The Emergence of 2D Building Units in Metal‐Organic Frameworks for Photocatalytic Hydrogen Evolution: A Case Study with COK‐47

Metal-organic frameworks (MOFs) are promising materials for photocatalytic water splitting reactions, but examples of visible light-responsive, catalytically active, and stable MOFs still rare. A detailed investigation is conducted COK-47 – a recently described MOF comprising 2D Ti-O6 secondary building units (SBUs) toward hydrogen evolution reaction (HER), showing how overall particle morphology, surface area, missing ligand defects central parameters governing the material's ultimate performance. The newly synthesized COK-47ISO among most active to date, yielding HER-rates 8.6 µmol h−1, an apparent quantum yield (AQY) 0.5% under light illumination. Optoelectronic photoluminescence investigations, supported by theoretical calculations, enable unraveling its electronic structure along with charge transfer recombination kinetics. wavelength-dependent mechanism proposed involving metal (LMCT) main challenges or UV photoexcitation identified, demonstrating that unique layered aids separation key high This work introduces as alternative well-known MIL-125 family offers directions future studies