Search

Noble metal-semiconductor hybrid nanocrystals represent an important class of materials for many potential applications, especially for photocatalysis. The utilization of transition metals to form alloys with noble metals can not only reduce the preparation costs, but may also offer tunable optical and catalytic properties for a broader range of applications. In this study, we report on the solution synthesis of AuCu3-ZnO hybrid nanocrystals with three interesting morphologies, including urchin-like, flower-like and multipod-like nanocrystals. In the synthetic strategy, Au-Cu bimetallic alloy seeds formed in situ are used to induce the heteroepitaxial growth of ZnO nanocrystals on the surface of bimetallic alloy cores; thus different types of morphologies can be achieved by controlling the reaction conditions. Through high-resolution transmission electron microscopy observations, well-defined interfaces between ZnO and AuCu3 are observed, which indicate that ZnO has a (0001) orientation and prefers to grow on AuCu3 {111} facets. The as-prepared hybrid nanocrystals demonstrate morphology- and composition-dependent surface plasmon resonance (SPR) absorption bands. In addition, much higher photocatalytic efficiency than pure ZnO nanocrystals is observed for the hybrid nanocrystals in the degradation of methylene blue. In particular, the multipod-like AuCu3-ZnO hybrid nanocrystals show the highest catalytic performance, as well as more than three times higher photocurrent density than the pure ZnO sample. The reported synthetic strategy provides a facile route to the effective combination of a plasmonic alloy with semiconductor components at the nanoscale in a controlled manner.

The functional synergy between the metal and the semiconductor in metal-semiconductor hybrid nanocrystals with specific structures and morphologies makes them suitable candidates for a wide range of applications. To date, the synthesis and the corresponding properties of ternary metal-semiconductor hetero-nanostructures, especially for hybrid nanocrystals containing magnetic metals, are seldom discussed and thus worthy of extensive research. In this study, we report a nonaqueous approach for the synthesis of Ni-Au-ZnO ternary hybrid nanocrystals with three morphologies, including nanomultipods, matchstick-like nanorods and nanopyramids. In the synthetic strategy, the Ni precursor dissolved in oleylamine was injected into a hot solution containing preformed Au-ZnO nanocrystals with specific morphologies. Then Ni prefers to grow on the unoccupied surfaces of Au, thus forming a hybrid hetero-nanostructure which retains the main morphologies of Au-ZnO nanocrystals. The ultraviolet-visible spectra not only show the band gap absorption of ZnO but also exhibit a broadened and weakened surface plasmon resonance (SPR) band of Au. The Ni-Au-ZnO nanocrystals exhibit much higher photocatalytic efficiency than pure ZnO in the degradation of Rhodamine B. Meanwhile, these hybrid nanocrystals are superparamagnetic at room temperature and can be readily recycled by a magnetic field for reuse. The as-prepared ternary Ni-Au-ZnO hybrid nanocrystals possess plasmonic, magnetic and enhanced photocatalytic properties, and thus are expected to find wide applications in the future.

Hierarchical ZnO-Ag-C composite porous microspheres are successfully synthesized by calcination of the preproduced zinc-silver citrate porous microspheres in argon. The carbon derives from the in situ carbonization of carboxylic acid groups in zinc-silver citrate during annealing treatment. The average particle size of ZnO-Ag-C composite porous microspheres is approximate 1.5 μm. When adopted as the electrode materials in lithium ion batteries, the obtained composite porous microspheres display high specific capacity, excellent cyclability, and good rate capability. A discharge capacity as high as 729 mA h g(-1) can be retained after 200 cycles at 100 mA g(-1). The excellent electrochemical properties of ZnO-Ag-C are ascribed to its unique hierarchical porous configuration as well as the modification of silver and carbon.

Previous preparation of iron phosphide nanowires usually employed toxic and unstable iron carbonyl compounds as precursor. In this study, we demonstrate that iron phosphide nanowires can be synthesized via a facile nonaqueous chemical route that utilizes a commonly available iron precursor, iron (III) acetylacetonate. In the synthesis, trioctylphosphine (TOP) and trioctylphosphine oxide (TOPO) have been used as surfactants, and oleylamine has been used as solvent. The crystalline structure and morphology of the as-synthesized products were characterized by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). The obtained iron phosphide nanowires have a typical width of ~16 nm and a length of several hundred nanometers. Structural and compositional characterization reveals a hexagonal Fe2P crystalline phase. The morphology of as-synthesized products is greatly influenced by the ratio of TOP/TOPO. The presence of TOPO has been found to be essential for the growth of high-quality iron phosphide nanowires. Magnetic measurements reveal ferromagnetic characteristics, and hysteresis behaviors below the blocking temperature have been observed.