Pd/TiO2/C复合催化剂的制备及其在碱性溶液中对乙醇氧化的电催化性能

钛酸四丁酯前驱体水热合成制备纳米TiO₂颗粒,在TiO₂和Vulcan XC-72活性炭复合载体上液相还原负载Pd纳米颗粒,制得Pd/TiO₂/C复合催化剂. 通过透射电镜（TEM）和X射线衍射（XRD）测试表明其具有面心立方结构,Pd金属粒子（粒径约3 ~ 4 nm）均匀分散在锐钛矿型的纳米TiO₂和活性炭的复合载体上. 循环伏安和计时电流曲线测试表明,与相同Pd载量的Pd/C相比,20% Pd载量的Pd/TiO₂/C颗粒在常温常压下对乙醇的电催化氧化有很高活性和稳定性. 这主要归功于纳米TiO₂改变了Pd表面的电子特性,且增大了其比表面积.     

高催化活性Pd-Co3O4/MWCNTs催化剂对甲醇氧化的电催化性能

以Co(NO3)3·6H2O为钴源,聚乙二醇(PEG)20000为表面活性剂,与多壁碳纳米管(MWCNTs)混合后通过水热氧化法成功地合成了表面均匀分布纳米絮状Co3O4的MWCNTs复合物,进一步还原Pd的前驱体而制备得到Pd-Co3O4/MWCNTs复合催化剂.利用扫描电镜(SEM)、透射电镜(TEM)及X射线粉末衍射(XRD)等手段对样品的形貌和晶型结构进行了表征,结果表明Pd纳米粒子为面心立方晶体结构,均匀地分布在Co3O4修饰的MWCNTs表面.用循环伏安法和计时电流法表征结果表明:催化剂Pd-Co3O4/MWCNTs具有较大的电化学活性表面积,在碱性介质中对甲醇氧化具有更高的电催化活性和稳定性.研究结果表明,过渡金属氧化物纳米Co3O4颗粒在提高直接甲醇燃料电池(DMFC)催化性能研究中具有十分重要的作用,是一类很有潜力的载体催化剂.     

Pd/Fe3O4-C催化剂对甲醇、乙醇和丙醇氧化的电催化活性

制备对醇氧化反应具有优异电活性的钯催化剂是醇燃料电池研究的重要内容。本文用硼氢化钠还原法制备了钯纳米颗粒, 然后沉积在Fe3O4/C复合物表面, 得到了不同Fe₃O₄负载量的Pd/Fe₃O₄-C催化剂. 透射电镜（TEM）图显示钯纳米颗粒均匀地分散在Fe₃O₄/C表面. 对制备好的Pd/Fe₃O₄-C催化剂进行了循环伏安法（CV）、计时电流（CA）和电化学阻抗谱（EIS）的测试, 研究了其在碱性介质中对C1-C3醇类（甲醇、乙醇和丙醇）氧化的电催化活性. 结果表明, 所制备的不同Fe₃O₄负载量的Pd/Fe₃O₄(2%)-C,Pd/Fe₃O₄(5%)-C, Pd/Fe₃O₄(10%)-C和Pd/C催化剂中, Pd/Fe₃O₄(5%)-C催化剂表现出最高的醇氧化电流密度. 依据循环伏安（CV）数据,Pd/Fe₃O₄(5%)-C催化剂对甲醇、乙醇、正丙醇和异丙醇氧化的阳极峰电流密度分别是Pd/C催化剂的1.7、1.4、1.7和1.3倍. Pd/Fe₃O₄(5%)-C催化剂对乙醇氧化的电荷传递电阻也远低于Pd/C催化剂. 制备的所有催化剂对C1-C3醇类电氧化的电流密度大小排序如下: 正丙醇﹥乙醇﹥甲醇﹥异丙醇. 此外, 碳粉中Fe₃O₄纳米颗粒的存在提高了钯纳米颗粒的电化学稳定性.     

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。     

基于纳米银/多壁碳纳米管修饰电极的电化学法测定磺胺甲唑

以表面处理多壁碳纳米管(MWCNTs)和硝酸银为原料,利用硼氢化钠还原法制备了纳米银/多壁碳纳米管复合材料(AgNPs/MWCNTs),并通过紫外-可见吸收光谱、红外光谱、拉曼光谱和X射线衍射进行表征。采用滴涂法将该纳米复合材料修饰至玻碳电极表面,得到纳米银/多壁碳纳米管修饰电极(AgNPs/MWCNTs/GCE)。以AgNPs/MWCNTs/GCE为工作电极,研究了缓冲溶液、pH值、支持电解质和扫描速度对磺胺甲■唑(SMZ)电化学反应活性的影响。结果表明,与多壁碳纳米管、纳米银单独修饰电极相比,该纳米复合材料修饰电极对SMZ显示了更高的电催化活性。优化条件下,SMZ浓度在3.0×10~(-7)～5.0×10~(-5) mol/L范围内与峰电流呈线性关系,检出限(S/N=3)为6.4×10~(-8) mol/L。该方法操作简单、快速,可用于河水样品中SMZ的检测。     

磁性离子液体中聚乙撑二氧噻吩/多壁碳纳米管纳米复合材料的球磨法制备及表征

以磁性离子液体1-丁基-3-甲基咪唑四氯化铁盐([bmim]FeCl₄)为介质, 将多壁碳纳米管(MWCNTs)机械球磨分散在其中形成[bmim]FeCl₄/MWCNTs凝胶后, 加入乙撑二氧噻吩(EDOT)单体, 利用阴离子 的氧化性进行原位聚合, 球磨法制备了均匀包覆不同含量MWCNTs的聚乙撑二氧噻吩/多壁碳纳米管(PEDOT/MWCNTs)纳米复合材料. 并以傅里叶红外光谱(FT-IR)、扫描电镜(SEM)和透射电镜(TEM)对PEDOT/MWCNTs的结构与形貌进行了表征|在0.5 mol/L硫酸溶液中, 用循环伏安测试(CV)研究了PEDOT/MWCNTs的电化学行为|采用四探针仪测定了PEDOT/MWCNTs的电导率|热重分析(TGA)研究了PEDOT/MWCNTs的热稳定性. 结果表明, PEDOT 纳米颗粒均匀包覆于MWCNTs表面, 形成了核壳结构|PEDOT与MWCNTs之间的共轭作用随着MWCNTs含量的增加而增强. MWCNTs的质量分数为30%的PEDOT/MWCNTs的电导率出现峰值, 达到7.46 S/cm, 且电化学活性最好. MWCNTs的质量分数为10%时, PEDOT/MWCNTs的热稳定性相对于PEDOT显著提高.     

基于钯纳米颗粒修饰直立碳纳米管电极的电化学葡萄糖生物传感器

将电化学氧化生成的Pd(Ⅳ)离子配合到直立碳纳米管(ACNTs)上, 使其还原为纳米颗粒(Pb nps), 从而制得Pd nps-ACNTs纳米复合物电极, 经过葡萄糖氧化酶(GOD)进一步修饰后, 制成GOD/Pds nps/ACNTs酶电极, 通过测量GOD和葡萄糖酶促反应中产生的H₂O₂含量, 进而监测葡萄糖浓度. 实验结果表明, 电极表面大量Pd纳米颗粒的存在显著提高了传感器的检测灵敏度, 使酶电极具有响应时间短(<5 s)及检测电位低(<0.4 V)等优点.     

Pd/MWCNTs贫燃甲烷催化燃烧性能研究

以MWCNTs为载体,用HNO_3做氧化剂对MWCNTs进行处理,通过XPS研究了处理前后MWCNTs表面官能团的变化,并采用超声浸渍法制得Pd/MWCNTs催化剂,借助TEM,揭示了Pd粒子在催化剂表面分散度和粒径与MWCNTs表面含氧量、羟基和羰基间的关系。并考察了Pd/MWCNTs催化剂预处理方法对低浓甲烷催化燃烧活性和稳定性的影响,研究表明,Pd的价态以及Pd粒子的粒径,都与催化剂的甲烷燃烧活性直接关联。单质Pd的氧化和Pd粒径的长大是导致催化剂性能衰减的原因。通过原位FT-IR技术对反应气氛下中间物种的监测,提出了Pd/MWCNTs催化剂上的低浓度甲烷催化氧化反应机理。     

Mb/AuNPs/MWCNTs/GC电极对H2O2电催化性能的研究

采用还原法制备了AuNPs/MWCNTs复合材料,并构建了氧化还原蛋白质的固定化和生物传感界面AuNPs/MWCNTs/GC电极.以肌红蛋白(Myoglobin,Mb)为例,研究了固定化蛋白质在AuNPs/MWCNTs/GC电极上的直接电化学.结果表明,AuNPs/MWCNTs复合材料不仅能有效地促进Mb与电极表面的直接电子转移,而且能很好地保持固定化Mb的生物催化活性.Mb/AuNPs/MWCNTs/GC电极对H2O2具有良好的电催化还原性能,其线性响应范围为1～138μmol·L-1,检测限为0.32μmol·L-1(S/N=3),并具有较低的米氏常数(0.143 mmol·L-1).该电极操作简单,响应迅速,稳定性和重现性好,有望用于蛋白质的固定化及第三代生物传感器的制备.     

芦丁在铂纳米/碳纳米管修饰电极上电化学行为研究

通过电沉积的方式在多壁碳纳米管(MWCNTs)修饰玻碳电极表面上沉积铂(pt)纳米粒子,并运用循环伏安法(CV)、示差脉冲伏安法(DPV)探讨了芦丁在铂纳米/碳纳米管/玻碳电极上的电化学行为.实验结果表明,芦丁在该修饰电极上呈现一对良好氧化还原峰,其氧化峰电流与浓度在3.2×10(-8)～1.2×10(-5)mol/L...     

Influence of the preparation conditions of Pd‐ZrO2 and AuPd‐ZrO2 nanoparticle–decorated functionalised MWCNTs: Electron spectroscopy study aided with the QUASES

The Pd, AuPd, and ZrO₂ nanoparticle–decorated functionalised multiwalled carbon nanotubes (f‐MWCNTs) were reported as efficient catalysts of formic acid (FA) electro‐oxidation. Different preparation conditions influence their chemical and structural properties analysed by X‐ray photoelectron spectroscopy aided with the quantitative analysis of surfaces by electron spectroscopy. Different reduction procedures such as NaBH₄, a polyol microwave‐assisted method (PMWA), and a high pressure microwave reactor (HPMWR) were applied for decorating ZrO₂/f‐MWCNTs with Pd and AuPd nanoparticles. The ZrO₂ nanoparticles are attached through oxygen groups to the surface of f‐MWCNTs. In NaBH₄ and HPMWR procedures, Pd nanoparticles precipitate predominantly on ZrO₂ of nearly nominal stoichiometry, whereas in PMWA procedure, Pd and AuPd nanoparticles precipitate predominantly on the surface of f‐MWCNTs, bridging with oxygen groups and ZrO_x (x < 2) and leading to Pd‐O‐Zr phase formation. Strong reducing procedures (NaBH₄ and FA) led to smaller Pd nanoparticle size, Pd oxide content, and PdO_x overlayer thickness in contrary to weak reduction procedures (HPMWR and PMWA). The highest content of Pd‐O‐Zr phase appeared for Pd predominant precipitation on ZrO₂ nanoparticles (HPMWR) in contrary to Pd and AuPd predominant precipitation on surface of f‐MWCNTs (NaBH₄ ~ FA > PMWA). Larger content of Pd‐O‐Zr phase in AuPd‐decorated ZrO₂/f‐MWCNTs in contrary to Pd‐decorated sample (PMWA) could be justified by different electronic properties of nanoparticles. The FA treatment of Pd and AuPd‐ZrO₂/f‐MWCNTs samples provided decreasing Pd oxide content, overlayer thickness, nanoparticle size, increasing nanoparticle surface coverage and density, amount of Pd‐O‐Zr, what results from reduction of oxygen groups bridging with Pd and ZrO_x nanoparticles, also through Pd‐O‐Zr phase.     

多壁碳纳米管负载Pd-Ni电催化剂对乙二醇的电催化氧化

采用微波加热还原法制备了不同化学计量比的Pd-Ni复合多壁碳纳米管(Pd-Ni/MWCNT)催化剂. 通过X射线衍射(XRD)、透射电镜(TEM)和能量散射谱(EDS)等微结构和组成表征表明, 所合成的催化剂中Pd-Ni合金具有较小的纳米颗粒以及较好的分散程度. 循环伏安(CV)、线性扫描(LSV)、计时电流方法(CA)和交流阻抗(EIS)等测试表明, Pd-Ni(3:1)/MWCNT催化剂对乙二醇的电化学氧化具有较高的催化活性.     

多壁碳纳米管负载Pt-Au电催化剂的微波合成及其催化氧还原性质

采用微波还原法合成了具有较小的纳米颗粒以及较高的分散程度的纳米Pt-Au复合多壁碳纳米管(Pt-Au/MWCNTs)电催化剂. 利用旋转圆盘电极(RDE)技术对Pt-Au/MWCNTs电催化剂在0.1 mol•L−1 HClO4溶液中的催化氧还原的动力学进行了研究. 结果表明, Pt和Au的质量比为1:2时, 表现出对氧气较好的催化还原活性.     

Amperometric sensor for nitrite using a glassy carbon electrode modified with thionine functionalized MWCNTs/Au nanorods/SDS nanohybrids

A sensitive nitrite (NO₂^‐) biosensor was fabricated by using sodium dodecyl sulfate (SDS), Au nanorods, and thionine functionalized MWCNTs (TH‐f‐MWCNTs) nanohybrids modified glassy carbon electrode. TH was covalently immobilized on the MWCNTs via a carbodiimide reaction. Comparing with MWCNTs/GCE, TH‐f‐MWCNTs/GCE displays higher catalytic activity toward the oxidation of NO₂^‐, since TH not only promoted the electronic transmission but also could improve the concentration of NO₂^‐ at the surface of the modified electrode in acidic solutions. The Au nanorods (AuNRs) were prepared through a simple wet chemical method and were characterized by TEM. The extremely high surface‐to‐volume ratios associated with one dimension nanostructures make their electrical properties extremely sensitive to species adsorbed on surfaces and result in excellent sensitivity and selectivity. SDS displays excellent film forming ability, which made the electrode stable. Under optimal conditions, the linear range for the detection of nitrite was 0.26 to 51 μM, and the low detection limit was 20 nM. In addition, the modified electrode was successfully applied to determine nitrite in real water samples. Copyright © 2012 John Wiley & Sons, Ltd.     

毛细管电泳-多壁碳纳米管/聚吡咯/磷钼酸修饰电极电化学检测饮用水中的溴酸根

用电化学聚合法制备多壁碳纳米管/聚吡咯/磷钼酸修饰电极,利用循环伏安法研究溴酸根在此修饰电极上的电化学行为.考察了实验参数对分离检测体系的影响,并在优化条件下,采用毛细管电泳-安培检测法对溴酸根进行检测.结果表明:溴酸根离子在1.0×10-6～5.0×10-3 mol/L范围内和峰面积呈良好的线性关系,检出限(S/N=...     

Highly Sensitive Hydrazine Sensor Based on Co(OH)2 Nanoflakes Electrochemically Deposited on MWCNTs

We delineate the electrochemical preparation of cobalt hydroxide nanoflakes Co(OH)₂ NFs on multi‐walled carbon nanotubes (MWCNTs) by potentiostatic methods. The preparation was done on the surface of glassy carbon electrode (GCE). The prepared nanocomposite was characterized by field emission scanning electron microscopy (FESEM), X‐ray diffraction spectroscopy (XRD) and X‐ray photo electron spectroscopy (XPS). The resulting f‐ MWCNTs/Co(OH)₂ NFs modified GCE exhibits a good electrocatalytic activity for the oxidation of hydrazine in terms of decreasing over potential and increasing peak current. The modified electrode holds good in the linear range from 0.5 to 15.5 μM with limit of detection as 87.5 nM. The sensitivity of our modified electrode is calculated to be 5733 μA/mM cm‐2. Remarkably, the obtained LOD value of our sensor is very lower compared to the recommended concentration of hydrazine in water by World health organization (WHO) and Environmental protective agency (EPA). The modified electrode detects hydrazine selectively even in the presence of common interferants. Various water samples were chosen to study the practical feasibility of our sensor. The sensor also exhibited an appreciable stability, repeatability and reproducibility.     

A sensitive amperometric sensor for hydrazine and hydrogen peroxide based on palladium nanoparticles/onion-like mesoporous carbon vesicle

Onion-like mesoporous carbon vesicle (MCV) with multilayer lamellar structure was synthesized by a simply aqueous emulsion co-assembly approach. Palladium (Pd) nanoparticles were deposited on the MCV matrix (Pd/MCV) by chemical reduction of H₂PdCl₄ with NaBH₄ in aqueous media. Pd(X)/MCV (X wt.% indicates the Pd loading amount) nanocomposites with different Pd loading amount were obtained by adjusting the ratio of precursors. The particular structure of the MCV results in efficient mass transport and the onion-like layers of MCV allows for the obtainment of highly dispersed Pd nanoparticles. The introduction of Pd nanoparticles on the MCV matrix facilitates hydrazine oxidation at more negative potential and delivers higher oxidation current in comparison with MCV. A linear range from 2.0 × 10⁻⁸ to 7.1 × 10⁻⁵ M and a low detection limit of 14.9 nM for hydrazine are obtained at Pd(25)/MCV nanocomposite modified glassy carbon (GC) electrode. A nonenzymatic amperometric sensor for hydrogen peroxide based on the Pd(25)/MCV nanocomposite modified GC electrode is also developed. Compared with MCV modified GC electrode, the Pd(25)/MCV nanocomposite modified GC electrode displays enhanced amperometric responses towards hydrogen peroxide and gives a linear range from 1.0 × 10⁻⁷ to 6.1 × 10⁻³ M. The Pd(25)/MCV nanocomposite modified GC electrode achieves 95% of the steady-current for hydrogen peroxide within 1 s. The combination of the unique properties of Pd nanoparticles and the porous mesostructure of MCV matrix guarantees the improved analytical performance for hydrazine and hydrogen peroxide.