Atomic evolution of hydrogen intercalation wave dynamics in palladium nanocrystals

TL;DR

This study uses atomic-resolution imaging and simulations to reveal how hydrogen intercalates in palladium nanocrystals, showing wave mechanisms that differ from traditional models and depend on atomic-scale boundary evolution.

Contribution

The paper provides the first atomic-scale visualization of hydrogen intercalation wave dynamics in palladium nanocrystals, challenging existing shrinking-core models and linking atomic boundary evolution to intercalation pathways.

Findings

Intercalation waves dominate over shrinking-core mechanisms at ambient temperature.

Atomic boundaries evolve from non-planar to {100} plane alignment during intercalation.

Simulations confirm pathways that minimize lattice mismatch strain.

Abstract

Solute-intercalation-induced phase separation creates spatial heterogeneities in host materials, a phenomenon ubiquitous in batteries, hydrogen storage, and other energy devices. Despite many efforts, probing intercalation processes at the atomic scale has been a significant challenge. We study hydrogen (de)intercalation in palladium nanocrystals as a model system and achieve atomic-resolution imaging of hydrogen intercalation wave dynamics by utilizing liquid-phase transmission electron microscopy. Our observations reveal that intercalation wave mechanisms, instead of shrinking-core mechanisms, prevail at ambient temperature for palladium nanocubes ranging from ~60 nm down to ~10 nm. We uncover the atomic evolution of hydrogen intercalation wave transitioning from non-planar and inclined boundaries to those closely aligned with {100} planes. Our kinetic Monte Carlo simulations demonstrate the observed intercalation wave dynamics correspond to sorption pathways minimizing the lattice mismatch strain at the phase boundary. Unveiling the atomic intercalation pathways holds profound implications for engineering intercalation-mediated devices and advancements in energy sciences.