Photosynthesis has been for many years a fascinating source of inspiration for the development of model systems able to achieve efficient light‐to‐chemical energetic transduction. This field of research, called “artificial photosynthesis,” is currently the subject of intense interest, driven by the aim of converting solar energy into the carbon‐free fuel hydrogen through the light‐driven water splitting. In this review, we highlight the recent achievements on light‐driven water oxidation and hydrogen production by molecular catalysts and we shed light on the perspectives in terms of implementation into water splitting technological devices.

The search for efficient noble metal-free hydrogen-evolving catalysts is the subject of intense research activity. A new family of molecular cobalt(II)-polypyridyl catalysts has recently emerged. These catalysts prove more robust under reductive conditions than other cobalt-based systems and display high activities under fully aqueous conditions. This review discusses the design, characterization, and evaluation of these catalysts for electrocatalytic and light-driven hydrogen production. Mechanistic considerations are addressed and structure-catalytic activity relationships identified in order to guide the future design of more efficient catalytic systems.

The π-extended ligand of a ruthenium complex stores two photo-generated electrons, mimicking a key step in photosynthesis.