MWCNT/TiO2复合材料光催化活性研究

以多壁碳纳米管(MWCNT)为基核,以钛酸丁酯为前驱体,分别用溶胶-凝胶法和水热法制备碳纳米管/二氧化钛纳米复合光催化材料.用X射线衍射仪(XRD)、透射电子显微镜(TEM)对样品进行了表征,研究了溶胶-凝胶法和水热法工艺的控制对碳纳米管/二氧化钛复合光催化剂显微组织及性能的影响.以甲基橙为目标降解物,考察了样品的自然光催化活性.结果表明,所得复合粉体中仅有碳纳米管和锐钛型二氧化钛两种物相,其中采用水热法所得样品,其纳米级的球形二氧化钛颗粒可均匀吸附在碳纳米管表面.     

铜掺杂纳米二氧化钛颗粒的相变研究

采用溶胶-凝胶法制备铜掺杂的纳米二氧化钛颗粒。应用X射线衍射(XRD)、透射电子显微镜(TEM)、扫描透射电子显微镜(STEM)、X射线光电子能谱(XPS)和紫外-可见分光光度计(UV-Vis)技术对纳米二氧化钛颗粒的物相组成、平均晶粒尺寸、微观结构、化学态及光吸收性能进行表征。结果表明:Cu掺杂抑制TiO_2的相变,在650℃时Cu的氧化物CuO在TiO_2颗粒表面出现,掺杂的Cu离子以Cu^+的形式存在。掺杂Cu的TiO_2光吸收带边显著红移,随着Cu掺杂量的提高,样品光吸收度提高,随着温度的升高,样品紫外-可见光光谱吸收带边红移。     

银粒子修饰下的介孔二氧化钛的制备及其光催化性能的研究（英文）

利用光还原的方法制备一系列不同银含量的改性介孔二氧化钛的颗粒。采用X射线粉末衍射(XRD)、透射电子显微镜(TEM)、紫外一可见漫反射谱(DRS)和X射线能谱仪(EDX)等技术手段对制备的样品进行了表征。结果表明,银纳米粒子被牢牢固定在二氧化钛表面,并在银和二氧化钛界面形成肖特基势垒用以提高电子–空穴的分离。而从紫外可见漫反射光谱中看出,银二氧化钛样品与未改性的二氧化钛样品相比显示出更高的红移。以亚甲基蓝(MB)为光降解模型,银改性二氧化钛表现出较高的活性。     

利用反相微乳液法制备纳米铜粒子

通过反相微乳液法制备了纳米铜粒子,并用透射电子显微镜(TEM)、电子衍射(SAED)和能谱对铜纳米粒子的形貌和物相进行了表征.在H2O/表面活性剂油酸钠摩尔比(W/O)为11、8时分别制得了粒径为50nm、10nm的铜粒子.结果表明:W/O值对纳米铜粒子的粒径有非常明显的影响,当其值由11降到8时,粒径则从50nm降到了10nm,且更加均匀.探讨了水与表面活性剂的摩尔比对制备的纳米铜颗粒的粒径的影响.     

碳包铜纳米颗粒的制备及其性能研究

采用碳弧法制备出碳包铜纳米粒子,并用透射电子显微镜(TEM)、X射线衍射仪(XRD)和DSC对产物的形貌、尺寸、物相结构组成以及抗氧化性能进行了表征分析,同时对碳包铜纳米粒子的导电性能进行了测量.测试结果表明碳包铜纳米粒子为核壳型结构,内部为金属铜核,外部为碳层.在铜核的周围碳以类石墨状形式存在,离铜核较远处碳以非晶态...     

铜负载二氧化钛复合材料的制备及其抗菌性能

以二氧化钛纳米颗粒和硫酸铜溶液为原料,在紫外线灯的照射下进行铜负载二氧化钛纳米带复合材料制备,采用扫描电子显微镜(SEM)、X-射线能谱仪(EDS)、X-射线衍射仪(XRD)、抑菌圈法、细菌比浊法等分析技术研究了所制备负载纳米带复合材料的微观结构及抗菌性能。结果表明,纳米二氧化钛粒子在水热条件下可生长成纳米带,铜均匀负载在纳米带上,从而制备出铜负载二氧化钛纳米带复合材料,负载程度可以通过更改照射时间、硫酸铜浓度等条件进行微调;该负载纳米带复合材料对革兰氏菌有很好的抗菌性能,且负载程度越高,产物抗菌性能越大。     

银粒子修饰下的介孔二氧化钛的制备及其光催化性能的研究

利用光还原的方法制备一系列不同银含量的改性介孔二氧化钛的颗粒。采用X射线粉末衍射(XRD)、透射电子显微镜(TEM)、紫外一可见漫反射谱(DRS)和X射线能谱仪(EDX)等技术手段对制备的样品进行了表征。结果表明, 银纳米粒子被牢牢固定在二氧化钛表面, 并在银和二氧化钛界面形成肖特基势垒用以提高电子-空穴的分离。而从紫外可见漫反射光谱中看出, 银二氧化钛样品与未改性的二氧化钛样品相比显示出更高的红移。以亚甲基蓝(MB)为光降解模型, 银改性二氧化钛表现出较高的活性。     

氧化硅包覆铁“壳/核”型纳米复合粒子的制备及其吸波特性研究

采用非平衡物理气相蒸发法在氢气氩气混合气氛下制备了氧化硅包覆铁“壳/核”型纳米复合粒子. 通过X射线衍射(XRD)、透射电子显微镜(TEM)和能谱分析(EDS)等方法表征了纳米复合粒子的相组分、结构以及颗粒形貌. 结果表明,制备的氧化硅包覆铁纳米复合粒子的尺寸在50nm左右,在铁纳米粒子的表面还出现了非晶态的氧化硅纳米棒,长度为150~200nm. 利用电磁参数模拟微波吸收特性得出,涂层厚度为1.79mm时,在15.4GHz频率处达到最小反射损耗值为-14.5dB,反射损耗在8~18GHz的频段低于-10dB,且损耗机制为自然共振.     

纳米碳纤维的低温制备——催化剂粒子尺寸的影响

以采用电阻加热法制备的纳米铜粒子为催化剂,在低温下催化乙炔制备了纳米碳纤维。所制备的纳米碳纤维具有螺旋型和直线型两种形貌。采用透射电子显微镜(TEM)和扫描电子显微镜(SEM)对纳米碳纤维进行了表征。纳米铜催化剂粒子在催化纤维的生长过程中,经历了一个重要的形状变化过程。催化剂粒子尺寸对所制备的纳米碳纤维的形貌有很大的影响。通常有两根螺旋纳米碳纤维以对称模式在单个粒径小于50nm的催化剂粒子上生长,它们的旋向相反,但是具有相同的螺旋直径、螺旋长度、螺旋缠绕程度和纤维直径。较大尺寸的催化剂粒子易生长直线型纳米碳纤维。     

NiFe2O4纳米粒子的水热合成及表征

以Ni(NO3)2·6H2O和Fe(NO3)3·9H2O为主要原料,在聚乙二醇(PEG)存在下,采用水热法制备了磁性NiFe2O4纳米粒子,用X射线衍射仪(XRD)、透射电子显微镜(TEM)和振动样品磁场计(VSM)等分析方法对样品进行了表征.结果表明:水热法合成的NiFe2O4纳米粒子为尖晶石结构,粒度分布均匀,为方形形貌,粒子直径范围在50～60nm;比饱和磁化强度为25.83emu/g,剩磁为6.167emu/g,矫顽力达85.87Oe.     

Rose Bengal-Cu-TiO2的制备及可见光制氢活性研究

用光还原方法制备了负载Cu的光催化剂Cu-TiO2，并通过染料Rose bengal敏化，制备了具有可见光活性的Rose bengal-Cu-TiO2光催化剂，通过可见光下光解水制氢考察了催化剂的活性，并利用XRD、UV-Vis等手段对样品进行了表征。实验表明：载Cu增强了TiO2对可见光的吸收，Cu负载量对催化剂活性有一定的影响，Cu的最佳负载量为5％（质量分数）。Cu的负载也增加了TiO2对染料的吸附强度和吸附量，从而提高了TiO2对可见光的吸收和光催化活性。但载Cu的TiO2催化剂的活性和传统的载贵金属Pt的TiO2催化剂相比，其光催化活性较低，有待进一步提高．     

Nanocomposite of Cu-TiO2-SiO2 with high photoactive performance for degradation of rhodamine B dye in aqueous wastewater

The nanocomposite of Cu-TiO2-SiO2 photocatalyst have been prepared by a sol-gel method, which is used for the degradation of Rhodamine B (RB) as a probe that is notorious organic compound present in dyes wastewater. Morphological and structural characteristics of the Cu-TiO2-SiO2 nanocomposite were studied with low temperature N2 adsorption (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectroscopy (DRS). The Fourier transformed infrared spectroscopy (FT-IR) analysis shows the enhanced chemical bonding of O-Ti and O-Ti-O after the composition of Cu and SiO2 species into TiO2. It is found that the Cu-TiO2-SiO2 nanocomposite exhibits much higher photocatalytic activity under both UV light and visible light irradiation as compared with that over commercial titania (Degussa P25) toward the dyes wastewater containing RB. The photodegradation rate of RB (5 mg/L) can reach above 95.0% under sunlight after 3 h. The addition of SiO2 not only inhibites the crystal growth and anatase-to-rutile transformation of TiO2 nanocatalyst, but also enhances the adsorption of organic compounds. Cu-doping extends the light response to the visible region. Synergetic effects between Cu-SiO2 and TiO2 have been investigated, which provides a good way and material in the degradation field of dyes wastewater.     

Influence of dispersant on the morphology of silica-coated cobalt nanoparticles synthesized by a wet based method

Co/SiO₂ nanospheres with nearly perfect core–shell structure were prepared by an improved sol–gel method combined with hydrogen reduction. The products were characterized by X-ray diffraction spectra (XRD), transmission electron microscopy (TEM) and Fourier transform infrared (FT-IR) spectra. The results indicated that polyethylene glycol (PEG 8000) could act as a more efficient dispersive reagent than citric acid monohydrate (CAM). The average size of Co nanoparticles can be well controlled with optimum concentration of PEG 8000 and the average diameter of Co nanoparticles reaches about 30 nm with PEG 8000 concentration of 50 mg ml⁻¹.     

Polymer electrolytes based on grafted inorganic nanoparticles for dye-sensitized solar cells

Inorganic nanoparticles such as TiO2 and SiO2 were grafted with poly(oxyethylene methacrylate) (POEM) and blended with poly(ethylene glycol) (PEG), 1-methyl-3-propylimidazolium iodide (MPII) and iodine (I2) to prepare polymer electrolytes for dye-sensitized solar cells (DSSC). The effects of the grafted nanoparticles on the coordination interactions and structures of electrolytes were investigated using FT-IR spectroscopy and differential scanning calorimetry (DSC). The energy conversion efficiencies were obtained as 3.3 and 2.9% for TiO2 and SiO2 based electrolytes, respectively. Good interfacial contact between the electrolyte and the electrodes was also confirmed by field emission scanning electron microscopy (FE-SEM).     

Shape transformation and relaxation dynamics of photoexcited TiO2/Ag nanocomposites

The laser-induced sintering of TiO2 nanoparticles into larger nanospheres is accelerated by adsorbed silver particles. For the same weight fraction of silver, silver nanoparticles of 5 nm in diameter modify TiO2 nanoparticles more effectively than those of 1.5 nm do, suggesting that the photocatalysis of TiO2 nanoparticles as well as their stability is highly dependent on the sizes, the shapes, and the distribution of adsorbed metal nanoparticles. The photoexcited electrons of TiO2 nanoparticles are quenched at trap sites and surface states by transfer to the conduction band of silver, implying that the presence of adsorbed silver nanoparticles enhances the photocatalytic effect of TiO2.     

Synthesis of capped TiO2 nanocrystals of controlled shape and their use with MEH-PPV to develop nanocomposite films for photovoltaic applications

The present study presents the synthesis details of titanium dioxide (TiO2) nanoparticles (NPs) of different morphologies using oleic acid (OA) and oleyl amine (OM) as capping agents. Different shapes of NPs, such as nanospheres, nanorods, and nanorhombics, were achieved. In order to develop nanocomposite thin films for photovoltaic cells, these TiO2 NPs were carefully dispersed in 2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene (MEH-PPV) matrix. The properties of synthesized TiO2 NPs and MEH-PPV/TiO2 nanocomposites were characterized using transmission electron microscopy (TEM), thermogravimetric analysis (TGA), UV-Visible spectroscopy, and Photoluminescence technique. Obtained results showed promising properties for photovoltaic devices, especially solar radiation absorption properties and charge transfer at the interface of the conjugated MEH-PPV matrix and TiO2 dispersed NPs.     

Synthesis and performance of novel magnetically separable nanospheres of titanium dioxide photocatalyst with egg-like structure

A magnetically separable photocatalyst TiO(2)/SiO(2)/NiFe(2)O(4) (TSN) nanosphere with egg-like structure was prepared by a unique process that combined a liquid catalytic phase transformation method, reverse micelle technique and chemical precipitation means. The prepared photocatalyst shows high photocatalytic activity for the degradation of methyl orange in water. The magnetic property measurements indicate that the photocatalyst possesses a superparamagnetic nature. It can be separated from water when an external magnetic field is added and redispersed into water solution after the external magnetic field is eliminated. It is one of the promising photocatalysts for wastewater treatment. A transmission electron microscope (TEM) and an x-ray diffractometer (XRD) were used to characterize the structure of the TSN photocatalyst. The results indicate that nickel ferrite core nanoparticles were completely encapsulated into monodisperse silica nanospheres as carrier, and titania nanoparticle aggregates were coated onto the surface of SN nanospheres, forming an imperfect TiO(2) shell for photocatalysis. The SiO(2) layer between the NiFe(2)O(4) core and the TiO(2) shell effectively prevents the injection of charges from TiO(2) particles to NiFe(2)O(4), which gives rise to an increase in photocatalytic activity. Moreover, the recycled TSN exhibits good repeatability of the photocatalytic activity.     

Effect of TiO2 nanoparticle shape on hydrogen evolution via water splitting

Pt/TiO2 nanospheres and nanorods were used to generate hydrogen via water splitting and the effect of the shapes of TiO2 nanoparticles were evaluated for hydrogen evolution. TiO2 nanorods exhibited an increase in charge transfer rate between the nanoparticle surface and the electrolyte. This led to improvement in the rate of photo-catalytic hydrogen evolution during the decomposition of water.     

几种纳米润滑油添加剂在齿轮油中的应用研究

研究了纳米Cu、纳米TiO2和纳米LaF3润滑油添加剂在85W／90基础油中的油溶性,比较了三种纳米润滑油添加剂在齿轮油中的应用效果,结果表明：纳米铜添加剂能够显著提高基础油的极压性能,同时具有良好的抗磨性能。采用SEM对铜纳米微粒在复合剂体系中的极压抗磨机理进行了分析,发现在摩擦过程中铜纳米微粒在表面形成沉积膜,从而表现出良好的极压抗磨性能。