Zhimao Yang

Preparation of copper nanoparticles by chemical reduction method using potassium borohydride

High dispersive copper nanoparticles were prepared by chemical reduction method using potassium borohydride as reducing agent. The effects of reactant ratio, concentration of CuSO4, reaction temperature, and dispersant on the size of product and conversion rate were studied. The morphologies of copper nanoparticles were characterized by scanning electron microscopy. The results show that the optimum process conditions are as follows: the molar ratio of KBH4 to CuSO4 is 0.75 (3:4), concentration of CuSO4 is 0.4 mol/L, reaction temperature is 30 °C, and dispersant is n-butyl alcohol. The average particles size of copper powders with spherical shape gained is about 100 nm.

Facile Water-Assisted Synthesis of Cupric Oxide Nanourchins and Their Application as Nonenzymatic Glucose Biosensor

We have demonstrated an interesting approach for the one-pot synthesis of cupric oxide (CuO) nanourchins with sub-100 nm through a sequential dissolution-precipitation process in a water/ethanol system. The first stage produces a precursory crystal [Cu7Cl4(OH)10H2O] that is transformed into monoclinic CuO nanourchins during the following stage. Water is a required reactant for the morphology-controlled growth of different CuO nanostructures. When evaluated for their nonenzymatic glucose-sensing properties, these CuO nanourchins manifest higher sensitivity. Significantly, this water-dependent precursor transformation method may be widely used to effectively control the growth of other metal oxide nanostructures.

Interface synthesis of gold mesocrystals with highly roughened surfaces for surface-enhanced Raman spectroscopy

Local electromagnetic enhancement excited from collective oscillations of free electrons on a highly roughened mental surface can induce greatly enhanced Raman scattering. Herein gold mesoparticles with various morphologies and highly roughened surfaces, including sea urchin-like, flower-like, star-like, meatball-like, and dendritic nanostructures are prepared using pentanol/water interface as a growth “bed”. The morphologies of the prepared gold mesoparticles are well controlled by varying the concentrations of additives such as gold ions, ascorbic acid (AA) and cetyltrimethylammonium bromide (CTAB). Due to the unique structures such as rough surface, high internal porosity as well as complex morphology, these as-prepared mesocrystals exhibit a remarkable performance in surface-enhanced Raman scattering (SERS) compared with polyhedral mesoparticles.

The crystal-facet-dependent effect of polyhedral Cu2O microcrystals on photocatalytic activity

We have systematically investigated the crystal-facet-dependent effect of polyhedral Cu2O microcrystals exposed with different-index facets on photodegradation of methyl orange, which provides the convincing evidence that the performance of catalysts can be enhanced by high-index facets tailoring.

Highly symmetric polyhedral Cu2O crystals with controllable-index planes

Novel highly symmetric multi-faceted polyhedral Cu2O crystals enclosed by controllable high-index facets and different low-index facets have been synthesized via a template-free complex-precursor solution route. The formation and evolution of these polyhedral shapes can be attributed to the aggregation and ripening mechanism with face-selective adsorption. The appearance of these novel polyhedral architectures further enriches the current morphologies of Cu2O crystals, and might become useful for the fundamental study of crystals design.

Sodium Chloride Template Synthesis of Cubic Tin Dioxide Hollow Particles for Lithium Ion Battery Applications

This paper describes a new synthesis and lithium ion charge-discharge property of tin dioxide (SnO(2)) hollow nanocubes. SnO(2) is one of the best-known anode materials for lithium-ion battery application because of its high lithiation-delithiation capacity. Hollow nanostructures with high surface area are preferred, because they accommodate large volume changes and maintain the structural stability of electrode materials during charge-discharge cycles. The SnO(2) hollow cubes made in this study had a discharge capacity of up to 1783 mA h g(-1) for the initial cycle and 546 mA h g(-1) after 30 cycles at a current density of 0.2 C between 0.02 and 2.0 V (vs Li/Li(+)).

Recent advances in tuning crystal facets of polyhedral cuprous oxide architectures

Polyhedral inorganic crystals exposed with controllable-index facets is as significant as size, composition, phase and crystallinity in determining their chemical and physical properties. To accurately tune the exposed facets and morphologies of crystals is imperative because a thorough understanding of the formation mechanism and unique performance has significant scientific value. Better understanding of the control of exposed facets would bring about new capability for us to design necessary structures for actual applications. This article presents recent research progress in the development of polyhedral Cu2O architectures, focusing on the expanding of crystal-facet-dependent properties. The challenge and prospects of polyhedral Cu2O architectures are discussed. The present article provides important scientific references and a basis for future work.

Templating synthesis of hollow CuO polyhedron and its application for nonenzymatic glucose detection

In this report, a novel type of a hollow CuO polyhedron-modified electrode for sensitive nonenzymatic glucose detection has been fabricated by a templating approach. The morphologies and structures were characterized by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectrum and X-ray photoelectron spectroscopy (XPS). These results show that the as-prepared hollow CuO consists of numerous CuO nanoplates. The electrochemical performance for glucose detection was investigated by cyclic voltammetry and chronoamperometry. The hollow CuO polyhedron-modified electrode exhibits a high sensitivity of 1112 μA mM−1 cm−2 with a detection limit of 0.33 μM (S/N = 3) at +0.55 V, and the linear range is up to 4 mM. Moreover, the hollow CuO polyhedron-modified electrode is highly resistant to the interference from interfering species such as sodium chloride (NaCl), ascorbic acid (AA) and uric acid (UA). The hollow CuO polyhedron-modified electrode exhibits high sensitivity, low detection limit, good stability and fast response towards the oxidation of glucose; thus, it may be a promising nonenzymatic glucose sensor.

Surfactant-free CuO mesocrystals with controllable dimensions: green ordered-aggregation-driven synthesis, formation mechanism and their photochemical performances

We have demonstrated the significant evidence on a green synthesis for the ordered-aggregation-driven growth from surfactant-free one-dimensional (1D) CuO nanosubunits into dimension-controlled mesostructures (three-dimensional (3D) mesospindles and two-dimensional (2D) mesoplates) by an additive-free complex–precursor solution route. Structural and morphological evolutions were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and field-emission scanning electron microscopy (FESEM). The formation of CuO mesostructures here is essentially determined by the characteristic of [Cu(OH)4]2− precursors, and an oriented nanoparticle aggregation with tailoring shapes in different dimensions can be achieved in different concentration of reactants at higher reaction temperature. The 3D “layer-by-layer” growth of mesostructural CuO spindles is successfully synthesized in low concentrations of reagents, while the 2D “shoulder-by-shoulder” growth of mesostructural CuO plates is obtained in high concentrations of reagents. The study is of great importance in the bottom-up assembly of controllable ordering architectures, and offers a good opportunity to understand the fundamental significance for the investigation of the formation mechanism and growth process of surfactant-free CuO mesostructures with controllable aggregation-based behaviours. Additionally, we further demonstrated that such CuO mesocrystals could serve as a potential photocatalyst for the degradation of rhodamine B (RhB) under visible light irradiation in the presence of hydroxide water (H2O2). The results also suggest that these 3D mesostructural CuO spindles exhibit a higher adsorption and photocatalytic degradation of RhB than that of 2D mesostructural CuO plates.

Facet-selective growth of Cu–Cu2O heterogeneous architectures

We have demonstrated a facile protocol for the synthesis of facet-selective growth of low-cost metal Cu nanoparticles on {111} facets of polyhedral 26-facet Cu2O architectures. The novel Cu–Cu2O heterogeneous architectures show better adsorption and photodegradation of methyl orange than those of the original Cu2O architectures.