We studied the chemical, optical and catalytic properties of metal (Pt, Pd, Ag, Au)-Cu 2 O core-shell nanoparticles grown via a simple and reproducible approach which utilizes aqueous-phase reactions at room temperature. We were able to control the thickness of the Cu 2 O shell and examine the effect of the core's shape and size on the structure and properties of the hybrid nanocrystals. We also studied the optical properties of the hybrid nanocrystals, in particular the effect of the Cu 2 O shell thickness on the frequency of the plasmon of gold nanorods. In addition, the catalytic activity of the hybrid nanostructures was examined by testing the reduction reaction of 4-nitrophenol with NaBH 4 . Finally, the hybrid metal-Cu 2 O nanostructures were used as templates to form the yolk-shell of metal-Cu 2 S materials. The interface and the crystalline structures of the four hybrid nanostructures were extensively characterized by high resolution transmission electron microscopy (HRTEM), energy-filtered TEM (EFTRM) and X-ray diffraction (XRD).

Multi-component nanostructures of Au-CdS-ZnO with a novel morphology were synthesized by a non-conventional strategy where seeded growth is combined with solution-liquid-solid (SLS) growth. Each of these synthetic routes is used for growing a different domain of the final heterostructure, where ZnO rods are grown first on Au nanoparticles via heterogeneous nucleation while CdS is later grown between these two domains via SLS, using the Au tip of the preformed Au-ZnO as a catalyst. The in situ alloying of the Au tip with Cd enabled the metal tip to function as an SLS catalyst at a relatively mild reaction temperature which is lower than the melting point of pure Au.

The synthesis of hybrid nanostructures that have specific properties has become a significant topic for construction of “smart” nanomaterials for various applications. Formation of hybrid nanostructures, particularly those combining metals and semiconductors, often introduces new chemical, optical, and electronic properties. Here, we show a simple solution phase synthesis of multicomponent heterostructures based on the growth of metal and semiconductor onto the tips of semiconductor nanorods, leading to the formation of a hybrid semiconductor/semiconductor/metal structure. The synthesis involves the reduction of Pt–acetylacetonate to achieve selective growth of a Pt metal tip onto one side of the CdS rod, followed by the thermal decomposition of Pb–bis­(diethyldithiocarbamate) to grow a PbS nanocrystal onto the other tip of the nanorod. The band alignment between the two semiconductor components as well as the alignment with the Fermi level of the metal could support intraparticle charge transfer, which is often sought after for photocatalysis applications. Yet, we show, using femtosecond transient differential absorption spectroscopy (TDA), that carrier dynamics in such a hybrid system can be more complex than that predicted simply by bulk band alignment considerations. This highlights the importance of the design of band alignment and interface passivation and its role in affecting carrier dynamics within hybrid nanostructures.

Hybrid nanostructures of metal (Cu, Au, Ag)-ZnO nanopyramids were synthesized. These hybrid nanostructures possess two distinct morphologies where the metal can be selectively attached to either the base or the tip of the ZnO pyramids. This is the first time that such morphologies are reported for Cu-ZnO and Ag-ZnO hybrid nanostructures.