation of the photosensitizer is the main cause for activity loss. Furthermore, it could be concluded that the degradation is accelerated by high light intensities that cause a high local concentration of sulfate radicals that oxidize the photosensitizer. With this, the working hypothesis that temporal changes of the irradiation intensities lead to long activity could be further strengthened and the link to mass transport effects became clearer. The manuscript was thoroughly revised to reflect these new insights.
Supporting Information to "Boosting efficiency in light-driven water splitting by dynamic irradiation through synchronizing reaction and transport processes"
Video: Mixing with custom made stirring bar
Video: Mixing with standard stirrbar