Au-Ni合金作为直接甲酸燃料电池阳极催化剂的研究

采用氩弧熔炼法制备Au-Ni合金催化剂.采用循环伏安和计时电流曲线研究甲酸在Au-Ni合金催化剂上的电催化氧化性能,结果与单质金作对比.结果表明,根据氧化主峰电位及电流密度的比较,Au-Ni合金具有比单质Au更好的催化活性.     

SnO_2纳米棒负载Pd-Sb催化甲酸电氧化

采用溶剂热法制备了SnO_2纳米棒载体,用溶剂热还原法制备了Pd/SnO_2催化剂和不同Pd/Sb原子数比的系列PdSb/SnO_2复合催化剂。用XRD、SEM、TEM、EDS等手段对样品进行分析表征,并以循环伏安法对比评价催化剂对甲酸的电催化氧化性能。表征结果表明,制备所得SnO_2纳米棒载体为针状,大小均匀,平均直径为100 nm;负载所得催化剂中活性粒子大小约为13.5 nm,掺杂Sb后,粒径约为9.5 nm。电催化氧化性能对比结果表明,Pd/Sb原子数比为4:1的Pd_4Sb/SnO_2复合催化剂对甲酸的氧化具有较好的催化能力,当E=0.25 V(vs SCE)时,Pd_4Sb/SnO_2上甲酸氧化的峰电流密度达到25 mA/cm~2,远远高于Pd/SnO_2催化剂。     

PtPb/ C 催化剂的制备及其对甲酸电氧化的催化性能

目的通过Pb元素的添加来提高Pt/C催化剂电催化氧化甲酸的性能。方法通过乙二醇协助硼氢化钠还原法,以氯铂酸为Pt源和硝酸铅为Pb源制备不同原子比的PtxPb/C催化剂。采用X射线衍射光谱法(XRD)和透射电子显微镜技术(TEM)表征样品的晶体结构和颗粒形貌;采用循环伏安法表征样品催化氧化甲酸的性能。结果利用乙二醇协助硼氢化钠还原法成功制得了Pt和Pb原子比不同的PtxPb/C催化剂,XRD和TEM测试结果表明这些样品均为Pt的面心立方结构,且颗粒大小均一、分散均匀,其平均粒径为4 nm左右。循环伏安测试结果表明PtxPb/C催化剂催化氧化甲酸的性能优于商业Pt/C催化剂的催化性能,且受Pt和Pb原子比的影响,当原子比为5∶1时,其对氧化甲酸的催化性能最好,峰电位对应的Pt的比质量活性达到2000 m A/(mg Pt),远远高于商业Pt/C,同时计时电流曲线表明其具备良好的稳定性。结论 Pb原子的加入影响了Pt原子的电子结构,与Pb对Pt的协同作用共同促进了CO等中间产物在Pt表面的快速氧化,降低了催化氧化甲酸的初始电位,促使甲酸在低电位直接氧化为CO2和H2O,提高了其催化氧化甲酸的峰电流,有效减轻了Pt中毒,提高了其催化活性。     

直接甲酸燃料电池阳极催化剂的研究

为了改善铂基催化剂氧化甲酸的活性,制备磷钼酸和钼酸钠修饰铂电极,并利用循环伏安曲线评价它们对甲酸氧化的电催化活性。结果表明:磷钼酸与钼酸钠修饰铂电极均可提高铂基电极氧化甲酸的催化活性。此外,NiSO4可以提高甲酸在磷钼酸修饰铂电极上的电催化氧化活性。     

钯锰纳米多孔材料对乙醇的电催化氧化

采用熔体快淬结合去合金化法制备了钯锰纳米多孔材料(NP-PdMn)。用X射线衍射(XRD)、X射线光电子能谱分析(XPS)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)对材料进行了表征,并研究了其在碱性条件下对乙醇氧化的电催化活性。表征显示,NP-Pd Mn为具有三维双连续纳米多孔结构的棒状材料;锰取代了晶格中部分钯的位置使得晶面间距变小;部分钯和锰在材料表面以氧化态存在。催化性能分析表明,与商业Pd/C相比,NP-PdMn/C催化剂具有优于商业Pd/C的催化活性和稳定性。     

Pd纳米盘的光热辅助合成及其对乙醇的电催化氧化

以氯化钯(Pd Cl2)为金属前驱体,乙醇为还原剂,十六烷基三甲基溴化铵(CTAB)为稳定剂和导向剂,利用普通市售白炽灯产生的光热作用,辅助合成Pd纳米盘材料。用XRD、TEM、选区电子衍射(SAED)和UV等技术对合成产物进行表征,考察了CTAB用量对纳米Pd微观形貌和尺寸的影响,并通过循环伏安法研究了纳米Pd修饰玻碳电极对乙醇的电催化氧化活性。结果表明,通过改变Pd Cl2和CTAB的摩尔比,可以调控纳米Pd的微观形貌和尺寸;当Pd Cl2与CTAB的摩尔比为1:80,可见光辐照6 h时,得到的Pd纳米盘呈多边形貌,平均粒径为46 nm,对乙醇有较好的电催化活性和抗中毒能力。     

碱性介质中Pd纳米线电极对甲醇的电催化氧化

采用交流电沉积法制备Pd纳米线阵列电极催化剂,循环伏安法测定催化剂对甲醇的电催化氧化活性,用AFM、TEM、XRD和XPS表征Pd纳米线的组织形貌、晶体结构和化学状态。结果表明:Pd纳米线的直径为65～75nm,径向表面呈毛刺结构,处于体心立方晶体结构的单质态。Pd纳米线阵列电极在KOH碱性介质中对甲醇的电催化氧化活性比其平板电极高约14倍,比文献中负载型Pt纳米颗粒催化剂在酸性介质中的催化活性高50～150倍,且具有较好的稳定性。     

碳载铂纳米微粒修饰的玻碳电极对甲醇的电催化氧化

利用X射线粉末衍射、透射电镜和扫描电镜对商用Pt/C催化剂反应前后的变化进行了物化表征，同时应用电化学方法研究了甲醇在碳载铂纳米微粒修饰的玻碳电极上的电催化氧化性能。结果表明，修饰电极对甲醇氧化呈现较高的电催化活性。铂氧化物的电化学还原在Pt/c催化剂中受到了抑制，该现象可能是由于Pt与载体碳间的强烈作用所引起的。通过扫描电镜和循环伏安研究表明，该催化剂对甲醇的氧化可能存在着表面结构敏感效应。     

从Pd-C催化剂废料制备纳米Pd

从Pd—C催化剂废料回收Pd（N03）2，然后在SDS／Brij30／H20体系O／W微乳液中制备纳米钯。结果表明：制备的钯纳米粒子的粒度在5-200nm之间：使用该体系不需外加还原剂，可直接利用非离子表面活性剂Brij30作为还原剂，简化后续单元操作。并初步探讨了SDS／Brij30／H2O体系O／W微乳液中纳米钯的制备机制。     

Pdx-Co/C催化甲酸的电氧化性能研究

以活性碳(Vulcan XC-72)为载体,用化学还原法制备了不同Pd/Co摩尔比的Pdx-Co/C催化剂。用透射电镜(TEM)、X射线衍射(XRD)及X射线光电子能谱(XPS)对催化剂进行了表征,采用循环伏安法考察了催化剂对甲酸电氧化反应的催化性能。结果表明,Pdx-Co复合催化剂粒子均匀分散在碳载体表面;催化剂中掺入的少量Co元素部分进入Pd晶格,形成了Pd-Co合金;随着Pd/Co摩尔比的增加,Pd颗粒粒径先增大后减小,催化活性也表现出相同的变化趋势;当Pd:Co=8:1时,所得Pd8-Co/C对甲酸氧化的催化活性最高,峰电流密度可达到15.907 mA/cm²。     

Novel nanoporous palladium catalyst for electroreduction of hydrogen peroxide

Titanium-supported nanoporous palladium catalyst(Pd/Ti) was prepared by a hydrothermal method using PdCl2 as a precursor,ethylenediamine tetraacetic acid(EDTA) as a ligand,and formaldehyde as a reduction agent.Complex Pd-EDTA2-is favorable for the formation of Pd particles with nanoscale sizes.The electroactivity of the Pd/Ti catalyst towards the electroreduction of hydrogen peroxide in 1 mol/L NaOH solution was evaluated by voltammetric techniques.Both linear scan voltammetric and chronoamperometric data p...     

Novel nanoporous binary Ag-Ni electrocatalysts for hydrazine oxidation

From an aqueous mixture of Ag(Ⅰ)-EDTA complex and Ni(Ⅱ) nitrate, silver and nickel particles were co-deposited on the surface of titanium substrates by the hydrothermal method using hydrazine hydrate as a reduction agent. The prepared titanium-supported nano-scale Ag and Ag-Ni particles (nano Ag/Ti, nano Ag_(86)Ni_(14)/Ti, nano Ag_(77)Ni_(23)/Ti, and nano Ag_(74)Ni_(26)/Ti) exhibit nanoporous 3D network textures. Their electrocatalytic activity towards hydrazine oxidation in alkaline solutions was evaluated by cyclic voltammetry and chronoamperometry. The results show that the four samples present a low onset potential of ca. -0.60 V vs. SCE and considerably high and stable anodic current den-sities for hydrazine oxidation. Among them, the nano Ag_(86)Ni_(14)/Ti electrode exhibits the highest anodic current density towards hydrazine oxidation, showing an increment of electro-active sites on the nano Ag_(86)Ni_(14)/Ti due to the addition of Ni to Ag particles.     

Electrocatalytic oxidation of methanol on carbon-nanotubes/graphite electrode modified with platinum and molybdenum oxide nanoparticles

Electrochemical codeposition and electrocatalytic properties of platinum and molybdenum oxide nanoparticles(Pt-MoOx) on carbon-nanotubes/graphite electrode for methanol oxidation were investigated.The micrograph and elemental composition of the resulting Pt-MoOx/CNTs/graphite electrode were characterized by scanning electron microscopy(SEM)and energy dispersive X-ray spectroscopy(EDS).The results show that the Pt-MoOx particles with the average size of about 50 nm are highly dispersed on the CNTs surface.The Pt-MoOx/CNTs/graphite electrode delivers excellent electrocatalytic properties for methanol oxidation.The highest mass activity(Am)reaches 264.8 A/g at the loading mass of 159.3μg/cm2.This may be attributed to the small particle size and high dispersion of Pt-MoOx catalysts deposited on the CNTs surface.The kinetic analysis from electrochemical impedance spectroscopy(EIS)reveals that the existed MoOx phase can improve the chemisorptive and catalytic properties for methanol oxidation.     

改性钛阳极对甲醇的电催化作用

采用热分解法制备了用于甲醇电氧化的改性钛阳极 ,用三电极体系测试了电极对甲醇的电催化氧化。循环伏安测试表明 ,甲醇氧化过程中中间产物的存在抑制了甲醇在阳极上的电催化氧化 ;稳态极化曲线则表明 ,阳极涂层中采用SnSb掺杂 ,改性钛阳极的催化活性得到显著提高 ;而往阳极涂层中加入少量Ru后 ,由于Ru遏制了PtO2 的分解 ,钛阳极催化活性有所下降。对电极制备方法加以改进后 ,可明显看出Ru促进了电极对甲醇的电催化活性。     

Electrocatalytic oxidation of ascorbic acid at polypyrrole nanowire modified electrode

Polypyrrole (PPy) nanowire modified electrodes were prepared electrochemically by template-free method based on graphite electrodes. The freshly prepared electrodes were dipped in 10% HClO₄ solution at least 24 h for removal of carbonate ions. The modified electrodes toward ascorbic acid were characterized by potentiostatic method. The experiment's results show that the PPy modified electrodes have obvious electrocatalytic effect toward ascorbic acid oxidation. The oxidation current density has a good linearity in the concentration range of 5.0 × 10⁻⁴ and 2.0 × 10⁻² mol L⁻¹ of ascorbic acid. The determination sensitivity may be significantly affected by the thickness of PPy film and pH of the test solution. The method has promising application in determination of ascorbic acid in the real samples.     

Electrocatalytic oxidation of methanol on Pt modified polyaniline in alkaline medium

A comparative study of the electrocatalytic oxidation of methanol is made in NaOH, Na₂CO₃ and NaHCO₃ on bare Pt (Pt), polyaniline covered Pt (PANI) and Pt modified polyaniline film on Pt (Pt/PANI) using cyclic voltammetry, polarization, ac impedance spectroscopy and chronoamperometric techniques at 25 °C. The cyclic voltammetry and polarization studies show that the potentials at which methanol oxidation commences on different electrodes in each of the alkaline medium examined follow the trend Pt/PANI < Pt < PANI whereas the potentials for initiation of oxidation on each electrode in different alkaline media follow the order NaHCO₃ > Na₂CO₃ > NaOH. The oxidation current is highest and charge transfer resistance lowest for Pt/PANI films compared to Pt in all the media studied. However, for the same Pt loading Pt/PANI films exhibit larger oxidation currents in NaOH followed by Na₂CO₃ and NaHCO₃. The Tafel slope for methanol oxidation on Pt/PANI in NaOH, Na₂CO₃ and NaHCO₃ has a value of about 115 mV decade⁻¹. The chronoamperometric response of the Pt/PANI film at the peak potential for methanol oxidation shows lesser sensitivity to poisoning by CO compared to bare Pt and platinised Pt (Pt/Pt).