ZnO/Al2O3复合纳米颗粒的制备与表征

以硫酸锌和氢氧化钠为原料,采用直接沉淀法制备了纳米氧化锌,并用硫酸铝水解生成的三氧化铝对钠米氧化锌进行了表面改性,并采用IR、TEM、SEM、XRD等手段对改性前后的粉体进行表征研究.TEM和SEM分析结果表明,改性后粉体颗粒的粒径小、团聚现象减轻.此外,进行了粉体的光催化降解甲基橙的实验研究.实验结果表明,改性后ZnO粉体的光催化活性明显下降,这进一步证明了纳米氧化锌颗粒表面存在三氧化二铝的包覆层.     

ZnO/Al2O3复合纳米颗粒的制备与表征

以硫酸锌和氢氧化钠为原料,采用直接沉淀法制备了纳米氧化锌,并用硫酸铝水解生成的三氧化铝对钠米氧化锌进行了表面改性,并采用IR、TEM、SEM、XRD等手段对改性前后的粉体进行表征研究.TEM和SEM分析结果表明,改性后粉体颗粒的粒径小、团聚现象减轻.此外,进行了粉体的光催化降解甲基橙的实验研究.实验结果表明,改性后ZnO粉体的光催化活性明显下降,这进一步证明了纳米氧化锌颗粒表面存在三氧化二铝的包覆层.     

纳米ZnO-γ-Al_2O_3复合粉体的制备及其光催化性能

以γ-Al2O3为载体,采用均相沉淀法制备不同ZnO负载量的纳米ZnO-γ-Al2O3复合粉体。通过X射线粉末衍射(XRD)、扫描电镜(SEM)和氮气吸附对复合粉体的结构、表面形貌和比表面积进行表征。以壬基酚聚氧乙烯醚(NPE-10)为模拟污染物,对复合粉体的光催化性能进行评价。结果表明:ZnO成功负载到了γ-Al2O3表面,且负载量随着ZnO比例的增加而增加,当ZnO与γ-Al2O3质量比为2:1时,ZnO在γ-Al2O3表面形成均匀的薄膜,且这时的复合粉体催化性能最好。煅烧温度、复合物用量对其光催化性能有显著影响,300℃下煅烧所得的复合粉体,当添加量为0.3 g时,在紫外光下照射4 h后降解率可达到96%以上,重复使用6次后降解率仍可达90%以上。     

超细氧化铝粉体的表面改性研究

利用两种硅烷偶联剂、三种钛酸酯偶联剂对Al2O3粉体颗粒表面有机改性,比较了不同偶联剂对颗粒表面的改性效果,结果表明硅烷偶联剂未能对粉体表面进行有效的有机改性.红外光谱分析证实了偶联剂NTC401在Al2O3粉体表面进行了化学吸附,而偶联剂JSC和CT136在Al2O3粉体表面主要发生物理吸附.电镜照片说明,经NTC401改性的Al2O3粉体粒子之间的团聚得到了有效改善,而经JSC和CT136改性的Al2O3粉体粒子之间的团聚未得到改善.机理分析认为中心钛原子六配位的结构能够有效阻止颗粒团聚.     

纳米SiO2氢氧化铝/十二烷基苯磺酸钠的表面包覆改性

通过氢氧化铝和十二烷基苯磺酸钠(SDBS)对纳米SiO2进行表面包覆和改性处理,改善纳米SiO2的表面结构和分散性.使用IR、FESEM、EDS、Malvern Zetasize 3000HSA自动电位粒度仪等表征手段,对表面包覆改性后纳米SiO2的表面结构、形貌及等电点等进行了测试和分析.结果表明,经Al(OH)3表面包覆后,纳米SiO2粉体等电点(IPE)的pH值从1.58变为7.1;经SDBS对表面包覆Al(OH)3的纳米SiO2进行改性后,纳米SiO2粉体团聚现象减少,单个纳米SiO2颗粒的粒径约为30nm.     

纳米氧化锌表面包覆改性及其表征

采用液相沉积法对纳米氧化锌进行表面包覆SiO2和SiO2/Al2O3改性,并用XRD、TEM、TG-DSC对其表面结构进行了表征,借助Zeta电位测定仪、静态沉降实验等分析手段考察了改性前后纳米氧化锌在水体系中的分散稳定性.结果表明,在ZnO表面形成的包覆物是以非晶态形式存在的,通过表面包覆SiO2和SiO2/Al2O3改性后明显提高了氧化锌的表面羟基含量,有效改变了氧化锌的等电点,显著提高了纳米氧化锌在水中的分散稳定性.     

表面接枝聚合法制备纳米Fe3O4/PMMA微球

通过在纳米Fe3O4颗粒表面引入过氧基因引发甲基丙烯酸甲酯(MMA)进行聚合,在纳米颗粒表面接枝上PMMA,研究了酰化反应时间、酰化剂用量、叔丁基过氧化氢的用量、聚合反应温度和时间等对纳米颗粒改性效果的影响.借助TEM观察改性后粉体的表观形貌,结果显示粉体呈球形,表面被无定形物质所包裹;FT-IR测试结果表明,在纳米Fe3O4表面已成功接枝上PMMA.     

纳米ZnO/电气石复合粉体的制备及其对亚甲基蓝光催化性能的研究

以NaOH、ZnSO4·7H2O和电气石为原料,采用室温固相法制备纳米ZnO/电气石复合粉体。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)对复合粉体的物相及形貌进行了表征,并考察了复合粉体对亚甲基蓝的光催化降解性能。实验结果表明,纳米ZnO可紧密地包覆在电气石表面形成ZnO/电气石复合粉体。光催化降解实验、紫外-可见漫反射光谱、荧光光谱分析等测试表明,添加电气石粉体可有效地提高ZnO/电气石复合粉体的光吸收能力、荧光发射能力以及对亚甲基蓝的光催化降解性能。     

Al2O3微粉的表面改性及表征

以α—Al2O3微粉为基体，Y(NO3)3溶液为包裹相，采用液相包裹法进行加钇颗粒表面改性。获得了表面均匀包裹Y2O3的α—Al2O3粉体。将此粉体与Al合金复合制备复合材料，复合材料组织更加均匀，对材料进行力学性能测试，结果表明：改性粉体对Al合金增强效果明显增加，抗拉强度提高27．2％，屈服强度提高33．1％，延伸率提高10．3％。     

纳米SiO2的表面改性及其在聚氨酯弹性体中的应用

用十二烷基苯磺酸钠(SDBS) 对表面包覆Al(OH)3的纳米SiO2进行了改性处理.通过IR、自动电位粒度仪和FESEM等测试手段对表面处理前后纳米SiO2的表面结构、界面电性能和分散状况进行了分析表征.考查了处理前后纳米SiO2与聚氨酯弹性体(PUE)的相容性及其对PUE材料力学性能的影响.结果表明,经SDBS对表面包覆Al(OH)3的纳米SiO2粉体进行改性后,纳米SiO2粉体的团聚现象减少,分散性提高,单个纳米SiO2颗粒的平均粒径约为30nm;经表面处理后的纳米SiO2粉体与有机基体PUE的相容性增强,并对PUE材料的力学性能有了较大的改善,能同时达到增强增韧的效果.     

非水溶胶凝胶法制备ZnO/Al2O3复合纳米颗粒

以无水ZnCl2和无水AlCl3为前躯体,丙酮为溶剂,油酸为氧供体,采用非水溶胶凝胶法制备ZnO/Al2O3复合纳米颗粒,通过X-ray衍射（XRD）、红外光谱（IR）、透射电镜（TEM）和紫外可见分光光度计对制备的颗粒进行表征,结果表明,颗粒为无定形态的ZnO/Al2O3复合纳米颗粒,平均粒径为61nm,呈球形单分散状态,具有良好的油溶性,能均匀稳定地分散在20#机械油中。     

Preparation of nanosized Pt-Au alloy catalyst and its activity in methanol oxidation

The alloy catalyst has been widely used because it will be able to improve the activity and selectivity of the single metal catalyst in a given chemical reaction. In this study, the preparation and characteristics of nanosized Pt and Au particles on alumina and their catalytic activity were described. Nanosized Pt-Au catalysts were prepared by impregnation (IMP) method and deposition (DP) method using alumina or ZnO/Al2O3 as support. The size of Pt and Au particles were observed by transmission electron microscopy (TEM), energy dispersive spectroscope (EDS), and X-ray diffraction (XRD). Catalytic activity for oxidation of methanol was measured using a flow reactor. It could be seen that the Pt particle size and dispersion in the alloy catalysts was rarely influenced by preparation methods and Au particles coated by deposition method were well dispersed. TEM images showed that Au particles were well dispersed in the Pt/Au/ZnO/Al2O3 catalyst of which Au particles was supported by deposition method. The catalytic activity for methanol are given in the order of Pt-Au[IMP]/ZnO/Al2O3 > Pt[IMP]/Au[DP]/ZnO/Al2O3 > Au[DP]/Pt[IMP]/ZnO/Al2O3 > Pt-Au[DP]/ZnO/Al2O3. Therefore, Au particle size was doing not play an important role in increasing the oxidation activity, but the Au particles may promote the methanol oxidation.     

Synthesis of ZnOAl2O3 core-shell nanocomposite materials by fast and facile microwave irradiation method and investigation of their optical properties

Alumina (Al₂O₃) coated ZnO core-shell structures were synthesized by a novel, fast, and facile route utilizing microwave (MW) irradiation to control photocatalytic property of ZnO. The phase analysis and the core–shell structure development were corroborated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), X-ray fluorescence (XRF), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray (EDX) analysis and Fourier transform infrared spectroscopy (FT-IR). The XPS results affirmed that elements on the coated surface were Al and O. Zeta potential analysis predicted the presence of Al₂O₃ layer on ZnO due to almost similar zeta potential curve for pure Al₂O₃ and Al₂O₃ coated ZnO nanoparticles. There was no significant change in band gap energy of ZnO after amorphous Al₂O₃ coating as obtained from derived data of the reflectance spectra but gradual decreasing of reflectance in the visible range, measured by UV–vis spectroscopy, of the prepared core-shell nanoparticle may be due to the coating of amorphous Al₂O₃ on ZnO. The photocatalytic efficiency of ZnO was reduced after amorphous Al₂O₃ layer as confirmed by the photodegradation of methylene blue under UV irradiation.     

Effect of nanosized gold particle addition to supported metal oxide catalyst in methanol oxidation

Gold has rarely been utilized as a catalytic component because of its poor affinity to chemical species. It is however known that nanosized gold particles promote the dissociation of oxygen or hydrogen. In this study, alumina-supported metal oxide catalysts were prepared by impregnation method and applied to methanol oxidation. The dispersion form and size of the gold particles were observed by transmission electron microscopy (TEM). In the results, the maximum catalytic activity was obtained over the ZnO/Al2O3 catalyst, and the optimum loading was 4 wt%. Furthermore, nano-sized gold particles at various loadings were added to ZnO/Al2O3 catalyst by deposition method. The gold particles on Au/ZnO/Al2O3 catalyst were well dispersed and the catalyst activity was remarkably increased compared to ZnO/Al2O3 catalyst. The role of gold particles in the increased catalytic activity is discussed and a possible mechanism is presented.     

纳米掺杂Al2O3/ZrO2等离子喷涂涂层组织结构研究

利用大气等离子喷涂技术,在N80钢基体上制备纳米掺杂Al2O3/ZrO2热障涂层。利用XRD、SEM等观察分析了纳米掺杂Al2O3/ZrO2粉末及等离子喷涂涂层组织形貌及结构,结果表明,Al2O3/ZrO2等离子喷涂粉末是由纳米包覆微米级粒子及少量的纳米团聚体球团粒子构成。纳米掺杂等离子喷涂Al2O3/ZrO2涂层的微观组织形貌复杂,存在着纳米柱状晶薄壳内包裹着微米级柱状晶、未熔化的ZrO2陶瓷粒子嵌镶在晶体内部的独特晶内结构。涂层主要由α-Al2O3及亚稳四方相t,-ZrO2相构成。     

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.     

Preparation and characterization of transparent Al doped ZnO/epoxy composite as thermal-insulating coating

In this article, transparent Al doped ZnO (AZO)/epoxy composite, as glass thermal insulation coating, was prepared by incorporating AZO nanoparticles into a transparent epoxy matrix. First, the as-synthesized AZO nanoparticles by the polymer pyrolysis method were characterized and the effect of Al doping content on the electrical conductivity of AZO nanoparticles was investigated. The results reveal that the AZO nanoparticles doped with 6 mol% Al obtained from calcination at 600 °C show the optimal electrical conductivity. The effects of AZO content on the optical and thermal insulation property of AZO/epoxy coating were also studied. It is shown that the AZO/epoxy composite coating with 0.5 wt% AZO possesses excellent optical properties, i.e. visible light transmittance above 50% and shading coefficient of 0.45 are simultaneously achieved. In addition, the large temperature difference between the chambers coated respectively with the AZO/epoxy coated glasses and the common glass indicates that the prepared AZO/epoxy coating has an excellent thermal insulation property.     

纳米氧化锌中空柱的制备及其光催化性能的研究

以醋酸锌和氨水为原料,超声法制备出氧化锌中空柱,采用扫描电镜(SEM)、X射线衍射(XRD)、Uv-vis漫反射对纳米ZnO的形貌、结构进行了表征,以有机染料亚甲基蓝溶液为光催化反应模型降解物,考察纳米ZnO的光催化性能。结果表明:制备出的纳米氧化锌呈中空的柱形,长约2～3μm,直径约300nm,壁厚约40nm,结晶良好。当加入纳米ZnO为0.4g/L,光降解时间为75min,对亚甲基蓝溶液的降解率可达到99.08%。