Preparation of a colloidal array of NaTaO3 nanoparticles via a confined space synthesis route and its photocatalytic application

The confined space synthesis method has been applied to the preparation of sodium tantalate (NaTaO(3)); hydrothermal reaction of NaOH and Ta(2)O(5) was carried out in the pores of a three-dimensional mesoporous carbon, which was replicated by the colloidal array of silica nanospheres (SNSs) 20 nm in size. This approach led to the formation of a colloidal array of NaTaO(3) nanoparticles 20 nm in size with a surface area of 34 m(2) g(-1). The photocatalytic performance of the colloidal array of NaTaO(3) nanoparticles for overall water splitting under UV irradiation (λ > 200 nm) was evaluated after loading a NiO cocatalyst onto NaTaO(3) samples. The NiO-loaded NaTaO(3) nanoparticles showed photocatalytic activity for overall water splitting more than three times as high as non-structured bulk NaTaO(3) particles.     

Highly efficient water splitting into H2 and O2 over lanthanum-doped NaTaO3 photocatalysts with high crystallinity and surface nanostructure

NiO-loaded NaTaO(3) doped with lanthanum showed a high photocatalytic activity for water splitting into H(2) and O(2) in a stoichiometric amount under UV irradiation. The photocatalytic activity of NiO-loaded NaTaO(3) doped with lanthanum was 9 times higher than that of nondoped NiO-loaded NaTaO(3). The maximum apparent quantum yield of the NiO/NaTaO(3):La photocatalyst was 56% at 270 nm. The factors affecting the highly efficient photocatalytic water splitting were examined by using various characterization techniques. Electron microscope observations revealed that the particle sizes of NaTaO(3):La crystals (0.1-0.7 microm) were smaller than that of the nondoped NaTaO(3) crystal (2-3 microm) and that the ordered surface nanostructure with many characteristic steps was created by the lanthanum doping. The small particle size with a high crystallinity was advantageous to an increase in the probability of the reaction of photogenerated electrons and holes with water molecules toward the recombination. Transmission electron microscope observations and extended X-ray absorption fine structure analyses indicated that NiO cocatalysts were loaded on the edge of the nanostep structure of NaTaO(3):La photocatalysts as ultrafine particles. The H(2) evolution proceeded on the ultrafine NiO particles loaded on the edge while the O(2) evolution occurred at the groove of the nanostep structure. Thus, the reaction sites for H(2) evolution were separated from those of O(2) evolution over the ordered nanostep structure. The small particle size and the ordered surface nanostep structure of the NiO/NaTaO(3):La photocatalyst powder contributed to the highly efficient water splitting into H(2) and O(2).     

NaTaO3及NaTaO3∶Bi3+光催化剂的光致发光光谱研究

采用光致发光光谱技术对一系列不同条件下制备的NaTaO3及不同掺杂量的NaTaO3∶Bi3+进行了研究. 结果表明, NaTaO3的发光性质与其制备条件密切相关: 在钠离子不足的条件下合成的样品, 其发光带主要位于515和745 nm左右; 而在钠离子充足条件下合成的样品, 其发光带位于460 nm左右, 随着n(Na)/n(Ta)的降低, 发光带向长波长方向移动; 掺入Bi3+之后, 其发光峰由515 nm移至455 nm, 随着Bi3+掺入量的增加, 455 nm的发光带强度减弱. 515 nm的发光带与替位缺陷TaNa....相关; 745 nm的发光带与VNa`缺陷相关; 而460 nm的发光带与本征TaO6基团相关. 将Bi3+掺入到钽酸钠样品, TaNa....由BiNa..替代, 相应的发光带向高的n(Na)/n(Ta)方向移动, 从而呈现出本征TaO6基团的发光带.     

Low-temperature, solvent-free solid-state synthesis of single-crystalline titanium nitride nanorods with different aspect ratios

Titanium nitride nanorods have been successfully synthesized by low temperature solid-state metathesis of titanium (III) chloride and sodium azide without using any organic solvent. The conditions required for the synthesis of these nanorods have been optimized. It was found that the temperature and time of reaction had a significant effect on the product morphology. Thermal treatment at 360 °C, for 3 days gave the nanorods of the aspect ratio ∼10 (i.e. diameter ∼50 nm and length ∼ 500 nm), whereas the thermal treatment at 400 °C for 3 days gave the nanorods of the aspect ratio ∼50 (i.e. diameter ∼50 nm and length ∼2-3 μm). Scanning and transmission electron microscopies clearly showed the rod-type morphology. Further evidence for the phase purity and crystallinity of titanium nitride nanorods was given by X-ray diffraction, field emission high-resolution electron microscopy and X-ray photoelectron spectroscopy analyses.     

Synthesis and evolution of PbS nanocrystals through a surfactant-assisted solvothermal route

We present a surfactant-assisted solvothermal approach for the controllable synthesis of a PbS nanocrystal at low temperature (85 degrees C). Nanotubes (400 nm in length with an outer diameter of 30 nm), bundle-like long nanorods (about 5-15 mum long and an average diameter of 100 nm), nanowires (5-20 mum in length and with a diameter of 20-50 nm), short nanorods (100-300 nm in length and an axial ratio of 5-10), nanoparticles (25 nm in width with an aspect ratio of 2), and nanocubes (a short axis length of 10 nm and a long axis length of 15 nm) were successfully prepared and characterized by transmission electron microscopy, scanning electron microscopy, and powder X-ray diffraction pattern. A series of experimental results indicated that several experimental factors, such as AOT concentration, ratio of [water]/[surfactant], reaction time, and ratio of the reagents, play key roles in the final morphologies of PbS. Possible formation mechanisms of PbS nanorods and nanotubes were proposed.     

Homoleptic copper(I) arylthiolates as a new class of p-type charge carriers: structures and charge mobility studies

Polymeric homoleptic copper(I) arylthiolates [Cu(p-SC(6)H(4)-X)](infinity) (X=CH(3) (1), H (2), CH(3)O (3), tBu (4), CF(3) (5), NO(2) (6), and COOH (7)) have been prepared as insoluble crystalline solids in good yields (75-95 %). Structure determinations by powder X-ray diffraction analysis have revealed that 1-3 and 6 form polymers of infinite chain length, with the copper atoms bridged by arylthiolate ligands. Weak intra-chain pi***pi stacking interactions are present in 1-3, as evidenced by the distances (3.210 A in 1, 3.016 A in 2, 3.401 A in 3) between the mean planes of neighboring phenyl rings. In the structure of 6, the intra-chain pi***pi interactions (d=3.711 A) are insignificant and the chain polymers are associated through weak, non-covalent C-H...O hydrogen-bonding interactions (d=2.586 A). Samples of 1-7 in their polycrystalline forms proved to be thermally stable at 200-300 degrees C; their respective decomposition temperatures are around 100 degrees C higher than that of the aliphatic analogue [Cu(SCH(3))](infinity). Data from in situ variable-temperature X-ray diffractometry measurements indicated that the structures of both 1 and 7 are thermally more robust than that of [Cu(SCH(3))](infinity). TEM analysis revealed that the solid samples of 1-5 and [Cu(SCH(3))](infinity) contained homogeneously dispersed crystalline nanorods with widths of 20-250 nm, whereas smaller plate-like nanocrystals were found for 6 and 7. SAED data showed that the chain polymers of 1-3 and [Cu(SCH(3))](infinity) similarly extend along the long axes of their nanorods. The nanorods of 1-5 and [Cu(SCH(3))](infinity) have been found to exhibit p-type field-effect transistor behavior, with charge mobility (micro) values of 10(-2)-10(-5) cm(2) V(-1) s(-1). Polycrystalline solid samples of 6 and 7 each showed a low charge mobility (<10(-6) cm(2) V(-1) s(-1)). The charge mobility values of field-effect transistors made from crystalline nanorods of 1-3 and [Cu(SCH(3))](infinity) could be correlated with their unique chain-like copper-sulfur networks, with the para-substituent of the arylthiolate ligand influencing the charge-transport properties.     

Synthesis and characterization of colloidal ternary ZnCdSe semiconductor nanorods

For the synthesis of colloidal ternary ZnCdSe nanorods, CdSe nanorods were first prepared under a mixture of tetradecylphosphonic acid/trioctylphosphine oxide surfactants at 250 degrees C, and then ZnSe shell layer was grown onto CdSe nanorods at 180 degrees C, forming CdSeZnSe core/shell nanorods. Green-yellow emitting ternary ZnCdSe nanorods were obtained by a subsequent alloying process at 270 degrees C for 1-3 h through the diffusion of Zn ions into CdSe nanorods. The photoluminescence quantum yield (QY) of ZnCdSe nanorods was 5%-10%, which is higher than that from pristine CdSe nanorods (0.6%). The QY of these alloy nanorods depends on the alloying time and is discussed in terms of compositional disorders and defects produced by the alloying process. The Raman and time resolved photoluminescence spectroscopies were used to understand the detailed alloying process from CdSeZnSe core/shell to ZnCdSe alloy nanorods.     

Branched mesoporous Mn3O4 nanorods: facile synthesis and catalysis in the degradation of methylene blue

Branched MnOOH nanorods with diameters in the range of 50-150 nm and lengths of up to tens of micrometers were prepared by using potassium permanganate (KMnO(4)) and PEG 400 (PEG=polyethylene glycol) as starting materials through a simple hydrothermal process at 160 °C. After annealing at 300 °C under a N(2) atmosphere for 5 h, MnOOH nanorods became gradually dehydrated and transformed into mesoporous Mn(3)O(4) nanorods with a slight size-shrinking. The as-obtained mesoporous Mn(3)O(4) nanorods had an average surface area of 32.88 m(2) g(-1) and a mean pore size of 3.7 nm. Through tuning the experimental parameters, such as the annealing atmosphere and temperature, β-MnO(2), Mn(2)O(3), Mn(3)O(4), MnO, and Mn(5)O(8) were selectively produced. Among these structures, mesoporous Mn(3)O(4) nanorods were efficient for the catalytic degradation of methylene blue (MB) in the presence of H(2)O(2) at 80 °C.     

High-yield carbon nanorods obtained by a catalytic copyrolysis process

Carbon nanorods were produced with a yield of about 90% by the copyrolysis of C(6)H(6) and C(5)H(6) at 600 degrees C under the cocatalysis of Fe and Mg. Many novel Y-junction carbon nanorods were found in the products. The obtained carbon nanorods have a diameter in the range of 200-350 nm and are several micrometers in length. The effects of reactants, catalysts, and the temperature were investigated, and the experimental results indicate that C(5)H(6) and cocatalysts Fe and Mg play crucial roles in the formation of carbon nanorods. The possible formation mechanism of the carbon nanorods is discussed.     

NaTaO_3及NaTaO_3∶Bi~(3+)光催化剂的光致发光光谱研究

采用光致发光光谱技术对一系列不同条件下制备的NaTaO3及不同掺杂量的NaTaO3∶Bi3 进行了研究.结果表明,NaTaO3的发光性质与其制备条件密切相关在钠离子不足的条件下合成的样品,其发光带主要位于515和745nm左右;而在钠离子充足条件下合成的样品,其发光带位于460nm左右,随着n(Na)/n(Ta)的降低,发光带向长波长方向移动;掺入Bi3 之后,其发光峰由515nm移至455nm,随着Bi3 掺入量的增加,455nm的发光带强度减弱.515nm的发光带与替位缺陷Ta.N.a..相关;745nm的发光带与VN`a缺陷相关;而460nm的发光带与本征TaO6基团相关.将Bi3 掺入到钽酸钠样品,TaN..a..由BiN..a替代,相应的发光带向高的n(Na)/n(Ta)方向移动,从而呈现出本征TaO6基团的发光带.     

Bi掺杂NaTaO3中Bi的化学价态对其光催化性能的影响

分别采用NaBiO3和Bi(NO3)3为Bi源制备了Bi掺杂NaTaO3光催化剂,研究了Bi离子的价态对NaTaO3光催化分解水制氢性能的影响.采用X射线衍射(XRD)、拉曼光谱、X射线光电子能谱(XPS)和紫外-可见吸收光谱研究了催化剂的晶体结构、Bi离子的化学状态和催化剂的光学吸收性能.以光催化分解水制氢反应研究了Bi离子掺杂NaTaO3的催化性能. XRD结果表明,对于两个不同Bi源掺杂的NaTaO3样品, Bi离子的掺杂没有改变催化剂的单斜相结构,但拉曼光谱证实Bi离子的掺杂致使Ta–O–Ta键角偏离了180o. XPS结果表明,以Bi(NO3)3为Bi源时, Bi离子以Bi3+掺杂于NaTaO3的A位;当以NaBiO3为原料时, Bi3+和Bi5+共掺杂于NaTaO3的A位.两种不同Bi源掺杂得到的样品在紫外-可见吸收光谱中给出了相似的光学吸收,但Bi3+的掺杂对NaTaO3光催化性能影响不大,而Bi3+和Bi5+共掺杂大大提高了NaTaO3的光解水制氢性能. Bi离子取代Na离子在A位的掺杂,在NaTaO3结构中引入了能够促进载流子分离的空位和缺陷;与此同时, Bi的掺杂导致Ta–O–Ta键角偏离180o而不利于载流子迁移.对于Bi3+掺杂的NaTaO3样品,这两种作用相互抵消,使得其催化性能与NaTaO3相比没有变化;而Bi3+和Bi5+的共掺杂和高价态Bi5+的掺杂引入了更多的空位和缺陷,提高了光生电子-空穴的分离效率,从而提高了光催化产氢性能.研究表明,光催化过程中载流子的迁移是影响催化性能的重要因素,而在ABO3钙钛矿结构的A位引入高价态离子是促进光生载流子分离的有效途径.     

NaTaO3:Cu/W的结构和可见光催化制氢性能

采用高温固相法合成了可见光响应的Cu和W共掺杂NaTaO3光催化剂NaTaO3: Cu/W, 研究了Cu与W的摩尔比和共掺杂量(摩尔分数)对NaTaO3: Cu/W晶体结构、形貌、光吸收性质和可见光催化分解甲醇水溶液制氢活性的影响规律. 结果表明, Cu, W分别以Cu(Ⅱ)和W(Ⅵ)存在于\{NaTaO3: Cu/W中; Cu, W共掺杂不改变NaTaO3的晶体结构, 但能引起晶格畸变, 减小表面台阶间距; 当固定Cu与W的摩尔比, 增大共掺杂量时, 进入NaTaO3晶格的掺杂离子逐渐增多, 使(020)晶面的衍射峰逐渐向高角度方向移动, 光吸收边红移; 进一步增大共掺杂量, (020)晶面衍射峰则向低角度方向移动. 说明过量的掺杂离子不能有效进入晶格, Cu, W对NaTaO3的掺杂存在最大值; 当Cu与W的摩尔比为1: 2, 1: 3和1: 4时, 最大共掺杂量分别为8%, 6%和4%; NaTaO3: Cu/W在最大共掺杂量时光催化制氢活性明显提高. 其中, NaTaO3: Cu/W的光催化制氢活性在Cu与W的摩尔比为1: 4, 共掺杂量为4%时达到最佳值. 结果表明, Cu, W共掺杂NaTaO3可在一定程度上实现电荷平衡, 降低光生电子和空穴的复合几率, 从而提高光催化活性.     

Large-scale synthesis of TiO2 nanorods via nonhydrolytic sol-gel ester elimination reaction and their application to photocatalytic inactivation of E. coli

A simple method of synthesizing a large quantity of TiO(2) nanorods was developed. A nonhydrolytic sol-gel reaction between titanium(IV) isopropoxide and oleic acid at 270 degrees C generated 3.4 nm (diameter) x 38 nm (length) sized TiO(2) nanocrystals. The transmission electron microscopic image showed that the particles have a uniform diameter distribution. X-ray diffraction and selected-area electron diffraction patterns combined with high-resolution transmission electron microscopic image showed that the TiO(2) nanorods are highly crystalline anatase crystal structure grown along the [001] direction. The diameters of the TiO(2) nanorods were controlled by adding 1-hexadecylamine to the reaction mixture as a cosurfactant. TiO(2) nanorods with average sizes of 2.7 nm x 28 nm, 2.2 nm x 32 nm, and 2.0 nm x 39 nm were obtained using 1, 5, and 10 mmol of 1-hexadecylamine, respectively. The optical absorption spectrum of the TiO(2) nanorods exhibited that the band gap of the nanorods was 3.33 eV at room temperature, which is 130 meV larger than that of bulk anatase (3.2 eV), demonstrating the quantum confinement effect. Oleic acid coordinated on the nanorod surface was removed by the reduction of the carboxyl group of oleic acid, and the Brunauer-Emmett-Teller surface area of the resulting naked TiO(2) nanorods was 198 m(2)/g. The naked TiO(2) nanorods exhibited higher photocatalytic activity than the P-25 photocatalyst for the photocatalytic inactivation of E. coli.     

Hydrothermal synthesis of Zn2SnO4 nanorods in the diameter regime of sub-5 nm and their properties

Single crystalline Zn(2)SnO(4) (ZTO) nanorods 2-4 nm in diameter and around 20 nm in length were successfully synthesized by a simple hydrothermal process with use of hydrazine hydrate as an alkaline mineralizer instead of NaOH or NH(3).H(2)O. By analyzing the UV-vis diffuse reflectance spectrum, the optical band gap (E(g)) of the nanorods was found to be 3.87 eV, which indicates a blue shift of 0.27 eV from that of bulk ZTO (3.6 eV). In situ high-temperature X-ray diffraction was employed to study the thermal expansion coefficient and the variation of lattice parameter with temperature of the product. Furthermore, we discussed the chemical mechanism and key factors to the hydrothermal formation of the sub-5 nm ZTO nanorods.     

Synthesis of quantum-sized cubic ZnS nanorods by the oriented attachment mechanism

Quantum-sized ZnS nanocrystals with quasi-spherical and rod shapes were synthesized by the aging reaction mixtures containing diethylzinc, sulfur, and amine. Uniform-sized ZnS nanorods with the average dimension of 5 nm x 21 nm, along with a small fraction of 5 nm-sized quasi-spherical nanocrystals, were synthesized by adding diethylzinc to a solution containing sulfur and hexadecylamine at 125 degrees C, followed by aging at 300 degrees C. Subsequent secondary aging of the nanocrystals in oleylamine at 60 degrees C for 24 h produced nearly pure nanorods. Structural characterizations showed that these nanorods had a cubic zinc blende structure, whereas the fabrication of nanorods with this structure has been known to be difficult to achieve via colloidal chemical synthetic routes. High-resolution TEM images and reaction studies demonstrated that these nanorods are formed from the oriented attachment of quasi-spherical nanocrystals. Monodisperse 5 nm-sized quasi-spherical ZnS nanocrystals were separately synthesized by adding diethylzinc to sulfur dissolved in a mixture of hexadecylamine and 1-octadecene at 45 degrees C, followed by aging at 300 degrees C. When oleic acid was substituted for hexadecylamine and all other procedures were unchanged, we obtained 10 nm-sized quasi-spherical ZnS nanocrystals, but with broad particle size distribution. These two different-sized quasi-spherical ZnS nanocrystals showed different proportions of zinc blende and wurtzite crystal structures. The UV absorption spectra and photoluminescence excitation spectra of the 5 nm ZnS quasi-spherical nanocrystals and of the nanorods showed a blue-shift from the bulk band-gap, thus showing a quantum confinement effect. The photoluminescence spectra of the ZnS nanorods and quasi-spherical nanocrystals showed a well-defined excitonic emission feature and size- and shape-dependent quantum confinement effects.     

硫化铜纳米棒的低热固相合成及其光学性能

在表面活性剂PEG-400存在的条件下,以醋酸铜和硫代乙酰胺为原料,利用低热固相化学反应,一步制备出分散均匀的硫化铜纳米棒.X射线粉末衍射和能量散射X射线能谱分析证明,产物为纯六角相的硫化铜.透射电镜和扫描电镜形貌分析表明,产物为棒状,直径为80～100nm,长度为200～500nm.紫外-可见光谱和光致发光光谱表明,硫化铜纳米棒的紫外和荧光最大吸收和发射波长与常规硫化铜相比均发生了明显的蓝移,表明所制备的硫化铜纳米棒具有良好的光学性质.     

Generalized synthesis of metal phosphide nanorods via thermal decomposition of continuously delivered metal-phosphine complexes using a syringe pump

We synthesized uniform-sized nanorods of transition metal phosphides from the thermal decomposition of continuously delivered metal-phosphine complexes using a syringe pump. MnP nanorods with dimensions of 8 nm x 16 nm and 6 nm x 22 nm sized were synthesized by the thermal decomposition of Mn-TOP complex, which was prepared from the reaction of Mn(2)(CO)(10) and tri-n-octylphosphine (TOP), using a syringe pump with constant injection rates of 10 and 20 mL/h, respectively. When Co-TOP complex, which was prepared from the reaction of cobalt acetylacetonate and TOP, was reacted in a mixture solvent composed of octyl ether and hexadecylamine at 300 degrees C using a syringe pump, uniform 2.5 nm x 20 nm sized Co(2)P nanorods were generated. When cobaltocene was employed as a precursor, uniform Co(2)P nanorods with 5 nm x 15 nm were obtained. When Fe-TOP complex was added to trioctylphosphine oxide (TOPO) at 360 degrees C using a syringe pump and then allowed to age at 360 degrees C for 30 min, uniform-sized FeP nanorods with an average dimension of 12 nm x 500 nm were produced. Nickel phosphide (Ni(2)P) nanorods with 4 nm x 8 nm were synthesized successfully by thermally decomposing the Ni-TOP complex, which was synthesized by reacting acetylacetonate [Ni(acac)(2)] and TOP. We measured the magnetic properties of these nanorods, and some of the nanorods exhibited different magnetic characteristics compared to the bulk counterparts.     

Phase-controlled synthesis and characterization of nickel sulfides nanorods

Different one-dimensional nickel sulfides, NiS nanorods and Ni₉S₈ nanorods were synthesized in the presence (Route 1) and absence (Route 2) of gas CO₂. X-ray powder diffraction patterns, scanning electron microscopy and transmission electron microscopy images show that the product from Route 1 is NiS nanorods with a diameter of about 50-120 nm, while the product from Route 2 is Ni₉S₈ nanords about 70-200 nm in diameter. A molecular-template-like mechanism was proposed for the one-dimensional structures growth. The products were also investigated by Raman and photoluminescence (PL) spectroscopy.     

Gold nanorods as nanoadmicelles: 1-naphthol partitioning into a nanorod-bound surfactant bilayer

As-prepared gold nanorods, stable in aqueous solution, bear a bilayer of the cationic surfactant cetyltrimethylammonium bromide (CTAB). This bilayer provides a approximately 3 nm thick hydrophobic layer that could be used to sequester hydrophobic organic molecules from aqueous solution. We have investigated the uptake of 1-naphthol as a model hydrophobic compound by CTAB-coated gold nanorods using both ultraviolet-visible spectroscopy and gas chromatography with flame ionization detection. We find the adsorption isotherm of 1-naphthol partitioning into the CTAB bilayer on gold nanorods fits the Langmuir model. The maximum number of bound 1-naphthol molecules is 14.6 +/- 2.2 x 10(3) molecules per gold nanorod, with an equilibrium binding constant of 1.97 +/- 0.79 x 10(4) M(-1) at room temperature.     

水热法合成α-MnO2纳米棒及其电化学性能

以KMnO4、氧化石墨(GO)和硫酸为原料,在120℃水热条件下3 h成功合成了直径为10~20 nm,长度为300~400 nm的α-MnO2纳米棒。研究发现GO的引入降低了纳米棒的制备温度,缩短了反应时间。电化学测试结果表明,在1 mol.L-1Na2SO4中性水系电解液中,该纳米棒表现出良好的电容性能,当扫描速率分别为2 mV.s-1和5 mV.s-1时,比电容分别为276 F.g-1和240F.g-1;该纳米材料是一种潜在的电化学电容器电极材料。