Solventless synthesis of copper sulfide nanorods by thermolysis of a single source thiolate-derived precursor

Organic monolayer protected Cu2S nanorods, 4 nm in diameter and 12 nm long, were synthesized using a novel solventless synthetic approach. Thermolytic degradation of a copper thiolate precursor at temperatures ranging from 140 to 200 degrees C produces Cu2S nanorods. Higher temperatures promote isotropic growth of spherical nanocrystals. X-ray diffraction and high-resolution TEM reveal that the nanorods exhibit a hexagonal Cu2S crystal structure, which in the bulk is ferroelectric. The appropriate reaction conditions produce nanorods that are size and shape monodisperse and organize into smectic superlattices. The extent of superlattice ordering and the appearance of extended strands of nanorods provide evidence for strong dipole-dipole coupling between Cu2S nanorods.     

Size-controlled chalcopyrite CuInS2 nanocrystals: One-pot synthesis and optical characterization

Chalcopyrite ternary CuInS2 semiconductor nanocrystals have been synthesized via a facile one-pot chemical approach by using oleylamine and oleic acid as solvents.The as-prepared CuInS2 nanocrystals have been characterized by instrumental analyses such as X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),transmission electron microscopy(TEM)/high-resolution TEM(HRTEM),energy-dispersive X-ray spectroscopy(EDS),UV-vis absorption spectroscopy(UV-vis) and photoluminescence(PL) spectroscopy.The particle sizes of the CuInS2 nanocrystals could be tuned from 2 to 10 nm by simply varying reaction conditions.Oleylamine,which acted as both a reductant and an effective capping agent,plays an important role in the size-controlled synthesis of CuInS2 nanocrystals.Based on a series of comparative experiments under different reaction conditions,the probable formation mechanism of CuInS2 nanocrystals has been proposed.Furthermore,the UV-vis absorption and PL emission spectra of the chalcopyrite CuInS2 nanocrystals have been found to be adjustable in the range of 527-815 nm and 625-800 nm,respectively,indicating their potential application in photovoltaic devices.     

Shape- and phase-controlled synthesis of monodisperse, single-crystalline ternary chalcogenide colloids through a convenient solution synthesis strategy

Colloidal, monodisperse, single-crystalline pyramidal CuInS2 and rectangular AgInS2 nanocrystals were successfully synthesized through a convenient and improved solvothermal process that uses hexadecylamine as a capping reagent. The crystal phase, morphology, crystal lattice, and chemical composition of the as-prepared products were characterized by using X-ray diffraction, transmission electron microscopy (TEM), high-resolution TEM, and energy dispersive X-ray spectroscopy. Results revealed that the as-synthesized CuInS2 colloid is in the tetragonal phase (size: 13-17 nm) and the AgInS2 in the orthorhombic structure (size: 17+/-0.5 nm). A possible shape evolution and crystal growth mechanism has been suggested for the formation of pyramidal CuInS2 and rectangular AgInS2 colloids. Control experiments indicated that the morphology- and/or phase-change of CuInS2 and orthorhombic AgInS2 colloids are temperature- and/or time-dependent. CuInS2 colloids absorb well in the range of visible light at room-temperature, indicating its potential application as a solar absorber. Two photoluminescence (PL) subbands at 1.938 and 2.384 eV in the PL spectra of CuInS2 colloids revealed that the recombination of the closest and the second closest donor-acceptor pairs within the CuInS2 lattice, in which the donor defect (Cui) occupies an interstitial position and the acceptor defect (VIn) resides at an adjacent cation site. In addition, the synthesis strategy developed in this study is convenient and inexpensive, and could also be used as a general process for the synthesis of other pure or doped ternary chalcogenides that require a controlled size (or shape). This process could be extended to the synthesis of other functional nanomaterials.     

Growth and optical properties of wurtzite-type CdS nanocrystals

This paper reports wurtzite-type CdS nanostructures synthesized via a hydrothermal reaction route using dithiol glycol as the sulfur source. The reaction time was found to play an important role in the shape of the CdS nanocrystals: from dots to wires via an oriented attachment mechanism. This work has enabled us to generate nanostructures with controllable geometric shapes and structures and thus optical properties. The CdS nanostructures show a hexagonal wurtzite phase confirmed by X-ray diffraction and show no evidence for a mixed phase of cubic symmetry. The Raman peak position of the characteristic first-order longitudinal optical phonon mode does not change greatly, and the corresponding full width at half-maximum is found to decrease with the CdS shape, changing from nanoparticles to nanowires because of crystalline quality improvement. The photoluminescence measurements indicate tunable optical properties just through a change in the shape of the CdS nanocrystals; i.e., CdS nanoparticles show a band-edge emission at approximately 426 nm in wavelength, while the CdS nanowires show a band-edge emission at approximately 426 nm as well as a weaker trap-state green emission at approximately 530 nm in wavelength. These samples provide an opportunity for the study of the evolution of crystal growth and optical properties, with the shape of the nanocrystals varying from nearly spherical particles to wires.     

Solvothermal synthesis of zincblende and wurtzite CuInS2 nanocrystals and their photovoltaic application

We report a simple solvothermal synthesis approach to the growth of CuInS(2) nanocrystals with zincblende- and wurtzite-phase structures. Zincblende nanocrystals with particle sizes of 10-20 nm were produced using oleylamine as the solvent. When ethylenediamine was used as the solvent, similarly sized wurtzite nanocrystals with some degree of particle aggregation were formed. Use of a mixture of these solvents gave products with mixed phases including some polyhedral nanostructures. The crystal phases of these nanocrystals were carefully determined by X-ray diffraction and transmission electron microscopy analysis. All the samples exhibit strong absorption from the entire visible light region to the near-infrared region beyond 1300 nm. Pure-phase zincblende and wurtzite CuInS(2) nanocrystals were employed as ink in the fabrication of solar cells. The spray-coated nanocrystal layer was subjected to a selenization process. A power conversion efficiency of ~0.74% and a good external quantum efficiency profile over broad wavelengths have been measured. The results demonstrate that wurtzite and zincblende CuInS(2) nanocrystals may be attractive precursors to light-absorbing materials for making efficient photovoltaic devices.     

Alloyed (ZnS)(x) (CuInS(2) )(1-x) Semiconductor Nanorods: Synthesis, Bandgap Tuning and Photocatalytic Properties

Rod-like nanocrystals of the semiconductor alloy (ZnS)(x) (CuInS(2) )(1-x) (ZCIS) have been colloidally prepared by using a one-pot non-injection-based synthetic strategy. The ZCIS nanorods crystallize in the hexagonal wurtzite structure and display preferential growth in the direction of the c axis. The bandgap of these quarternary alloyed nanorods can be conveniently tuned by varying the ratio of ZnS to CuInS(2) . A non-linear relationship between the bandgap and the alloy composition is observed. The ZCIS nanorods are found to exhibit promising photocatalytic behaviour in visible-light-driven degradation of Rhodamine?B.     

Praseodymium hydroxide and oxide nanorods and Au/Pr6O11 nanorod catalysts for CO oxidation

Praseodymium hydroxide nanorods were synthesized by a two-step approach: First, metallic praseodymium was used to form praseodymium chloride, which reacted subsequently with KOH solution to produce praseodymium hydroxide. In the second step the hydroxide was treated with a concentrated alkaline solution at 180 degrees C for 45 h, yielding nanorods as shown by the scanning and transmission electron microscopy images. The results of X-ray diffraction and energy-dispersive X-ray spectroscopy experiments indicate that these nanorods are pure praseodymium hydroxide with a hexagonal structure, which can be converted into praseodymium oxide (Pr6O11) nanorods of a face-centered cubic structure after calcination at 600 degrees C for 2 h in air. Gold was loaded on the praseodymium oxide nanorods using HAuCl4 as the gold source, and NaBH4 was used to reduce the gold species to metallic nanoparticles with sizes of 8-12 nm on the nanorod surface. These Au/Pr6O11 nanorods exhibit superior catalytic activity for CO oxidation.     

Solvent-Free Synthesis of ZnO Nanoparticles by a Simple Thermal Decomposition Method

This paper reports on a novel processing route for producing ZnO nanoparticles by solid-state thermal decomposition of zinc(II) acetate nanostructures obtained by the sublimation of zinc(II) acetate powder. The sublimation process of the Zn(OAc)₂ powder was carried out in the temperature 150 °C for 2 h. In addition, nanoparticles of ZnO were obtained by solid-state thermal decomposition of the synthesized Zn(OAc)₂ nanostructures. The synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, photoluminescence spectroscopy, and energy dispersive X-ray spectroscopy. The sublimation process of the Zn(OAc)₂ powder was carried out within the range of 150–180 °C. The XRD studies indicated the production of pure hexagonal ZnO nanoparticles after thermal decomposition.     

Syntheses of CuO nanostructures in ionic liquids

A simple and efficient approach is developed to fabricate single-crystalline CuO nanostructures through an ionic liquid assisted one-step low-temperature solid-state route.Both nanoparticles(5 nm in size)and nanorods(5-10 nm in diameter and 50-100 nm in length)of monoclinic CuO were obtained. These synthesized CuO nanostructures were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),selected area electron diffraction(SAED),X-ray photoelectron spectros- copy(XPS),energy dispersive spectroscopy(EDS)and nitrogen adsorption analysis.The morpholo- gies of the nanostructures can be controlled by tuning the amount of NaOH and ionic liquids.The growth mechanism of CuO nanostructures is investigated.     

Au-ZnO hybrid nanopyramids and their photocatalytic properties

We successfully synthesized Au-ZnO hybrid nanoparticles with a novel hexagonal pyramid-like structure. The growth process of the as-prepared hybrid nanopyramids is clearly discussed. Because of their homogeneous composition and controlled morphology, the Au-ZnO hybrid nanopyramids demonstrate better photocatalytic efficiency than pure ZnO nanocrystals.     

From (Cd2Se2)(pa) (pa=propylamine) hybrid precursors to various CdSe nanostructures: structural evolution and optical properties

Nanostructural evolution of II-VI semiconductors emerges as a hot research field because it offers a novel route for the synthesis of functional semiconductor nanomaterials. Here, we report a "top-down" process of structural evolution from two dimensional Cd(2)Se(2)(pa) hybrid structures to zero- or one- dimensional CdSe nanostructures. We firstly synthesized the Cd(2)Se(2)(pa) hybrid by a facile solvothermal reaction and determined the hybrid crystal structure through the Rietveld refinement based on the PXRD data. The (Cd(2)Se(2))(pa) hybrid consists of [Cd(2)Se(2)] slabs sandwiched by coordinated n-propylamine layers. Then, we used this hybrid as a precursor to explore the "top-down" fabrication process of structural evolution from two dimensional layered structures to zero- or one- dimensional nanocrystals. It has been shown that various CdSe nanostructures including lamellar structures, nanoparticles, nanowires, and nanorods can be obtained through the pyrolysis of (Cd(2)Se(2))(pa) hybrid precursor under different conditions. It is worth mentioning that the oriented attachment of nanoparticles has been observed during the pyrolysis process. Additionally, the variation of optical properties with structural evolution has been investigated in detail.     

The synthesis of Cu/plate-like ZnO nanostructures and their self-assembly mechanism

A composite Cu/ZnO nanostructure with Cu nanoparticles supported on ZnO hexagonal nanoplates has been successfully fabricated by a heating approach, using their metal oleate salts as the precursors without any additives. Combined Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and other examination technologies, the structural properties and formation mechanism of as-synthesized Cu/ZnO nanocomposites are studied in detail. The results reveal that the nanostructures are plate-like with uniform shape and size, and Cu nanoparticles exhibit specific (111) plane matching with the (002) facet of ZnO, indicating a surface-induced interaction mechanism. Further characterization demonstrates that copper nanoparticles can be generated by a decomposition/self-reduction route of copper salts, and the oleate ions act as dual roles in the process: reducing and protecting agents. The difference of decomposition temperature between metal oleates also plays important roles in the formation of Cu/ZnO nanostructure. In addition, the catalytic performance of these nanocomposites is evaluated and it can be found that compared with Cu/rod-like ZnO, as-synthesized samples are highly selective for methanol.     

Formation of uniform CuO nanorods by spontaneous aggregation: Selective synthesis of CuO, Cu2O, and Cu nanoparticles by a solid-liquid phase arc discharge process

Uniform and monodisperse CuO nanorods have been synthesized by directional aggregation and crystallization of tiny CuO nanoparticles generated from a solid-liquid arc discharge process under ambient conditions in the absence of any surfactants. Uniform CuO nanorods with sharp ends are formed from tiny nanoparticles via a process that involves the rapid oxidation of Cu nanoclusters, the spontaneous aggregation of CuO nanoparticles, and the Ostawald ripening process. The spontaneous aggregation and oriented attachment of tiny CuO nanoparticles contributed obviously to the formation of these kinds of nanostructures. By choice of suitable reducing agent to prevent the oxidation of Cu nanoclusters, Cu and Cu2O nanoparticles can be selectively synthesized.     

Mesoporous rare earth fluoride nanocrystals and their photoluminescence properties

YF(3) and YF(3):Eu(3+) mesoporous hexagonal nanocrystals were successfully synthesized via a simple hydrothermal process based on the in situ assembly of the as-synthesized YF(3) and YF(3):Eu(3+) nanoparticles. The well defined mesoporous nanostructures are formed by phenanthroline assisted assembly of ～20 nm nanoparticles, and 2-4 nm pores are contained as indicated by N(2) adsorption-desorption studies. The obtained YF(3):Eu(3+) mesoporous hexagonal nanoplates show a significant photoluminescence intensity enhancement compared with other shaped YF(3):Eu(3+) nanocrystals.     

Photophysical properties of spherical aggregations of CdS nanocrystals capped with a chromophoric surface agent

A novel sulfur-terminal Cd(II) complex, CdS(2)L (L = N-hexyl-3-{2-[4-(2,2':6',2'-terpyridin-4'-yl)phenyl]ethenyl}-carbazole), was successfully synthesized from CdS nanocrystals and the organic chromophores (L), which was confirmed by single-crystal X-ray diffraction analysis. Its photophysical properties have been investigated both experimentally and theoretically. The novel hybrid nanoparticles (CdS/L) were then obtained using the L as surface capped agent, which aggregate into large spheres, exhibiting novel luminescent properties, strong two photon absorption (TPA) and obvious prolonged fluorescence lifetime, which differ from those of the pure CdS nanocrystals and free L.     

Cu2ZnSnS4纳米晶的制备及其三阶非线性光学性能的研究

以乙酰丙酮铜、醋酸锌、二氯亚锡、油胺和硫粉为前驱体,采用one-pot法合成出了单分散的Cu2ZnSnS4(CZTS)纳米晶.所得样品采用X射线粉末衍射仪(XRD),能量色散谱仪(EDS),透射电子显微镜(TEM),高分辨透射电子显微镜(HRTEM),光电子能谱仪(XPS),紫外-可见光谱仪(UV-vis)和Z-扫描(Z-scan)技术对其结构组成、形貌、性能等进行了表征.结果表明:所获得的产物为四方相结构的六边形CZTS纳米颗粒,直径约为10 nm.计算出尺寸大小为10 nm,13 nm的纳米晶的三阶非线性光学折射率γ(-1.08×10-15,-9.08×10-17 m2·W-1),三阶非线性光学吸收系数β(6.5×10-9,3.69×10-11 m·W-1)以及三阶非线性光学极化率χ(3)(1.49×10-9,4.35×10-10 esu).并探讨了CZTS纳米晶可能的形成机理,及引起三阶光学非线性发生变化的原因。     

Synthesis and shape-tailoring of copper sulfide/indium sulfide-based nanocrystals

Heterostructured Cu2S-In2S3 nanocrystals with various shapes and compositions were synthesized by a high-temperature precursor-injection method using the semiconductor nanocrystal Cu1.94S as a catalyst. The intrinsic cationic deficiencies formed at high temperature by Cu ions made the Cu1.94S nanocrystal a good candidate for catalyzing the nucleation and subsequent growth of In 2S3 nanocrystals, eventually leading to the formation of heterostructured Cu2S-In2S3 nanocrystals. Gelification of the reaction systems, which were composed of different types of nanocrystal precursors and solvent, was found to be a very effective measure for controlling the growth kinetics of the heterostructured particles. Consequently, matchsticklike Cu2S3-In2S3 heterostructured nanorods, teardroplike quasi-core/shell Cu2S@In2S3 nanocrystals, and pencil-like In2S3 nanorods were successfully obtained by manipulating the gelification of the reaction system; this formed a solid experimental basis for further discussion of the growth mechanisms for differently shaped and structured nanocrystals. By reaction with 1,10-phenanthroline, a reagent that strongly and selectively binds to Cu(+), a compositional transformation from binary matchsticklike Cu2S-In2S3 nanorods to pure In2S3 nanorods was successfully achieved.     

掺杂CuInS2纳米晶玻璃的三阶非线性光学性质

采用溶胶-凝胶法结合气氛控制制备了CuInS2纳米晶玻璃. 利用X射线粉末衍射仪(XRD)和透射电子显微镜(TEM)对CuInS2纳米晶在玻璃中的形貌和微结构进行了表征, 并利用飞秒Z扫描技术对该玻璃的三阶非线性光学性质进行了研究. 结果表明, 在钠硼硅玻璃中形成了尺寸分布为10 nm左右的均一的CuInS2四方晶系纳米晶. 该玻璃体现出优良的三阶非线性光学性能, 其三阶非线性光学折射率γ、吸收系数β和极化率χ(3)分别为8.57×10-16 m2/W, 3.74×10-8 m/W和1.95×10-17 m2/V2.     

Formation of zinc sulfide nanorods and nanoparticles in ternary W/O microemulsions

A simple, easy approach to the synthesis of semiconductor ZnS nanorods and nanoparticles exhibiting versatile morphology-formation ability is reported. Water-insoluble zinc sulfide nanocrystals were synthesized in ternary water-in-oil (w/o) microemulsion systems stabilized by either nonionic or, in contrast, cationic surfactant. Products were visualized by transmission electron microscopy (TEM) and identified by energy-dispersive X-ray spectroscopy (EDAX); electron diffraction (ED) was also performed for individual nanorods. With varying molar ratios of water to surfactant (omega0) in solution, hence changing droplet sizes of water pool of microemulsions consequently, several morphologies with different size spans were encountered in the formation of ZnS, such as nanorods and spherical or ellipsoidal particles. Meanwhile, product morphology was also found to be sensitive to the absolute reactant concentration and concentration ratio of [Zn2+] to [S2-], the incubation time, and the ambient temperature. A schematic mechanism for the formation of ZnS nanocrystals and their morphological diversity is described. It is feasible to extend this method to the synthesis of one-dimensional nanocrystals of other semiconductors, given suitable formulae of microemulsions and other appropriate reaction conditions.     

Enhanced photocatalytic activity of cobalt-doped CeO2 nanorods

In this paper, CeO₂ and cobalt-doped CeO₂ nanorods synthesized by surfactant free co-precipitation method. The microstructures of the synthesized products were characterized by XRD, FESEM and TEM. The structural properties of the grown nanorods have been investigated using electron diffraction and X-ray diffraction. High resolution transmission electron microscopy studies show the polycrystalline nature of the Co-doped cerium oxide nanorods with a length of about 300?nm and a diameter of about 10?nm were produced. The X-ray Photoelectron spectrum confirms the presence of cobalt in cerium oxide nanorods. From BET, the specific surface area of the CeO₂ (Co-doped) nanostructures (131 m²?g^??) is found to be significantly higher than that of pure CeO₂ (52 m²?g^??). The Co-doped cerium nanorods exhibit an excellent photocatalytic performance in rapidly degrading azodyes acid orange 7 (AO7) in aqueous solution under UV illumination.