title: Direct visualization of hydrogen absorption dynamics in individual palladium nanoparticles.
abstract: Many energy storage materials undergo large volume changes during charging and discharging. The resulting stresses often lead to defect formation in the bulk, but less so in nanosized systems. Here, we capture in real time the mechanism of one such transformation-the hydrogenation of single-crystalline palladium nanocubes from 15 to 80 nm-to better understand the reason for this durability. First, using environmental scanning transmission electron microscopy, we monitor the hydrogen absorption process in real time with 3 nm resolution. Then, using dark-field imaging, we structurally examine the reaction intermediates with 1 nm resolution. The reaction proceeds through nucleation and growth of the new phase in corners of the nanocubes. As the hydrogenated phase propagates across the particles, portions of the lattice misorient by 1.5%, diminishing crystal quality. Once transformed, all the particles explored return to a pristine state. The nanoparticles' ability to remove crystallographic imperfections renders them more durable than their bulk counterparts.
authors.affiliation: Department of Materials Science and Engineering, Stanford University, 496 Lomita Mall, Stanford, California 94305, USA.
authors.forename: Tarun C
authors.initials: TC
authors.lastname: Narayan
authors.affiliation: Department of Electrical Engineering, Stanford University, 496 Lomita Mall, Stanford, California 94305, USA.
authors.forename: Fariah
authors.initials: F
authors.lastname: Hayee
authors.affiliation: Department of Materials Science and Engineering, Stanford University, 496 Lomita Mall, Stanford, California 94305, USA.|DIFFER-Dutch Institute for Fundamental Energy Research, De Zaale 20, 5612 AJ Eindhoven, The Netherlands.
authors.forename: Andrea
authors.initials: A
authors.lastname: Baldi
authors.affiliation: Stanford Nano Shared Facilities, Stanford University, Stanford, California 94305, USA.
authors.forename: Ai
authors.initials: A
authors.lastname: Leen Koh
authors.affiliation: Department of Materials Science and Engineering, Stanford University, 496 Lomita Mall, Stanford, California 94305, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Sinclair
authors.affiliation: Department of Materials Science and Engineering, Stanford University, 496 Lomita Mall, Stanford, California 94305, USA.|Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Dionne