The size effect in the hydrogen production from formic acid decomposition has been investigated using a series of carbonsupported Pd NPs with different particle sizes ranging from 2.7 to 5.5 nm. A volcano type relationship between catalytic activity and NPs size was obtained. This result suggests that there is an optimum relative proportion of low-and high-coordination surface atoms within a regular arrangement of the Pd NPs, which was achieved at 3.9 nm in diameter under the present experimental conditions. By performing calculations on the pal-ladium crystallites, decomposition of formic acid is considered as a structure-sensitive reaction, and high-coordination sites principally act as catalytically active species in this size range. Kinetic isotope effect using HCOOD and DCOOH was well corresponded to the catalytic tendency. A k H /k D value obtained with Pd/C with optimal size was smallest among investigated, indicating the positive promoting effect in the rate-determining CÀH bond dissociation step from the Pd-formate intermediate.[a] Dr.

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A screening of carbon-supported PdAg nanoparticles (NPs) (PdAg/C) in the H 2 production from formic acid (FA) dehydrogenation was carried out by using uniform ~3-5 nm PdAg alloy NPs with a wide compositional range in terms of PVP/Metal and Pd/Ag ratios. The evaluation of the catalytic performance combined with the detailed characterization indicated the beneficial effect of the Ag incorporation and also revealed that the best performance achieved by Pd1Ag2/C (PVP/metal = 1) can be ascribed to its optimum composition and electronic features.

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