Understanding structure of nanoparticles is important because their structures determine physical, chemical, and catalytic properties. However, there is no right tool to map 3D structures of nanoparticles with details of atomic positions in the native liquid condition. Our method based on high-resolution liquid cell TEM has been developed to reconstruct the 3D structures of colloidal nanoparticles. When Pt nanoparticles are immersed in graphene liquid cell, the freely rotating nanoparticles can be observed by high-resolution TEM. A time-series TEM images capture two-dimensional projections of the rotating particle from different directions. Using reconstruction algorithm, 2D projections can be merged to 3D structure map of individual nanoparticle with angstrom spatial resolution. Obtained 3D density maps unveil face-centered cubic structures Pt nanoparticles with distortions, grain boundaries, and strains applied along particular directions. <br/> We observe individual particles have different morphologies and internal structures with respect to the assembly of constituent elements. With high-resolution 3D density maps with atomic positions assigned, local strain and the volume occupied by individual elements are investigated for nanoparticles with different size.

Atomic resolution 3D reconstruction of single colloidal nanoparticle

256th National Meeting (2018)

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