Structural Complexity from Consecutive Postsynthetic Transformations: The Site-Specificity of Sequential Tellurium Anion and Cadmium Cation Exchange on Roxbyite Copper Sulfide Nanoparticles

A crucial tool in the design of multicomponent nanoheterostructures is the ability to carry out reactions with site-specificity. Here, we examine the interplay of two site-specific postsynthetic transformations─tellurium anion exchange followed by cadmium cation exchange on Cu2-xS nanorods─to reveal how, together, they create numerous new nanoheterostructures with various interfaces and chemical components. By varying the temperature of the initial exchange, we obtained Cu2-xS/Cu2-xTe structures with varying numbers of Cu2-x Scores and thicknesses of Cu2-xTe shells. We then subjected these Cu2-xS/Cu2-xTe nanoheterostructures to either low- or high-temperature cadmium exchange. While many different factors dictating the position of cation exchange have been identified, here we find that differences in the ease of ion diffusion through Cu2-xS and Cu2-xTe direct the incoming Cd2+ toward reaction with Cu2-xS. This straightforward site preference for cation exchange, coupled with the ability to modulate the extent of tellurium and cadmium exchange, is used to create several distinctive nanostructure patterns. In particular, we demonstrate that the regioselectivity of Te2– anion exchange on Cu2-xS nanorods can be leveraged to produce distinct templates for cation exchange, resulting in a library of nontrivial nanoheterostructures. The demonstration of such a variety of different copper/cadmium chalcogenide structures shows that consecutive anion and cation exchanges offer new routes to novel materials.