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In Situ Liquid Cell TEM Reveals Bridge-Induced Contact and Fusion of Au Nanocrystals in Aqueous Solution
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posted on 2018-09-06, 00:00 authored by Biao Jin, Maria L. Sushko, Zhaoming Liu, Chuanhong Jin, Ruikang TangDuring nanoparticle
coalescence in aqueous solution, dehydration
and initial contact of particles are critically important but poorly
understood processes. In this work, we used in situ liquid-cell transmission
electron microscopy to directly visualize the coalescence process
of Au nanocrystals. It is found that the Au atomic nanobridge forms
between adjacent nanocrystals that are separated by a ∼0.5
nm hydration layer. The nanobridge structure first induces initial
contact of Au nanocrystals over their hydration layers and then surface
diffusion and grain boundary migration to rearrange into a single
nanocrystal. Classical density functional theory calculations and
ab initio molecular dynamics simulations suggest that the formation
of the nanobridge can be attributed to the accumulation of auric ions
and a higher local supersaturation in the gap, which can promote dehydration,
contact, and fusion of Au nanocrystals. The discovery of this multistep
process advances our understanding of the nanoparticle coalescence
mechanism in aqueous solutions.
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multistep process advancessurface diffusionsolutiondehydrationClassical densitynanoparticle coalescence mechanismnanobridge structuretheory calculationsnanocrystalliquid-cell transmission electron microscopynanobridge formsauric ionsnanoparticle coalescencehydration layersab initiograin boundary migrationAqueous Solutioncoalescence processdynamics simulationscontactSitu Liquid Cell TEMBridge-Induced Contact
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