Anion Exchange Impedes Subsequent Cation Exchange: Ion Mobility Is Altered by Vacancies and Ion Size.

One method of achieving spatially specific, multi-component nanoheterostructures is to combine multiple forms of post-synthetic modification. Applying cation or anion exchange to CuS nanorods creates complex nanoheterostructures. Combining such anion and cation exchanges generates a system which uncovers the interplay between these two processes and understands the cooperativity between postsynthetic modifications more broadly. Cd exchange was carried out on various plasmonic and nonplasmonic CuS/CuTe nanoheterostructures to test how the presence of Te ions would affect the extent of Cd incorporation. Three hypotheses were presented for how the presence of CuTe could alter the incorporation of Cd and these were used to interpret the observed changes in the extent of Cd exchange and crystalline phase of the resulting particles. We found that Te anion exchange impedes subsequent Cd cation exchange. Low extents of Te exchange cause a phase change where ion mobility is slowed by a decrease in Cu vacancies. Higher extents of Te exchange slow ion mobility due to the presence of large Te ions.