Water-Based Synthesis of Ultrasmall Nanoparticles of PlatinumGroup Metal Oxides (1.8 nm) br

Ultrasmall nanoparticles of platinum group metal oxides (corediameter of about 1.8 nm) were prepared by alkaline hydrolysis of metal precursorsin the presence of NaBH4and by colloidal stabilization with tripeptide glutathione.We obtained water-dispersed nanoparticles of Rh2O3, PdO, RuO2, IrO2, Os/OsO2,and Pt/PtO. Their size was probed using high-resolution transmission electronmicroscopy, differential centrifugal sedimentation, small-angle X-ray scattering, anddiffusion-ordered1H NMR spectroscopy (1H DOSY). Their oxidation state wasclearly determined using X-ray photoelectron spectroscopy, X-ray powderdiffraction, and electron diffraction. The chemical composition of the nano-particles, that is, the ratio of the metal oxide core and glutathione capping agent, was quantitatively determined by a combination ofthese methods.