2025/08/26 by Hyunggu Kim, Kevin R. Kittilstved · 1 voice
Biochemistry, Genetics and Molecular Biology · Computer Science · Materials Science · #Machine Learning in Materials Science #Protein Structure and Dynamics #Quantum Computing Algorithms and Architecture
paper · doi:10.1021/acs.jpca.5c04100
openalex publication_date 2025/08/26 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/15
The versatility and stability of semiconductor magic size clusters (MSCs) have been exploited to synthesize unique nanostructures with well-controlled dimensionality. Strategies to incorporate dopant ions such as transition metals into II–VI MSCs typically result in substitutional doping at surface sites. In this study, we investigate the speciation of Co 2+ in ZnS MSCs using three different cation exchange reactions at moderate temperatures. Using electronic absorption spectroscopy and ligand field theory, we confirm in every scenario that Co 2+ either substitutes at the surface, remains as a precursor in solution, or forms a Co-rich impurity. However, upon growth of the Co 2+ -doped ZnS MSCs at higher temperatures, we observe conversion of the surface Co 2+ to internal sites. This observation is consistent with tetrahedral Co 2+ coordinated to μ 4 –S 2– based on comparison of the same transition observed previously with internally doped Co 2+:ZnS QDs. We propose the internalization is due to a coalescence growth mechanism involving direct attachment, interface relaxation, and reshaping of the Co 2+ -doped ZnS MSCs in contrast to typically observed stepwise MSC growth or Ostwald ripening in doped QDs.