Stoichiometry-Controlled Fabrication of CuxS Hollow Structures With Cu2O as Sacrificial Templates

In this work, we report the successful composition-controlled synthesis of copper sulfides hollow structures using Cu2O nanocrystals as sacrificial templates via a Kirkendall-based process. The direct introduction of S2- glycol solution into the Cu2O-containing mother solution produced Cu7S4 nanocrystals, while CuS formed with Cu2O experienced a separation and drying process as sacrificial templates. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) data reveal that a layer of CuO existed on the surface of the dried Cu2O. We believe the surface states of Cu2O templates played key roles in the stoichiometry control. The presence of CuO catalyzed the oxidation from Cu+ to Cu2+. The type of sulfur source is importance for the formation of hollow structures. The UV-vis-NIR absorption investigation demonstrates a significant quantum confinement effect and stoichiometry-dependent features. It may provide a new approach for the stoichiometry-controlled synthesis of chalcogenides and would aid a better understanding of the optical behaviors of copper sulfides.