Effects of a low-temperature sulfidation process on the microstructural properties of ZnO nanowires: ZnS formation and nanoscale Kirkendall effect

Abstract

We report on the microstructural characterization of ZnO nanowires during a low-temperature sulfidation process. The morphology of ZnO–ZnS core–shell nanowires obtained for different reaction times was observed. After sulfidation, two different interfaces were observed between the crystalline ZnO core and nanostructured ZnS shell. One is flat {100} planes covered with a dense ZnS NP layer and the other is rough {100} planes covered with two porous layers of ZnO and ZnS NPs. Voids were formed inside the crystalline ZnO core, resulting in Kirkendall voids with a hexagonal shape and six symmetrically located {100} planes, which have lower surface energy compared to {110}. It is believed that these Kirkendall voids are considerably affected by surface energy.