Metals and alloys bonded on solid polymer electrolyte for electrochemical reduction of pure benzaldehyde without liquid supporting electrolyte

Metals and alloys bonded on the solid polymer electrolyte (SPE) Nafion® 117 were studied as both the electrodes and electrolyte for the electrochemical reduction of pure benzaldehyde without liquid supporting electrolyte. The results indicated that SPE electrodes modified with metals such as Pt, Ni, Pb, Cu and Ag by the ion exchange chemical deposition method had a more stable structure and could provide a larger electrochemical active surface area than those prepared by other methods. The composition of reducing agents and the pH value have a significant effect on the characteristics of the prepared SPE electrodes. In this study a novel method was developed to prepare a Pt+Pb/Nafion® electrode which formed a protective Pt layer on the surface of Pb/Nafion®. The results of scanning electron microscopy further confirmed that Pt+Pb/Nafion® electrodes had obvious advantages for the electrochemical reduction of benzaldehyde. The results also revealed that the current efficiencies of benzylalcohol production at various SPE electrodes decreased in the order Pt+Pb/Nafion® > Pb/ Nafion® > Ni/Nafion® > Cu/Nafion® > Ag+Cu/Nafion® > Ag/Nafion® > Pt/Nafion®.     

负载型Pt/C催化剂的制备条件对Pt晶粒尺寸的影响

纳米级催化剂;浸渍还原法;晶粒结构;负载型Pt/C催化剂的制备条件对Pt晶粒尺寸的影响     

催化剂制备工艺对PEMFC氧电极性能的影响

聚合物电解质膜燃料电池（PEMFC）具有高能量密度、运行温度较低、水热管理较为容易、稳定性较好等优点，可以应用在航天领域、潜艇、电动车、电站等领域，是目前燃料电池领域中令人关注的研究课题．在提高电池性能所作的各种尝试中，膜电极制备工艺的改进依旧是研究的重点［'1     

纳米铂微粒修饰电极上甲醛电催化氧化的电位振荡和电流振荡

通过阴极还原-阳极氧化法制备了钛基纳米铂微粒修饰电极, 扫描电镜观察发现, 分布于钛基体表面的氧化钛膜三维网状孔道中的纳米铂微粒具有高度分散状态. 采用多种电化学手段在该电极上不仅观察到甲醛在恒电流条件下产生的电位振荡, 而且在循环伏安和恒电位两种条件下均观察到强烈的电流振荡, 这进一步证明高度分散的纳米铂微粒使电极的催化活性大大提高, 促进了甲醛及其毒化中间产物的电催化氧化过程, 从而有利于电极上电化学振荡的产生. 研究结果还表明, 甲醛底物浓度、硫酸介质浓度、恒电位或恒电流大小等多种因素对振荡强度、范围或类型会产生规律性的影响.     

The Electrochemical Behavior and the Quantitative Determination of Nitrogen Dioxide at a Solid Polymer Electrolyte Supported Pt‐Au Electrode

The electrochemical behavior of NO₂ at Au/Nafion, Pt/Nafion and Pt‐Au/Nafion electrodes was investigated by using electrochemical and SEM methods, respectively. It was found that the Pt‐Au/Nafion electrode showed higher electrocatalytic activity than Pt/Nafion and Au/Nafion electrodes. The net current density of Au/Nafion electrode decayed significantly during the reaction, though it showed high initial value. Pt/Nafion and Pt‐Au/Nafion electrodes, on the contrary, showed good stability. A quantitative determination of NO₂ concentration was carried out at Pt‐Au/Nafion electrode and a satisfactory linear relationship was found for the NO₂ concentration in the range of 0–100 ppm.     

High dispersion Pt nanoparticles using mesoporous carbon support for enhancing conversion efficiency of dye-sensitized solar cells

<正>Mesoporous carbon(MC) with surface area of 380 m~2/g was prepared and employed as the carbon support of Pt catalyst for counter electrode of dye-sensitized solar cells.Pt/MC samples containing 1 wt%Pt were prepared by reducing chloroplatinic acid on MC using wet impregnation.It was found that Pt nanoparticles were uniform in size and highly dispersed on MC supports.The average size of Pt nanoparticles is about 3.4 nm.Pt/MC electrodes were fabricated by coating Pt/MC samples on fluorine-doped tin oxide glass.The overall conversion efficiency of dye-sensitized solar cells with Pt/MC counter electrode is 6.62%,which is higher than that of the cells with conventional Pt counter electrode in the same conditions.     

甲醇在铂修饰的氧化钛电极上电催化氧化行为的研究

运用电化学方法评价了电化学阴极还原-阳极氧化两步法制得的以钛为基体的铂修饰的钛氧化物(Pt-TiO_x/Ti)电极对甲醇电催化氧化的性能,结果表明,制得的修饰电极对甲醇氧化呈现了很高的电催化活性和好的稳定性.通过X光电子能谱(XPS)、扫描隧道显微镜(STM)和现场傅立叶变换红外(FTIR)反射光谱等技术,发现修饰电极对甲醇氧化具有高的电催化性能,可归属于纳米级Pt粒子在TiO_x中的高度分散及由于Pt和TiO_x的相互作用,使电极表面对甲醇氧化中间产物CO的吸附量大大降低.     

纳米碳纤维载铂作为质子交换膜燃料电池阳极催化剂

采用化学还原法合成了微结构不同的纳米碳纤维(板式、鱼骨式、管式)载铂催化剂(分别记为Pt/p-CNF、Pt/f-CNF、Pt/t-CNF). 通过高分辨透射电镜(HRTEM)和X射线衍射(XRD)等分析技术对催化剂的微观结构进行了表征, 并利用循环伏安(CV)法分析了催化剂的电化学比表面积(ESA). 在此基础上, 制备了膜电极(MEA), 通过单电池测试了催化剂的电催化性能. 结果表明: 铂纳米粒子在不同的纳米碳载体上表现出不同的粒径, 在板式、鱼骨式和管式纳米碳纤维上的铂纳米粒子平均粒径分别为2.4、2.7和2.8 nm. 板式纳米碳纤维载铂催化剂作单电池阳极时表现出良好的电催化性能, 其对应的最高功率密度可达0.569 W·cm^-2, 高于鱼骨式纳米碳纤维载铂催化剂和管式纳米碳纤维载铂催化剂对应的最高功率密度(分别为0.550和0.496 W·cm^-2). 同时, 也制备了碳黑(Pt/XC-72)载铂催化剂. 相比于Pt/XC-72, 纳米碳纤维载体上的铂纳米颗粒有较小的粒径、较好的分散和较高的催化活性, 说明纳米碳纤维是质子交换膜燃料电池(PEMFCs)催化剂的良好载体.     

Electroreduction of Oxygen and Electrooxidation of Methanol at Carbon and Single Wall Carbon Nanotube Supported Platinum Electrodes

The present research aimed at investigating the electrocatalytic properties and the electrochemical deposition of Pt nanoparticles on carbon powder, carbon nanotube and preparation of carbon and single wall carbon nanotube supported platinum electrodes. The Pt nanoparticles were synthesized by electroreduction of hexachloroplatinic acid in aqueous solution at ?200 mV. Electrocatalytic properties of the modified electrodes for oxygen reduction were investigated by cyclic voltammetry in O₂ saturated solution containing 0.1 M HClO₄. Methanol electrooxidation at the modified surfaces in 0.5 M HCLO₄ was studied by cyclic voltammetry. The corresponding results showed that the Pt/SWCNT/GC electrode exhibits more improved catalytical activity than the Pt/C/GC electrode.     

葡萄糖在纳米Pt/C电极上的电催化氧化

用交替微波法制备纳米PVC催化剂,研究和比较葡萄糖在光亮Pt和纳米Pt/C电极上的氧化行为.实验表明,Pt纳米化后,电极反应过电位降低,动力学速率相应提高,从而使电化学性能得到改善.其催化活性和抗毒化能力大于光亮Pt的可能原因即在Pt纳米化后,大幅度提高了表面积,结果不仅增加其电极活性,而且含氧物也容易接近受毒化的反应点,从而较易氧化毒化物而使电极再次活化.