Platinum atomic layer deposition (ALD) using MeCpPtMe 3 was employed to prepare high loadings of uniformsized, 1-2 nm Pt nanoparticles on high surface area Al 2 O 3 , TiO 2 , and SrTiO 3 supports. X-ray absorption fine structure was utilized to monitor the changes in the Pt species during each step of the synthesis. The temperature, precursor exposure time, treatment gas, and number of ALD cycles were found to affect the Pt particle size and density. Lower-temperature MeCpPtMe 3 adsorption yielded smaller particles due to reduced thermal decomposition. A 300°C air treatment of the adsorbed MeCpPtMe 3 leads to PtO. In subsequent ALD cycles, the MeCpPtMe 3 reduces the PtO to metallic Pt in the ratio of one precursor molecule per PtO. A 200°C H 2 treatment of the adsorbed MeCpPtMe 3 leads to the formation of 1-2 nm, metallic Pt nanoparticles. During subsequent ALD cycles, MeCpPtMe 3 adsorbs on the support, which, upon reduction, yields additional Pt nanoparticles with a minimal increase in size of the previously formed nanoparticles. The catalysts produced by ALD had identical water-gas shift reaction rates and reaction kinetics to those of Pt catalysts prepared by standard solution methods. ALD synthesis of catalytic nanoparticles is an attractive method for preparing novel model and practical catalysts.

With an eye toward using surface morphology to enhance heterogeneous catalysis, Pt nanoparticles are grown by atomic layer deposition (ALD) on the surfaces of SrTiO(3) nanocubes. The size, dispersion, and chemical state of the Pt nanoparticles are controlled by the number of ALD growth cycles. The SrTiO(3) nanocubes average 60 nm on a side with {001} faces. The Pt loading increases linearly with Pt ALD cycles to a value of 1.1 x 10(-6) g cm(-2) after five cycles. Scanning electron microscopy images reveal discrete, well-dispersed Pt nanoparticles. Small- and wide-angle X-ray scattering show that the Pt nanoparticle spacing and size increase as the number of ALD cycles increases. X-ray absorption spectroscopy shows a progression from platinum(II) oxide to metallic platinum and a decrease in Pt--O bonding with an increase in Pt--Pt bonding as the number of ALD cycles increases.

Pt/SrTiO3 shows promise as a low temperature hydrocarbon combustion catalyst for automotive applications. In this study, SrTiO3 nanocuboid supports were synthesized using sol-precipitation coupled with hydrothermal synthesis, and platinum was deposited on the nanocuboids with 1, 3, and 5 cycles of atomic layer deposition (ALD). The platinum particles have a highly uniform distribution both before and after reaction testing, and range from 1 to 5 nm in size, depending upon the number of ALD cycles. These materials have a >50 °C lower light-off temperature for propane oxidation than a conventional Pt/Al2O3 catalyst, turn over frequencies up to 3 orders of magnitude higher, and show improved resistance to deactivation. The increased activity is attributed to the stabilization of a Pt/PtO core/shell structure during operating conditions by the strong epitaxy between the Pt and the SrTiO3 support.