Boosting Efficiency in Light‐Driven Water Splitting by Dynamic Irradiation through Synchronizing Reaction and Transport Processes**

Abstract

This work elaborates the effect of dynamic irradiation on lightdriven molecular water oxidation to counteract deactivation. It highlights the importance of overall reaction engineering to overcome limiting factors in artificial photosynthesis reactions. Systematic investigation of a homogeneous 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.

Poly(dehydroalanine)‐Based Hydrogels as Efficient Soft Matter Matrices for Light‐Driven Catalysis

“…[77,78] Under photocatalytic OER conditions with Na 2 S 2 O 8 as an electron acceptor, very fast and efficient degradation of the PS by the attack of reactive sulfate species has recently been proposed as a key deactivation pathway. [79] To see the effect of PDha PEG2 hydrogel on the decomposition of photosensitizer and O 2 production during a longer period, we kept tracking the evolved O 2 amount of the sample having 5 μm Co 4 POM and 100 μm [Ru(bpy) 3 ] 2+ for 27 days. Figure 4b shows the difference in the O 2 production rate of a comparative sample in solution and within a hydrogel.…”

Enhancing Photocatalysis: Understanding the Mechanistic Diversity in Photocatalysts Modified with Single‐Atom Catalytic Sites

“…For practical applications, operational stability issues should be addressed by engineering efforts to achieve process intensification using optimized operational parameters and photoreactor designs. [ 33 ]…”

Rationalizing In Situ Active Repair in Hydrogen Evolution Photocatalysis via Non‐Invasive Raman Spectroscopy

“…Optical analysis methods offer an interesting alternative, as they potentially enable rapid and non‐invasive diagnostics even in small sample volumes. Such optical sensors based on luminescence quenching are already in use for non‐invasive oxygen monitoring [32–37] . Schiel et al [38] .…”

“…Such optical sensors based on luminescence quenching are already in use for non-invasive oxygen monitoring. [32][33][34][35][36][37] Schiel et al [38] introduced rotational Raman spectroscopy as a possible strategy for monitoring and evaluating a variety of gases. Recently, Schwarz et al [39] described a device applied for the detection of H 2 and O 2 gas in a prototypic photocatalytic process employing rotational Raman spectroscopy confirmed as an in situ identification and quantification method for application times up to 8 h. Next to the inherent molecular selectivity, this technology facilitates non-invasive direct analysis, as especially demanded in photocatalytic micro-environments.…”