Effects of Photosensitizers and Reaction Media on Light-Driven Water Oxidation with Trinuclear Ruthenium Macrocycles

Photocatalytic water oxidation is a promising process for the production of solar fuels and the elucidation of factors that influence this process is of high significance. Thus, we have studied in detail light-driven water oxidation with a trinuclear Ru(bda) (bda: 2,2'-bipyridine-6,6'-dicarboxylate) macrocycle MC3 and its highly water soluble derivativem-CH2NMe2-MC3 using a series of ruthenium tris(bipyridine) complexes as photosensitizers under varied reaction conditions. Our investigations showed that the catalytic activities of these Ru macrocycles are significantly affected by the choice of photosensitizer (PS) and reaction media, in addition to buffer concentration, light intensity and concentration of the sensitizer. Our steady-state and transient spectroscopic studies revealed that the photocatalytic performance of trinuclear Ru(bda) macrocycles is not limited by their intrinsic catalytic activities but rather by the efficiency of photogeneration of oxidant PS(+)and its ability to act as an oxidizing agent to the catalysts as both are strongly dependent on the choice of photosensitizer and the amount of employed organic co-solvent.

Automated summary

The study revealed that the process of photocatalytic water oxidation is influenced by various factors such as the choice of photosensitizer, reaction media, buffer concentration, light intensity, and sensitizer concentration. The catalytic activities of Ru macrocycles are not only limited by their intrinsic catalytic activities, but also by the efficiency of photogeneration of oxidant PS(+) and its ability to act as an oxidizing agent to the catalysts, both of which strongly depend on the choice of photosensitizer and the amount of employed organic co-solvent.