共查询到20条相似文献,搜索用时 421 毫秒
1.
应用循环伏安法(CV),扫描电子显微镜(SEM)和电化学原位红外反射光谱(in situFTIRS)研究了不同介质对碳载铂纳米薄膜电极(Pt/GC)的表面结构以及该薄膜电极对甲酸电催化氧化性能的影响.结果表明,使用不同介质的镀铂溶液,均可电沉积出分布较为均匀的Pt粒子,但其尺寸与形貌却相差很大.当以H2SO4作介质,由循环伏安法于玻碳电极上电沉积Pt得到的(Pt/GC1)电极,其Pt粒子粒径约100~200 nm;而在HClO4介质得到的(Pt/GC2)电极,则含有两种Pt微晶:其一是立方体形,粒径约200 nm,其二为菜花状,粒径约400 nm.电化学循环伏安和原位红外反射光谱测试指明,不同介质制备的Pt/GC电极对甲酸的电催化氧化均表现出与本体铂电极(Pt)相类似的特性,即可通过活性中间体或毒性中间体将甲酸氧化至CO2,但不同结构的Pt/GC电极具有不同的电催化活性.进一步以Sb或Pb修饰Pt/GC电极,不仅可以有效地抑制毒性中间体CO的生成,而且还能显著提高其电催化活性.比较本文研究的7种电极,其电催化活性顺序依次为:Sb-Pt/GC2>Pb-Pt/GC2>Pb-Pt/GC1>Sb-Pt/GC1>Pt/GC2>Pt/GC1>Pt. 相似文献
2.
V.M. Jovanovi S. Terzi A.V. Tripkovi K.Dj. Popovi J.D. Lovi 《Electrochemistry communications》2004,6(12):1
Effect of electrochemical oxidation of glassy carbon on deposition of platinum particles and electrocatalytic activity of platinum supported on oxidized glassy carbon (Pt/GCOX) were studied for methanol oxidation in H2SO4 solution. Platinum was potentiostatically deposited from H2SO4 + H2PtCl6 solution. Glassy carbon was anodically polarised in 0.5 M H2SO4 at 2.25 V vs. saturated calomel electrode (SCE) during 35 s. Electrochemical treatment of GC support, affecting not significantly the real Pt surface area, leads to a better distribution of platinum on the substrate and has remarkable effect on the activity. The activity of the Pt/GCOX electrode for methanol oxidation is larger than polycrystalline Pt and for more than one order of magnitude larger than Pt/GC electrode. This increase in activity indicates the pronounced role of organic residues of GC support on the properties of Pt particles deposited on glassy carbon. 相似文献
3.
《Electrochemistry communications》2005,7(10):1039-1044
Formic acid oxidation at platinum electrochemically deposited on polished (GC/Pt) and oxidized glassy carbon (GCox/Pt) was examined with the objective of studying the effect of electrochemical treatment of the support on deposition of platinum and on the activity of Pt catalyst. The electrodes were characterised by STM and XPS techniques. The oxidative treatment of the support leads to deposition of smaller Pt particles in comparison with the one on the polished substrate. The XPS spectra indicated the increased fraction of functional (acidic) groups on the treated support as well as the higher fraction of oxygen containing species on Pt catalyst deposited on oxidised referring to Pt deposited on polished substrate.The activity of GCox/Pt electrode is increased by the factor of 2–4 for formic acid oxidation compared to the activity of GC/Pt electrode. This result is explained by the oxidative removal of COad species leading to enhanced amount of Pt free sites available for direct formic acid oxidation to CO2. 相似文献
4.
A comparative investigation of electrocatalytic and adsorption properties of platinum microparticles electrodeposited onto a glassy carbon surface (Pt/GC) and within a thin Nafion® film formed on a GC electrode (Pt/Nf/GC) is described. As test reaction the methanol oxidation in sulfuric acid solutions is used. Dependences of the steady-state specific reaction rates upon potential and methanol concentration were established, as well as those of the platinum surface coverage with methanol chemisorption products upon concentration. It was shown that at higher platinum loadings (above 60 μg cm−2) the specific activities of Pt/GC and Pt/Nf/GC are nearly the same and close to that of smooth platinum. At such loadings the surface coverage of the platinum deposit surface with organic particles does not differ from that of smooth platinum. At very low platinum loadings in the polymeric matrix (10–30 μg cm−2) a considerable decrease in the adsorption of strongly chemisorbed methanol particles is observed. These deposits are characterized by a low specific activity, which may be caused by the decrease of the platinum particle’s size, leading to a decrease in the amount of weakly bound methanol particles participating in the limiting reaction step. 相似文献
5.
Andromahi Tegou Sofia Papadimitriou Georgios Kokkinidis Sotirios Sotiropoulos 《Journal of Solid State Electrochemistry》2010,14(2):175-184
Platinized nickel and cobalt coatings, Pt(Ni) and Pt(Co), have been prepared on glassy carbon, GC, rotating disc electrode
substrates by a two-step room temperature procedure that involved the electrodeposition of nickel and cobalt layers and their
spontaneous partial replacement by platinum (“transmetalation”) when immersed into a chloroplatinic acid solution. By tuning
the quantity of initially deposited nickel and cobalt, Pt(Ni) and Pt(Co) bimetallic coatings having a 26% atom Ni and 30%
atom Co composition have been prepared. For both materials typical Pt surface electrochemistry was recorded during fast voltammetry
in deaerated acid, pointing to the existence of a continuous Pt skin over a Pt–Ni and Pt–Co core. Oxygen reduction at the
Pt(Ni)/GC and Pt(Co)/GC electrodes was studied by means of steady-state voltammetry at a rotating disc electrode and the construction
of Tafel plots from corresponding voltammetric data. It was found that, when the initial potential of the voltammetric sweep
allowed the formation of a complete Pt oxide monolayer, then oxygen reduction was hindered for low overpotentials at Pt(Ni)
and Pt(Co), compared to pure bulk Pt. On the other hand, when the initial potential was less positive (thus leading to the
formation of a fraction of surface oxide monolayer) the presence of Ni and Co enhanced the kinetics of oxygen reduction. The
former behaviour is attributed to a decrease in oxide reduction ability of Pt in the presence of Ni and Co, while the latter
to an increase in dissociative oxygen chemisorption due to Ni and Co. 相似文献
6.
V. V. Kuznetsov B. I. Podlovchenko K. V. Kavyrshina Yu. M. Maksimov 《Russian Journal of Electrochemistry》2010,46(12):1353-1359
The electrocatalytic Pt-Mo system was obtained by formation of platinum particles on the Mo surface under its contact with
PtC62− (PtCl42−) under the open circuit conditions. Cyclic voltammograms of the obtained Pt(Mo) electrodes feature well pronounced peaks
of hydrogen adsorption and desorption on Pt particles. Nonuniform platinum distribution across the electrode surface was found.
Pt(Mo) electrodes showed a higher specific activity in the reaction of methanol oxidation in the potential range of 0.35–0.45
V (RHE) as compared to Pt/Pt. 相似文献
7.
Carey L. Scortichnini Charles N. Reilley 《Journal of Electroanalytical Chemistry》1982,139(2):233-245
This paper is the first in a series describing the in situ surface characterization of platinum electrodes using H and Cu deposited at underpotentials. The surface of a Pt(100) electrode pretreated by simple flame annealing and quenching in aqueous sulfuric acid is shown to contain a high concentration of defects such as vacancies and self-adsorbed Pt atoms. Adsorbed hydrogen is more strongly bound at these defects than on a uniform Pt(100) surface. Potential cycling in 1 M HCl produces a higher concentration of defects, while oxide formation and reduction in 0.5 M H2SO4 has the opposite effect. The nature of (100)-like sites at a polycrystalline platinum electrode is also discussed. 相似文献
8.
离子注入Pt的玻碳电极上甲酸和甲醛的电氧化 总被引:3,自引:0,他引:3
制备了离子注入Pt的玻碳电极(Pt/GC),注入剂量为5×1017ion/cm2,此电极的表面组成和各元素的浓度-深度分布用AES测量,注入Pt的价态用XPS测量.在0.5mol/LHClO4溶液中,用Pt/GC电极和纯Pt电极研究了甲酸的电氧化行为,并在五种不同种类的电解质溶液中研究了甲醛的电氧化行为.结果表明,Pt/GC电极对甲酸和甲醛的电催化性能按真实表面积计算优于纯Pt电极.这可能与离子注入Pt过程中形成纳米团簇有关.此外,在同一电极上,甲醛在不同种类的电解质溶液中产生不同的氧化电流.说明阴离子对甲醛的电氧化过程有明显影响 相似文献
9.
O. V. Sherstyuk S. N. Pron’kin A. L. Chuvilin A. N. Salanov E. R. Savinova G. A. Tsirlina O. A. Petrii 《Russian Journal of Electrochemistry》2000,36(7):741-751
The deposition of platinum on glassy carbon (GC) is studied by chronoamperometry. Basic tendencies of the formation of aggregate
platinum particles on the oxidized carbon surface are established. These include a primary instantaneous nucleation of platinum
under diffusion control and the beginning of a secondary nucleation prior to filling primary active centers. The deposit morphology
is examined byex situ methods of scannng electron microscopy (SEM), transmission electron microscopy (TEM), and scanning tunneling microscopy (STM).
A globular structure of platinum, formed by crystallites 3–5 nm in size, is revealed. A comparison of the STM, SEM, and TEM
data demonstrates a high information value and accuracy of STM in studies of disperse materials in both nanometer and submicron
ranges. Various coulometry techniques intended for the determination of the true surface area of deposited platinum are compared.
The most informative techniques are the voltammetry of desorption of copper adatoms and chemisorbed carbon monoxide at, respectively,
low and high platinum contents. Differences in the formation kinetics and properties of aggregate particles in Pt/GC and Pt/Pt
are found, specifically, smaller Pt/GC crystallites and higher degrees of their concrescence (screening) 相似文献
10.
Electrocatalytic oxidation of small organic molecules has attracted considerable at-tentionin system of fuel celll-4. In this research field, Parsons4 pointed out that the electrodeswhich were prepared from non-noble substrates modified by excellent dispersal noblemetal particles and which still exhibited better catalytic activity should be studied. Ionimplantation is a technique with unique advantage and has been used in manyelectrochemical research fieldss'6. The present study is an at-tempt… 相似文献
11.
Dongyan Shen Yong Liu Dr. Guangxing Yang Prof. Hao Yu Prof. Feng Peng 《Chemphyschem》2019,20(21):2791-2798
A detailed understanding of the electrochemistry of platinum electrodes is of great importance for the electrochemical oxidation of fuels and electrochemical reduction of dioxygen in fuel cells. The Pt(111) facet is the most representative model mimicking Pt nanoparticles and polycrystals for fundamental studies. Herein, we propose a site-specific model accompanied with the typical elementary steps of the electrochemistry of Pt(111) in non-adsorbing electrolyte within the potential range between 0.05 and 1.15 V versus reversible hydrogen electrode. Simulations were conducted at different scanning rates based on the kinetics models. We reproduce all the anodic and cathodic peaks observed in the reported experimental curves. These results demonstrate the underlying mechanisms of the peak formation in different potential regions. 相似文献
12.
The role of the oxidation state of a platinum polycrystalline surface in the electrocatalytic oxidation of C1 to C4 primary alcohols has been studied by using electrochemical techniques, in situ FTIR spectroscopy and X-ray photoelectron spectroscopy. The results revealed that the oxidation state of the Pt surface plays a key role in the oxidation of primary alcohols, and demonstrated that the oxidation of C1 to C4 primary alcohols on a Pt electrode is controlled by the formation of surface oxides on the Pt electrode at different potentials. It was found that the dependence of the reaction process on the oxidation states of the platinum surface yielded similar features in the cyclic voltammogram for oxidation of different primary alcohols at a Pt electrode. According to the effects in the oxidation of primary alcohols, the surface oxides of platinum may be classified as active and poison species. The Pt surface oxides of higher oxidation states (Pt(OH)3 and PtO2) formed at potentials above 1.0 V (SCE) were identified as poison species, while other lower oxidation states of Pt surface oxides such as PtOH, Pt(OH)2 and PtO may be identified as the possible active species for primary alcohol oxidation. 相似文献
13.
分别采用玻碳( GC)、铂( Pt)和金( Au)电极研究了在Br?nsted酸性离子液体[ HMIm] HSO4中电解水制氢的催化活性,活性大小为Pt > Au >> GC。水中离子液体的含量对析氢电流影响很大,当[ HMIm] HSO4含量为30%(V/V)时,Pt电极催化电解水产氢的阈值电位高达-0.3 V (Ag丝为准参比电极, Ag QRE),在-0.5 V (Ag QRE)处电流密度高达110.52 mA/cm2,为相同条件下Au电极的15倍,GC电极的650倍。计算结果表明,Pt电极在该电解液中的反应活化能为5.68 kJ/mol。电极的高催化活性与[ HMIm] HSO4电离产生的质子有关,使水以H3 O+的形式捕集电子,效率更高。 相似文献
14.
15.
通过循环伏安法(CV)在玻碳(GC)电极表面电沉积出分布较为均匀的纳米Fe粒子,制得纳米Fe粒子修饰的GC(纳米Fe/GC)电极,再经“电荷置换”制得具有Fe核Pt壳结构的纳米粒子修饰的(纳米PtFe/GC)电极。 SEM结果显示,纳米Fe/GC和纳米PtFe/GC表面粒子的形貌均呈立方体形,分布较为均匀,粒径在60 nm左右。 纳米PtFe/GC电极对亚硝酸盐的还原具有很高的电催化活性。 3种电极的电催化活性顺序依次为:纳米Fe/GC<纳米Pt/GC<纳米PtFe/GC。 相对于纳米Pt/GC电极,纳米PtFe/GC电极的起始还原电位(Ei)正移了0.14 V,还原峰电流(ip)增大了3倍。 相似文献
16.
17.
Influence of the Solvent on the “Casting” Methodology for MWCNT‐Modified Glassy Carbon and Platinum Electrodes
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Ana Carolina Ângelo Dorim Herbert Aleixo Edilton de Souza Barcellos Leonardo Luiz Okumura 《Electroanalysis》2015,27(11):2663-2669
The choice of electrode material and surface preparation method are usually dictated by the suitability of the electrode to observe an electrochemical parameter, such as heterogeneous electron transfer rate, surface coverage, or redox potential. Thus, the glassy carbon (GC) and platinum (Pt) electrodes were modified with multiwalled carbon nanotubes (MWCNT) by direct “casting” modification using nine different aliquots of solvents. After drying at room temperature, the modified electrode showed distinct redox peaks corresponding to ferrocyanide oxidation/reduction. Using chemometrics, the cyclic voltammograms with higher current intensity were obtained for those in which ethanol, water and acetone as dispersing agents were used for GCE and dimethylformamide, water and acetone for Pt electrode modification. 相似文献
18.
《Electroanalysis》2003,15(19):1555-1560
Cyclic voltammetry was used to investigate the oxidation of 8‐oxo‐2′‐deoxyguanosine (8‐oxo‐dG) on the glassy carbon (GC), platinum, gold and SnO2 electrodes over a range of the sweep rate, 8‐oxo‐dG concentration and the solution pH. Reaction mechanism that is common to all these electrodes involves the two‐electron two‐proton charge transfer step followed by the irreversible chemical reaction(s). Rate of the charge transfer reaction decreases with the increasing solution pH (GC, Pt, Au), and depends on the nature of the electrode material following the sequence GC>Pt, Au>>SnO2. These effects can be related to the degree of oxidation of the electrode surface (Pt, Au, SnO2), or to the density of the active surface sites (GC). Any of these electrodes can be used for the fabrication of an amperometric detector for 8‐oxo‐dG . 相似文献
19.
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. 相似文献
20.
A single‐wall carbon nanotube functionalized by carboxylic groups (SWNT‐CA) was found to be adsorbed on an indium tin oxide (ITO) electrode by chemical interaction between carboxylic groups and the ITO surface. The adsorption experiments indicated that the narrow pH conditions (around pH 3.0) exist for its adsorption which is restricted by preparation of stable fluid dispersion (favorable at higher pH) and by the chemical interaction (favorable at lower pH). Atomic force microscopic (AFM) measurements suggest that fragmented SWNT‐CA are adsorbed, primarily lying on the surface. Electrochemical impedance analysis indicated that an electrochemical double layer capacitance of the SWNT‐CA/ITO electrode is considerably higher than that for the ITO electrode, suggesting that the interfacial area between the electrode surface and the electrolyte solution is enlarged by the SWNT‐CA layer. Pt particles were deposited as a catalyst on the bare ITO and SWNT‐CA‐coated ITO (SWNT‐CA/ITO) electrodes to give respective Pt‐modified electrodes (denoted as a Pt/ITO electrode and a Pt/SWNT‐CA/ITO electrode, respectively). The cathodic current for the Pt/SWNT‐CA/ITO electrode was 1.7 times higher than that for the Pt/ITO electrode at 0.0 V, showing that the Pt/SWNT‐CA/ITO electrode works more efficiently for O2 reduction at 0.0 V due to the SWNT‐CA layer. The enhancement by the SWNT‐CA layer is also effective for electrocatalytic proton reduction. It could be ascribable to the enlarged interfacial area between the electrode surface and the electrolyte solution. 相似文献