氢钼青铜修饰铂电极对甲醇催化剂的电催化作用

利用循环伏安法研究了氢钼青铜在铂电极上的修饰作用和修饰铂电极在c(H2SO4)=0.5mol/L，溶液中对甲醇的催化作用，研究结果表明：铂电极因钼酸盐的还原和钼青铜的氧化而得到修饰，低电位范围内修饰钱电极对甲醇的氧化有催化作用，催化氧化电流是未修饰电极上的1．6倍，酸性条件下，含高价态钼的钼青铜不稳定，会不断溶解对铂失去修饰作用，对甲醇姝氧化效果与未修饰铂电极上的效果相同，而低电位时，钼青铜修饰电极则相对稳定。     

甲醇在聚苯胺修饰铂钼共沉积电极上的催化氧化

用恒电位法和循环伏安法在铂电极上分别制备了聚苯胺修饰的分散氢钼青铜电极和分散铂电极,以及聚苯胺修饰的不同铂钼比例的铂与氢钼青铜共沉积电极。用循环伏安法研究了制备电极在c(H2SO4)=0.5mol/L水溶液中的电化学行为,以及对c(CH3OH)=0.1 mol/L的催化氧化行为。其中,分散氢钼青铜电极对甲醇无催化氧化的作用,铂与氢钼青铜共沉积电极对甲醇的催化氧化效果优于分散铂电极。铂-氢钼青铜共沉积电极对甲醇氧化的催化能力与共沉积铂钼的比例有关,当制备电极所用的溶液中n(氯铂酸)∶n(钼酸钠)=2∶1时,共沉积电极对甲醇的催化氧化活性最高,此时甲醇在共沉积电极上的氧化峰电流是单纯铂电极的2.632倍。     

用磷钼酸修饰甲醇燃料电池的铂电极

近年来以杂多化合物为基础的催化体系受到广泛的关注.为了研究杂多酸与铂电极对甲醇电催化氧化的协同效应,通过循环伏安扫描法制备了磷钼酸（H3PMo12O40）修饰铂电极.通过循环伏安和计时电流法研究了该修饰电极对甲醇氧化的电催化活性和抗中间产物的毒化作用,并比较了该修饰电极与其单酸盐（Na2MoO4）修饰铂电极的性能,测试结果表明：磷钼酸修饰铂电极能够提高对甲醇氧化反应的催化活性,基本上同其单酸盐Na2MoO4修饰铂电极的催化活性相当,并且这种促进作用主要是由Mo原子价态变化引起的.同时计时电流曲线测试结果表明,该修饰电极具有一定的抗毒化作用,但不如钼酸钠好.     

铂修饰聚吡咯电极电催化氧化甲醇的CO毒化特性

采用循环伏安法和电化学原位红外光谱技术研究了铂修饰聚吡咯电极(nm-Pt/PPy)对甲醇的电催化氧化反应,结果表明,nm-Pt/PPy对甲醇具有较好的电催化活性,当电位为1000mV时,可清楚地观察到甲醇经电氧化生成了最终产物CO2。但是在电化学氧化过程中仍存在CO的毒化现象,在低电位下,CO分别以桥式和线性方式吸附,随着电位升高,逐渐变为以线性吸附为主。另外,电氧化电位不宜过高,nm-Pt/PPy的电催化活性易因聚吡咯过氧化而降低。     

甲醇在碳载纳米Pt电极上的电化学研究

应用循环伏安法制备了nano-Pt/GC修饰电极,优化了铂微粒在电极表面的沉积条件,并用扫描电子显微镜(SEM)和在硫酸中的循环伏安曲线对其进行了表征。结果表明铂微粒较为均匀地分散在玻碳电极表面,粒径约为140nm,电极具有很大的比表面积。循环伏安实验结果表明nano-Pt/GC电极对甲醇电氧化的催化活性明显高于铂片电极,在该修饰电极上甲醇正向扫描和反向扫描时的氧化峰电位分别是0.67V和0.49V,峰电流为61.00mA/cm2和50.50mA/cm2,分别是铂片电极上的3.13倍和3.10倍,有效地提高了金属铂的利用率,铂微粒在电极表面的最佳沉积条件是循环次数为100次和沉积速度为5mV/s。     

载铂聚苯胺/聚砜复合膜修饰电极对甲醇的电催化氧化行为研究

采用循环伏安法制备聚苯胺(PAN)/聚砜(PSF)复合膜修饰电极,在其上电沉积铂粒子,制得载铂聚苯胺/聚砜复合膜修饰电极,用循环伏安法和交流阻抗法研究它对甲醇的电催化氧化行为。复合膜的化学组分用FTIR进行表征,复合膜内层载铂后的表面形态用SEM进行表征。结果表明,复合膜的内层(与工作电极接触的一面)是聚苯胺,外层(与溶液接触的一面)是聚砜,铂粒子在复合膜内层的多孔聚苯胺上均匀沉积,从而使载铂聚苯胺/聚砜复合膜修饰电极对甲醇有好的电催化氧化性能。     

钯复合材料电极催化甲醇氧化机理

在NaY/Teflon修饰玻碳电极上电化学辅助沉积钯微粒,制备钯复合材料电极,研究催化反应机理。采用循环伏安法(CV)、计时电流法和扫描电镜进行表征,结果表明,钯复合材料电极对甲醇的催化是单电子过程,改变甲醇氧化途径,降低活化能。该电极具有优越的放电特性,提高甲醇和电极利用率,对甲醇氧化具有良好的电催化活性。     

电沉积Ni-P/Ti电极电催化氧化甲醇性能研究

研究了钛电极上负载Ni-P和Ni在碱性介质中的甲醇氧化催化性能。结果表明,在Ni电极中掺杂P原子能够显著提高Ni电极电催化氧化甲醇的性能,主要表现在提高甲醇氧化反应电流和降低甲醇氧化反应的起始电位。氢与Ni-P之间的结合能较弱,使得吸附在Ni-P电极表面的氢原子能够快速容易的去除,提供更多的清洁表面来吸附甲醇分子以及形成甲醇氧化中间物CO的主要氧化剂H2Oa。研究还发现,Ni-P电极上甲醇氧化的起始电位与Ni(OH)2/NiOOH的氧化电位一致,而在Ni电极上甲醇氧化的起始电位比Ni(OH)2/NiOOH的电位更高,其主要是由于H原子与Ni之间的结合能比Ni-P更强。另外,P的存在能够显著降低Ni-P的晶粒尺寸、增加比表面积,从而有利于提高甲醇氧化反应电流。     

正丁醇在Pt及其修饰电极上氧化的EQCM研究

运用电化学石英晶体微天平 (EQCM)研究了正丁醇在Pt、Pt/Sbad和Pt/Sad电极上的电氧化过程 ,结果表明正丁醇的氧化与电极表面氧化物种有着密切的关系。Pt电极表面Sb修饰原子能在较低的电位下吸附氧 ,催化正丁醇的氧化在较低电位下进行。相反 ,Pt电极表面S修饰原子的氧化会消耗表面氧化物种 ,从而抑制正丁醇的电氧化。     

乙二醛在纳米TiO2-Pt电极上的电催化氧化

通过电沉积修饰铂微粒制备Ti基纳米TiO₂-Pt（Ti/nano-TiO₂-Pt）修饰电极,采用循环伏安法研究了乙二醛在Ti/nano-TiO₂-Pt上的电催化氧化。结果表明：Ti/nano-TiO₂-Pt修饰电极对乙二醛的氧化呈现较高的电催化活性,可作为乙二醛电氧化合成乙醛酸的高活性催化电极。     

K_3[Fe(CN)_6]溶液中普鲁士蓝修饰电极的制备及其对H_2O_2的电催化还原

应用循环伏安法和微分脉冲伏安法研究了K3[Fe(CN)6]溶液中普鲁士蓝(PB)修饰电极的制备及其电化学行为。结果表明,在连续循环伏安扫描的条件下,K3[Fe(CN)6]会在对电极上发生解离生成Fe3+,Fe3+可以跟单室电解池三电极体系中的[Fe(CN)6]3-生成在Au电极表面有较强吸附作用的PB,所获得的PB修饰电极的稳定性受介质和外加电位的影响。修饰电极上的PB在c(KCl)=0 2mol/L中性或弱酸性溶液中于-0 10 5V较稳定,而在c(H2SO4)=1 0mol/L溶液中PB会在Au电极上溶出;于-0 11 5V扫描时PB也会在Au电极上溶出。尤为重要的是,所获得的PB修饰电极对H2O2的还原既有很好的间接电催化作用,又可以降低H2O2在其上反应的活化能,对H2O2还原反应的电子传递起到促进作用。     

Adsorption of hydrogen and oxygen and oxidation of methanol on ruthenium electrodes

Sorption of hydrogen and oxygen on ruthenium in 1N H₂SO₄ have been investigated by potentiodynamic and potentiostatic methods. It has been shown that adsorption and absorption of hydrogen and oxygen take place on a smooth ruthenium electrode. The solubility of hydrogen grows linearly with potential in the range 0·41–0·04 V, whereas the solubility of oxygen increases linearly with potential in the range 0·37–1·3 V. Adsorption of hydrogen on a smooth ruthenium electrode takes place in the potential range 0·4–0·0 V; on ruthenized ruthenium electrode the main portion of hydrogen is adsorbed at potentials 0·2–0·0 V. No maxima corresponding to specific types of chemisorbed oxygen exist on the potentiodynamic curves of oxygen adsorption. The oxygen adsorption rate on ruthenium is of the same order as on platinum. The kinetics of methanol oxidation on smooth and ruthenized ruthenium electrodes were investigated. The chemisorption of methanol was found to be the limiting step in both cases in the potential range 0·4–1·0 V; the chemisorption rate on smooth ruthenium exceeds the chemisorption rate on ruthenized electrode by two orders of magnitude. This results is consistent with the difference in the surface bond energies of adsorbed hydrogen for smooth and ruthenized ruthenium.     

Effect of cations in solution on the oxidation of methanol on the surface of platinum electrode

The effect of metal cations in solution on the oxidation of methanol on the electrode surface of platinum is a neglected aspect to direct methanol fuel cell (DMFC). In this paper, a smooth platinum electrode absorbing metal cations as the working electrode was applied to investigate the methanol oxidation with the cyclic voltammetry (CV) in 1.0 mol L⁻¹ H₂SO₄. From the analysis of experiment, it is found that the cations, Li⁺, Ce⁴⁺, Mn²⁺, Ni²⁺, Cu²⁺, have some negative effect on the catalytic oxidation of methanol on the surface of platinum. The degree of the effect from different cations was analyzed.     

Electrocatalytic oxidation of methanol and C1 molecules on highly dispersed electrodes Part II: Platinum-ruthenium in polyaniline

The oxidation of methanol and C1 molecules at electrodes modified with polyaniline and particles of platinum and ruthenium has been studied in aqueous HClO₄ electrolyte. The platinum and ruthenium particles were incorporated into the polyaniline film by electrochemical reduction. The activity for the oxidation of C1 molecules is higher for bimetallic electrodes than for polyaniline-coated electrodes modified with platinum alone. Indeed, a negative shift of more than 100 mV is observed as compared to the potential obtained with a polyaniline film modified by pure platinum. Moreover, the oxidation of methanol is faster and more complete on the Pt-Ru modified polyaniline electrode, since carbon dioxide is the main reaction product.     

Electro-oxidation of methanol and ethylene glycol on platinum in alkaline solution: Poisoning effects and product analysis

The electrochemical oxidation of ethylene glycol on platinum was investigated and compared with that of methanol in alkaline solution by using various electrochemical and analytical measurements. Ethylene glycol showed much less significant electrode poisoning than methanol at low potential (400 mV). This phenomenon was clarified by analyzing the products of ethylene glycol oxidation. In ethylene glycol oxidation, partial oxidation to glycolate was much faster than complete oxidation to CO₂. In addition, there were two paths for ethylene glycol oxidation: poisoning and non-poisoning paths. The poisoning path led to the production of C1 compounds and the non-poisoning path gave oxalate. The non-poisoning path prevented the formation of poisonous species on platinum.     

Electrocatalytic oxidation of methanol on the nickel–cobalt modified glassy carbon electrode in alkaline medium

In this work, Ni–Co alloy coating on the surface of glassy carbon (GC) electrode was performed by cyclic voltammetry. The results showed that the deposition of Ni–Co is an anomalous process. The deposition bath was prepared according to the metal ion Ni/Co ratio of 4:1 using NiSO₄·7H₂O and CoSO₄·8H₂O, and the total concentration of all solutions was 40.0 mM. The pH of the bath solution was adjusted at 2.0 using boric acid at room temperature. The modified electrode was conditioned by potential recycling in a potential range of 100–700 mV (vs. Ag/AgCl) by cyclic voltammetric method in an alkaline solution. The Ni–Co modified electrode showed a higher activity towards methanol oxidation in the Ni (III) and Co (IV) oxidation states. Cyclic voltammetry was used for the electrochemical characterization of the Ni–Co modified electrode and the mechanism of methanol oxidation is proposed. The result of double steps chronoamperometry shows that the methanol electrooxidation is an irreversible reaction. Moreover, the effects of various parameters such as mole ratio of Ni–Co in the alloy in modification step, potential scan rate, methanol concentration and solution temperature on the electro-oxidation of methanol have also been investigated.     

聚苯胺修饰电极对甲醇的电催化氧化研究

应用电化学方法制备了Pt/PAn/GC电极,优化了苯胺在玻碳电极上的聚合条件,并对其进行了表征.结果表明,铂微粒在聚苯胺膜电极上具有很高的分散度,电极具有很大的比表面积,Pt/PAn/GC电极对甲醇电氧化的催化活性明显高于Pt/GC电极和Pt电极,在该电极上甲醇正向扫描和反向扫描时的氧化峰电流为58.68mA/cm2和50.00mA/cm2,为Pt/GC电极的1.6倍和1.7倍,为Pt电极的3.0倍和3.1倍,从而有效地提高了铂的催化活性,并得到在玻碳电极上聚合苯胺的最佳条件为扫描速度50mV/s,扫描上限1.2V.