Concurrent Etching and Exchange Reactions During the Partial Replacement of Cu+ with Ni2+ in Copper Sulfide Nanorods

Partially exchanging a fraction of the Cu+ cations in copper sulfide nanoparticles with other cations can produce heterostructured derivatives that incorporate multiple metal sulfides. Cation exchange reactions can compete with etching processes, where the exchanging cation facilitates dissolution of any remaining copper sulfide. Here, we show that during partial Ni2+ exchange of Cu1.8S nanorods to form Cu1.8S-NixSy heterostructures, etching instead occurs in the NixSy region that is undergoing exchange, rather than in Cu1.8S. Experiments that isolated individual exchange variables identified competing cation extraction, sulfur abstraction, and cation reincorporation processes that are conceptually related to reactions implicated in the hydrometallurgical processing of nickel-copper converter matte. These insights help to rationalize the unusual etching behavior observed during partial Ni2+ exchange of Cu1.8S.