Hydrothermal synthesis of Na4Mn9O18 nanowires for sodium ion batteries

Na₄Mn₉O₁₈ was recognized as the most interesting material for sodium ion batteries due to its low cost, high specific capacity and good cycle performance. The excellent electrochemical performance of Na₄Mn₉O₁₈ nanostructures was shown in literature. In this work, Na₄Mn₉O₁₈ nanowires were synthesized by hydrothermal reactions of Mn₂O₃ powder and NaOH solution at the temperatures of 185–205 °C for 48–96 h. The investigation of composition and structure of the synthesized products via scanning electron microscopy and X-ray diffraction analyses showed that major intermediate products at the low and high temperatures were Mn₃O₄ and birnessite Na_0.55Mn₂O₄1.5H₂O, respectively. The synthesized Na₄Mn₉O₁₈ nanowires showed a good electrochemical performance with discharge capacities of over 90 mAhg⁻¹, and Coulombic efficiencies of more than 91% at a rate of 0.2C during 30 cycles of charge/discharge.     

Hydrothermal synthesis and characterization of Lanthanum-doped NaTaO3 with high photocatalytic activity

Lanthanum-doped NaTaO₃ (NaTaO₃:La) nanocrystals have been synthesized by a hydrothermal method. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), transmission electron microcopy (TEM), inductive coupled plasma atomic absorption spectrometric analysis, volumetric adsorption method (BET) and UV–vis spectroscopy were used to characterize the samples. The NaTaO₃:La nanocubes show a higher photocatalytic activity than that of the pure NaTaO₃ in the degradation of the safranine T dye under UV irradiation. The highest photocatalytic activity was achieved when 2 mol% lanthanum was doped.     

钙钛矿型铌氧化物K_(0.7)Ba_(0.3)NbO_3的水热合成及表征

采用水热法合成了K0.7Ba0.3NbO3催化材料,通过XRD、SEM、XPS对样品进行表征。实验结果表明,该化合物的结晶度非常好。SEM分析,该化合物粒径均一、具有规则的正方形结构。XPS测试结果表明,合成出Nd为混合价态的复合材料。由于铌酸盐通常具有合适的能带结构和特殊的晶体结构,在光催化反应系统中也表现出较强的促进剂和载体的特性,为此本文所研究的是近年来研究较多的一类新型材料。     

Ferroelectric K0.5Na0.5NbO3 catalysts for dye wastewater degradation

K_0.5Na_0.5NbO₃ (KNN) particles were prepared by a solid–state method. X–ray diffraction, scanning electron microscopy, UV–visible spectrophotometry, and electrochemical impedance spectroscopy were used to study the structure, morphology, and properties of the samples. The obtained KNN is a ferroelectric material with orthorhombic perovskite structure at room temperature. The KNN particles can be used as piezo/photo–bicatalysts for degrading organic pollutants by utilizing vibrational and solar energy; the catalytic activity of the particles can be significantly improved owing to their polarization under an applied electric field. Poled KNN particles show a bicatalytic degradation ratio of rhodamine B (RhB) dye reaching 92% after 60 min. The results indicate that the KNN particles can be applied as attractive ferroelectric catalysts for organic pollutant degradation.     

纳米ZnO的水热合成及性能研究

采用简单的水热方法制备出纯净且粒径均匀的纳米Zn O粒子,借助于X射线粉末衍射仪(XRD)和扫描电子显微镜(SEM)对其物相组成及表面形貌进行了表征,通过日光下亚甲基蓝的降解研究了其光催化性能。将获得的ZnO纳米粒子沉积成膜,经表面修饰低表面能物质1H,1H,2H,2H-全氟辛基三氯硅烷(CAS)后,采用接触角测量仪研究了其润湿性能。结果表明,反应时间为20 h的ZnO纳米粒子在日光照射20 min后,亚甲基蓝的降解率达到90%以上;经表面修饰CAS后,Zn O膜呈现良好的疏水性能;经紫外光照射后,疏水性ZnO膜转换为亲水性,实现了润湿性的转换。     

ZnO nanorods surface-decorated by WO3 nanoparticles for photocatalytic degradation of endocrine disruptors under a compact fluorescent lamp

Nanoscaled tungsten oxide (WO₃) particles coated on ZnO nanorods (ZNRs) were newly synthesized by combining a hydrothermal technique with a chemical solution process. The structure, morphologies and compositions of the as-prepared WO₃–ZNR nanocomposites were characterized through XRD, FESEM, TEM and Raman measurements. The results revealed that pure monoclinic WO₃ nanoparticles with an average size range of 18–26 nm were distributed on the surfaces of ZNRs and attached strongly. Particularly, the optical properties as well as photocatalytic characteristics of pure ZNRs and WO₃–ZNR nanocomposites with different loadings of WO₃ were also examined. The absorption of WO₃–ZNR nanocomposites was redshifted due to effective immobilization of WO₃ on ZNRs. Under irradiation of a 55 W compact fluorescence lamp, the photocatalytic activities of the WO₃–ZNR nanocomposites were superior to those of pure ZNRs and P25 in the degradation of resorcinol (ReOH). Furthermore, WO₃–ZNR nanocomposites showed very favorable recycle use potential and high sedimentation rate. Other endocrine disrupting chemicals (EDCs) such as phenol, bisphenol A (BPA) and methylparaben were also successfully photodegraded under identical conditions. These characteristics showed the practical applications of the WO₃–ZNR nanocomposites in indoor environmental remediation.     

Multi-walled carbon nanotubes modified Bi2S3 microspheres for enhanced photocatalytic decomposition efficiency

A series of multi-walled carbon nanotubes (MWCNTs)-loaded Bi₂S₃ nanomaterials composites (MWCNTs/Bi₂S₃) were prepared by hydrothermal method. The crystallization, morphology and other properties of the obtained MWCNTs/Bi₂S₃ composites were completely characterized by powder X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transformed infrared spectroscopy (FT-IR), Thermal gravimetric analysis and differential thermal analysis (DTA-TG), N₂ adsorption-desorption isotherm, and UV–vis diffuse reflectance spectroscopy (DRS). In this work, the photocatalytic activity of the as-prepared materials was evaluated for methylene blue (MB) degradation under visible light irradiation. Comparing with others work, the composites showed excellent photocatalytic performance and maintained a good stability during the constant cycling experiment. Finally, a possible photocatalytic reaction mechanism on the MWCNTs/Bi₂S₃ composites was proposed.     

Hydrothermal synthesis of morphology-controlled KNbO3, NaNbO3, and (K,Na)NbO3 powders

NaNbO₃, (K,Na)NbO₃ and KNbO₃ powders were synthesized using (1− y) NaOH–y KOH solutions ([OH⁻] =7.5–15 M) with y=0, 0.78, and 1 at 200 °C by the hydrothermal method, respectively. Their compositions, structures, and morphologies were analysed. Both of the synthesized NaNbO₃ and KNbO₃ powders had sub-micron- or micron-sized grains. The [OH⁻] drastically influenced the size and morphology of the KNbO₃ particles but did not influence those of the NaNbO₃ particles. In contrast, the morphology of the (K,Na)NbO₃ particles, which were aggregates of nano-grains, was influenced by the hydrothermal-treatment time rather than [OH⁻]. Moreover, their composition and phase were influenced by both annealing and the hydrothermal-treatment time, and their formation mechanism was discussed by comparison with those of KNbO₃ and NaNbO₃ particles. The present synthetic strategy enables tailoring the compositions, morphologies, and structures of the niobate products to different applications by controlling the process parameters.     

Hydrothermal synthesis of S-doped TiO2 nanoparticles and their photocatalytic ability for degradation of methyl orange

A simple synthesis route to nanocrystalline S-doped TiO₂ photocatalysts by a hydrothermal method at 180 °C was developed and the photocatalytic activity of the obtained powders for the degradation of methyl orange was studied. The products were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The phase composition (anatase/rutile ratio) and the photocatalytic activity of the final materials were found to be markedly influenced by the amount of the incorporated sulphur. On increasing the S-dopant amount, the anatase/rutile ratio and the photocatalytic activity of the as-prepared powders increased.     

Immobilization of hydrothermally produced TiO2 with different phase composition for photocatalytic degradation of phenol

Hydrothermally produced TiO₂ powders with different phase composition (anatase, rutile and mixed phase) were immobilized on glass fibers and tested in the phenol mineralization process. Both H₂O₂ and O₂ were used as oxygen donors, and their performances were compared with those of the same TiO₂ samples as slurries.The catalytic properties of the immobilized different crystalline phases, rutile and anatase, show the same trend as the slurry samples: pure rutile displays the highest catalytic efficiency in the presence of H₂O₂, while samples containing anatase improve the photodegradation efficacy with O₂. It was suggested that the stability of the photogenerated electron–hole couple allows high activity of rutile in the presence of H₂O₂, while the relevant oxygen chemisorption on anatase causes high catalytic activity in the presence of O₂. A four parameters kinetics model shows that both reaction steps, the phenol degradation and the mineralization of the intermediates, are photoactivated by TiO₂.Photoactivity of the coated glass fibers is generally lower than that of slurries, even if their efficiencies are almost comparable when the oxidation is performed by H₂O₂, while much lower when the oxygen donor is O₂. As a matter of fact, the morphology of immobilized catalysts shows the presence of chestnut burr aggregates of large rutile crystalline rods on the glass fiber, which are much less compact than the aggregates of small anatase particles. This preserves rutile surface area from the coarsening effects; thus, when rutile is the more active species, as in the presence of H₂O₂, the photocatalytic activity is less affected by immobilization.     

Synthesis and photocatalytic activity of Na+ co-doped CaTiO3:Eu3+ photocatalysts for methylene blue degradation

The Na⁺ co-doped CaTiO₃:Eu³⁺ powders were produced through the solution combustion method. The phase structure and optical properties of the synthesized samples were adequately characterized by X-ray diffraction (XRD), photoluminescence (PL) spectra, ultraviolet–visible (UV–vis) diffuse reflection spectroscopy and scanning electron microscopy (SEM). The XRD patterns revealed that a low level of Eu³⁺ doping could not cause lattice distortion of CaTiO₃. Photoluminescence (PL) displayed the CaTiO₃:0.5% Eu³⁺ sample synthesized at 900 °C has the weakest PL emission and the low electrons and holes recombination rate. The morphology of the sample was small nanoscale spherical particles. The UV–vis diffuse reflection spectra proved that doping Na⁺ and Eu³⁺ enlarged the absorption region and reduced band energy of pure CaTiO₃. The photocatalytic properties of Na⁺ co-doped CaTiO₃:Eu³⁺ samples were investigated via degrading methylene blue (MB) under ultraviolet light irradiation. The CaTiO₃:0.5% Eu³⁺, 0.5% Na⁺ sample, by contrast, exhibited the greatest photocatalytic property and the degradation rate was as high as 96.62%, which makes it a promising multi-functional material (photocatalytic material and red phosphor) for decreasing organic pollution in water.     

Semiconductor-mediated photocatalytic degradation of anazo dye, chrysoidine Y in aqueous suspensions

The photocatalytic degradation of an azo dye derivative, chrysoidine Y (1), was investigated in aqueous suspensions of titanium dioxide and zinc oxide by monitoring the change in substrate concentration employing UV spectroscopic analysis and decrease in total organic carbon content as a function of irradiation time under a variety of conditions. The degradation of the dye was studied under different conditions such as pH, catalyst concentration, substrate concentration and in the presence of electron acceptors such as hydrogen peroxide (H₂O₂) and potassium bromate (KBrO₃) besides molecular oxygen. The degradation rates were found to be strongly influenced by all the above parameters. The photocatalyst Degussa P25 was found to be more efficient as compared with zinc oxide     

Fast synthesis of NaNbO3 nanoparticles with high photocatalytic activity for degradation of organic dyes

NaNbO₃ nanoparticles were obtained using the microwave-assisted hydrothermal method followed by heat treatment. It has been shown that heat treatment to increase the crystallinity of the material and modifies particle shape, from nanowires to nanograins. Nanowires with a diameter of approximately 35 nm and a length of tens of micrometers were obtained in the shortest time ever reported in the literature. Particles in the shape of nanograins with a diameter of approximately 35 nm were obtained by burning the nanowires. The photocatalytic activity of the nanoparticles was investigated through the photodegradation of Rhodamine B dye. Electronic structure analysis using density functional theory (DFT) along with experimental techniques was performed to help understand the photocatalytic activity of each sample. The obtained nanoparticles were highly favorable for photocatalytic applications, especially the nanograins, which degraded 100% of the dye in 50 min.     

Growth of ZnO nanowires on carbon fibers for photocatalytic degradation of methylene blue aqueous solutions: An investigation on the optimization of processing parameters through response surface methodology/central composite design

In this work, effects of hydrothermal (HT) synthesis method parameters, temperature, concentration and growth time, on the formation of zinc oxide nanowire structures on carbon fibers (ZnO NWs/CFs) were evaluated. Morphological, structural, photocatalytic properties were determined through scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV–Visible spectrophotometer. In addition, response surface methodology (RSM) and central composite design (CCD) were applied to optimize the hydrothermal synthesis parameters. The results pointed out that, the change in hydrothermal solution concentration (from 3.2 to 37 mM ZnNO_3·6H₂O) and process time (from 2.6 to 9.2 h) lead to the increase in thickness and decrease in aspect ratio of zinc oxide nanowires. Whereas, the temperature increases from 80 to 130 °C had a minute effect on the structure. ZnO nanowires with zincite structure were obtained for all processing conditions. Finally, photocatalytic activity of ZnO NWs/CFs on the degradation of aqueous methylene blue solution (MB) were recorded comparatively. ZnO NWs/CFs structure exhibited photocatalytic activity in the degradation of methylene blue (MB). The most effective structure was obtained at 120 °C, 30 mM Zn(NO₃)_2·6H₂O and 4 h HT synthesis parameters.     

Co负载TiO2/氧化石墨烯纳米复合材料的水热法合成及光催化性能

首先采用改进的Hummers法制得氧化石墨烯(GO)，再利用氧化石墨烯为基体，硫酸钛和氯化钴为前驱体，并通过修饰石墨烯的聚乙烯亚胺(PEI)为交联剂，采用一步水热法成功合成了三维柱状自组装的钴负载TiO2/氧化石墨烯纳米复合材料(Co@/TiO2/PEI/RGO)。通过紫外-可见吸收光谱法、X射线衍射、透射电子显微镜和X射线光电子能谱对复合材料的结构和光电性能进行了表征。在紫外和可见光照条件下，研究了复合材料的光催化降解亚甲基蓝(MB)的性能。结果表明钴负载TiO2/RGO纳米复合材料具有较高的光催化活性，在60min内降解率为99%，可循环至少10次。     

Ternary phase diagrams and solvate transformation thermodynamics of omeprazole sodium in different solvent mixtures

Omeprazole sodium(OMS), a typical non-hydrogen bond donors API, is only available in solvates so far, including monohydrate, ethanol solvate and methanol solvate. The methanol solvate was found for the first time. Solvate transformation thermodynamics of OMS was studied in this paper. First, the ternary phase diagrams forming two solvates for OMS in binary solvent mixtures including methanol + water, ethanol + water, and methanol+ ethanol were measured at temperature ranging of T =(278.15 to 313.15) K under atmospheric pressure. Further, the standard equilibrium constants of the solvate transformation reactions were evaluated according to the chemical reaction isothermal equation. The standard molar Gibbs free energy, the standard molar enthalpy, and the standard molar entropy of solvate transformation reactions were then calculated based on van't Hoff equation. Moreover, the thermodynamic stability of the OMS solvate was analyzed based on phase diagram. The results are of great importance to develop a crystallization process for manufacturing OMS solvate, and could be helpful to other solvate transformation research.     

Hydrothermal synthesis of boehmite nanorods from alumina sols

Boehmite nanorods (BNRs) were synthesized via the sol-gel process and hydrothermal method from alumina sols. Four influence factors, i.e. hydrothermal temperature and time, acetic acid contents, alcohol contents and stirring patterns, were explored to understand the reasons of BNRs growth. Scanning electron microscopy (SEM), transmission electron microscope (TEM), Fourier transform infrared (FT-IR) spectra and X-ray diffraction (XRD) were used to investigate the micromorphology, functional groups and phase composites of BNRs. The results show that the hydrothermal temperature and the contents of acetic acid play important parts in the one-dimension (1D) growth of BNRs. However, the hydrothermal time and the contents of alcohol have little effects. The growth mechanism of BNRs is related to the formation, growth and directional assembling of boehmite crystallites. After the simulation of dissipative particle dynamics (DPD), the increase of shear rate is beneficial to the 1D growth of BNRs.     

十聚钨酸钠的制备及其光催化降解甲基橙的研究

自制了不同于TiO2的绿色光催化剂十聚钨酸钠(Na4W10O32),通过紫外-可见吸收光谱、红外吸收光谱对制得的产物进行了表征.以紫外灯为光源,研究了Na4W10O32对模拟甲基橙染料废水的光催化脱色性能.实验结果表明,溶液初始pH对Na4W10O32光催化活性有影响,催化剂投加量及甲基橙初始浓度是影响脱色率的重要因素.20mg/L的甲基橙溶液在300W紫外灯辐照下,Na4W10O32质量浓度为0.6 g/L,溶液初始酸度pH=2,光照30 min即可完全脱色.实验利用Na4W10O32光催化降解模拟甲基橙染料废水取得了良好效果,在国内尚未见相关报道,为以后利用多金属氧酸盐光催化降解水中有机污染物的研究提供了参考.     

单氟磷酸钠合成研究

从六偏磷酸钠、焦磷酸钠、三聚磷酸钠等几种不同大宗原料中筛选出六偏磷酸钠作为合成单氟磷酸钠的原料.以六偏磷酸钠为原料,采用单因素试验,考察了原料干燥时间、合成温度、合成时间和原料氟磷比[n(F)/n(P)]对反应的的影响.通过正交试验优选,确定了最佳工艺条件:原料干燥温度475℃,原料干燥时间22 min,原料氟磷比1.10,合成温度760℃,合成时间22 min.在最佳条件下,产品纯度达到99.86%,原料转化率99.74%,产品游离氟浓度7.8 mmol/L.研究结果为工业生产提供了实验数据.     

Hydrothermal synthesis of multiwalled TiO2 nanotubes and its photocatalytic activities for Orange II removal

The solvothermal synthesis of multiwalled TiO₂ nanotubes (MWTNTs) with the reaction of titanium dioxide (TiO₂) nanoparticles and sodium hydroxide aqueous solution at moderate temperature is presented. The kinetic and isotherm studies were investigated for Orange II removal mechanism. MWTNTs were prepared in length 70–200 nm, average diameter 4–10 nm, and inter-shell spacing 0.78 nm. Different characterizations were performed to confirm anatase and mesoporous structure of MWTNTs. An improvement in properties as compared to commercial TiO₂ was observed; specific surface area 244.81 m²/g and band gap 3.0 eV. An excellent photocatalytic activity for Orange II removal was exhibited using synthesized MWTNTs.