Recent Advances in First-Row Transition Metal Clusters for Photocatalytic Water Splitting

Water splitting based on first-row transition metal (3d) photocatalysts is a cost-effective technology for the conversion of abundant solar energy into useful energy on a large scale. The catalytic core of photosynthetic enzymes is a cubic CaMn4O5 cluster. Illuminated by natural photosynthesis, artificial solar water splitting photocatalysts composed of metal clusters are now being designed and tested. Ideally, such photocatalysts composed of atomically precise metal clusters with regular crystal structures are promising model catalysts that can be used to study structure-performance relationships. Recent advances based on metal cluster designs have improved our understanding of photoinduced charge separation and catalytic water redox reactions. This Minireview summarizes the recent advances in 3d metal cluster photocatalysts with well-defined structures for photocatalytic water splitting and focuses on different clusters with tunable structures that are capable of achieving better photocatalytic properties.