Hydrogen absorption in oxide-supported palladium nanocrystals

Abstract

Substantial hydrogen absorption in nanometer-sized palladium crystallites on a thin film alumina support is observed at 90-350 K under low H 2 pressure conditions ͑Ͻ2 ϫ 10 −3 Pa͒ by 1 H͑ 15 N,␣␥͒ 12 C nuclear reaction analysis. The enthalpy of H solution varies with the absorbed H content and with −͑0.28Ϯ 0.02͒ eV/ H exceeds that of bulk Pd at H / Pd ratios below 0.20. By resolving absorbed H from surface-adsorbed H, this enhanced H stability is identified as an intrinsic volume property of the small crystallites rather than being associated with particular binding sites on or near their surfaces.

Models in Catalysis

“…The former method (described in detail in Ref. [91]) was used to independently monitor the concentrations of the surface-adsorbed and subsurface (or volumeabsorbed) H species as a function of hydrogen pressure in the environment (Fig. 12).…”

“…The hypothesis was established that those two species are surface and subsurface hydrogen. Measurements of the concentrations of surface and subsurface H species by NRA for hydrogen depth profiling and complementary transient molecular beam experiments were combined to measure the reaction rates [83,91]. The former method (described in detail in Ref.…”

Dynamic structural change of Pd particles on LaFeO3under redox atmosphere and CO/NO catalytic reaction studied by dispersive XAFS

“…Gas-solid interaction in the metal fine particles has been widely studied from the viewpoint of the dependence of the mean particle size [23,24,25]. The small metal fine particles have many steps, edges and kinks, which induces the dissociative adsorption at the surface of particle.…”

Model Studies in Heterogeneous Catalysis

“…We have used resonant nuclear reaction analysis (r-NRA) to quantitatively determine the amount of surface versus sub-surface hydrogen in supported nanoparticles, and used that knowledge to prove the importance of the sub-surface species for the hydrogenation reaction. [26,44] One result is shown in Figure 6. Here we compare four traces in a set of molecular beam experiments.…”