Manipulating Cation Exchange Reactions in Cu 2- x S Nanoparticles via Crystal Structure Transformation.

Copper-deficient Cu 2- x S nanoparticles (NPs) are extensively exploited as a superior cation exchange (CE) template to yield sophisticated nanostructures. Recently, it has been discovered that their CE reactions can be facilely manipulated by copper vacancy density, morphology, and NP size. However, the structural similarity of usually utilized Cu 2- x S somewhat limits the manipulation of the CE reactions through the factor of crystal structure because it can strongly influence the process of the reaction. Herein, we report a methodology of crystal structure transformation to manipulate the CE reactions. Particularly, roxbyite Cu 1.8 S nanodisks (NDs) were converted into solid wurtzite CdS NDs and Janus-type Cu 1.94 S/CdS NDs by a "full"/partial CE reaction with Cd 2+ . Afterward, the roxbyite Cu 1.8 S were pseudomorphically transformed into covellite CuS NDs. Unlike Cu 1.8 S, the CuS was scarcely exchanged because of the unique disulfide (S-S) bonds and converted into hollow wurtzite CdS under a more reactive condition. The S-S bonds were gradually split and CuS@CdS core@shell-type NDs were generated. Therefore, our findings in the present study provide not only a versatile technique to manipulate CE reactions in Cu 2- x S NPs but also a better comprehension of their reaction dynamics and pathways.