Template‐free synthesis of hierarchical zinc oxide with improved photocatalytic properties

Novel hierarchical nano materials possess tremendous latent force in many applications. In this paper, hierarchical flower‐like, spherical and bowl‐like zinc oxide was successfully synthesized by altering solvent ratio (absolute ethanol and diethylene glycol) via a simple and template‐free solvothermal synthetic route. The solvent ratio also plays a vital role in deciding the structure, crystalline, band gap energy and specific surface area of the as‐synthesized samples. The preparation mechanism of ZnO in mixed alcohols was discussed. The obtained samples were characterized by energy dispersive spectroscopy(EDS), X‐ray diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), N2 adsorption‐desorption, UV–vis diffuse reflectance spectroscopy (DRS). Photocatalytic activity of the as‐prepared ZnO nanocrystals was evaluated by the degradation of MB under UV irradiation. Among, the most effective photocatalyst was synthesized when the diethylene glycol was 10 ml.     

Effect of chlorine ion on the crystalline and photocatalytic activity of BiOCl for the degradation of Rhodamine B

Two kinds of layer‐structured BiOCl photocatalysts (BiOCl‐01 and BiOCl‐02) were synthesized using NaBiO₃ and HCl as the raw materials, and KCl as the Cl⁻ conditioning agent. These photocatalysts were characterized by X‐ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), and ultraviolet visible diffuse reflectance spectra (DRS) measurements. The effects of chlorine ion in the reaction solutions on the crystalline of BiOCl and photodegradation of Rhodamine B (RhB) under 365 nm and 530 nm monocharomatic light irradiation were investigated. The XRD spectra confirmed the formation and purity of BiOCl photocatalysts, revealed that Cl⁻ ion existed in the preparation solution restrained the growth of BiOCl and influenced the surface configuration. The TEM and HRTEM analysis gave the similar results with XRD. The band gaps of BiOCl‐01 and BiOCl‐02 were estimated about 3.19 and 3.29 eV, respectively. The photocatalytic degradation results of RhB under 365 nm showed that the photocatalytic activity of BiOCl‐02 was better than that of BiOCl‐01, and the main active species were h⁺ and . Meanwhile, the photosensitized results of RhB under 530 nm indicated that the photosensitized activity of BiOCl‐01 and BiOCl‐02 was similar, and the main active species was .     

多孔纳米氧化钛的制备及其光催化降解罗丹明B

以聚乙二醇(PEG)为造孔剂,采用溶胶-凝胶法制备了多孔纳米TiO_2粉末,并对样品进行了氮吸附测试和X射线衍射分析.结果表明:煅烧过程中,聚乙二醇的受热分解在TiO_2颗粒中形成了4～6 nm的中孔结构;600 ℃煅烧的TiO_2样品均呈单一的锐钛矿相结构,且适量聚乙二醇的加入可抑制TiO_2粒径的长大.光催化降解罗丹明B表明:催化剂具有很强的氧化能力,适量聚乙二醇的加入可提高TiO_2的光催化性能,在本实验进行的条件下,PEG最佳加入量为0.50 g.     

Hydrothermal syntheses of silver phosphate nanostructures and their photocatalytic performance for organic pollutant degradation

Photocatalysis has been recognized as a potential strategy for energy conversion and environmental remediation. In this study, we present a facile hydrothermal method for the controlled syntheses of Ag₅P₃O₁₀, Ag₄P₂O₇/Ag₃PO₄ and Ag₃PO₄ photocatalysts by using sodium triphosphate (Na₅P₃O₁₀) as the phosphate source. The phase structure and morphology of the products were investigated by X‐ray powder diffraction (XRD) and scanning electron microscopy (SEM). The photocatalytic activities of the synthesized Ag₅P₃O₁₀, Ag₄P₂O₇/Ag₃PO₄ and Ag₃PO₄ nanostructures were evaluated by the degradation of organic pollutants under simulated sunlight irradiation. The kinetics of the photocatalytic degradation reaction is presented. It is revealed that the photocatalytic activity increases in the order of Ag₅P₃O₁₀, Ag₄P₂O₇/Ag₃PO₄ and Ag₃PO₄, and the Ag₃PO₄ nanocrystals show the best photocatalytic performance. The photocatalytic mechanism was systematically investigated, and the superoxide radicals (O₂^•−) and photoinduced holes are considered to contribute mostly to the high photocatalytic activity of Ag₃PO₄.     

ZnS空心微球的制备及其光催化性能研究

采用简单的一步溶剂热法合成了ZnS空心微球.利用X射线衍射(XRD)、扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)、X射线光电子能谱(XPS)和紫外可见吸收光谱(UV-vis)等测试手段对其形貌、结构和光学性质进行了分析,并以罗丹明B(RhB)为模型污染物研究了样品的光催化性能.结果表明:样品为纯度较高的立方闪锌矿型ZnS微球,且球体由纳米级小微粒组装而成;在降解RhB的光催化研究中,以乙醇-水为溶剂合成的ZnS微球光催化性能较优.     

Optical,photocatalytic properties of novel CuS nanoplate‐based architectures synthesised by a solvothermal route

CuS architectures were successfully prepared by a simple solvothermal route without any surfactant, in which copper nitrate trihydrate and element sulfur were used as reactants. The products were characterized by X‐ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. The optical properties of CuS architectres were investigated by Raman spectrometer, ultraviolet‐visible spectroscopy, and fluorescence spectrophotometer. The results showed that the CuS architectures were hexagonal‐structured phase and composed of intersectional nanoplates. UV‐Vis absorption peaks of CuS architectures showed large blue shifts and PL spectrum exhibited a strong blue emission and a weak green emission. Photocatalytic activity of the CuS architectures was evaluated by measuring the decomposition rate of methylene blue solution under solar light. The CuS architectures show good photocatalytic activity. The effects of the molar ratio of Cu:S and the growth time on the synthesis of CuS crystalline were discussed and the growth mechanism of CuS nanoplate‐based architectures was also proposed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

花状TiO2的制备及光催化性能研究

采用溶剂热法合成了花状TiO2,运用SEM、XRD和N2物理吸附-脱附等对其形貌、结构、比表面积和孔径进行了表征,并以甲基橙为模拟污染物研究了它们的光催化性能.结果表明,花状TiO2结构为锐钛矿相,是由纳米晶定向聚集形成纳米棒组成的3D花状结构,花状结构的直径在0.7～1.5 μm,平均直径在1.1μm,细小纳米晶聚集形成的纳米棒的直径在20～25 nm,长度100～ 150 nm.该样品具有较高的比表面积,表现出良好的光催化活性.     

Solvothermal synthesis of mesoporous slabstone‐like TiO2 and its photodegradation preference in a methyl orange‐rhodamine B mixture solution

Mesoporous slabstone‐like anatase TiO₂ micro‐nanometer composite structure has been successfully synthesized by a facile solvothermal method at 180 °C using polyethylene glycol (PEG) as a structure‐directing agent, followed by calcination at 400 °C for 2 h. The crystal structure and morphology of the product were characterized by XRD, SEM, TEM and HRTEM. Its BET specific surface area was obtained from N₂ adsorption‐desorption isotherm measurement. Rhodamine B (RB) aqueous solution was used to evaluate the photocatalytic activity of the as‐prepared TiO₂ under simulated sunlight irradiation and compared with that of commercial TiO₂ (P25). A RB and methyl orange (MO) coexisting solution was chosen to investigate the photodegradation preference of the slabstone‐like TiO₂ on these two dyes. The results show that the photocatalytic activity of the as‐prepared TiO₂ is much higher than that of P25, and MO is the preferential degradation species in the MO‐RB mixture solution.     

Photocatalytic activity of Ag‐ZnO heterostructure for degradation of rhodamine B under direct sunlight

Ag‐ZnO heterostructure was obtained through a simple method that is suitable for general laboratory production. The X‐ray diffraction (XRD), transmission electron microscopy (TEM) results showed that Ag‐ZnO heterostructure had excellent purity and crystalline properties. Meanwhile, the catalytic degradation results demonstrated that it had high photocatalytic activity to the degradation of rhodamine B (RhB). Besides, in order to explore the optimum catalytic activity of the sample, the influences of experimental parameters including additives, the amount of catalyst, the concentration and initial pH of RhB were studied in detail.     

Solvothermal synthesis and growth mechanism of asymmetric ZnO hierarchical structures in diethylene glycol with ammonia solution

Several novel asymmetric ZnO hierarchical structures were synthesized in diethylene glycol (DEG) with different amount of ammonia solution via solvothermal process. The submicron‐rods or nanorods as the building units are distributed on the two sides in an asymmetric manner, resulting in formation of the shiitake‐like or bouquet‐like morphology. A possible formation mechanism was proposed on the basis of the experimental result. The consumption of the precursor could lead to a two‐step nucleation and growth process. The relative content of the [Zn(OH)₄]²⁻ and the [Zn(NH₃)₄]²⁺ precursors varies with the amount of ammonia solution, which affect the size and morphology of the asymmetric structures. The [Zn(OH)₄]²⁻ complex and the [Zn(NH₃)₄]²⁺ complex are absorbed on the positive (0001)‐Zn polar surface and the negative (000–1)‐O polar surface respectively, which lead to the alteration of growth rate of these polar surfaces.     

Synthesis of ZnO films in different solvents and their photocatalytic activities

ZnO thin films have been successfully synthesized via the chemical bath deposition (CBD) method without using any catalysts or templates. The effects of solvents (such as water, ethanol and n‐propanol) on structure and morphology of ZnO thin films have been studied. XRD analysis showed that all ZnO thin films with wurtzite crystal structure were obtained via various solvents. SEM images showed that ZnO thin films prepared in different solvents have different sizes and morphologies. TEM images showed that crystalline ZnO samples prepared in different solvents have different growth habits. Photoluminescence and photocatalysis properties have been investigated at room temperature. ZnO thin films prepared in water showed superior photocatalytic activity in the degradation of rhodamine B (RhB) compared to other samples.     

Fabrication and photocatalytic property of CuO nanosheets via a facile solution route

Two‐dimensional (2D) CuO nanosheets were fabricated on Cu foils using a solution method. The method was novel, easy and can be completed at room temperature in the absence of any surfactant. The obtained materials were characterized by X‐ray diffraction (XRD), X‐ray Photoelectron Spectroscopy (XPS), scanning electron microscopy (SEM) and ultraviolet‐visible (UV‐Vis) spectroscopy. The effects of reaction time and temperature on the morphology and formation of CuO nanosheets were investigated, and a possible mechanism for the formation of CuO nanosheets was proposed. Experiments demonstrated that the formation of CuO nanosheets were significantly influenced by the growth time, and the reaction temperature was a key factor in determining the size of CuO nanosheets. Photocatalytic performance of CuO nanosheets was evaluated by measuring the decomposition rate of methyl orange solution. About 93% of the methyl orange was degraded after 150 min, which was much more efficient than that of CuO nanoparticles.     

Solvothermal synthesis of flower‐like lanthanum tartrate and lanthanum oxide microspheres in ethanol‐water mixed system

Monodispersed lanthanum tartrate microspheres with flower‐like shape were synthesized by a mild solvothermal method using ethanol‐water mixed system as the solvent. Lanthanum oxide with reserved spherical shape was subsequently fabricated by a following calcination process. X‐ray diffraction analyses (XRD), X‐ray spectroscopy (EDS), scanning electron microscopy (SEM), thermogravimetry‐differential thermal analysis (TG‐DTA) were employed to characterize the composition, structure, and morphology of the products. The lanthanum tartrate microspheres were aggregated by nanosheets as petals. Size of the aggregation and thickness of the petal vary with the vol.% of ethanol. As the vol.% of ethanol increases the degree of aggregation and the thickness of the petal decrease, and other properties such as the size distribution, dispersion are also modulated. These alterations can be interpreted by the changing dielectric constant of mixed solvent. Such lanthanum tartrate can be applied to fabricate micro‐sphereshaped lanthanum oxide after calcination. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

ZnO-SiO2的制备及其光催化降解罗丹明B

采用溶胶-凝胶法制备负载型ZnO-SiO2光催化材料,研究升温速率及负载量对ZnO结构、形貌及光催化活性的影响.通过X射线衍射、N2物理吸附-脱附、扫描电子显微镜、光致发光光谱和紫外-可见漫反射光谱等手段对催化剂进行表征,并以罗丹明B为模拟污染物,紫外光为光源,评价催化剂活性.结果表明,升温速率对ZnO-SiO2光催化剂结晶度和光催化活性影响显著.当ZnO与SiO2的质量比为1∶1时,ZnO-SiO2具有均匀、平滑的球形形貌,并且ZnO光催化活性明显改善.     

Synthesis of Ru microspheres by self‐assembly in tungstosilicate acid solution and photocatalytic degradability of cango red

The formation of Ru microspheres by hydrothermal treated method in tungstosilicate acid (H₄SiW₁₂O₄₀, TSA) solution is described. The particles are characterized by X‐ray diffraction analysis (XRD) and scanning electron microscopy (SEM), respectively. The growth process of these microspheres has been examined. The results show that it is possible to synthesize and assemble other noble metal particles with unique superstructure. The characteristic catalytic behavior of the Ru microspheres is established by studying the decolorization of cango red in the presence of UV light. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Tunable synthesis of hierarchical TiO2 spheres consisting of rutile nanowires for dye‐sensitized solar cells and photocatalysis

Hierarchical TiO₂ spheres consisting of rutile nanowires (HTS) are successfully prepared in the bulk solution via a non‐polar solvent/polar solution interfacial syntheses strategy. The effect of reaction temperature on the morphology, size, BET surface area and monodispersion of HTS is studied systematically. Increasing reaction temperature decreases the diameter of spheres in micro‐scale whereas increases the diameter of nanowires in nano‐scale for these HTS. Monodisperse HTS are formed at 230 °C for 20 h, which can suitably be served as light scattering structure for dye‐sensitized solar cell with the additional advantage of rapid electron transport rate. A high efficiency of 8.54% was achieved for the composite DSSC consisting of nanoparticles and monodispersed HTS (synthesized at 230 °C), showing 31.38% improvement compared with that (6.5%) of the DSSCs made from pure P25 nanoparticles at the similar thickness. Furthermore, the photocatalytic performances of HTS for the degradation of methyl orange were also investigated. Contrary to the effect on the performance of DSSC, the HTS synthesized at 150 °C show higher photocatalytic degradation efficiency due to larger BET surface area.     

B,Ru共掺杂TiO2纳米粉体的制备及光催化性能

采用溶胶凝胶法制备了B、Ru共掺杂TiO2纳米粉体,采用XRD、TEM、XPS、FT-IR及UV-Vis等技术对催化剂进行了表征.结果表明:B部分掺入到TiO2晶格间隙中形成B-O-Ti键,部分以B2O3的形式存在;Ru掺入到TiO2品格;B、Ru掺杂均能抑制TiO2由锐钛矿相向金红石相的转变,同时促使TiO2晶粒细化;B掺杂能减少光生电子-空穴的复合、促进TiO2表面活性基团Ti-OH的生成、减小光学带隙值,而Ru掺杂的这三方面的作用却有限.Ru掺杂降低了TiO2的光催化活性,而B掺杂却能大幅提高了TiO2的光催化活性,因而Ru、B共掺杂样品的光催化活性比仅B掺杂样品还稍低,当B掺杂质量百分数为1.0;时,可见光下光催化降解亚甲基蓝的2h降解率由未掺杂TiO2的68.5;提高至84.3;.     

Synthesis and photoluminescence properties of bundle‐like CdS nanostructures assembled by high‐quality nanorods

Bundle‐like cadmium sulfide (CdS) nanostructures assembled by high‐quality nanorods have been successfully synthesized on a large scale via a facile solvothermal route in a mixed solvent of ethylenediamine and dodecanethiol. The typical lengths of bundle‐like CdS nanostructures are several tens of micrometers, and the diameters and lengths of CdS nanorods are about 50–70 nm and several micrometers, respectively. The influence of the concentration of dodecanethiol on the morphologies of CdS nanostructures has been investigated carefully. Photoluminescence spectra (PL) of CdS nanostructures reveal that the bundle‐like CdS nanostructures exhibited two fluorescence emission peaks centered at 495nm (2.51 eV) and 522 nm (2.38 eV) as the excitation wavelength is 405 nm. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

溶剂热法制备片状结构CaTiO3及光催化性能研究

在无模板或无表面活性剂条件下,利用溶剂热制备片状结构的CaTiO3.探究了水热时间对CaTiO3显微结构和在紫外光下催化降解罗丹明B溶液的光催化活性.分析了CaTiO3光催化剂加入量和不同pH值的罗丹明B溶液对样品光催化性能的影响.通过扫描电镜(FESEM)、X-衍射仪(XRD)、紫外-可见吸收光谱仪(UV-vis)和比表面积分析仪(BET)对样品进行了性能表征.实验结果表明:当水热时间24 h时制备了具有较好光催化性能的CaTiO3片状结构.同时加入0.1g CaTiO3样品降解pH值为9的罗丹明B溶液中,在紫外光的照射下CaTiO3样品光催化降解效果最好,60 min可达到K=0.0526 min-,其降解完后的溶液pH呈现中性,对环境不会造成酸碱污染.     

有机溶剂热生长技术制备Zn(en)2S、ZnS纳米棒及其光学性能的研究

以有机溶剂热生长技术（organic solvothcmml technique）制备Zn（en）2S（en为乙二胺）纳米棒,以IR、XRD、TG等测试表明该化合物中乙二胺与中心离子Zn^2＋通过配位键结合。以TEM、ED初步研究了该纳米材料的形貌、结构;以制得的纳米Zn（en）2S为母体,在氮气氛中,煅烧至900℃,制得棒状纳米ZnS;溶胶提拉法,在导电玻璃（ITO）基体上制备出Zn S、Zn（en）：S纳米微粒／ITO复合膜,并研究其光学特性。结果表明,二者均为纳米棒构型,Zn（en）2S属立方晶系,棒直径约为30nm;ZnS属六方纤锌矿型,棒直径较大,在60nm左右。PL分析表明Zn（en）2S的荧光红移至452nm处。