Synthesis of Cu2−xS nanocrystals induced by foreign metal ions: phase and morphology transformation and localized surface plasmon resonance

Abstract

High-quality rhombohedral digenite (Cu_1.8S) nanocrystals (NCs) were synthesized using a facile one-pot approach, in which foreign metal ions (Zn²⁺ and Cd²⁺) were added to drive a transformation in the phase and morphology of the as-obtained Cu_2−xS NCs. During this process, the as-obtained products could transform from monoclinic djurleite (Cu_1.94S) NCs to rhombohedral Cu_1.8S NCs in the presence of Zn²⁺ and Cd²⁺ ions by extending the reaction time and increasing the reaction temperature, which could provide sufficient energy to overcome activation energy barriers. Moreover, we further studied the evolution of the plasmonic properties of the as-obtained Cu_2−xS NCs, and the near-infrared (NIR) localized surface plasmon resonance (LSPR) absorption wavelength could be tuned by varying the amount of Zn²⁺ and Cd²⁺ ions added into the reaction system, which was in close association with the change in copper deficiencies and free hole densities induced by foreign metal ions.