The present invention concerns a photocatalytic system comprising or consisting of: a titanium-based metal-organic framework MOF based on or including a single ligand type or a plurality of different ligand types for generating photo-generated charge carriers upon irradiation; and a co-catalyst to thwart recombination of the photo-generated charge carriers and allow electrons to drive a chemical reaction, wherein the titanium-based metal-organic framework (MOF) and the co- catalyst are bound together by Van der Waals bonding or weak electrostatic bonds.