Effects of mineral tourmaline particles on the photocatalytic activity of TiO2 thin films

Titania composite thin films (T/TiO2) containing tourmaline particles were prepared by a sol-gel method, using alkoxide solutions as precursor. The tourmaline particles and thin films were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and so on. The effects of tourmaline on the photocatalytic activity of TiO2 were measured with methyl orange as an objective photodegradation substance. The results showed that the photocatalytic degradation of methyl orange conformed to the first-order kinetic equation and the composite thin films had better photocatalytic activity due to the cooperation of polarity and the far infrared emission of tourmaline. The T/TiO2 thin films including 0.5 wt% tourmaline exhibited better photocatalytic activity when heat-treated at 250 degrees C for 3 h, than pure TiO2 thin films under the ultraviolet irradiation.     

PANI/CeO_2纳米复合纤维材料的合成和表征

用水热法制备了纳米CeO2,并利用其氧化性通过原位聚合法制备出PANI/CeO2复合纳米纤维。采用X射线衍射(XRD)、扫描电镜(SEM)、红外光谱(FT-IR)等检测技术对复合材料的结构进行了表征。结果表明:复合材料两相间存在化学键合作用;酸浓度和无机纳米相影响了聚苯胺纤维结晶。当CPANI0.1mol/L,随着酸浓度的升高,PANI/CeO2的结构形态从球状逐渐发展成纤维状,CeO2粒子的粒径会影响聚苯胺结晶状态,粒径越小,越易形成结晶规整的纤维结构。     

Cerium oxide dispersed multi walled carbon nanotubes as cathode material for flexible field emitters

Nanomaterials based electron sources are omnipresent in modern flat panel displays. Multi walled carbon nanotubes (MWNT) are the well studied electron emitter among the carbon materials. Since the surface modification of MWNT with low work function materials would have a positive impact on the field emission property of MWNT, cerium oxide (CeO2) nanoparticles dispersed multi walled carbon nanotubes (CeO2/MWNT) were synthesized by catalytic chemical vapour deposition followed by chemical reduction and its field emission property was investigated. The high-purity MWNT as well as CeO2/MWNT showed crystalline structure conformed by X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Further characterisation was done with Raman spectroscopy, UV-Visible absorption spectra and Fourier transform IR spectroscopy (FT-IR). The morphology and structural details of CeO2/MWNT composite was probed by field-emission scanning electron microscopy (FESEM) and energy dispersive X-ray analysis (EDX). The direct evidence of the formation of CeO2/MWNT composites was given by transmission electron microscopy (TEM). The synthesized sample was coated over a flexible carbon paper using spin coating technique. The experiment was performed under a vacuum of 1 x 10(-6) Torr and Fowler-Nordheim equation was used to analyse the data. The turn-on voltage for the cerium oxide dispersed MWNT was found for a current density of 10 microA/cm2. The emission current density from the CeO2 nanoparticles dispersed MWNT reached 0.2 mA/cm2 at a reasonable bias field of 2.58 V/microm. The results were compared with those of pure MWNT and pure CeO2 nanoparticles with literature values.     

镁合金表面纳米二氧化铈/磷酸盐复合转化膜的制备及其防护性能

添加纳米颗粒可改善金属表面膜层的性能,但目前添加纳米颗粒改善镁合金表面磷化膜性能的报道较少。通过向磷化处理液中添加纳米二氧化铈(nano-CeO_2)颗粒在镁合金表面制备了一层纳米二氧化铈/磷酸盐复合转化膜,采用X射线衍射仪(XRD)、X射线光电子能谱(XPS)、电化学阻抗谱(EIS)和极化曲线等手段研究了添加nano-CeO_2颗粒对膜层成分和防护性能的影响,讨论了nano-CeO_2颗粒的作用机制。结果表明:复合转化膜的相成分为Zn_3(PO_4)_2·4H_2O、Zn_2Mg(PO_4)_2和CeO_2,在单组分磷化膜成分的基础上多出了CeO_2相。在硼酸缓冲溶液中,单组分磷化膜的膜层电阻(R_c)和低频阻抗值(R_(0.01 Hz))分别为561.74 kΩ·cm~2和938.11 kΩ·cm~2,而复合转化膜的R_c和R_(0.01 Hz)分别为2 428.98 kΩ·cm~2和3 985.61 kΩ·cm~2;与此同时,覆盖复合转化膜镁合金的腐蚀电流密度为4.05×10~(-7)A/cm~2,而覆盖单组分磷化膜镁合金的为8.38×10~(-6)A/cm~2,R_c和R_(0.01 Hz)的增大以及J_(corr)的减小说明复合转化膜的防护作用明显优于单组分磷化膜的防护作用。nano-CeO_2颗粒的作用机制主要归因于两个方面:第一,nano-CeO_2颗粒在处理液中的添加有利于磷酸盐晶核的形成;第二,nano-CeO_2颗粒作为一种不溶性固体粒子在膜层中的存在可以强化膜层的物理屏蔽效应。     

硬脂酸对CeO2纳米粒子的表面修饰研究

利用表面修饰法合成了硬脂酸修饰的 CeO2 纳米粒子,采用透射电子显微镜(TEM)观察了经表面修饰的CeO2 纳米粒子的形貌及分散性,并采用红外光谱(IR)、紫外可见分光光度计等对修饰的CeO2 纳米粒子进行了表征。结果表明:表面修饰剂硬脂酸与 CeO2 纳米粒子表面之间发生了化学键合作用;修饰后的CeO2 纳米粒子表面存在疏水有机基团,阻隔了 CeO2 纳米粒子的团聚,起到了分散作用;同时,修饰后的CeO2 纳米粒子在苯乙烯中的稳定性得到了提高。并且获得了硬脂酸的修饰量与CeO2 纳米粒子的最佳配比。     

Far infrared emission and portable testing device of fine powders

In order for industrial and mining enterprises to fast detect the quality of fine mineral powders with far infrared emission, a simple testing model was set up according to the relationship between the emission intensity of powders and their surface temperature. The corresponding testing device was designed and assembled into three parts containing Constant Temperature Heating Part, Temperature Measuring Part and Sample Loading Part. By using the tourmaline mineral powders with far infrared emission as the research object and combining Fourier transform infrared spectroscopy, the calibration for the testing device was carried out. The results showed that the far infrared emission intensity of the tourmaline powders with different mining area and particle size could be judged. The testing results exhibited correct values when compared with those from FTIR measurements.     

Performance and application of far infrared rays emitted from rare earth mineral composite materials

Rare earth mineral composite materials were prepared using tourmaline and cerous nitrate as raw materials. Through characterization by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, dynamic contact angle meter and tensiometer, and Fourier transform infrared spectroscopy, it was found that the composite materials had a better far infrared emitting performance than tourmaline, which depended on many factors such as material composition, microstructure, and surface free energy. Based on the results of the flue gas analyzer and the water boiling test, it was found that the rare earth mineral composite materials could accelerate the combustion of liquefied petroleum gas and diesel oil. The results showed that the addition of Ce led to the improvement of far infrared emitting performance of tourmaline due to the decrease of cell volume caused by the oxidation of more Fe2+ ions and the increase of surface free energy. The application of rare earth mineral composite materials to diesel oil led to a decrease in surface tension and flash point, and the fuel saving ratio could reach 4.5%. When applied to liquefied petroleum gas, the composite materials led to the enhanced combustion, improved fuel consumption by 6.8%, and decreased concentration of CO and O2 in exhaust gases by 59.7% and 16.2%, respectively; but the temperature inside the flue increased by 10.3%.     

Role of ZnO-CeO2 Nanostructures as a Photo-catalyst and Chemi-sensor

ZnO-CeO2 nanostructures were synthesized by simple and effcient low temperature method. The structure and morphology of the ZnO-CeO2 nanostructures were characterized by X-ray powder diffraction (XRD) and field emission scanning electron microscopy (FESEM), which revealed elongated shaped CeO2 nanoparticles with diameters of 40-90 nm distributed on the surface of elongated ZnO nanostructures with diameters of 50-200 nm (edge-centre). Further the structure of the synthesized ZnO-CeO2 nanostructure was supported by Raman spectra and Fourier transform infrared spectroscopy (FTIR). UV-vis absorption spectrum was used to confirm the optical properties of the CeO2 doped ZnO nanostructures. Photo-catalytic activity of CeO2 doped ZnO nanostructure was evaluated by degradation of acridine orange and methylene blue which degraded 84.55% and 48.65% in 170 min, respectively. ZnO-CeO2 nanostructures also showed good sensitivity (0.8331 μA·cm-2·(mol/l)-1) in short response time (10 s) by applying to chemical sensing using ethanol as a target compound by I-V technique. These degradation and chemical sensing properties of ZnO-CeO2 nanostructures are of great importance for the application of ZnO-CeO2 system as a photo-catalyst and chemical sensor.     

Functionalized bio-artifact fabricated via selective slurry extrusion. Part 1: Preparation of slurry containing tourmaline superfine powders

The far infrared dental porcelain slurry for fabricating artificial tooth via selective slurry extrusion (SSE) of solid freeform fabrication (also known as rapid prototyping) techniques was prepared by using tourmaline as additive and employing ball-milling approach. After characterization by transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectrometry, it was found that the far infrared emission properties of the dental porcelain were apparently improved in the ranges of 2000-1201 cm(-1) and 881-600 cm(-1). This is due to the increase of the number of infrared active bonds that are from the tourmaline superfine powders. Moreover, it was also found that the tourmaline superfine powders can improve the pseudo-plastic properties of dental porcelain slurries, which results from the increase of the absolute value of zeta potential of the suspensions. Slurries with pseudo-plastic behavior are highly desirable in controlling the shape of the extrudate during solid freeform fabrication. With the functionalized material, a variety of bio-artifacts beneficial to body health can be built by using selective slurry extrusion machine.     

Synthesis and characterization of ZnO/SiO2 core/shell nanocomposites and hollow SiO2 nanostructures

In this paper, we prepared the ZnO nanoparticles by a simple hydrothermal method and fabricated the ZnO/SiO₂ core/shell nanostructures through a sol-gel chemistry process successfully. The hollow SiO₂ nanostructures were obtained by selective removal of the ZnO cores. The structure, morphology and composition of the products were determined by the techniques of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). The results indicated that the ZnO nanoparticles were sphere-like shape with the average size of 60 nm and belonged to hexagonal wurtzite crystal structure. With the coating of SiO₂, the vibration modes of Si-O-Si and Si-OH were found. Furthermore, the measurement results of optical properties showed that spectra of bare ZnO nanoparticles and ZnO/SiO₂ core/shell nanocomposites exhibited similar emission features, including a blue emission peak and an orange emission band.     

Particle size distribution study by small-angle X-ray scattering technique and photoluminescence property of ZnO nanoparticles

ZnO nanoparticles have been synthesised by thermal decomposition of zinc acetate at ～800°C. The structural characteristics and size distribution of ZnO nanoparticles have been investigated by X-ray powder diffraction (XRD) and small-angle X-ray scattering (SAXS), respectively. SAXS study reveals nanoparticles are of different sizes: namely 23 wt% of 8 nm, 19 wt% of 21 nm and 58 wt% of 51 nm. These ZnO nanoparticles possess yellow visible emission at 552 nm. The polydispersity and single emission peak at 552 nm in ZnO nanoparticles suggest that the yellow emission might be a bulk property instead of having a surface origin in nanostructured ZnO. The surface impurities are characterised by Fourier-transform infrared spectroscopy. The quenching of band edge emission in ZnO nanoparticles seems due to the presence of surface impurities.     

Synthesis of Fe3O4@PbS hybrid nanoparticles through the combination of surface-initiated atom transfer radical polymerization and acidolysis by H2S

A versatile approach to fabricate nanoparticles with multiple functionalities through the combined use of both surface-initiated ATRP and acidolysis by H2S techniques was demonstrated. The hybrid nanoparticles exhibited the core-shell structure having the magnetite nanoparticles as the core and the polymethacrylate as the shell with PbS nanoparticles distributing in the shell. The structure and morphology of the synthesized nanoparticles were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The optical and magnetic properties of the nanoparticles were investigated by UV-Vis spectroscopy, photoluminescence spectroscopy and vibrating sample magnetometer (VSM), respectively. It is observed that the absorption and emission behaviors of the Fe3O4@PbS hybrid nanoparticles were seriously influenced by the ATRP time and the reaction time with H2S. The saturated magnetization (Ms) decreased with the increase of ATRP time due to the formation of thicker shells coating on the surfaces of magnetite nanoparticles.     

Rapid synthesis, characterization and optical properties of TiO2 coated ZnO nanocomposite particles by a novel microwave irradiation method

A novel and rapid microwave method was used to prepare TiO₂ coated ZnO nanocomposite particles. The resulted particles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). Results show that ZnO nanoparticles were coated with 6-10 nm amorphous TiO₂ layers. In addition, zeta potential analysis demonstrated the presence of TiO₂ layer on the surface of ZnO nanoparticles. Photoluminescence (PL) spectroscopy and UV-visible spectroscopy were used to investigate the optical properties of the nanoparticles. Compared to uncoated ZnO nanoparticles, the TiO₂ coated ZnO nanoparticles showed enhanced UV emission. The UV-visible diffuse reflectance study revealed the significant UV shielding characteristics of the nanocomposite particles. Moreover, amorphous TiO₂ coating effectively reduced the photocatalytic activity of ZnO nanoparticles as evidenced by the photodegradation of Orange G with uncoated and TiO₂ coated ZnO nanoparticles under UV radiation.     

Synthesis of C-N co-doped nano-CeO2 and dye degradation under compact fluorescent lamp irradiation

Carbon and nitrogen (C-N) co-doped nano-CeO2 was synthesized by the solvothermal method using hexamethylenetetramine (HMT) as a precipitator at 140 degrees C for 24 h. We found that the degradation of acid orange 7 (AO7) was 94.4% and 98.8% with C-N co-doped nano-CeO2 upon irradiation with a 100-watt high-pressure mercury lamp (HML) and a 10-watt compact fluorescent lamp (CFL), respectively. By comparison, TiO2 degraded 68.4% and 43.0% of the AO7 irradiated by HML and CFL, respectively. We found that the degradation efficiencies of AO7 upon irradiation with the 10-watt CFL in the presence of the samples synthesized using different precipitators decreased as follows: CeO2(HMT)> CeO2-TiO2(HMT) > TiO2(HMT) > CeO2(NaHCO3) > CeO2(Na2CO3).     

Synthesis of superparamagnetic cobalt nanoparticles through solvothermal process

The superparamagnetic (SPM) cobalt nanoparticles with an average size of 2 nm have been prepared through a solvothermal process in the presence of triethanolamine. The synthesized nanoparticles are characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy, and superconducting quantum interference device magnetometer. X-ray diffraction analysis confirms the face centered cubic phase of as-prepared cobalt nanoparticles. Transmission electron microscopy was employed to study the morphology of the as-prepared product, which exhibit spherical-like shape with size around 2 nm. The high resolution transmission electron microscopy image of cobalt nanoparticles shows the lattice spacing value of 0.204 nm. This is well matched with the (111) lattice spacing of fcc Co. XPS revealed the prepared product is pure cobalt. The blocking temperature of 17 K was obtained and confirmed by field-cooled and zero-field-cooled plots. The hysteresis loop revealed the synthesized nanoparticles have SPM character at room temperature.     

Enhanced activity and stability of Cu-Mn and Cu-Ag catalysts supported on nanostructured mesoporous CeO2 for CO oxidation

Cu, Mn and Ag nanoparticles are loaded on nanostructured mesoporous CeO2 as catalysts for CO oxidation. The Cu/CeO2 catalyst exhibits an obvious deactivation after the stability test at 95 degrees C for 60 h. This is caused by carbon deposition as confirmed by FTIR spectroscopy, Raman spectroscopy and thermogravimetry-differential scanning calorimetry-mass spectroscopy (TG-DSC-MS) analysis. It is found that the Cu-Mn or Cu-Ag binary metal catalysts supported on the nanostructured CeO2 exhibit much improved activity and stability in CO oxidation. In ease case, carbon deposition is absent in the similar stability test, due to enhanced oxygen adsorption property.     

电气石晶体微粉对酸溶液pH值和电导率的影响

系统地研究了电气石晶体微粉的粒度、质量分数及环境条件(pH值、温度、搅拌情况)对盐酸溶液pH值、电导率的影响,采用X射线衍射仪和红外光谱分析仪分析了电气石的作用原理.结果表明,在酸性条件下电气石微粉没有发生晶型变化,利用其永久极化、表面吸附和离子交换来调节溶液pH值和电导率.本文的实验结果为电气石晶体微粉在水处理、保健纺织品等方面的应用奠定了基础.     

Sonochemical fabrication and characterization of ceria (CeO2) nanowires

Ceria (CeO2) nanowires have been successfully synthesized by a sonochemical method in ambient air and alkali aqueous solution from CeO2 nanoparticles without using any templates. The results showed that both alkali concentration and ultrasonic irradiation played critical roles in the formation of the nanowires. The crystalline structure and dimensions of the nanowires were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED). The UV-visible absorption spectrum result showed that the products had conspicuous shape-specific effect. Microstructural analysis in HRTEM revealed that the preferential growth direction of CeO2 nanowires was [110]. Moreover, the catalytic activity of Au/CeO2 using CeO2 nanowires as support for CO conversion was higher than that obtained using bulk CeO2 as support.     

碳化铈水解氧化法制备CeO2纳米粉

提出了一种可大规模制备CeO2纳米粉的有效方法.用碳化铈水解氧化制得颗粒大小为3~5 nm的CeO2纳米粉.研究了各种实验参数包括水解温度、反应时间和投料比对CeO2纳米粉比表面积的影响.结果表明:较低的水解温度(室温附近),较高的投料比(1:20(g/mL))和适当的反应时间(18 h)可得到比表面积为149 m2/g的CeO2纳米粉.优化实验参数(水解温度为30℃,水解时间为18 h,投料比为1:20(g/mL),滤饼在空气中80℃烘干4 h)得到中间产物Ce(OH)3和目标产物CeO2,并用XRD、TEM、SAED及紫外可见光分光光度计进行测试表征.发现Ce(OH)3是由大量长为50~100 nm,直径为5~20 nm的纳米棒组成.CeO2纳米粉具有较高的紫外吸收性能和较好的催化CO性能.     

Surface passivation of CeO2 catalyst and its ultraviolet screening effect

A new strategy was attempted to fabricate CeO2 nanoparticles using the surface fluorination technique to control the particle size and suppress the catalytic activity. The fluorinated CeO2 nanoparticles are fully characterized with XRD, XANES, UV-vis spectroscopy, HR-TEM, XPS along with the evaluation of photo and thermal catalytic activities. XRD patterns were not affected by surface fluorination. That is to say, the crystalline structure of CeO2 was not deteriorated upon fluorination. The TEM analysis showed that the fluorinated CeO2 nanoparticles with the primary particle size of 7 nm could be prepared. According to the X-ray absorption near edge structure (XANES) analysis, overall XANES spectrum was not changed upon fluorination, suggesting that the local structure of fluorinated CeO2 resembled that of the starting CeO2 nanoparticles. It was also revealed that both photo and thermal catalytic activities could be almost totally suppressed at the fluorination level of ca. 6.0 wt%. It is suggested that the selective surface fluorination with fluoride could lead to fluorinated CeO2 nanoparticles, which could be applied to new fields such as the cosmetics industries.