Spectroscopic Studies of Light-driven Water Oxidation Catalyzed by Polyoxometalates

This review is focused on the spectroscopic studies of the charge transfer dynamics in polyoxometalate (POM)-catalyzed artificial photodriven water oxidation systems. We first describe the general challenges in solar fuel production, showing that water oxidation catalysts (WOCs) are of central importance. After the introduction of a new class of highly efficient WOCs based on all-inorganic polyoxometalates, we summarize the performance of these WOCs in homogeneous water oxidation systems. We show that the individual steps involved in the overall light-driven water oxidation reaction can be investigated by spectroscopic techniques (fluorescence quenching, transient absorption, and stopped flow). These studies provide important insight into the factors that limit the overall conversion efficiency in these systems and suggest possible approaches for improving these devices.