自生长燃烧法合成纳米铁酸钇固溶体光催化剂

以硝酸铁和硝酸钇作为前驱体,甘氨酸为燃料用自生长燃烧法合成了可见光光催化剂YFeO₃及其固溶体。样品通过X射线粉末衍射(XRD)、N₂吸附、紫外-可见漫反射(UV-Vis DRS)、扫描电子显微镜(SEM)和透射电镜(TEM)等表征了其晶相结构、BET比表面积和形貌。结果表明掺杂一定量的金属能有效地提高自生长燃烧法合成的YFeO₃的纯度,所合成的样品晶粒大小约为55 nm。与YFeO₃相比其固溶体吸收边红移。光催化降解亚甲基蓝(MB)和罗丹明B(RhB)结果表明YFeO₃及其固溶体均具有活性,Bi修饰的YFeO₃表现出最高的光催化活性,而且对于不同染料的降解程度不同。     

Synthesis and Characterization of TiO2/YFeO3 and Its Photocatalytic Oxidation of Gaseous Benzene

YFeO₃ was prepared by coprecipitation method and citric acid method, and TiO₂/YFeO₃ heterosystem photocatalysts were synthesized by loading TiO₂ sol on the surface of YFeO₃via sol-gel method. Their photocatalytic activities were evaluated by the decomposition of gaseous benzene under UV light illumination. The prepared photocatalysts were characterized by nitrogen adsorption-desorption, X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-Vis diffuse reflectance spectroscopy. Results revealed that the heterosystem photocatalysts prepared by coprecipitation method showed higher activity, and the maximum conversion of benzene could reach 44.7% within 180 min. The YFeO₃ samples prepared from coprecipitation method and citric acid method were absolutely in orthorhombic phase. The deposited titania was dispersed on the surface of carrier and a certain interaction existed between TiO₂ and YFeO₃. The two heterosystems photocatalysts had narrow band-gap energies.     

The role of pre-nucleus states in formation of nanocrystalline yttrium orthoferrite

Formation of hexagonal and orthorhombic YFeO₃ nanocrystals from an amorphous phase upon heat treatment of glycine–nitrate combustion products has been studied. The initial X-ray amorphous precursor has been shown to have pre-nucleus species of two types. Rapid formation of h-YFeO₃ nanocrystals is explained by the presence of structurally similar pre-nucleus species in the precursor, while o-YFeO₃ nanocrystals are formed much more slowly through recrystallization of the hexagonal and amorphous yttrium orthoferrite phases.     

Synthesis and structural characterization of perovskite YFeO<Subscript>3</Subscript> by thermal decomposition of a cyano complex precursor,Y[Fe(CN)<Subscript>6</Subscript>]·4H<Subscript>2</Subscript>O

The thermal decomposition of Y[Fe(CN)₆]·4H₂O has been studied in order to investigate the formation of the multi-ferroic oxide YFeO₃. The starting material (Y[Fe(CN)₆]·4H₂O) and the decomposition products were characterized by IR spectroscopy, thermal analysis, X-ray powder diffraction (PXRD), and scanning electron microscopy. Metastable YFeO₃ with hexagonal structure, space group P6 ₃ /mmc, was obtained by thermal decomposition of Y[Fe(CN)₆]·4H₂O at 600 °C in air. Orthorhombic YFeO₃ was obtained by the same method at T ≥ 800 °C in air. The crystal structure of orthorhombic YFeO₃ was refined by Rietveld analysis using PXRD data. We found that it was slightly deficient in Y³⁺, which is in agreement with the small amount of Y₂O₃ found as impurity in the sample. The formula of the orthorhombic phase is Y_0.986FeO₃.     

Mechanochemical Synthesis of YFeO<Subscript>3</Subscript> Nanoparticles: Optical and Electrical Properties of Thin Films

Nanoparticles (NPs) of orthorhombic YFeO₃, has been successfully synthesized via an uncomplicated mechanochemical method from yttrium and iron chloride salts in a basic medium. The YFeO₃ NPs were characterized by micro-Raman and Fourier-transform infrared spectroscopy. Their crystalline structure and average diameter of 30 nm was determined from X-ray powder diffraction pattern and by transmission electron microscopy images. Thin films (TF) of these NPs in polystyrene were prepared by spin coating in order to study their electrical and optical properties, as well as to verify their possible application in the manufacture of optoelectronic devices. UV–visible diffuse reflectance was performed for YFeO₃ NPs and for YFeO₃ TF and optical band gaps of 2.38 and 3.7 eV, respectively, were estimated from optical absorption measurements. The electrical conductivity of the YFeO₃ TF was evaluated in a glass/ITO/YFeO ₃ TF/Ag device. At low voltages, electric current in the forward direction was found to obey an ohmic I–V relationship; at higher voltages, the behavior of the film in the device is defined by a Space Charge Limited Current model and, at around 1 V, current saturation. These results suggest the possibility of using YFeO₃ TF in the production of dielectric layers in electronic or optoelectronic devices.     

Synthesis and evolution of novel double tower-like ZnO by a simple method

Delicate double tower-like ZnO have been fabricated through the decomposition of the zinc nitrate hexahydrate (Zn(NO₃)₂6H₂O). The phase transformation and morphology evolution of the products were carefully studied and investigated with X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectra. The resultant results indicated that the obtained double tower-like ZnO materials possess pure wurtzite hexagonal phase, growing along the [100] direction. A reasonable formation mechanism was also presented in this paper.     

Mn3O4 nanoplates and nanoparticles: Synthesis, characterization, electrochemical and catalytic properties

Mn₃O₄ hexagonal nanoplates and nanoparticles were synthesized via a solvent-assisted hydrothermal oxidation process at low temperature and a solvothermal oxidation method, respectively. The synthesized product was characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), electron diffraction (ED), Fourier transform infrared (FT-IR) spectroscopy. Their capability of catalytic oxidation of formaldehyde to formic acid at room temperature and atmospheric pressure and electrochemical properties by cyclic voltammogram (CV) were compared. The results showed that Mn₃O₄ hexagonal nanoplate is a better catalyst, and the hexagonal nanoplates and nanoparticles modified electrodes blended with carbon black have a higher specific capacitance.     

亚稳态MInS2(M=Ag,Cu)花状微米球的热分解法合成及其生长机理

采用热分解法制备了三维的亚稳态正交相AgInS_2和六方相CuInS_2花状微米球。通过X射线衍射(XRD),场发射扫描电子显微镜(FESEM)等对样品进行表征,对AgInS_2的光催化性能进行了评估,并借助于热重-差热分析(TG-DTA)等手段研究了亚稳态正交相AgInS_2和六方相CuInS_2花状微米球的生长机理。实验结果表明,反应温度和反应物中金属离子的投料比对生成纯相的MIn S2均有影响,而AgInS_2花状微米球能在可见光下较好地催化降解亚甲基蓝。     

亚稳态MInS2(M=Ag，Cu)花状微米球的热分解法合成及其生长机理

采用热分解法制备了三维的亚稳态正交相AgInS₂和六方相CuInS₂花状微米球。通过X射线衍射（XRD）,场发射扫描电子显微镜（FESEM）等对样品进行表征,对AgInS₂的光催化性能进行了评估,并借助于热重分析（TG-DTA）等手段研究了亚稳态正交相AgInS₂和六方相CuInS₂花状微米球的生长机理。实验结果表明,反应温度和反应物中金属离子的投料比对生成纯相的MInS₂均有影响,而AgInS₂花状微米球能在可见光下较好地催化降解亚甲基蓝。     

Zn3(OH)2V2O7·2H2O纳米片的水热制备

采用硝酸锌、五氧化二钒和氢氧化钠作为反应物,通过一个简单的CTAB辅助的水热方法制备了Zn₃(OH)₂V₂O₇·2H₂O纳米片。运用XRD,ICP-AES,FTIR,HRTEM,EDS,FE-SEM对产物的晶相和形貌进行了表征。结果表明CTAB在控制产物的形貌、尺寸分布和自组装过程中起着关键作用。同时我们研究了产物的晶体生长行为和自组装过程。     

Preparation and characterization of NiO nanoparticles from thermal decomposition of the [Ni(en)3](NO3)2 complex: A facile and low-temperature route

NiO nanoparticles with an average size of 15 nm were easily prepared via the thermal decomposition of the tris(ethylenediamine)Ni(II) nitrate complex [Ni(en)₃](NO₃)₂ as a new precursor at low temperature, and the nanoparticles were characterized by thermal analysis (TGA/DTA), X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FT-IR), UV-Vis spectroscopy, BET specific surface area measurement, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and magnetic measurements. The magnetic measurements confirm that the product shows a ferromagnetic behavior at room temperature, which may be ascribed to a size confinement effect. The NiO nanoparticles prepared by this method could be an appropriate photocatalytic material due to a strong absorption band at 325 nm. This method is simple, fast, safe, low-cost and also suitable for industrial production of high purity NiO nanoparticles for applied purposes.     

Temperature-induced phase transition in h-MoO3: Stability loss mechanism uncovered by Raman spectroscopy and DFT calculations

This paper reports the study of the metastable hexagonal molybdenum oxide (h-MoO₃) rods by looking at the vibrational, structural and morphological properties. The MoO₃ as-synthesized rods were prepared by the precipitation method and characterized by X-ray diffraction, Raman spectroscopy and scanning electron microscopy, revealing a hexagonal phase and submicrometric size of the MoO₃. The vibrational modes of the h-MoO₃ were calculated by density-functional perturbation theory (DFPT) and used by first time to do the signature of the experimentally observed Raman modes, filling a gap in this field. Experimental temperature-dependent Raman spectroscopy study was carried out on h-MoO₃ rods and pointed out to a phase transition in the 675-690 K temperature range. This phase transition was confirmed by scanning electron microscopy that was used to analyze the morphological changes in the MoO₃ samples during the heating cycle. Temperature-dependent Raman data analysis combined with DFT calculations allowed us to confirm the mechanism that underlies the stability loss of the hexagonal phase at the critical temperature and to correlate the wavenumber difference of two specific Raman bands with the real temperature of the sample.     

A novel chelating acid-assisted thermolysis procedure for preparation of tin oxide nanoparticles

Pure tin dioxide (SnO₂) nanoparticles were synthesized via thermolysis of tin phthalate and tin oxalate in the presence of oleic acid (OA) as solvent. Oleic acid (OA) was employed as an organic solvent, which can be applied to control particle growth and to stabilize the particles. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectroscopy. The orthorhombic phase SnO₂ nanoparticles with average size about 12 nm were synthesized through thermolysis of tin phthalate in the presence of oleic acid.     

Simple and low-temperature synthesis of NiO nanoparticles through solid-state thermal decomposition of the hexa(ammine)Ni(II) nitrate, [Ni(NH3)6](NO3)2, complex

NiO nanoparticles with an average size of about 12 nm were easily prepared via the thermal decomposition of hexa(ammine)Ni(II) nitrate complex, [Ni(NH₃)₆](NO₃)₂, at low temperature of 250 °C. The product was characterized by thermal analysis (TGA/DTA), X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FT-IR), UV-Vis spectroscopy, BET specific surface area measurement, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and magnetic measurement. The magnetic measurement revealed a small hysteresis loop at room temperature, confirming a superparamagnetic (weak ferromagnetic) nature of the synthesized NiO nanoparticles. Indeed, the NiO nanoparticles prepared by this method could be an appropriate semiconductor material due to the optical band gap of 3.35 eV which shows a red shift in comparison with the previous reports. This method is simple, fast, safe, low-cost and also suitable for industrial production of high purity NiO nanoparticles for applied purposes.     

Enhanced photocatalytic activity of Eu2O3/Ta2O5 mixed oxides on degradation of rhodamine B and 4-nitrophenol

Europium oxide/tantalum pentoxide (Eu₂O₃/Ta₂O₅) mixed oxides with different Eu₂O₃ dopings were prepared by a single-step sol–gel process via hydrolysis of tantalum pentachloride in the presence of europium nitrate. The products were in the amorphous and orthorhombic phase structures, respectively, based on the different calcination temperatures (200 and 500 °C). Composition, morphology, phase structure, Eu₂O₃-doping mode in the Ta₂O₅ matrix and optical absorption property of the products were characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES), field emission scanning electron microscopy (FESEM), X-ray diffraction patterns (XRD), X-ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectroscopy (UV–vis/DRS). The UV-light photocatalytic activity of the products was evaluated by degradation of aqueous rhodamine B (RB) and 4-nitrophenol (4-NP). The results showed that the photocatalytic activity of as-prepared Eu₂O₃/Ta₂O₅ was higher than that of pure Ta₂O₅ regardless of their phase structures. Among the tested samples, Eu₂O₃/Ta₂O₅ with 0.49% Eu loading obtained with 200 °C exhibited the highest activity to degradation of the above two model molecules. The reasons of this enhanced photocatalytic activity were discussed.     

L-Tyrosine-Pd complex supported on Fe3O4 magnetic nanoparticles: A new catalyst for C–C coupling and Synthesis of sulfides

In the present work, Fe₃O₄@L-Tyrosine-Pd heterogeneous nanocatalyst was prepared by a simple and inexpensive procedure. The prepared nanocatalyst was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray Diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), inductively coupled plasma optical emission spectroscopy (ICP-OES), scanning electron microscopy (SEM), Transmission electron microscopy)TEM(, X-ray mapping, thermal gravimetric analysis (TGA), N₂ adsorption and desorption (BET) and vibrating sample magnetometer (VSM) techniques. Besides, it was employed as an efficent catalyst for C-C cross coupling and S-arylation reactions under green conditions. The optimized conditions for these reactions are described. The heterogeneous catalyst can be easily separated by applying a simple magnet and can also be reused in several consecutive runs without appreciable change in its catalytic activity.     

Iron Oxide Nanoparticles: Biosynthesis,Magnetic Behavior,Cytotoxic Effect

Iron oxide nanoparticles have attracted much attention because of their superparamagnetic properties and their potential applications in many fields such as magnetic storage devices, catalysis, sensors, superparamagnetic relaxometry (SPMR), and high-sensitivity biomolecule magnetic resonance imaging (MRI) for medical diagnosis and therapeutics. In this study, iron oxide nanoparticles (Fe₂O₃ NPs) have been synthesized using a taranjabin (camelthorn or persian manna) aqueous solution. The synthesized Fe₂O₃ NPs were identified through powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), field energy scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDX), vibrating-sample magnetometer (VSM) and Raman technics. The results show that the nanoparticles have a hexagonal structure with 20 to 60 nm in size. The cytotoxic effect of the synthesized nanoparticles has been tested upon application against lung cancer cell (A549) lines. It was found that there is no cytotoxic activity at lower concentrations of 200 μg/mL. The ability of the synthesized nanoparticles for lead removal in wastewaters was tested. Results show that highest concentration of adsorbent (50 mg/L) has maximum removal efficiency (96.73 %). So, synthesized Fe₂O₃ NPs can be a good candidate to use as heavy metals cleaner from contaminated waters.     

回流法可控合成BiPO4纳米棒及其光催化性能

采用回流法合成了BiPO₄纳米棒光催化剂, 探讨了反应时间、反应物比例、pH值和反应物浓度对BiPO₄晶相结构和形貌尺寸的影响, 利用粉末X射线衍射(XRD)、透射电镜(TEM)、比表面积分析(BET)和紫外-可见漫反射光谱(UV-Vis DRS)等对产物进行了表征, 以亚甲基蓝(MB)为探针研究了其光催化活性. 反应时间和反应物浓度对产物的形貌尺寸影响较大, 反应物比例和pH值对产物晶相结构和形貌尺寸均有较大的影响, 进一步影响BiPO₄光催化剂的活性. 调控各种因素后可合成出具有单斜相独居石/六方相混晶结构的高紫外光活性BiPO₄纳米棒光催化剂.     

Enhanced Photocatalytic Degradation of Methylene Blue over Hexagonal WO<Subscript>3</Subscript>/Graphene under Visible-Light Irradiation

A series of composites containing hexagonal tungsten trioxide (h-WO₃) and reduced graphene oxide (rGO) sheets are synthesized via a modified one-step hydrothermal route without assisted additive. The composites are characterized by transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and UV-vis absorption spectroscopy. The new procedure made it possible to increase the reduction degree of GO. Based on the evidence presented hexagonal WO₃ grows on the surface of graphene through chemical interactions with the surface. The visible-light photocatalytic degradation of methylene blue shows that the h-WO₃/rGO composites exhibit superior photocatalytic performance of 96% with a maximum degradation rate achieved under visible-light irradiation for 6 h. The speculations concerning the mechanism of photocatalytic reactions are discussed. The improved photocatalytic activity can be accounted for by the increased adsorption toward chemical species, the enhanced light absorption and an efficient separation of photogenerated electron-hole pairs and transfer of charge carriers.     

Template induced sol-gel synthesis of highly ordered LaNiO3 nanowires

The highly ordered LaNiO₃ nanowires of the rare-earth perovskite-type composite oxide were controlled synthesized within a porous anodic aluminum oxide (AAO) template by means of sol-gel method using nitrate as raw materials and citric acid as chelating agent. The results of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that the obtained LaNiO₃ nanowires had a uniform length and diameter, which were determined by the thickness and the pore diameter of the applied AAO template. The results of X-ray diffraction (XRD) and the selected-area electron diffraction (SAED) indicated that the LaNiO₃ nanowires were perovskite-type crystalline structures. Furthermore, X-ray photoelectron spectroscopy (XPS) and the energy dispersive X-ray (EDX) spectroscopy demonstrated that the stoichiometric LaNiO₃ was formed.