Imperfect Oriented Attachment of Gold Nanoparticles.

Particle coalescence is a fundamental pathway of nanoparticle growth, directly governing structural reconstruction, defect formation, and morphological evolution. However, the underlying driving forces behind imperfect oriented attachment, including what initiates the coalescence of misoriented crystals and determines the resulting structures remain unclear, particularly in liquid environments. This study combines in situ liquid-phase transmission electron microscopy with molecular dynamics calculations to investigate the coalescence dynamics of misoriented gold nanoparticles. Our findings reveal that misoriented nanoparticles can coalesce into a single crystal via a kinetically driven jump-to-coalescence process triggered by instantaneous hydration layer collapse. This coalescence is accompanied by a significant potential energy reduction, and the released energy enhances atomic mobility, particularly in small nanoparticles, enabling rapid structural rearrangement into a single crystal. Moreover, the initial contact position relative to the twin boundary determines the atomic diffusion pathway during the coalescence process of twin nanoparticles, while the twin boundary exhibits high stability during the merging process. These findings clarify the regulatory role of the kinetic factor in nanoparticle coalescence behavior and offer guidance for controlling crystal structure and designing twinned nanostructures in the liquid phase synthesis.