Pd/PEI-GNs复合材料的制备及对对硝基苯酚的电催化还原性能

以聚乙烯亚胺(PEI)功能化的石墨烯(PEI-GNs)为载体, 利用电化学还原法制备了Pd/PEI-GNs复合物. 采用红外光谱仪、 X射线光电子能谱仪、 X射线粉末衍射仪和扫描电子显微镜等对复合物的组成、 结构和形态进行了表征. 结果表明, Pd/PEI-GNs复合物中Pd颗粒均匀分散在PEI-GNs基底上. 采用循环伏安法、 交流阻抗法和计时电流法等电化学方法研究了Pd/PEI-GNs复合物的电化学性能. 结果表明, 制备的复合物催化剂对对硝基苯酚还原具有较好的催化活性和稳定性, 这主要是由于Pd纳米颗粒在PEI-GNs载体上均匀分散以及PEI-GNs优异的电子传递能力.     

采用积雪草树叶提取物生物合成二氧化镁纳米粒子负载的铜纳米颗粒用于高效催化还原有机染料和芳香硝基化合物（英文）

本文设计了一个经济、绿色的新型方法,采用积雪草树叶提取物作为自然的还原剂,在不使用稳定剂或表面活性剂的情况下合成了MnO_2纳米粒子负载的Cu纳米颗粒(CuNPs).该合成过程环境友好,且避免使用有毒的还原剂.树叶提取物中的酚羟基将溶液中的Cu~(2+)还原为Cu NPs,后者再稳定在MnO_2 NPs表面.采用X射线衍射、透射电镜、场发射扫描电镜、能量散射谱和红外光谱对所得Cu/MnO_2纳米复合物进行了表征.结果表明,该材料可用作高活性、高效可重复使用的多相催化剂,用于室温水溶液NaBH_4存在下刚果红、罗丹明B和亚甲基蓝,以及硝基化合物,如2,4二硝基苯肼和4-硝基苯酚的催化还原.Cu/MnO_2纳米复合物的高稳定性可使其被分离出来,重复使用数次而活性无明显下降.     

碳包铁负载纳米钯催化苯甲醇选择氧化

以碳包铁纳米晶(Fe@C)为载体,采用浸渍法制备了一种磁可分离的Pd/Fe@C催化剂,并运用X射线荧光光谱、透射电镜、X射线衍射和X射线光电了能谱对催化剂进行了表征,结果表明,纳米Pd颗粒的粒径分布在4～10 nm,平均粒径约为7nm,Pd物种以Pd0为主,其Pd 3d5/2结合能为335.6 eV.将该催化剂应用于苯...     

锐钛矿型TiO_2担载的Pd催化剂用于乙炔选择加氢的催化性能及其表征（英文）

采用水热法合成了含有89%{101}晶面的TiO_2纳米锭(TiO_2-101)和77%{001}晶面的TiO_2纳米片(TiO_2-001),将其用作载体来制备担载钯催化剂;研究了上述制备的TiO_2纳米材料对Pd/TiO_2-101和Pd/TiO_2-001催化剂用于乙炔选择加氢制聚合级乙烯催化性能的影响。结果表明,Pd/TiO_2-101催化剂表现出更好的乙炔转化率和乙烯收率。通过氢气程序升温脱附(H_2-TPD)、氢气程序升温还原(H_2-TPR)、透射电子显微镜(TEM)、CO化学吸附、X射线光电子能谱(XPS)和热重分析仪(TGA)等对催化剂进行了结构表征和分析。TEM和CO化学吸附结果表明,Pd纳米颗粒(NPs)在TiO_2-101载体上有较小的颗粒尺寸(1.53 nm)和较高的分散度(15.95%);而Pd纳米颗粒在TiO_2-001载体上的颗粒尺寸是4.36 nm和9.06%的分散度。Pd/TiO_2-101催化剂上较小的Pd颗粒尺寸及其较高的分散度使催化剂具有更多的反应活性位点,这促进了其反应的催化活性。     

金属有机骨架材料MIL-53(Al)负载纳米Pd颗粒：一种CO氧化的活性催化剂

通过等体积浸渍法制备了金属有机骨架材料MIL-53(Al) (MIL：Materials of Institut Lavoisier)负载纳米Pd催化剂. 采用X射线衍射(XRD)、透射电子显微镜(TEM)和X射线光电子能谱(XPS)等手段对催化剂的结构进行了表征. 催化剂在反应前后XRD衍射峰保持不变,说明载体MIL-53(Al)具有良好的稳定性. 采用TEM对催化剂进行表征,结果表明,MIL-53(Al)的多孔晶体结构有助于形成高度分散的纳米Pd颗粒,样品2.7% (w) Pd/MIL-53 中Pd颗粒的平均粒径为2.21 nm. 该催化剂在CO氧化反应中表现出较高的催化活性,115 ℃达到完全转化. 同时催化剂可循环使用,多次反应后催化活性和催化剂结构都保持稳定.     

高效组合型 Pd/C 催化剂用于 Suzuki 偶联反应

 采用有机金属 Pd2(dba)3 (dba 为二亚苄基丙酮) 还原分解法制得均匀分布的 Pd 纳米颗粒 (粒径为 3~6 nm) 混合液, 并用活性炭直接吸附得到了组合型 Pd/C 纳米催化剂. 采用透射电子显微镜、X 射线光电子能谱和 X 射线衍射等手段测定了催化剂表面 Pd 颗粒大小分布、晶型和化学态等. 将该催化剂用于 Suzuki 碳-碳偶联反应, 其催化活性比浸渍法制备的 Pd/C 催化剂高 2 倍以上. 以溴代芳烃为底物时, 在 80 oC 下 0.5 h 后偶联产物收率可达 98% 以上. 以邻氯硝基苯为底物时, 在 110 oC 下 1 h 后偶联产物收率可达 64%; 延长反应时间, 产物收率可达 90% 以上.     

镁铝复合金属氧化物负载纳米Pd催化剂的制备及其在醇胺一步合成亚胺反应中的应用

以共沉淀法制备的Pd2+掺杂水滑石为前驱体,通过焙烧、还原得到了镁铝复合金属氧化物负载纳米Pd催化剂.利用X射线粉末衍射(XRD),X射线光电子能谱(XPS),场发射透射电子显微镜(TEM)等手段对催化剂进行表征,发现通过Pd2+掺杂水滑石为前驱体制备的复合金属氧化物负载纳米Pd催化剂,可以实现Pd纳米颗粒(3.6 nm)在镁铝复合氧化物表面的均匀分散.该催化剂在催化苯甲醇和苯胺一步法合成N-苄叉苯胺时,在温和的反应条件下表现出良好的催化性能以及对N-苄叉苯胺较高的选择性,产物收率99%.在循环实验过程中,催化剂表现出较好的稳定性,并且催化活性未见下降.     

金属有机骨架材料MIL-53(Al)负载纳米Pd颗粒:一种CO氧化的活性催化剂(英文)

通过等体积浸渍法制备了金属有机骨架材料MIL-53(Al)(MIL:Materials of Institut Lavoisier)负载纳米Pd催化剂.采用X射线衍射(XRD)、透射电子显微镜(TEM)和X射线光电子能谱(XPS)等手段对催化剂的结构进行了表征.催化剂在反应前后XRD衍射峰保持不变,说明载体MIL-53(Al)具有良好的稳定性.采用TEM对催化剂进行表征,结果表明,MIL-53(Al)的多孔晶体结构有助于形成高度分散的纳米Pd颗粒,样品2.7%(w)Pd/MIL-53中Pd颗粒的平均粒径为2.21 nm.该催化剂在CO氧化反应中表现出较高的催化活性,115°C达到完全转化.同时催化剂可循环使用,多次反应后催化活性和催化剂结构都保持稳定.     

Pt-NiO/SiO_2纳米杂化体催化剂的制备及其催化合成对氨基苯酚的研究

采用液相还原法合成出具有面心立方结构的PtNi双金属合金纳米颗粒,将其负载到SiO_2载体上,然后在500℃空气氛下预处理原位合成Pt-NiO/SiO_2纳米杂化体催化剂。采用XRD和TEM对样品进行了表征,结果表明,Pt-NiO/SiO_2催化剂中Pt颗粒尺寸在焙烧过程中未增长,具有良好的稳定性。采用紫外吸收可见光谱仪对Pt-NiO/SiO_2纳米杂化体催化剂和Pt/SiO_2催化剂催化硼氢化钠还原对硝基苯酚合成对氨基苯酚的过程进行追踪测试。结果表明,Pt-NiO/SiO_2纳米杂化体催化剂的催化活性和反应速率远高于Pt/SiO_2催化剂的活性,这可能归因于Pt-NiO/SiO_2之间的强相互作用。     

Pd/MWCNTs纳米复合材料的制备及其电催化性能研究

采用简便的原位合成法,将立方晶形Pd纳米粒子高效负载在多壁碳纳米管(MWCNTs)表面,制备了Pd/MWCNTs纳米复合材料。通过改变Pd(acac)2和MWCNTs的投料比,调控负载于MWCNTs表面的Pd纳米粒子的粒径及密度。运用扫描电子显微镜(SEM)、热重分析仪(TG/DTA)、X射线粉末衍射仪(XRD)等技术手段对Pd/MWCNTs纳米复合材料进行详细表征。电化学实验结果表明,Pd/MWCNTs纳米复合材料对甲醇和过氧化氢展现出良好的电催化性能。     

Palladium nanoparticles encapsulated in a metal-organic framework as efficient heterogeneous catalysts for direct C2 arylation of indoles

Highly dispersed palladium nanoparticles (Pd NPs) encapsulated in the mesoporous cages of the metal-organic framework (MOF) MIL-101(Cr) have been prepared by using the wetness impregnation method. The Pd NPs were characterized by powder X-ray diffraction (PXRD), N(2) adsorption, transmission electron microscopy, inductively coupled plasma atomic emission spectroscopy (ICP-AES), and X-ray photoelectron spectroscopy (XPS). The particles size ((2.6±0.5) nm) of the obtained Pd NPs was in good agreement with the cage diameters (2.9 and 3.4 nm) of the MOF. The resulting Pd/MIL-101(Cr) catalyst exhibited extremely high catalytic activities in the direct C2 arylation of substituted indoles by using only 0.1 mol% of the Pd catalyst. Moreover, the catalyst is easily recoverable and can be reused several times without leaching into solution and loss of activity. The combination of the highly dispersible Pd NPs within the accessible mesoporous cages and the favorable adsorption of the aryl halides on MIL-101 are suspected to be the main reasons for the observed high activities of the Pd/MIL-101(Cr) catalyst in the direct C2 arylation of indoles.     

多重栾晶钯颗粒的可见光简易合成及对乙醇的电催化氧化

以氯化钯(PdCl₂)为金属前驱体, 乙醇为还原剂, 聚乙烯吡咯烷酮(PVP)为稳定剂和导向剂, 利用普通市售节能灯产生的光热作用, 辅助制备多重栾晶钯纳米颗粒。用HRTEM、FFT、PXRD、XPS、UV-Vis和FT-IR等技术对产品的形貌、晶体结构、光学性质和稳定性进行了表征, 并通过循环伏安法研究了多重栾晶Pd修饰玻碳电极对乙醇的电催化氧化活性。结果表明, 多重栾晶钯结构的形成依赖于光和热的协同作用。该材料的表面等离子共振吸收峰在可见光区域, 对乙醇有较好的电催化活性和抗中毒能力。     

多重栾晶钯颗粒的可见光简易合成及对乙醇的电催化氧化

以氯化钯(PdCl₂)为金属前驱体,乙醇为还原剂,聚乙烯吡咯烷酮(PVP)为稳定剂和导向剂,利用普通市售节能灯产生的光热作用,辅助制备多重栾晶钯纳米颗粒.用HRTEM、FFT、PXRD、XPS、UV-Vis和FT-IR等技术对产品的形貌、晶体结构、光学性质和稳定性进行了表征,并通过循环伏安法研究了多重栾晶Pd修饰玻碳电极对乙醇的电催化氧化活性.结果表明,多重栾晶钯结构的形成依赖于光和热的协同作用.该材料的表面等离子共振吸收峰在可见光区域,对乙醇有较好的电催化活性和抗中毒能力.     

树枝状钯纳米结构的控制合成及硝基苯加氢反应的催化活性

以氯钯酸为前驱体, 苯甲醇为还原剂和溶剂, 十六烷基吡咯烷酮(PVP)为稳定剂, 在微波辐射下制备了分散均匀、形貌均一的树枝状钯纳米结构. 产物用透射电子显微镜(TEM), X射线粉末衍射(XRD), X射线光电子能谱(XPS)进行了表征, 表明所制备的Pd纳米颗粒呈树枝状, 形貌单一, 分散均匀, 是由许多近似圆形的小颗粒自组装而成的二级结构. 对树枝状钯催化硝基苯加氢反应进行探究, 表明树枝状钯的催化活性比市售的钯碳催化剂的催化活性高.     

Remediation of azo-dyes based toxicity by agro-waste cotton boll peels mediated palladium nanoparticles

The present study reports an environmental benign route for the synthesis of palladium nanoparticles (Pd NPs) using agro-waste empty cotton boll peels aqueous extract for the first time. Surface Plasmon Resonance (SPR) band in absorption spectrum of Pd NPs at 275 nm confirmed the formation of Pd NPs by using UV–Vis spectroscopy. Crystalline nature of Pd NPs was confirmed by powder XRD analysis. Size and morphology was studied by transmission electron microscopy (TEM). The cotton peels extract acted as a source of phytochemicals which primarily reduced Pd⁺² to Pd⁰ nanoparticles (Pd NPs) and imparted stability of Pd NPs by surface capping. The characteristic functional groups of phytochemicals in extract and capped Pd NPs surfaces were identified by FT-IR analysis. Catalytic activity of the synthesised Pd NPs was checked against reduction of hazardous azo-dyes such as Congo red, Methyl orange, Sunset yellow and Tartrazine with NaBH₄ as electron donors. Pd NPs catalysed reduction of all azo-dyes by NaBH₄ in aqueous medium was monitored by UV–visible spectroscopy where Pd NPs mediated transfer of electrons from NaBH₄ to azo-dyes as carrier. The synthesized Pd NPs acted as a good catalyst and could be a promising material in degrading toxic azo-dyes from industrial effluents and wastewater.     

Highly Porous Amidoximed Carbon Nanofibers Supported Palladium(0) Nanoparticle Catalyzed Heck Reaction

Highly porous amidoximed carbon nanofibers(AOCNFs), which were fabricated via a conventional electrospinning technique followed by chemically modification, impregnation-reduction and carbonization process, had been used for the immobilization of palladium nanoparticles(Pd NPs) catalyst. During the carbonization process, polystyrene(PS) was selectively decomposed from bicomponent fibers, generating porous fibers. Fourier transform infrared spectroscopy(FTIR) result revealed the functional groups on PAN-PS fibers(PAN=polyacrylonitrile), AOPAN-PS fibers and AOCNFs; scanning electron microscopy(SEM) was used to observe the morphology of all stages of nanofibers; transmission electron microscopy(TEM) result gave the structure of through-hole morphology clearly visible and the dispersion of Pd NPs on the surface of nanofibers; and X-ray photoelectron spectra(XPS) confirmed that Pd nanoparticles on the surface of AOCNFs was of the metallic state. Moreover, the as-prepared catalyst exhibited high catalytic activity and efficient recycle for Heck coupling reactions between iodobenzene and acrylates.     

The controllable preparation of electrospun carbon fibers supported Pd nanoparticles catalyst and its application in Suzuki and Heck reactions

The palladium nanoparticles/carbon nanofibers(Pd NPs/CNFs) catalyst was prepared by the electrospinning method, the hydrazine hydrate solution reduction in an ice bath environment, the high temperature carbonization. The catalyst was characterized by X-ray diffraction(XRD), fieldemission scanning electron microscope(FE-SEM), and transmission electron microscopy(TEM). The nanofibers are not cross-linked and arranged in order. The surface of Pd NPs/CNFs is smooth, and it can be observed that a large number of particles were loaded and well-dispersed in carbon fiber matrix, and the particle distribution is uniform. The activity center of catalyst is Pd(0). The Pd NPs/CNFs exhibited a high efficiency, good reusability and stability in the Suzuki and Heck reactions. It can be used for at least five consecutive runs without significant loss of its catalytic activity. The good recyclability of Pd NPs/CNFs provides a way to greatly reduce the cost of the catalyst.     

Biosynthesis of palladium nanoparticles as a heterogeneous and reusable nanocatalyst for reduction of nitroarenes and Suzuki coupling reactions

A facile and green route for the synthesis of palladium nanoparticles (Pd‐NPs) was developed utilizing non‐toxic and renewable natural green tea extract as the reducing, stabilizing and capping agent. The as‐prepared Pd‐NPs@Oak Gum catalyst was characterized using UV–visible spectroscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy and energy dispersive X‐ray spectroscopy. The Pd‐NPs@Oak Gum catalyst could be used as an efficient and heterogeneous catalyst for Suzuki coupling reactions between phenylboronic acid and a range of aryl halides containing iodo, bromo and chloro moieties and also for the reduction of nitroarenes using sodium borohydride in an environmental friendly medium. Excellent yields of products were obtained with a wide range of substrates and the catalyst was recycled multiple times without any significant loss of its catalytic activity. Copyright © 2016 John Wiley & Sons, Ltd.     

Greener approach for synthesis of monodispersed palladium nanoparticles using aqueous extract of green tea and their catalytic activity for the Suzuki–Miyaura coupling reaction and the reduction of nitroarenes

A facile and green route for the synthesis of palladium nanoparticles (NPs) was developed utilizing non‐toxic and renewable natural green tea extract as the reducing, stabilizing and capping agent. The as‐prepared Pd‐NPs@G.Tea extract was characterized using UV–visible spectroscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, field‐emission scanning electron microscopy, transmission electron microscopy and energy‐dispersive X‐ray spectroscopy. The Pd‐NPs@G.Tea extract could be used as an efficient and heterogeneous catalyst for Suzuki coupling reactions between phenylboronic acid and a range of aryl halides containing iodo, bromo and chloro moieties, and also for the reduction of nitroarenes using sodium borohydride in an environmentally friendly medium. Excellent yields of products were obtained with a wide range of substrates and the catalyst was recycled multiple times without any significant loss of its catalytic activity.     

Preparation of palladium clusters protected by silica-supported,crosslinking, partially phosphorylated poly(vinyl alcohol) and their catalytic activity

The palladium cluster protected by silica-supported, crosslinking, partially phosphorylated poly(vinyl alcohol) (P-PVA) was prepared from a crosslinking P-PVA–Pd(II) complex by reduction in alcohol. The P-PVA–Pd complex and the palladium cluster protected by P-PVA were analyzed by electron spectroscopy, X-ray photoelectron spectrometry and transmission electron microscopy. The complex formation between the Pd(II) ion and phosphoric acid groups in P-PVA was important in the formation of a fine palladium cluster. Palladium clusters protected by silica-supported crosslinking P-PVA were used as catalysts for the hydrogenation of nitrobenzene or acrylic acid at 30°C under atmospheric pressure. The palladium cluster protected by crosslinking P-PVA supported on silica was the most active catalyst, was stable and had no by-products, compared with the palladium cluster protected by silica-supported noncrosslinking P-PVA or PVA.