“…5,6 Using natural photosynthesis as a blueprint, in articial photosynthesis employing photo(electro)chemical devices for solar energy conversion and storage, there is an increasing interest in the use of light absorbing molecules or semiconductors coupled to molecular catalysts, as they provide a unique and tuneable active site that can also be mechanistically investigated. [7][8][9][10] In these systems, much progress has been made in understanding and optimising light absorption and charge separation, [11][12][13][14][15] but rather little is known about the mechanism of function of the catalysts within such systems. [16][17][18][19][20][21] The mechanism of catalysts in articial photosynthetic devices is usually not well understood, in particular because of the difficulty in characterising the reactive intermediates involved and the kinetics of the individual steps of the catalytic mechanism.…”