Jingyi Chen1
University of Arkansas1
Inorganic hybrid core-shell nanoparticles integrate the material properties from individual components which may open doors for new applications. However, the synthesis of core-shell nanoparticles made of dissimilar materials such as metal and metal oxide remains challenging due to strain and interfacial mismatch. In this work, we develop a metal-on-metal thin film growth approach to control the conformal deposition of nonprecious metal shells on the Cu-based metal cores to form core-shell structures of metal-metal oxide hybrids. The deposition kinetics could be controlled by a temperature-regulated, thermal decomposition of zero-valent transition metal complexes. It is found that the conformal deposition can be promoted by keeping the initial deposition temperature close to the thermal decomposition temperature of the zero-valent precursors. While maintaining a slow reaction kinetics, the strain reduction and interdiffusion facilitate conformal deposition over island growth in the synthesis. This study provides insightful guidance to metal-on-metal growth in solution at the nanoscale and thus the seed-mediated approach to hybrid core-shell structures. The optical properties of these metal-metal oxide hybrids are investigated experimentally and interpreted by theoretical simulation. Despite damping effects, the plasmonic properties of these Cu-based core-metal oxide shell structures may have the potential to enable plasmon-enhanced applications. Coupling with selective chemical etching of the Cu core, this synthesis approach developed in this study allows to access hollow nanoshells of metal oxides with well-defined morphology adopted from the core.