Surface Coordination Layer to Enhance the Stability of Plasmonic Cu Nanoparticles

The fast oxidation of plasmonic Cu nanomaterials caused by surface-absorbed oxygen has been a serious problem and has hindered their applications in many aspects. Herein, a lollipop-shaped Cu@Cu2O/ZnO heterojunction with a core–shell head and a rodlike stem was successfully prepared using the colloidal chemical method, which exhibits ultralong-term stability against air oxidation in hexane. The enhanced stability of Cu@Cu2O/ZnO was due to the presence of zinc acetate, which resulted in the crystal face reconstruction of Cu@Cu2O and the formation of a thin surface carboxylate coordination layer on the partial surface of Cu@Cu2O. The passivation layer effectively hindered the absorption of surface oxygen, thus reducing the oxidation rate of Cu. Our current work was expected to provide new insights into the protection of active metal nanostructures.