In Situ Imaging of Ion Motion in a Single Nanoparticle: Structural Transformations in Selenium Nanoparticles

Intraparticle ion motions are critical to the structure and properties of nanomaterials, but rarely disclosed. Herein, in situ visualization of ion motions in a single nanoparticle is presented by dark-field microscopy imaging, which shows HgCl -induced structural transformation of amorphous selenium nanoparticles (SeNPs) with the main composition of Se . Owing to the high binding affinity with selenium and coulomb interactions, Hg ions can permeate into the interior of SeNPs, making the amorphous Se turn to polycrystalline Hg Se Cl . As a proof of concept, SeNPs then serve as a highly effective scavenger for selective removal of Hg ions from solution. This new finding offers visual proof for the photophysical process involving intraparticle ion motion, demonstrating that tracking the ion motions is a novel strategy to comprehend the formation mechanism with the purpose of developing new nanostructures like nanoalloys and nano metal compounds.