WC/TiO_2纳米复合材料晶相形成机理及电催化性能

以金红石相纳米TiO_2为载体,偏钨酸铵为钨源,采用表面修饰技术制备了纳米复合材料的前体,将前体在甲烷/氢气气氛下还原碳化并采用XRD对其进行表征,研究了还原碳化温度、时间对纳米复合材料晶相组成的影响,并探讨了WC/TiO_2纳米复合材料的形成机理。通过扫描电子显微镜、热重-差热分析等手段对WC/TiO_2纳米复合材料的形态结构和热稳定性进行了表征。采用循环伏安法研究了纳米复合材料物相组成与电催化性能之间的关系,结果表明由WC和TiO_2两相组成的WC/TiO_2纳米复合材料对对硝基苯酚电还原反应的电催化性能最佳。     

WC/MMT纳米复合材料制备及其对PNP的电催化活性

以剥离后的蒙脱石(MMT)为载体,将浸渍法与原位还原技术相结合制备了碳化钨/蒙脱石(WC/MMT)纳米复合材料。采用X射线衍射、扫描电子显微镜和透射电子显微镜等手段对样品进行了表征。结果表明,剥离后蒙脱石的片层厚度为10～15 nm,层间距增大,边缘发生卷曲;复合材料由碳化钨(WC)、碳化二钨(W₂C)和蒙脱石组成,碳化钨颗粒均匀地分布于蒙脱石外表面。采用循环伏安法测试了样品对对硝基苯酚(PNP)的电化学还原性能,结果表明,WC/MMT纳米复合材料对对硝基苯酚具有良好的电催化活性,且具有较好的稳定性。蒙脱石是碳化钨基复合电催化材料良好的载体。     

纳米Ag/TiO2复合材料的抗菌性能

采用Sol gel法制备掺杂不同质量分数银的纳米Ag/TiO2复合材料,研究了其对抗菌性能的影响。结果表明,银掺杂后的复合材料和应用其整理的纺织品不需紫外光照射就具有较强的抗菌性能,对大肠杆菌和金黄葡萄球菌的透明抑菌圈达到13～17mm。复合材料中银的掺杂能抑制粒径的长大,促进TiO2从锐钛型向金红石相的转移,但其质量分数对复合材料的抗菌性能影响不大。n(Ti)∶n(Ag)=20∶1时,复合材料的抗菌性能最佳,透明抑菌圈达到17mm。     

HIPS／TiO2／TAS纳米复合材料的制备及性能

通过对纳米TiO2表面预处理及选择特定的大分子分散H(TAS)和母料法制备工艺制备了HIPS／TiO2/TAS纳米复合材料,测试结果表明,制备的HIPS／TiO2/TAS纳米复合材料较原HIPS具有更好的综合力力学性能,且较原HIPS的硬度、耐热性能、阻燃性能亦同时得到提高。     

PMMA/TiO2纳米复合材料的性能研究

利用偶联剂钛酸正丁酯对纳米二氧化钛颗粒进行预处理, 而后通过原位聚合制备了表面包覆聚甲基丙烯酸甲酯的纳米二氧化钛粉体. 通过红外光谱(FI-IR)、热重分析(TG)、差热扫描(DSC)、X射线衍射(XRD)、透射电镜(TEM)和扫描电镜(SEM)等研究了PMMA/TiO2有机-无机纳米复合材料的结构和性能.结果表明,PMMA包覆在TiO2的表面,包覆率为38.44%;PMMA/ TiO2纳米复合材料的起始分解温度和玻璃化温度分别为337 ℃和138 ℃,平均粒径为22.7 nm.表面改性后的纳米二氧化钛颗粒在有机溶剂中具有良好的分散稳定性能,同时确定了原位聚合PMMA/TiO2的最佳工艺条件为改性剂的用量15.8%,超声聚合反应时间1.5 h,反应温度为80 ℃.     

碳化钨纳米晶薄膜电极在对硝基苯酚电化学还原中的催化性能

采用磁控溅射物理气相沉积和等离子体增强化学气相沉积技术,在金属镍基体上制备具有纳米晶结构的碳化钨薄膜;采用循环伏安、准稳态极化和恒电位阶跃等电化学方法研究了对硝基苯酚(PNP)在碳化钨纳米晶薄膜电极上电化学还原的特性和机理.研究表明,采用磁控溅射物理气相沉积技术制备得到的薄膜是由直径为20nm的WC1-X构成,在这种薄膜电极上,PNP电化学还原在电位为(0.95V(Vs. SCE)时,出现一个电流密度为6.0mA(cm(2还原峰,还原反应的表观活化能为12.0kJ(mol(1;而采用等离子体增强化学气相沉积技术制备得到的薄膜是由直径为35nm的纯相WC构成,PNP在该薄膜电极上电化学还原峰电位为(1.05 V(Vs. SCE),还原电流达10.0 mA(cm(2,表观活化能为10.9 kJ(mol(1. PNP在这两种碳化钨薄膜电极上都经过两步不可逆的电化学反应还原成对氨基苯酚,控制步骤为电极反应的电荷传递过程.     

纳米TiO2/沸石复合材料光催化降解苯酚的性能

苯酚是一种较难处理的有毒有机污染物。本文以TiOSO₄为钛源,尿素为沉淀剂,沸石为载体,采用均匀沉淀法制备了纳米TiO₂/沸石复合材料,并以苯酚作为降解对象,研究了不同TiO₂负载量、煅烧温度以及重复使用对纳米TiO₂/沸石复合材料的光催化降解苯酚性能的影响。结果表明:TiO₂负载量为30%、煅烧晶化温度为650℃时,经300W高压汞灯照射3.5h,纳米TiO₂/沸石复合材料对20mg/L苯酚溶液的光催化降解率达到91.6%;重复使用5次仍对苯酚溶液具有85%的光催化降解率。     

TiO2分散对HIPS/纳米TiO2复合材料性能影响

用透射电子显微镜（TEM）、扫描电子显微镜（SEM）及电子能谱（EDS）表征了高抗冲聚苯乙烯（HIPS）基体中纳米TiO2粒子的分散，研究了HIPS／纳米TiO2复合材料中纳米粒子的分散对复合材料力学性能的影响。结果表明，EDS可较好地表征纳米TiO2的分散行为；在纳米HIPS／TiO2复合体系中，当纳米TiO2质量分数为1．0％时，纳米粒子在复合材料中呈较均匀分散，对HIPS基体起着提高强度和韧性的作用；随着纳米TiO2含量的提高，纳米粒子发生明显团聚，对HIPS的增强增韧作用减弱；TEM，SEM及EDS结合使用，可较好地表征纳米粒子在复合材料的分散行为。     

PET/纳米TiO2复合材料的结晶性能

采用光学解偏振、DSC等研究了原位聚合法制备的PET／纳米TiO2复合材料的结晶行为。结果表明：添加了锐钛型纳米TiO2之后，PET的最大晶体生长速率出现的温度有所降低，纳米TiO2对PET的结晶起到了异相成核的作用；加入锐钛型纳米TiO2时，如果添加量较少，PET纳米TiO2复合材料的结晶度升高、成核作用较明显；随着TiO2用量的增加，结晶度呈下降趋势，而加入2％的金红石型纳米TiO2对PET结晶具有良好的促进作用。     

活性炭载碳化钨复合材料的制备及其对对硝基苯酚的电催化性能

以浓度为10%的偏钨酸铵溶液为前驱体、CH4/H2为还原碳化气氛,采用表面修饰技术和还原碳化技术制备了碳化钨(WC)/活性炭(C)复合材料。通过FT-IR、XRD、SEM等对制备的WC/C材料进行表征,结果表明,酸处理后的活性炭外表面大幅度增加了羟基和羰基,WC/C复合材料是由WC、W2C和C三相组成,碳化钨均匀地分散于活性炭表面,粒径约50～100nm。采用循环伏安法研究了碱性介质中WC/C-PME对对硝基苯酚的电还原行为,结果表明,该材料对对硝基苯酚的电催化活性优于WC和C,且WC/C材料在对硝基苯酚电还原过程中保持良好的化学稳定性。     

纳米TiO2光催化剂的制备及其活性研究

采用溶胶-凝胶法制备了纳米TiO₂光催化剂，通过XRD表征产物的晶相结构。在单因素试验的基础上，用正交试验法对影响催化剂活性的条件进行了优化研究，结果表明，在焙烧温度600 ℃ 、焙烧时间2.5 h和V(醋酸)∶V(水)＝1∶1.67条件下，催化剂活性最大，对次甲基蓝的降解率可以达到85.4%。     

纳米TiO2的制备研究进展

介绍了纳米TiO2的制备方法研究进展，对各种制备方法的优缺点进行了比较，并简要介绍了纳米TiO2粉末的分析测试技术。     

Electrochemical synthesis and In situ spectroelectrochemistry of conducting NMPy‐TiO2 and ZnO polymer nanocomposites for Li secondary battery applications

Poly(N‐methylpyrrole) (PNMPy), poly(N‐methylpyrrole‐TiO₂) (PNMPy‐TiO₂), and poly (N‐methylpyrrole‐ZnO) (PNMPy‐ZnO) nanocomposites were synthesized by in situ electropolymerization for cathode active material of lithium secondary batteries. The charge–discharging behavior of a Li/LiClO₄/PNMPy battery was studied and compared with Li/LiClO₄/PNMPy‐nanocomposite batteries. The nanocomposites and PNMPy films were characterized by cyclic voltammetry, in situ resistivity measurements, in situ UV–visible, and Fourier transform infra‐red (FTIR) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The differences between redox couples (ΔE) were obtained for polymer nanocomposites and PNMPy films. During redox scan, a negative shift of potential was observed for polymer nanocomposite films. Significant differences from in situ resistivity of nanocomposites and PNMPy films were obtained. The in situ UV–visible spectra for PNMPy and polymer nanocomposite films show the intermediate spectroscopic behavior between polymer nanocomposites and PNMPy films. The FTIR peaks of polymer nanocomposite films were found to shift to higher wavelengths in PNMPy films. The SEM and TEM micrographs of nanocomposite films show the presence of nanoparticle in PNMPy backbone clearly. The result suggests that the inorganic semiconductor particles were incorporated in organic conducting PNMPy, which consequently modifies the properties and morphology of the film significantly. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41526.     

结构有序的Si/void/C/graphene纳米复合结构的制备及储锂性能

采用简单的超声、冷冻干燥和热还原相结合的自组装方法,设计和构建了纳米硅核/间隙/无定形碳壳层/石墨烯（Si/void/C/graphene） 三维有序纳米复合结构。在该结构中,纳米硅核与碳壳层之间的空隙有效避免了硅的巨大体积膨胀对碳层的破坏,大幅度提高了锂离子电池的循环稳定性;将Si/void/C纳米结构嵌入在石墨烯层与层之间,利用石墨烯卓越的导电性和柔韧性,进一步缓冲了硅材料的体积效应和提高了复合材料的导电性能。该复合材料在4200 mA·h·g^-1（1 C）电流密度下循环1000次后比容量仍高达1603 mA·h·g^-1;在67 A·g^-1（16 C）的高倍率下,比容量仍有310 mA·h·g^-1,显示出了在锂离子电池负极材料领域的巨大应用潜力。     

Erosive and corrosive wear performance and characterization studies of plasma-sprayed WC/Cr3C2 coating on SS316

Plasma spray coating with ceramic carbide is a promising approach for improving the surface quality of the materials. In this work, the effectiveness of tungsten carbide (WC), chromium carbide (Cr₃C₂), and the composite coating of the two powders in the weight ratio of 50:50 were investigated. In the erosion test, aluminum oxide (Al₂O₃) particles were combined with a high-speed air-jet and impinged at 90° on the top surface of the material. Electrochemical polarization and electrochemical impedance spectroscopy studies were conducted with a 3.5 wt.% of sodium chloride (NaCl) solution as the electrolyte. Using a scanning electron microscope, the surface morphology of powders and coatings, as well as the mechanisms of erosion and corrosion, were studied. Energy-dispersive X-ray analysis and X-ray diffractometry were used to reveal the composition and elemental distribution of the feedstock powders and coatings. Because of the presence of hard phases, the composite coating shows the highest average microhardness of 1350.2 HV. The composite coating exhibits improved erosive wear resistance with an increase in erodent exposure time. The Cr₃C₂ coating has a reduced corrosion current density of 1.404 × 10⁻⁵ mA/cm² and a higher charge transfer resistance of 2086.75 Ω cm² due to passivation.     

Pt/WC-CNTs催化剂的制备及其对氧还原的电催化性能

通过表面修饰和还原碳化技术制备了以WC为主相的碳化钨/碳纳米管材料（WC-CNTs）,并进一步采用微波多元醇法载铂制备复合催化剂Pt/WC-CNTs。该催化剂相比于Pt/CNTs催化剂,具有更低的过电位、更大的电流密度和交换电流密度,且具有更小的电荷转移电阻和更好的氧还原选择性,显示了优异的氧还原电催化性能。XRD结果表明催化剂由多晶面的WC、Pt晶粒和CNTs组成,TEM和HRTEM显示细小的Pt颗粒均匀地分布在WC-CNTs表面。Pt颗粒和WC颗粒紧密接触,这有利于它们之间的催化协同效应,从而大大增强了Pt的氧还原催化活性。旋转圆盘电极研究结果表明Pt/WC-CNTs催化剂对氧还原反应为直接四电子过程。碳化钨/碳纳米管载铂催化剂性能优异、成本较低,在燃料电池阴极催化剂的研究应用中具有良好的发展前景。     

WC@TiO2核壳结构纳米复合材料制备与电催特征

Monotungsten carbide and titania nanocomposite with core-shell(WC@TiO2)structure was prepared by a new approach of spray drying and reduction-carbonization reaction,with titania nanopowder and ammonium metatungstate as precursors,methane as carbon source,and hydrogen as reduction gas.The sample was characterized by X-ray diffraction,scanning electron microscope,high resolution transmission electron microscope and X-ray energy dispersion spectroscopy.The results show that its crystal phase is composed of brookite,tungsten and monotungsten carbide.The morphology of the sample particle is irregular sphere-like,with a diameter smaller than 100 nm.Its chemical components are titanium,tungsten,carbon and oxygen.Monotungsten carbide nanoparticles lie on the surface of titania core and form an incomplete shell around titania core in the nanocomposite.The measurement with a microelectrode system of three electrodes shows that the sample is electrocatalytic active to nitrophenol in basic solution at room temperature.Its peak potential is at0.988 V(vs saturated calomel electrode (SCE)),which is more negative than the peak potential,0.817 V(vs SCE),of mesoporous monotungsten carbide, and its peak current is 8.809μA,which is higher than the peak current,4.058μA,of mesoporous monotungsten carbide.The hydrogen generation potential of the sample is at1.199 V(vs SCE),which is more negative than that of pure nanosized monotungsten carbide at1.100 V(vs SCE).These results show that the presence of titania in the sample can lower the peak potential of nitrophenol electrocatalysis and its hydrogen generation potential,and increase its peak current of nitrophenol electrocatalysis in basic solution at room temperature.This indicates a synergistic effect of titania and monotungsten carbide in electrocatalysis.     

Preparation,thermostability, and hydrophobic properties of TiO2/poly(dodecafluoroheptyl methacrylate) nanocomposites

Poly(dodecafluoroheptyl methacrylate) (PDFMA)/titanium dioxide (TiO₂) nanocomposites with high TiO₂ content were successfully prepared by emulsion polymerization process. Before polymerization, nano‐TiO₂ was pretreated by silane coupling agent. Surface groups and composition of the modified nano‐TiO₂ were characterized by Fourier transform infrared and X‐ray photoelectron spectra. The microstructure of nanocomposites was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In addition, the thermo‐stability and wetting behavior were also investigated in relation to the dosage of TiO₂. The results showed that the thermostability is improved with the increment of TiO₂ content while hydrophilic properties exhibit nonlinear variation with the content of TiO₂. The optimal percentage of TiO₂ content in the TiO₂/PDFMA nanocomposites is 30% that could lead to the higher thermostability and hydrophobicity properties of composites. The maximum water contact angle (WCA) of nanocomposites can reach 120° ± 1°. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44377.     

介孔二氧化钛负载硅钨杂多酸的制备及其催化性能

以介孔TiO2为载体,分别采用浸渍法和溶胶-凝胶法合成了2种负载型硅钨酸/介孔TiO2催化剂,对其结构进行了表征,将其用于柠檬酸三丁酯合成反应,考察了催化活性和重复使用性. 结果表明,用溶胶-凝胶法所制硅钨酸/介孔二氧化钛对柠檬酸三丁酯的合成反应具有很好的催化活性和重复使用性,重复使用6次,260 min时柠檬酸转化率可达86.49%.