Co-WC电极

从钴镀液中添加ＷＣ微粒复合电沉积制备Ｃｏ－ＷＣ镀层,ＷＣ微粒的加入,加快了阴极电化学反应．Ｃｏ－ＷＣ复合电极在碱性溶液中具有优越的电催化析氢性能,并经受了长期间断电解的试验,电极性能稳定     

不是过氧化铅电极 而是二氧化铅电极

1987年第2期所刊登的“过氧化铅电极的制作和碘酸钾的电化合成”一文中,介绍用电解PB(NO_3)_2和Cu(NO_2)_2酸性溶液,在阳极石墨棒上沉积过氧化铅黑色镀层,称此电极为过氧化铅电极。我们按本文所述实验条件,将电解得到的镀层物洗净进行如下的实验:(1)取电解黑色镀层物少许,放入试管中,加入6mol·L~(-1)HCl 2ml,有浅黄色气体产生,此气体使淀粉     

固溶体电极

近年来,随着快离子导体材料和高能量密度锂电池的发展,在材料科学、固体物理和电化学领域内,一类新的物质——具有混合电导的化合物受到了人们的广泛重视。这类化合物同时具有电子电导和离子电导,且其活动离     

化学修饰电极

化学修饰电极就是通过共价键键合、强吸附或高聚物涂层方法,把具有某种功能的化学基团赋于电极表面上,这种电极就具有了某种特定的性质。电极反应是在电极-溶液界面发生的电子转移的非均相反应。以往电化学上所用的电极材料为汞、碳和贵金属等,这些材料制成的电极只有受授电子的单一作用,而且溶液中的分子、     

酶电极

酶是具有特殊生物学活性的催化剂,曾被作为一种“生物化学试剂”广泛地用于医学,化学,食品,环境保护等方面的分析检测。但酶具有不稳定,难制备,价格高等缺点,因而它的应用有一定的限制。六十年代发展了固定化酶这一新技术,由于它具有反应快速、性能稳定等特点。这种技术被迅速地引进到分析检测这个领域,以改进用溶液态酶时所遇到的缺点和问题。目前,固定化酶在分析检测中的应用主要有二种方式,一种所谓酶电极(Enzyme Electrode)     

软嵌式薄层粉末电极 I: 薄层粉末旋转电极和光电化学电极

研究粉末电催化剂目前多采用多孔电极(如气体扩散电极)方法, 也用糊状电极或粉末悬浮液方法, 但均不适于研究电极过程动力学.为了研究粉末催化剂, 我们制备了软嵌式超薄层粉末旋转盘环电极和光电化学电极. 这种电极制备简单, 实验数据重现性良好, 能广泛用于各种电极过程动力学研究.     

氢电极反应绝对电极电位的表达式

本文将量子电化学热活化理论的氢电极反应的电子传递条件式在紧密双电层中展开,得到该电极反应的绝对电极电位表达式。     

溶剂聚合膜pH电极作内电极的气敏电极的研究

研究了以中性载体为活性物的石墨内导平头溶剂聚合膜(SPM)pH电极作内电极的二氧化碳和氨气敏电极。电极的性能取决于中性载体的特性,其中以菸酸十八酯为内电极膜活性物的二氧化碳气敏电极和以二辛基十八胺为活性物的氨气敏电极性能较佳。二氧化碳气敏电极用作丙酮酸脱羧酶酶电极的原电极,其性能院于传统的以玻璃pH电极作内电极的二氧化碳气敏电极。     

采用粉末电极技术改善葡萄糖氧化酶电极的抗干扰性能

研究了对电流型ＧＯＤ电极有干扰作用的抗坏血酸、尿酸、Ｌ－半胱氨酸和对－乙酰氨基苯酚在铂、玻碳以及由Ｋｅｔｊｅｎｂｌａｃｋ碳黑填制的粉末微电极上的电化学行为。结果表明：由于这些杂质的电化学活性较高,难以通过选择电极材料及改变工作电位来完全避免它们的干扰作用。然而,抗坏血酸、尿酸及对－乙酰氨基苯酚在粉末微电极上极限电流是由电极端面液相中的扩散传质所控制的,只与电极的表现直径有关而与其真实表面积无关,因而采用粉末微电极技术可明显地提高ＧＯＤ电极的信噪比。     

钴卟啉修饰电极为基底的葡萄糖酶电极

生物电化学传感器的开发和应用是目前电分析化学研究中的一个重要方向,其中最引人注目的是电流式生物电化学传感器的研究。传统的电流式生物电化学传感器的基础电极采用的是能检测氧气和过氧化氢的贵金属电极。本文采用四苯基钴卟啉化学修饰电极代替     

Carbon nanotubes as a secondary support of a catalyst layer in a gas diffusion electrode for metal air batteries

In this paper, we report the use of binary carbon supports (carbon nanotubes (CNTs) and active carbon) as a catalyst layer for fabricating gas diffusion electrodes. The electrocatalytic properties for the oxygen reduction reaction (ORR) were evaluated by polarization curves and electrochemical impedance spectroscopy (EIS) in an alkaline electrolyte. The binary-support electrode exhibits better performance than the single-support electrode, and the best performance is obtained when the mass ratio of carbon nanotubes and active carbon is 50:50. The results from the electrode kinetic parameters indicate that the introduction of carbon nanotubes as a secondary support provides high accessible surface area, good electronic conductivity, and fast ORR kinetics. Furthermore, the effect of CNT support on the electrocatalytic properties of Pt nanoparticles for binary-support electrodes was also investigated by different loading-reduction methods. The electrocatalytic activity of the binary-support electrodes is improved dramatically by Pt loading on CNT carbon support, even at very low Pt loading. Additionally, the EIS analysis results indicate that the process of ORR may be controlled by diffusion of oxygen in the electrode thin film for binary-support electrodes with or without Pt catalyst.     

Pt/纳米碳管空气电极氧还原反应的电催化性能

以不同质量比的铂、纳米碳管、活性炭为催化层制备空气电极并测定其稳态极化曲线和交流阻抗.研究发现,纳米碳管经硝酸处理后其氧还原反应性能得到提高,特别是将表面氧化后再沉积Pt,对氧的电还原反应影响更显著.以质量比4∶1的活性炭/纳米碳管载Pt制备的空气电极,在过电位ηc为500～600mV下,氧还原电流可达600～700mA·cm-2.EIS测试表明,纳米碳管载Pt后的欧姆极化阻抗和电化学阻抗均非常小.     

质子交换膜燃料电池Pd修饰Pt/C催化剂的电催化性能

通过对Pt催化剂表面进行Pd修饰提高质子交换膜燃料电池阴极催化剂的氧还原反应(ORR)活性. 采用乙二醇还原法制备了不同比例的Pd修饰Pt/C催化剂. 透射电镜(TEM)和X射线衍射(XRD)测试结果表明, 制备的催化剂贵金属颗粒粒径主要分布在1.75～2.50 nm之间, 并均匀地分散在碳载体表面. 循环伏安方法(CV)研究表明Pd修饰Pt/C催化剂的电化学活性面积低于传统的Pt/C催化剂. 但通过旋转圆盘电极(RDE)测试研究发现, 制备的催化剂具有比传统Pt/C催化剂高的ORR活性.     

多壁纳米碳管空气电极的交流阻抗研究

研究了多壁纳米碳管、活性炭和石墨等空气电极的交流阻抗特性.结果表明,纳米碳管空气电极的阻抗谱由两个半圆组成,高频区半圆对应欧姆极化阻抗,低频区半圆对应电化学极化阻抗.催化剂Pt以纳米颗粒的形式沉积在碳管的外表面,明显减小了电极的欧姆阻抗和电化学极化阻抗,提高了氧还原反应的电催化活性.活性炭电极除存在电化学阻抗外,还存在薄液膜扩散阻抗(Nernst扩散),石墨电极形成的薄液膜反应区域较小,电极反应呈Warburg扩散阻抗特征,相应的电催化活性较低.采用交流阻抗等效电路分析方法,对拟合的动力学数据进行了解释.     

Single-wall carbon nanotubes supported platinum nanoparticles with improved electrocatalytic activity for oxygen reduction reaction

Significant enhancement in the electrocatalytic activity of Pt particles toward oxygen reduction reaction (ORR) has been achieved by depositing them on a single wall carbon nanotubes (SWCNT) support. Compared to a commercial Pt/carbon black catalyst, Pt/SWCNT films cast on a rotating disk electrode exhibit a lower onset potential and a higher electron-transfer rate constant for oxygen reduction. Improved stability of the SWCNT support is also confirmed from the minimal change in the oxygen reduction current during repeated cycling over a period of 36 h. These studies open up ways to utilize SWCNT/Pt electrocatalyst as a cathode in the proton-exchange-membrane-based hydrogen and methanol fuel cells.     

Enhanced oxygen reduction at Pd catalytic nanoparticles dispersed onto heteropolytungstate-assembled poly(diallyldimethylammonium)-functionalized carbon nanotubes

Both Keggin-type phosphotungstic acid (HPW) and Pd are not prominent catalysts towards the oxygen reduction (ORR), but their composite Pd-HPW catalyst produces a significantly higher electrochemical activity for the ORR in acidic media. The novel composite catalyst was synthesized by self-assembly of HPW on multi-walled carbon nanotubes (MWCNTs) via the electrostatic attraction between negatively charged HPW and positively charged poly(diallyldimethylammonium (PDDA)-wrapped MWCNTs, followed by dispersion of Pd nanoparticles onto the HPW-PDDA-MWCNT assembly. The as-prepared catalyst was characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). TEM images show that Pd nanoparticles were uniformly dispersed on the surface of MWCNTs even when the Pd loading was increased to 60 wt%. Electrochemical activity of the catalysts for the ORR was evaluated by steady state polarization measurements using a rotating disk electrode. Compared with the acid treated MWCNTs, Pd nanoparticles supported on the HPW-assembled MWCNTs show a much higher ORR activity that is comparable to conventional Pt/C catalysts. The high electrocatalytic activities could be related to high dispersion of Pd nanoparticles as well as synergistic effects originating from the high proton conductivity of HPW. The Pd/HPW-PDDA-MWCNTs system as the cathode catalyst in proton exchange membrane fuel cells is demonstrated.     

Electrocatalysis of oxygen reduction on multi-walled carbon nanotube supported copper and manganese phthalocyanines in alkaline media

Manganese phthalocyanine (MnPc) and copper phthalocyanine (CuPc)-modified electrodes were prepared using multi-walled carbon nanotubes (MWCNTs) as a support material. The catalyst materials were heat treated at four different temperatures to investigate the effect of pyrolysis on the oxygen reduction reaction (ORR) activity of these electrocatalysts. The MWCNT to metal phthalocyanine ratio was varied. Scanning electron microscopy (SEM) was employed to visualise the surface morphology of the electrodes and the x-ray photoelectron spectroscopic (XPS) study was carried out to analyse the surface composition of the most active catalyst materials. The ORR was studied in 0.1 M KOH solution employing the rotating disk electrode (RDE) method. Glassy carbon (GC) electrodes were modified with carbon nanotube-supported metal phthalocyanine catalysts using Tokuyama AS-4 ionomer. The RDE results revealed that the highest electrocatalytic activity for ORR was achieved upon heat treatment at 800 °C. CuPc-derived catalyst demonstrated lower catalytic activity as compared to the MnPc-derived counterpart, which is in good agreement with previous literature, whereas the activity of MnPc-based catalyst was higher than that reported earlier.     

Thermodynamic guidelines for the design of bimetallic catalysts for oxygen electroreduction and rapid screening by scanning electrochemical microscopy. M-co (M: Pd, Ag, Au)

We propose guidelines for the design of improved bimetallic (and related) electrocatalysts for the oxygen reduction reaction (ORR) in acidic media. This guide is based on simple thermodynamic principles assuming a simple mechanism where one metal breaks the oxygen-oxygen bond of molecular O(2) and the other metal acts to reduce the resulting adsorbed atomic oxygen. Analysis of the Gibbs free energies of these two reactions guides the selection of combinations of metals that can produce alloy surfaces with enhanced activity for the ORR when compared to the constituent metals. Selected systems have been tested by fabricating arrays of metallic catalysts consisting of various binary and ternary combinations of Pd, Au, Ag, and Co deposited on glassy carbon (GC) substrates. The electrocatalytic activity of these materials for the ORR in acidic medium was examined using scanning electrochemical microscopy (SECM) in a new rapid-imaging mode. This was used to rapidly screen arrays covering a wide range of catalyst compositions for their activity for the ORR in 0.5 M H(2)SO(4). Using the SECM technique, we have identified combinations of metals with enhanced electrocatalytic activities when compared with the constituent, pure metals. Addition of Co to Pd, Au, and Ag clearly decreases the ORR overpotential, in agreement with the proposed model. Catalyst spots that exhibited enhanced electrocatalytic activity in the SECM screening technique were then examined using classical rotating disk electrode (RDE) experiments. The activity of carbon black supported catalyst mixtures on a GC RDE and the electrocatalytic activity determined using the SECM screening technique showed excellent agreement. C/Pd-Co electrodes (10-30% Co) exhibited remarkable activity for ORR catalysis, close to that of carbon-supported Pt.     

溶剂热法制备磷掺杂碳纳米管作为氧气还原和氧气析出反应双功能电催化剂的研究

对氧气还原(ORR)和氧气析出(OER)反应都具有催化活性的双功能催化剂在金属-空气电池中起着关键作用.本文通过溶剂热反应,一步原位合成了磷掺杂碳纳米管(P-CNT).旋转环盘电极测试表明磷掺杂能够明显提高碳纳米管的催化活性,P-CNT在碱性电解质中对ORR和OER都具有优异的催化活性.P-CNT对ORR的催化还原为近4电子反应,可与商业催化剂Pt/C(20 wt%)相比;而其对OER的催化活性则高于Pt/C(20 wt%).此外,P-CNT的长期稳定性优于Pt/C(20 wt%).P-CNT对ORR和OER的高催化活性和稳定性主要归因于磷对碳的掺杂以及磷与碳间强的化学键合.     

活性炭表面性质对氧气扩散电极电催化性能的影响

 分别采用硝酸和空气氧化处理制得具有不同表面性质的粉末活性炭,并以此为催化层材料制成炭基氧气扩散电极,测定了不同电极的极化曲线和电化学阻抗谱. N2物理吸附和He程序升温脱附(He-TPD)研究表明,硝酸处理对活性炭孔结构的影响较小,但可使其表面含氧基团明显增加; 而空气氧化处理则会导致活性炭的中孔面积和孔容显著增大,但对表面含氧基团的影响较小. 极化曲线和电化学阻抗谱研究发现,当活性炭的孔结构相近时,电极的催化性能随着表面含氧基团的增多而急剧下降; 当活性炭表面含氧基团的量相近时,中孔孔容增大将导致电极催化性能的恶化. 与活性炭表面含氧基团相比,孔结构对氧气扩散电极的电化学性能具有更显著的影响.