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The effect of the Pt shell thickness on the oxygen reduction reaction (ORR) of a Pd@Pt core-shell catalyst was studied using surface science technics and computational approaches. We found Pt shells on Pd rods to be negatively charged because of charge transfer from the Pd substrate when the shell thicknesses were 0.5 or 1 monolayer (ML). The activities of the ORR of the model surface with a Pt shell of 0.5 or 1 ML were similar and more than twice the activities of a Pt/C or Pt rod. The relationship between the ORR activity and the thickness of the Pt shell was the exact opposite of the relationship between the Pt binding energy and the Pt shell thickness. The indication was that more negatively charged Pt had higher ORR activity. Density functional theory calculations confirmed that a single layer of Pt atoms located on Pd was negatively charged compared to pure Pt and resulted in a lower barrier to the rate-limiting step of the ORR.

Ammonia decomposition on Ru/MgO was strongly affected by the pore structure of the MgO support. We found that highly active Ru/MgO catalysts were successfully prepared by using Ru hydroxide and hyd...

A flow manufacturing process was investigated for the synthesis of Pd@Pt core-shell nanoparticles (NPs) with high productivity and exact structural control. Pd@Pt core-shell NPs were successfully synthesized in a flow reactor using polyvinylpyrrolidone (PVP) as a capping agent. However, the oxygen reduction reaction (ORR) activity of the Pd@Pt/PVP/C catalyst was found to be significantly lower than that of commercial Pt/C as the remaining PVP inhibited ORR. In order to improve ORR activity, it is necessary to support the highly dispersed Pd@Pt NPs on activated carbon without the use of PVP. Cyclic voltammetry, transmission electron microscopy, and X-ray absorption fine structure analyses showed that Pd@Pt NPs could be uniformly dispersed on activated carbon by adding bis(2-methoxyethyl) ether (diglyme) as a capping agent. The particle size and core-shell structure of the Pd@Pt NPs did not differ significantly between the NPs synthesized with PVP or diglyme, indicating that advanced structural control was possible without PVP. Furthermore, the mass activity per Pt weight of the Pd@Pt/C catalyst using diglyme was found to be 1.8-fold higher than that of Pt/C. We thus succeeded in synthesizing Pd@Pt core-shell NPs with precisely controlled structure and high ORR activity by flow process.

Carbon supported Pd@Pt core-shell nanoparticles catalyst was prepared in a flow reactor toachieve enhanced catalytic activities with low Pt loading for the acceptorless dehydrogenative synthesis of pyrimidines. Spectroscopic (XAS analysis) and microscopic (HAADF-STEM) techniques reveled that the core-shell structure was formed by the applied preparation method. The Pd@Pt/PVP (polyvinylpyrrolidone)/C catalyst showed the activity for the three component one pot synthesis of pyrimidines through a series of consecutive reactions including oxidation of alcohols, C C, and C N coupling, followed by heterocyclization and dehydrogenation employing various primary alcohols, secondary alcohols, and amidines. The reaction mechanism on Pd@Pt/PVP/C catalyst was explored by comparison with the control experiments.

The asymmetric hydrogenation of pyrimidines proceeded with high enantioselectivity (up to 99% ee) using an iridium catalyst composed of [IrCl(cod)]2, a ferrocene-containing chiral diphosphine ligand (Josiphos), iodine, and Yb(OTf)3 (cod = 1,5-cyclooctadiene). The chiral catalyst converted various 4-substituted pyrimidines into chiral 1,4,5,6-tetrahydropyrimidines in high yield. The lanthanide triflate is crucial for achieving the high enantioselectivity as well as for activating the heteroarene substrate.

The asymmetric hydrogenation of pyrimidines proceeds with high enantioselectivity using an iridium catalyst composed of [IrCl(cod)]2, a ferrocene-containing chiral diphosphine ligand (Josiphos), iodine, and Yb(OTf)3.