Dendrimer-Encapsulated Pt Nanoparticles: An Artificial Enzyme for Hydrogen Production

Two series of dendrimer encapsulated Pt nanoparticles (DENPt) were created by using sixth generation poly(amidoamine) (PAMAM) dendrimers terminated with different numbers of hydroxyl groups (s-G6-OH and t-G6-OH) to mimic hydrogenases. Pt nanoparticles act as the active site to generate H2 by reducing H+, and dendrimers provide cavities to maintain the integrity of small Pt nanoparticles and prevent agglomeration. The artificial hydrogenases (t-G6-OH/Pt x and s-G6-OH/Pt x ) were successfully applied to a light-induced hydrogen production system with Pt-tppa+, ethyl viologen, and TEOA as photosensitizer, electron relay, and sacrificial reagent, respectively, exhibiting excellent stability and efficient catalytic activity. No passivation effect is caused by the periphery hydroxyl groups of dendrimers. The optimal size of the Pt clusters consists of 200 Pt atoms, and the most adapted pH value is 9 to gain the highest catalytic efficiency in the applied hydrogen production system. This study provides a new strategy for developing artificial hydrogenases by using dendritic architectures.