Seeded Growth Combined with Cation Exchange for the Synthesis of Anisotropic Cu(2–x)S/ZnS, Cu(2–x)S, and CuInS(2) Nanorods

[Image: see text] Colloidal copper(I) sulfide (Cu(2–x)S) nanocrystals (NCs) have attracted much attention for a wide range of applications because of their unique optoelectronic properties, driving scientists to explore the potential of using Cu(2–x)S NCs as seeds in the synthesis of heteronanocrystals to achieve new multifunctional materials. Herein, we developed a multistep synthesis strategy toward Cu(2–x)S/ZnS heteronanorods. The Janus-type Cu(2–x)S/ZnS heteronanorods are obtained by the injection of hexagonal high-chalcocite Cu(2–x)S seed NCs in a hot zinc oleate solution in the presence of suitable surfactants, 20 s after the injection of sulfur precursors. The Cu(2–x)S seed NCs undergo rapid aggregation and coalescence in the first few seconds after the injection, forming larger NCs that act as the effective seeds for heteronucleation and growth of ZnS. The ZnS heteronucleation occurs on a single (100) facet of the Cu(2–x)S seed NCs and is followed by fast anisotropic growth along a direction that is perpendicular to the c-axis, thus leading to Cu(2–x)S/ZnS Janus-type heteronanorods with a sharp heterointerface. Interestingly, the high-chalcocite crystal structure of the injected Cu(2–x)S seed NCs is preserved in the Cu(2–x)S segments of the heteronanorods because of the high-thermodynamic stability of this Cu(2–x)S phase. The Cu(2–x)S/ZnS heteronanorods are subsequently converted into single-component Cu(2–x)S and CuInS(2) nanorods by postsynthetic topotactic cation exchange. This work expands the possibilities for the rational synthesis of colloidal multicomponent heteronanorods by allowing the design principles of postsynthetic heteroepitaxial seeded growth and nanoscale cation exchange to be combined, yielding access to a plethora of multicomponent heteronanorods with diameters in the quantum confinement regime.