Advances in Electrocatalyzed Water Oxidation by Molecular Complexes of First Row Transition Metals

Energy transition toward sustainable, alternative, and affordable solutions is likely to be one of the major challenges of the anthropocene era. The oxygen evolution reaction (OER) is a pivotal electrocatalytic process essential for advancing renewable energy conversion and storage technologies, including water splitting, artificial photosynthesis, metal-air batteries, and fuel cells. Electrocatalytic pathways can significantly reduce the overall energy requirements of these devices, particularly focusing on the energy demands associated with water splitting for hydrogen production. This review, after introducing the state of the art in heterogeneous catalysis, will be devoted to the description of molecular water oxidation electrocatalysts (MWOCs), focusing on the recent advancements on catalysts composed of various metals, including Mn, Co, Cu, Ni, and Fe, in combination with a range of mono- and multidentate ligands. Critical insights are presented and discussed to provide readers with suggestions for ligand design in assisted catalysis. These observations aim to identify synergistic solutions that could enhance technological maturity by reducing energy absorption while improving stability and efficiency.