Structure-Selective Cation Exchange in the Synthesis of Zincblende MnS and CoS Nanocrystals

Angewandte Chemie - International Edition

5 years ago

Structure-Selective Cation Exchange in the Synthesis of Zincblende MnS and CoS Nanocrystals

Raymond E. Schaak, Julie L. Fenton

The ability to selectively form one crystal structure among several options in a polymorphic system is an important goal in solid-state synthesis. Nanocrystal cation exchange, which proceeds rapidly under mild conditions, can retain key structural features and yield otherwise inaccessible phases, but the extent to which crystal structure can be retained and therefore selectively targeted during such reactions has been limited. Here, we show that nanocrystals of digenite Cu2−xS transform to zincblende MnS and CoS upon cation exchange. Zincblende MnS and CoS, which are metastable in bulk, retain both the tetrahedral cation coordination and cubic close packed anion sublattice of digenite Cu2−xS. Comparison with wurtzite MnS and CoS, which have been accessed previously through analogous cation exchange of roxbyite Cu2−xS, demonstrates the selective formation of the related zincblende vs. wurtzite polymorphs by cation exchange of structurally distinct templates. This structure, not that one! The anion and cation sublattices of digenite Cu2−xS nanocrystals are retained upon cation exchange to form zincblende MnS and CoS, which are metastable compounds in bulk. Using this synthesis pathway, multiple phases in the same system can now be accessed selectively and rationally.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/anie.201701087