Grain boundary mediated hydriding phase transformations in individual polycrystalline metal nanoparticles

Abstract

Grain boundaries separate crystallites in solids and influence material properties, as widely documented for bulk materials. In nanomaterials, however, investigations of grain boundaries are very challenging and just beginning. Here, we report the systematic mapping of the role of grain boundaries in the hydrogenation phase transformation in individual Pd nanoparticles. Employing multichannel single-particle plasmonic nanospectroscopy, we observe large variation in particle-specific hydride-formation pressure, which is absent in hydride decomposition. Transmission Kikuchi diffraction suggests direct correlation between length and type of grain boundaries and hydride-formation pressure. This correlation is consistent with tensile lattice strain induced by hydrogen localized near grain boundaries as the dominant factor controlling the phase transition during hydrogen absorption. In contrast, such correlation is absent for hydride decomposition, suggesting a different phase-transition pathway. In a wider context, our experimental setup represents a powerful platform to unravel microstructure–function correlations at the individual-nanoparticle level.

Flickering nanometre-scale disorder in a crystal lattice tracked by plasmonic flare light emission

“…While the effects of Au adatoms are seen in UHV at low temperatures in scanning tunnelling microscopy (STM) 28,29 , as well as recently in the optics 18 of plasmonic gaps, defect planes ( Fig. 1b) are also prevalent in these nanoparticles 30 . Even at temperatures well below their melting point, nanoparticles can fluctuate between different microstructures 31 , while detailed quasi-molten models indicate near-surface atoms are much more mobile than bulk atoms.…”

Atomistic modeling and analysis of hydride phase transformation in palladium nanoparticles

“…Larger nanoparticle sizes also promote decomposition into grains separated by grain boundaries. Under those conditions, grain boundaries are known to mediate hydrogenation and to influence the storage characteristics of individual nanoparticles [61]. These and other trade-offs suggest themselves as worthwhile directions for further study.…”

Resolving single Cu nanoparticle oxidation and Kirkendall void formation with in situ plasmonic nanospectroscopy and electrodynamic simulations

“…To this end, we have recently introduced single particle plasmonic nanospectroscopy, which enables in situ real time characterization of multiple individual nanoparticles at identical experimental conditions and the direct correlation of the obtained response with the particle nanostructure obtained from post mortem electron microscopy analysis. 21 Here we demonstrate how this approach, in combination with detailed Finite-Difference Time-Domain (FDTD) electrodynamics simulations, can be applied to quantitatively monitor the oxidation process of individual Cu nanoparticles at high temperature in the gas phase without interfering with the kinetics, and how it enables the real time identification of the oxidation mechanism both in the initial oxide shell growth phase and during Kirkendall void formation.…”

“…Single particle plasmonic nanospectroscopy measures the spectral characteristics of the LSPR scattering peak of multiple individual metal nanoparticles by means of dark-field scattering spectroscopy, 21 and how it responds due to changes in and around the particles. For the case of Cu, this is very effective because in the metallic state, like the other coinage metals, it exhibits distinct LSPR at visible frequencies.…”