Co‐Based Molecular Water Oxidation Catalysts: Structural Modulation and Ligand Engineering Strategies

Efficient catalysts for water oxidation are important in the development of artificial photosynthesis. Although noble metal catalysts show excellent catalytic performance and stability, their scarce availability and high cost have restricted their further practical application. Accordingly, Co‐based molecular catalysts are currently the focus of very intense research as highly appealing earth‐abundant alternatives. This review highlights a systematic consideration of their design principles, with emphasis on two major factors: nuclearity (mono‐, di‐, and multinuclear architectures) manipulation, and ligand engineering. The nuclearity dictates the catalytic framework, the degree of metal–metal cooperativity, and the catalytic mechanism. The ligands are intended to function as stabilizing high‐valent intermediates, promoting electron/proton transfer and thereby enhancing efficiency through fine electronic, steric, and redox‐active tuning. By connecting these features, this review establishes a consistent structure–activity relationship and offers perspectives on the design of robust and high‐performance Co‐based molecular catalysts for sustainable energy conversion.