碳纳米管负载金属氮化物催化剂的制备及其性能研究

采用等体积浸渍法结合程序升温还原技术制备出一系列负载型过渡金属氮化物催化剂。利用XRD、BET、TPR等表征手段,结合氨分解制氢反应,研究了它们的表面性质和反应性能。发现改性碳纳米管负载的氮化钴催化剂具有较大的比表面积,对氨分解制氢反应的催化活性最高。新鲜态CoNx/CNTs催化剂的比表面积可达151.85m2/g,在650℃时氨转化率为80.3%,850℃达到完全转化。     

碳纳米管负载氮化钴催化剂的制备及其对氨分解反应的活性

采用等体积浸渍法结合程序升温还原技术合成了一系列CoN_x/CNTs催化剂,通过XRD、BET、TGDSC、TPR等手段,结合氨分解反应,研究了它们的表面性质和反应性能,结果表明,CoNx/CNTs催化剂对氨分解反应具有良好的催化活性,在500℃时氨转化率可达到66.46%.     

钯钌原子比对碳载Pd-Ru催化剂催化H2O2电还原性能影响

利用化学还原法制备了不同原子比的碳载Pd-Ru催化剂,考察了钯钌原子比对碳载Pd-Ru催化剂催化H2O2电还原反应性能的影响。研究结果表明,随着Ru元素的增加,碳载Pd-Ru催化剂的粒径逐渐减小,各催化剂上H2O2电还原反应的起始还原电势稳定在0.82V,电流密度先增大后减小。当Pd∶Ru=1∶1时,PdRu/C催化剂表现了最好的催化性能。     

反胶束法制备PEMFC用Pt-Ru／C催化剂

采用反胶柬法制备质子交换膜燃料电池（PEMFC）用Pt-Ru／C催化剂．反胶柬体系由环己烷、水、表面活性剂和正辛醇组成．研究了反胶束体系中水与表面活性剂的物质的量之比（ω）、不同类型的表面活性剂和不同还原剂等因素对Pt-Ru／c催化剂性能的影响．研究表明,采用SDS为表面活性剂,控制ω值在适宜的范围内,采用强还原剂KHB4,在室温下反应,可得到粒径小、分布均匀的Pt-Ru／c催化剂．透射电镜（TEM）测试结果表明,Pt—Ru粒子的平均粒径为3．1nm;X射线衍射（XRD）分析表明,Pt—Ru／c催化剂合金化程度高,相对结晶度为3．1;能量散射能谱（EDS）分析表明,形成的Pt和Ru的含量接近实验设定值在0．5mol／L的H2SO4以及与0．5mol／L的CH3OH混合溶液中的循环伏安测试结果表明,自制Pt—Ru／C催化剂与Johnson公司商品Pt—Ru／C催化剂的电化学性能相近。     

Ni／CNTs及钙改性Ni／CNTs催化剂在二氧化碳甲烷化反应中性能

分别以碳纳米管（CNTs）和活性氧化铝（Al2O3）为载体,通过浸渍法制备了负载型镍基催化剂和钙改性的镍基催化剂,用二氧化碳甲炕化反应评价其催化性能,通过X射线衍射（XRD）、程序升温还原（H2-TPR）、程序升温脱附（H2-TPD）和氮气等温吸附脱附等手段对催化剂进行表征,结果表明,Ni／CNTs催化剂中的镍物种比Ni／Al2O3中的镍物种容易还原,同时钙改性Ni／CNTs催化剂更能促进镍物种的还原,添加钙可以促进CNTs载体催化剂的分散度,这些特性能提高钙改性Ni／CNTs催化剂的催化活性和稳定性。     

Pd-P/g-C3N4催化剂的优化制备及在甲酸分解制氢中的应用

以氮化碳(g-C₃N₄)为载体，采用液相还原法制备了一系列Pd-P/g-C₃N₄催化剂用于甲酸分解制氢，通过优化还原温度和活性组分负载量可以显著提高催化剂性能。采用X射线衍射仪、透射电子显微镜和X射线光电子能谱仪对催化剂的晶相结构、微观形貌、活性组分分布以及价态进行分析，并通过甲酸分解制氢实验测试了催化剂的甲酸分解制氢活性。结果表明：使用次磷酸钠还原剂需要在较高还原温度(90℃)才能实现Pd-P活性组分在g-C₃N₄载体表面的高度分散，获得较小的纳米粒子，过高或过低的还原温度都不利于制备高性能催化剂。当Pd负载量为8.0%(质量分数)时，2-Pd-P/g-C₃N₄催化剂表现出最佳催化性能，通过动力学研究和Arrhenius方程计算得到该催化剂的甲酸分解活化能为33.83kJ/mol。     

CoMoN_x/CNTs催化剂氯代硝基苯选择性催化加氢反应性能

采用等体积浸渍法结合程序升温还原技术制备出一系列负载型过渡金属氮化物催化剂,并利用XRD、BET、TG-DSC等手段对催化剂进行表征。将此催化剂用于邻氯硝基苯液相催化加氢。结果表明,单组分MoN/CNTs催化剂的活性较低,氯代硝基苯转化率为57.5%,双组份CoMoN_x/CNTs的活性较高,氯代硝基苯转化率为89.8%,添加了稀土La后CoMoN_x/CNTs催化剂活性改善不明显,但对o-CAN选择性达到了99.3%。     

乙二醇溶剂中纳米镍的制备研究

采用乙二醇为溶剂在60℃恒温水浴中,碱性条件下,不加任何表面活性剂,用联氨还原氯化镍,制备了粒径小于10nm的球形镍粉,溶液中Ni2 的浓度可在0.04-0.1mol/L之间变化.考察了pH值、温度、N2H4·H2O与Ni2 的摩尔比、溶剂等对纳米镍粒径和反应时间的影响,通过改变条件,经XRD,TEM等检测手段进行表征,制备了粒径范围在10～100nm的球形镍.且反应时间和纳米镍粒径随各个反应条件的变化具有一定的相似性.     

还原气氛、助催化剂对SrTiO3光催化分解水制氢性能的影响

采用水热法制备了SrTiO3光催化材料,研究了在还原气氛下不同处理时间对SrTiO3光催化分解水制氢性能的影响;此外还研究了单一和复合助催化剂以及担载方法对光解水制氢性能的影响。结果表明:还原气氛中处理1h的样品,其制氢速率比未经处理的样品提高了近40%;担载单一助催化剂比复合助催化剂效果更好;光沉积Pt助催化剂样品具有最高的光催化活性。     

铂钌/聚苯胺/聚砜复合膜电极的制备及对甲醇的电催化氧化

利用电化学聚合分别制备了铂(Pt)及其铂钌(PtRu)/聚苯胺(PAN)/聚砜(PSF)复合膜电极。采用循环伏安法和电化学交流阻抗对复合膜电极的甲醇电催化氧化性能进行了比较与分析。结果表明:PtRu/PAN/PSF电极对甲醇的电催化活性比Pt/PAN/PSF电极的高,铂钌的沉积不仅改变了催化剂表面对氢的吸附性质,而且使氧化物还原峰电位向阴极方向移动。另外,对在不同浓度下沉积的铂钌电极对甲醇的催化效果也做了讨论,验证了RPt∶Ru=2∶1时,复合膜电极具有最好的催化活性。     

An efficient method for decoration of the multiwalled carbon nanotubes with nearly monodispersed magnetite nanoparticles

A one-pot method has been developed to prepare magnetite nanoparticles decorated carbon nanotubes (CNTs) by thermal decomposition of iron chloride on CNTs templates in diethylene glycol. The morphological and structural characterizations indicate that magnetite nanoparticles are coated on the surfaces of the CNTs to form CNT-based nanocomposites. The density of magnetite nanoparticles on CNTs could be easily tuned by adjusting the weight ratio of iron chloride to CNTs. Magnetic measurements showed that the nanocomposites are superparamagnetic at room temperature and the magnetic properties of the samples can also be tuned by adjusting preparing conditions. The nanocomposites can be readily dispersed in water to form a stable solution and can be manipulated using an external magnetic field. As-synthesized nanocomposites may have potential applications in target–drug delivery, detection and separations, and in clinical diagnosis.     

分散方法对低含量碳纳米管玻纤/环氧层板性能的影响

采用超声波振荡与超声波破碎两种分散方法制备了低含量碳纳米管(CNTs)增强的环氧树脂, 研究了CNTs对树脂流变特性、 固化特性和力学性能的影响。进一步采用该树脂体系通过真空灌注工艺(VARIM)制备了CNTs含量为0.01%的CNTs-玻璃纤维/环氧树脂复合材料层板, 研究了两种分散方式下CNTs对复合材料层板力学性能的影响和CNTs的增强机制。结果表明: 超声波破碎分散使CNTs长度变短, 分散性更好, 与超声波振荡分散方式相比, CNTs对树脂增黏效果和树脂固化反应的影响更明显。采用双真空灌注工艺, 两种超声波分散方式下CNTs均提高了复合材料的弯曲性能、 层间剪切性能和树脂与纤维的粘结强度, 而单真空灌注工艺下CNTs的增强效果不明显, 说明受纤维过滤作用的影响, 选择合适的灌注工艺和CNTs分散方式, 低含量CNTs可实现对灌注工艺复合材料层板的增强。     

碳纳米管-铜复合粉的制备

用CVD法制备碳纳米管,将碳纳米管超声分散在硫酸铜水溶液中,经过脱水、氢还原,制得碳纳米管-铜复合粉体。用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)对样品进行了表征。结果表明,碳纳米管在复合粉体中分散均匀,一些碳纳米管与纳米铜粒子结合在一起或被铜包覆。     

Microwave-assisted synthesis of pt nanocrystals and deposition on carbon nanotubes in ionic liquids

In this work, a simple, fast and efficient route is presented for the metal (such as Pt, Rh, etc.) nanocrystal synthesis and deposition on carbon nanotubes (CNTs) in ionic liquids (ILs) via microwave heating. In this method, inorganic salts (such as H2PtCl6.4H2O, RhCl3.2H2O, etc.) dissolved in ILs, 1,1,3,3-tetramethylguanidinium trifluoroacetate or 1,1,3,3-tetramethylguanidinium lactate, were reduced to metal nanoparticles by glycol with the aid of microwave heating, and the produced metal nanoparticles could be decorated on CNTs in the presence of CNTs in ILs. The resulting nanomaterials were characterized by means of transmission electron microscopy and X-ray diffraction. It was demonstrated that the homogeneously dispersed Pt nanocrystals with the size of 2-3 nm were obtained using H2PtCl6.4H2O as precursor, and they deposited on CNTs with the similar size when CNTs was present in ILs. This technique also can be extended to fabricate other noble metal nanocrystals (including Rh, Au, etc.) and corresponding CNT composites.     

Ce-Ti-O_x/CNTs复合粒子的制备及其对风化煤氧解的催化性能

以柠檬酸为螯合剂,以自制碳纳米管(CNTs)为载体,采用柠檬酸螯合沉积法制备了Ce-Ti-Ox/CNTs复合粒子,考察了柠檬酸的用量和乙二醇的添加对产物形貌的影响,采用TEM、XRD和FR-IR等手段对样品的形貌和晶相结构进行表征。结果表明,乙二醇的"桥接"作用有效地改善了负载效果及被负载的粒子均匀。探讨了复合金属氧化物的负载机理,并在此基础上研究了所得样品在风化煤硝酸氧解制备腐植酸中的催化性能,催化结果表明,Ce-Ti-Ox/CNTs复合粒子的催化性能明显优于单纯的CNTs、CeO2、TiO2、CeO2/CNTs以及TiO2/CNTs的催化性能,使腐殖酸的产率达到了65.43%。     

In situ synthesis of ceria decorated carbon nanotubes by chemical vapor deposition

Ceria decorated carbon nanotubes (CNTs) were in-situ synthesized by chemical vapor deposition using a Ni/Ce/Cu catalyst. Ceria nanoparticles, with a diameter of about 3-8 nm, were highly dispersed on the CNTs, and it is believed that they are formed at the same time as the CNTs.     

Single-step high-speed nanogranulation of metal alloy around carbon nanotubes by flash light irradiation

We demonstrate to decorate carbon nanotubes (CNTs) with metal alloy nanoparticles by flash light from a xenon lamp highlighting dramatically simplified process and ultrafast speed of millisecond. By managing the pulse energy of the irradiation, we customize the nucleation and growth rates of homogeneous binary and ternary nanoparticles with Pt–Ru and Pt–Ru–Mo thin layers that are e-beam deposited onto CNTs. No damage of CNTs during the light-induced nanogranulation is guaranteed by the rapid and surface-localized heating mechanism. The fabricated nanoparticle/CNT nanostructures are characterized using variety of microscopic and spectroscopic techniques such as SEM, TEM and Raman spectroscopy.     

Nanotubules-supported Ru nanoparticles for preferential CO oxidation in H2-rich stream

CO present in H₂ provided as fuel for polymer electrolyte membrane fuel cells (PEMFC) can degrade the electrochemical performance and needs efficient removal, which can be accomplished by CO preferential oxidation (PROX). PROX catalytic activities in a H₂-rich stream were tested and compared using ruthenium (Ru) nanoparticles supported on two different nanotubularly structured materials, carbon nanotubes (CNTs) and halloysite nanotubes (HNTs). In both of the support materials the morphology remains unchanged after Ru deposition and reduction, demonstrating that their tubular structure is thermally-stable. The catalytic results show that the Ru/HNTs perform better than Ru/CNTs at temperatures below about 110 °C, owing to the easier reducibility of Ru particles over the former than the latter. However, Ru/HNTs can only reach a maximum CO conversion of 55%, with an O₂ selectivity of around 27% applying an O₂/CO mole ratio = 1 at 123 °C, which is insufficient for PROX applications. CNTs, on the other hand, provide larger surface area and have functional groups with stronger interaction with Ru nanoparticles, presenting a better Ru dispersion, which accounts for the superior catalytic activity at higher reaction temperature. Ru/CNTs catalyst exhibits a CO conversion over 90% and O₂ selectivity of around 50% applying the same O₂/CO mole ratio at temperatures above 120 °C.     

Preparation and catalytic activity of Ni/CNTs nanocomposites using microwave irradiation heating method

Ni nanoparticles supported on carbon nanotubes were prepared by microwave-assisted heating hydrazine reduction in ethylene glycol. The Ni/CNTs nanocomposites by microwave-irradiation method (MIM-Ni/CNTs) were characterized by XRD, SEM, EDS and BET. The results indicated that MIM-Ni/CNTs had compact coating, high nickel loading and large BET surface area. The catalytic activity of obtained products on the thermal decomposition of ammonium perchlorate (AP) was carried out by DTA. The burning rate of the propellant modified by MIM-Ni/CNTs was measured by strand burner method. Moreover, the experimental results showed that the obtained products could play a catalytic role in the thermal decomposition of AP and combustion of AP-based propellant.     

Energy absorption capability of carbon nanotubes dispersed in resins under compressive high strain rate loading

The focus of the present study is on energy absorption capability (E_A) of carbon nanotubes (CNTs) dispersed in thermoset epoxy resin under compressive high strain rate loading. Toward this objective, high strain rate compressive behavior of multi-walled carbon nanotube (MWCNT) dispersed epoxy is investigated using a split Hopkinson pressure bar. The amount of MWCNT dispersion is varied up to 3% by weight. Calculation methodology for the evaluation of E_A of individual CNTs and CNTs dispersed in resins/composites is presented. Quantitative data on E_A of individual CNTs and CNTs dispersed in resins under quasi-static and high strain rate loading is given.