Phase/size Tuning Of Copper Sulifde And Its Properties

Preparation of metal chalcogenides micro/nanomaterials with novelstructures and exploring their growth mechanism, then realization thecontrol of size, dimension and phase, which is significant for people todesign and synthesis functional materials in accordance with their wishes.Copper sulfide, as an important semiconductor material, exhibits manyunusual physical and chemical properties and has great potentialapplications in numerous fields, such as cathode material of lithium-ionbatteries, solar controller and solar radiation absorber, nonlinear opticalmaterial, catalyst, super ionic material and superconductor at lowtemperature. The article choose copper sulfide as the research object,prepared micro/nanocrystals with different morphology and explore theirformation mechanism and properties. The main contents are summarizedas follows:1. The transformation mechanisms of thiourea in ethylene glycolsolution was systematically investigated in this report, which shows theisomerization process is influenced by the anion (NO-3、Cl-、Br-) andpoly(vinylpyrrolidone)(PVP). Thiourea isomerizes into ammoniumthiocyanate when NO-3is present, regardless of the existence of PVP. ForCl-, thiourea coordinates with copper anion to form [Cu(tu)]Cl·1/2H2Ocomplex whether PVP is present. When it comes to Br-, thioureahydrolyzes in the cooperation of PVP or coordinate with copper anion toform [Cu(tu)Br]·1/2H2O complex without PVP. The differenttransformation routes will lead to different phase evolution of the Cu-Ssystem. This work may provide a new understanding of thetransformation of thiourea in ethylene glycol solution. And the opticalproperties of the as-prepared copper sulfides exhibit significantstoichiometry-dependent features which may have potential applicationsin semiconductor photovoltaic devices.2. A simple strategy to synthesize monodispersed, high-homogeneous Cu39S28nanocrystals (NCs) was reported via a solvothermal method byreacting Cu(NO3)2·3H2O with thiourea in N,N-dimethylformamide withthe assistance of poly(vinylpyrrolidone)(PVP). The structure,morphology and size of the products were characterized by X-ray powderdiffraction (XRD), X-ray energy dispersive spectroscopy (EDS), scanningelectron microscopy (SEM) and transmission electron microscopy (TEM).It was found that the dosage of PVP, reaction temperature andconcentration of reactants all have a big influence on the size of thenanocrystals. Besides, a possible and reasonable nucleation-Ostwaldripening-anisotropy growth mechanism for the formation of Cu39S28hierarchical sphere-like structure was proposed based on thetime-dependent SEM observations. The visible-light photocatalyticactivity of different sizes NCs was evaluated by the degradation of theaqueous solution of rhodamine B in the presence of H2O2at ambienttemperature. We found that the small-sized NCs have a superiorphotocatalytic activity for degradation of rhodamine B dye because it canyield more highly reactive hydroxyl radicals. Furthermore, this method isadopted to degradation of familiar dyes in water under visible light. Thismay open up a cleanup and efficient way for treatment of the dyecontaminated wastewater using solar radiation.3. Flower-like, carambola-like, ball-like shaped copper sulfidestructures have been synthesized by using mixed CuCl2·2H2O andthiourea(tu) in a simple hydrothermal process employingpoly(vinylpyrrolidone)(PVP) as the surfactant. The different shapedmorphologies are strongly dependent on the different dosage of PVP. Andthe dosage of PVP also influence on the stoichiometric of the finalproducts. In addition, the photocatalytic activity of different shapedcopper sulfide architectures have been tested by the degradation ofrhodamine B (RhB) under visible light irradiation in the presence of H2O2,showing that the as-prepared flower-like shaped CuS structurescomposed of flakes exhibit high photocatalytic activity for the degradation of RhB.