Application of a Water-Soluble Matrix-Stabilized Palladium Nanoparticle Catalyst for Photocatalytic Hydrogen Generation with High Activity and Stability

Pd@(BiPy-PEG-OMe) is a catalyst comprised of palladium nanoparticles (Pd-NPs) stabilized and made water soluble by 2,2′-bipyridine-end-functionalized polyethylene glycol monomethyl ether (BiPy-PEG-OMe). The catalyst has been used in the past for nitrile hydrogenation. In this work, we prove that it is also very active for photocatalytic hydrogen generation, which might be true for more catalysts of its kind and therefore worthy of further investigation. Using the inexpensive photosensitizer Eosin Y, high turnover numbers (TONs) of over 4 500 were achieved for the evolution of molecular hydrogen from pure water under visible-light irradiation. Replacing Eosin Y, which showed only a short lifetime under experimental conditions (i.e. a few hours), by a novel osmium-based metal complex, which is also characterized by its crystal structure, the longevity of the system can be boosted to over one and a half months with a maximum TON of 1 500. Combining excellent yield and stability is a clear goal for further research.