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Journal Cover   Electrocatalysis
  [SJR: 0.883]   [H-I: 10]   [0 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1868-2529 - ISSN (Online) 1868-5994
   Published by Springer-Verlag Homepage  [2276 journals]
  • Electrochemical Degradation of an Anthraquinonic Dye on an Expanded
           Graphite-Diamond Composite Electrode
    • Abstract: Abstract In recent times, there has been increasing interest in the exploration of electrochemical approaches for the destruction of organic pollutants in wastewater owing to their ability to degrade recalcitrant pollutants in our water. This work demonstrated the use of expanded graphite-diamond anode for the degradation of acid blue 40 (AB 40) dye. Expanded graphite (EG) and expanded graphite-diamond (EG-diamond) electrodes were prepared and characterised using Raman spectrometry, x-ray diffraction, scanning electron microscopy and cyclic voltammetry. The electrolysis of the analyte in 0.1 M Na2SO4 electrolyte resulted in ca. 80 % dye removal at the EG-diamond electrode and 66 % removal at the pristine EG electrode at a current density of 20 mAcm−2 after 4 h. However, in a chlorine-mediated electrolysis (NaCl as supporting electrolyte), the decolourisation of the dye was very rapid with over 98 % decolourisation in 25 min. The extent of mineralisation was measured by total organic carbon (TOC). EG-diamond and EG electrodes yielded TOC removal of 44 and 26 % respectively in the sodium sulphate supported cell. The degradation of AB 40 follows a pseudo first-order kinetic model with apparent rate constants of 2.34 × 10−3 min−1 and 4.41 × 10−3 min−1 obtained at EG and EG-diamond electrodes, respectively. The EG-diamond electrode was further applied in the degradation of orange II dye (OG II) and a mixture of OG II and AB 40 with a TOC removal of 49 % for the dye mixture.
      PubDate: 2015-11-13
  • Membrane Electrolysis of Toluene Hydrogenation with Water Decomposition
           for Energy Carrier Synthesis
    • Abstract: Abstract Large-scale technology for energy storage and transportation is needed to increase renewable energies which unevenly distribute with fluctuations, such as wind and solar power. The organic hydride of the toluene/methylcyclohexane system is one of the best energy carriers. In order to improve the energy conversion efficiency of the hydrogenation of toluene using electric power, a membrane electrolyzer, which consists of a carbon-supported precious metal-coated porous carbon cathode, perfluorosulfonic acid (PFSA) membrane separator, and DSE® anode for the oxygen evolution reaction, has been designed and evaluated. The activity of the PtRu/C catalyst layer for the electrohydrogenation of toluene was higher than that of Pt/C. Hydrophilization of the anode side of the PFSA effectively discharged oxygen gas from the anode compartment. The electrohydrogenation of toluene without hydrogen evolution has been successfully up to a 450 mA cm−2 current density with 100 % toluene feed at ca. 2 V cell voltage. In order to evaluate the conversion ratio for the hydrogenation, the current efficiency as a function of the current density was evaluated at various concentrations of toluene. Significant hydrogen was generated above 100 mA cm−2 of current density for 10 times the stoichiometry of a 5 % toluene feed. During the electrolysis, by-products were hardly detected except for hydrogen. Although the improvement of the mass transport in the catalyst layer occurred, more than 95 % of the toluene conversion with a high energy efficiency should be feasible based on these experiments.
      PubDate: 2015-11-05
  • Electrochemical Evaluation of Pt-Based Binary Catalysts on Various
           Supports for the Direct Methanol Fuel Cell
    • Abstract: Abstract Multi-walled carbon nanotubes (MWCNTs), TiO2, MoO2, and carbon black Vulcan XC-72 were investigated as supports for PtRu and PtSn catalysts. X-ray diffraction (XRD) confirmed that all electrocatalysts examined display characteristic patterns similar to that of the Pt/C electrocatalyst, an indication that the catalysts have predominantly the Pt face-centered cubic (fcc) crystal structure. High-resolution transmission electron microscopy (HRTEM) images showed spherical PtRu and PtSn nanoparticles with a narrow particle size distribution, dispersed on the support materials. The metal loading for the prepared electrocatalyst was estimated using energy-dispersive X-ray spectroscopy (EDS), and it was observed to be closest to that of the catalysts supported on Vulcan XC-72. Cyclic voltammograms showed PtSn/C to be the most active, as it possessed a higher electroactive surface area than that of the other catalysts, followed by Pt/C > PtRu/MWCNT > PtRu/C > PtSn/MWCNT > PtSn/MoO2 > PtRu/MoO2 > PtSn/TiO2 > PtRu/TiO2. It was also observed that catalysts supported on MWCNTs were more active than those supported on metal oxides. Furthermore, catalysts supported on MWCNTs proved to be more stable than all the other supported catalysts examined. Therefore, MWCNTs have been proven in this study to be the best material for supporting electrocatalysts for direct methanol fuel cells.
      PubDate: 2015-11-05
  • Cathodic Evolution of Hydrogen on Platinum-Modified Nickel Foam Catalyst
    • Abstract: Abstract This paper reports on cathodic evolution of hydrogen, examined at Pt-modified nickel foam material. Hydrogen evolution reaction (HER) was studied in 0.1 M NaOH solution on platinum-activated nickel foam catalyst material, obtained via a spontaneous deposition method. Catalytic Pt modification of nickel foam resulted in a substantial enhancement of the HER kinetics, as compared to those recently recorded on Pd/Ru-modified Ni foam catalyst materials. Electrochemical investigations were carried out by means of AC impedance spectroscopy and quasi-potentiostatic cathodic polarization experiments. In addition, importance of nano-catalytic nature of the Pt deposit and its influence on the HER characteristics were discussed in detail with help of SEM/EDX spectroscopy analysis.
      PubDate: 2015-11-04
  • Novel Noble-Metal-Free Electrocatalyst for Oxygen Evolution Reaction in
           Acidic and Alkaline Media
    • Abstract: Abstract This study focuses on the feasibility of using TMTiP (where TM is a 3d transition metal or a mixture of 3d transition metals, Cr, Mn, Fe, Co, and Ni; TiP denotes titanium phosphide) as the electrode material for the oxygen evolution reaction (OER) by systematic modification to the atomic ratio of the constituent metals. The catalytic activity of the electrode materials is expected to be governed by the d electrons of the transition metals; the electrical conductivity is provided by TiP even under highly acidic conditions. The OER activity followed a “volcano plot” as the TM was changed from Cr to Ni and assumed the maximum value for the composition cobalt titanium phosphide (CoTiP). The CoTiP electrode also exhibited excellent corrosion resistance and metallic conductivity (on the order of 10−6 Ω m) over the pH range 0–14. The OER activity of CoTiP was comparable to that of Pt but inferior to that of state-of-the-art IrO2 and RuO2.
      PubDate: 2015-11-02
  • Effect of Addition of Ru and/or Fe in the Stability of PtMo/C
           Electrocatalysts in Proton Exchange Membrane Fuel Cells
    • Abstract: Abstract In this work, the activity, stability, and CO tolerance of ternary and quaternary electrocatalysts formed by PtMo/C-PtFe/C, PtMo/C-PtRu/C, and PtMo/C-PtRuC-PtFe/C were studied in the anodes of proton exchange membrane fuel cells (PEMFCs). Cyclic voltammetry (CV) was used to study the surface characteristics and stability of the electrocatalysts and polarization curves were used to investigate the performance of PEMFC anodes supplied with pure hydrogen and hydrogen containing 100 ppm CO. Online mass spectrometry (OLMS) and CO stripping experiments were conducted to investigate the CO tolerance mechanism. The PtMo/C-PtRu/C-PtFe/C, PtMo/C-PtFe/C, and PtMo/C-PtRu/C electrocatalysts showed better performance for the oxidation of hydrogen in the presence of hydrogen containing 100 ppm CO as compared to the PtMo/C electrocatalyst. It was found that the partial dissolution of Mo, Ru, and Fe, and their migration/diffusion from the anode to the cathode occur during a CV cycling from 0.1 to 0.7 V vs. RHE at a scan rate of 50 mVs-1 up to total of 5,000 cycles. The results also showed that the stability of PtMo/C-PtRu/C-PtFe/C, PtMo/C-PtFe/C, and PtMo/C-PtRu/C are better than that of PtMo/C.
      PubDate: 2015-11-01
  • The Effects of a Low-Level Boron, Phosphorus, and Nitrogen Doping on the
           Oxygen Reduction Activity of Ordered Mesoporous Carbons
    • Abstract: Abstract In order to elucidate the role of B, N, and P dopants in carbon materials on the kinetics of oxygen reduction reaction (ORR) and to provide a fair comparison of the effects of each dopant, a series of ordered mesoporous carbons (OMCs) with low concentration of heteroatoms (<1 at%) has been prepared. Doped OMCs were characterized using X-ray photoelectron spectroscopy (XPS), inductively coupled plasma optical emission spectroscopy (ICP-OES), Raman spectroscopy, X-ray powder diffraction (XRD), and N2 physisorption measurements. Comparative study of the ORR activity of these materials in alkaline solution was performed using rotating disk electrode voltammetry. The experiments evidenced that, compared to non-doped OMC, charge transfer kinetics was improved independently on the nature of the heteroatom. The decrease of the ORR overvoltage and the increase of the mass activity upon doping are similar for B and P and less prominent for N. On the other hand, OMCs doped with low levels of B and N were found to be selective for O2 reduction to peroxide, while for P-doped OMCs, the apparent number of electrons consumed per O2 molecule was up to 3.1. Experimental measurements were complemented by density functional theory (DFT) calculations.
      PubDate: 2015-11-01
  • First Insight into Fluorinated Pt/Carbon Aerogels as More
           Corrosion-Resistant Electrocatalysts for Proton Exchange Membrane Fuel
           Cell Cathodes
    • Abstract: Abstract This study evaluates the fluorination of a carbon aerogel and gives first insights into its durability when used as platinum electrocatalyst substrate for proton exchange membrane fuel cell (PEMFC) cathodes. Fluorine has been introduced before or after platinum deposition. The different electrocatalysts are physico-chemically and electrochemically characterized, and the results discussed by comparison with commercial Pt/XC72 from E-Tek. The results demonstrate that the level of fluorination of the carbon aerogel can be controlled. The fluorination modifies the texture of the carbons by increasing the pore size and decreasing the specific surface area, but the textures remain appropriate for PEMFC applications. Two fluorination sites are observed, leading to both high covalent C-F bonds and weakened ones, the quantity of which depends on whether the treatment is done before or after platinum deposition. The order of the different treatments is very important. Indeed, the presence of platinum contributes to the fluorination mechanism, but leads to amorphous platinum, which is demonstrated rather inactive towards the oxygen reduction reaction. On the contrary, a better durability was demonstrated for the fluorinated and then platinized catalyst compared both to the same but not fluorinated catalyst and to the reference commercial material (based on the loss of the electrochemical real surface area after accelerated stress tests).
      PubDate: 2015-11-01
  • Electrochemical Hydrogen Oxidation on Pt(100): a Combined Direct Molecular
           Dynamics/Density Functional Theory Study
    • Abstract: Abstract We have studied the hydrogen oxidation reaction on various catalytic sites at the water/Pt(100) interface with first-principles direct molecular dynamics and minimum energy pathway calculations. The calculations indicate that the mechanism for electro-oxidation of H2 on terrace sites of the Pt(100) surface depends on the concentration of inactive adsorbed hydrogen on the electrode surface. Near the reversible potential, the electro-oxidation follows the Tafel-Volmer homolytic cleavage of H2 at low coverage of adsorbed hydrogen. If the surface is covered with ca. 1 monolayer of hydrogen, however, the oxidation proceeds by the Heyrovsky-Volmer mechanism. We found good agreement between measured and predicted Tafel plots, indicating that hydrogen oxidation/reduction reaction on Pt(100) takes place via the Heyrovsky-Volmer mechanism under ca. 1 monolayer coverage of inactive adsorbed hydrogen.
      PubDate: 2015-11-01
  • NiO/MWCNT Catalysts for Electrochemical Reduction of CO 2
    • Abstract: Abstract This communication reports the electrochemical reduction of CO2 on high surface area NiO/multi-walled carbon nanotube (MWCNT) catalysts. The catalysts are prepared by an incipient wetness technique with different NiO loadings. The prepared catalysts are characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) techniques. A conventional two compartments half-cell and a reverse fuel cell are employed to establish the effects of variation of NiO loading on MWCNT. The characterization results indicate that high surface area of MWCNT provides good NiO dispersion on the catalyst surface. The NiO on MWCNT also shows high electrical conductivity in the fuel cells. In CO2 reduction, the catalysts demonstrate good CO2 conversion activity and produce high-pressure effects even at ambient conditions. The reduction product mainly contains syngas (CO and H2). In half-cell evaluation, an increase in current is observed with increasing NiO content up to 20 wt%. Further increase of NiO loading shows no significant increase in current density. Among the studied catalysts, NiO (20 wt%)/MWCNT displays optimum activity in both the half-cell and reverse fuel cell evaluations. With this catalyst, the total faradaic efficiency of 35.2 % is obtained at the potential of −1.7 V versus normal hydrogen electrode (NHE).
      PubDate: 2015-11-01
  • In Situ IR Studies on the Electro-Oxidation of Cyanide on Ni, Cu and Au
           Electrodes Electrically Polarized in Dimethyl Sulfoxide (DMSO) Electrolyte
    • Abstract: Abstract Subtractively normalised Fourier transform infrared spectroscopy (SNIFTIRS) studies are reported on the electrical polarisation of nickel (Ni), copper (Cu) and gold (Au) electrodes in KCN dissolved in the polar aprotic solvent, dimethyl sulfoxide (DMSO) with tetrabutyl ammonium perchlorate (TBAP) (0.1 mol L−1) as supporting electrolyte. These studies have shown clearly that each of the metal electrodes investigated oxidised (as the applied potential was adjusted in an anodic direction) to form Ni(II), Cu(I) and Au(I)-cyano complex ions of [Ni(CN)4]2−, [Cu(CN)3]2−, [Cu(CN)2]− and [Au(CN)2]−. The distribution of other electro-oxidation products of cyanide observed, namely KOCN(s) and CO2 depended on the electrode under consideration. For Ni electrodes, DMSO-solvated CO2 and solid KOCN were observed together as the oxidation products while on Cu and Au electrodes CN− was oxidised to DMSO-solvated CO2 exclusively without any solid cyanate salt film deposition being simultaneously observed. Cu was found to be particularly electrocatalytic towards the electro-oxidation of CN− ion to CO2 with high current density values being observed. It is proposed that the metal-cyano complex ion species observed in SNIFTIRS experiments are implicated in the oxidation mechanism of CN− to KOCN and/or CO2 on these electrodes, particularly on the Cu and Au electrodes. This resembled the electrochemistry observed in similar systems involving the electrochemical oxidation of cyanide on Cu electrodes in aqueous media.
      PubDate: 2015-10-12
  • Electrochemical Reduction of CO 2 on Ni- and Pt-Epitaxially Grown Cu(111)
    • Abstract: Abstract The electroreduction of CO2 on well-defined M/Cu(111) (M = Ni and Pt) bimetallic surface systems fabricated using molecular beam epitaxy was studied. The total faradic efficiency for CO2 reduction using one-monolayer (ML)-thick Pt epitaxially grown on a Cu(111) substrate (1-ML Pt/Cu(111)) was nearly the same as that for clean Pt(111). In contrast, the 1-ML-thick Ni/Cu(111) system exhibited increased selectivity for CH4 production compared with that of clean Ni(111), which may stem from the geometric tensile strain induced by the underlying Cu(111) substrate. Notably, bimetallic surfaces consisting of 0.1-ML-thick Ni or Pt grown on Cu(111) exhibited significantly different reduction behaviors compared with those of Cu because of the presence of the a small amount of epitaxially grown metal. For the 0.1-ML-thick Ni/Cu(111) system, the total faradaic efficiency for CO2 reduction and the production rate for CO were enhanced compared with those for clean Cu(111), whereas the production of CH4 decreased. In contrast, the total faradaic efficiency was significantly suppressed for the 0.1-ML-thick Pt/Cu(111) bimetallic substrate, with only a very small amount of CH4 production. The difference in the catalytic properties is attributed to the difference in the adsorption energies for CO, which is an intermediate in the electrochemical production of CH4 and C2H4.
      PubDate: 2015-10-07
  • Evaluating Activity for Hydrogen-Evolving Cobalt and Nickel Complexes at
           Elevated Pressures of Hydrogen and Carbon Monoxide
    • Abstract: Abstract Molecular cobalt and nickel complexes are among the most promising homogeneous systems for electrocatalytic hydrogen evolution. However, there has been little exploration into the effect of gaseous co-additives such as CO and H2, which may be present in operating hydrogen-evolving or carbon-dioxide reduction systems, on the performance of these molecular electrocatalysts. In this report, we investigate the electrocatalytic activity of six cobalt and nickel complexes supported by tetraazamacrocyclic or diazadiphosphacyclooctane ligands for the reduction of p-toluenesulfonic acid to hydrogen in acetonitrile under inert atmosphere and in the presence of CO and H2. We present an elevated-pressure electrochemical apparatus capable of reaching CO and H2 pressures of ca. 15–520 pounds per square inch (psia) (∼1–35 atm), and we use this apparatus to determine binding constants for CO addition for each catalyst and study the inhibition of the electrocatalysis as a function of CO and H2 pressure. In the case of CO, the extent of catalytic inhibition is correlated to the binding constant, with the cobalt complexes showing a greater degree of catalyst inhibition compared to the nickel complexes. In the case of H2, no complex showed appreciable electrocatalytic inhibition even at H2 pressures of ca. 500 psia.
      PubDate: 2015-10-05
  • Effect of Gold Modification with 3-Mercaptopropionic Acid, Cysteamine and
           Gold Nanoparticles on Monoethanolamine Electrooxidation
    • Abstract: Abstract In this work, a gold electrode modified with self-assembled layers (SAMs) composed of 3-mercaptopropionic acid, cysteamine and gold nanoparticles was prepared. The electrode with SAMs endowed with gold nanoparticles gave the high catalytic effect for monoethanolamine (MEA) electrooxidation in solution at pH 7. For this novel sensor, a linear relationship between the current response of MEA at the potential of peak maximum (j p) and the concentration of this compound in solution (c MEA) was found, over the range 0.1 μM to 0.8 M with the detection sensitivity equal to about 5 A cm−2 mol−1 dm3 (at v = 0.1 V s−1) and the detection limit of 0.046 μM.
      PubDate: 2015-10-02
  • Polymer of Intrinsic Microporosity Induces Host-Guest Substrate
           Selectivity in Heterogeneous 4-Benzoyloxy-TEMPO-Catalysed Alcohol
    • Abstract: Abstract The free radical 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl (4B-TEMPO) is active as an electrocatalyst for primary alcohol oxidations when immobilised at an electrode surface and immersed into an aqueous carbonate buffer solution. In order to improve the catalytic process, a composite film electrode is developed based on (i) carbon microparticles of 2–12 μm diameter to enhance charge transport and (ii) a polymer of intrinsic microporosity (here PIM-EA-TB with a BET surface area of 1027 m2 g−1). The latter acts as a highly rigid molecular framework for the embedded free radical catalyst with simultaneous access to aqueous phase and substrate. The resulting mechanism for the oxidation of primary alcohols is shown to switch in reaction order from first to zeroth with increasing substrate concentration consistent with a kinetically limited process with competing diffusion of charge at the polymer layer-electrode interface (here the “LEk” case in Albery-Hillman notation). Reactivity optimisation and screening for a wider range of primary alcohols in conjunction with DFT-based relative reactivity correlation reveals substrate hydrophobicity as an important factor for enhancing catalytic currents. The PIM-EA-TB host matrix is proposed to control substrate partitioning and thereby catalyst reactivity and selectivity. Graphical Abstract The water-insoluble molecular alcohol oxidation catalyst 4-benzoyloxy-TEMPO is employed here embedded in a nano-composite film based on a hydrophobic polymer of intrinsic microporosity (PIM)
      PubDate: 2015-09-29
  • Surface and Catalytical effects on Treated Carbon Materials for Hydrogen
           Peroxide Electrogeneration
    • Abstract: Abstract This work focuses on the catalytic activity and surface modification of Vulcan XC 72R and Printex L6 toward the oxygen reduction reaction (ORR) after the carbon supports were subjected to a pre-treatment with nitric acid or ammonia. The results indicated that acid-treated Printex L6 was the best-suited material toward the two-electron pathway of the ORR. This material contained the largest concentration of oxygenated acid species and hydrogen, as determined by XPS, the Boehm method, and elemental analysis. The enhanced formation of H2O2 for acid-treated Printex L6 can be explained by the presence of oxygenated acid species increasing the hydrophilic character of the carbon support. The hydrophilicity of the material was investigated by contact angle measurements. However, the changes of the surface area, porosity, and the aliphatic chains of the carbons induced by the pre-treatments and the contributions of these factors to H2O2 production cannot be disregarded.
      PubDate: 2015-09-28
  • Evaluation of Polycrystalline Platinum and Rhodium Surfaces for the
           Electro-Oxidation of Aqueous Sulfur Dioxide
    • Abstract: Abstract Polycrystalline Rh and Pt were studied to ascertain their electrocatalytic activity for the electro-oxidation of SO2, an important reaction in sulfur dioxide depolarized electrolyzers used to produce hydrogen. Cyclic voltammetry and linear polarization methods were employed to evaluate the catalytic activity of these surfaces. Rh exhibited 25-fold lower catalytic activity than Pt and was more susceptible to poisoning by adsorbed intermediate sulfur species. Koutecky-Levich analysis indicated a two-electron transfer reaction on the Pt surface, which corresponded to the most commonly accepted SO2 electro-oxidation reaction mechanism. The Tafel slopes in the low potential region (near the onset potential), in conjunction with an analysis of well-known reaction mechanisms, suggested that the step leading to the oxidation of water to form adsorbed hydroxyl species was the rate-determining step (RDS). This mechanistic model predicts a decrease in Tafel slope with increasing coverage of catalyst active surface sites by adsorbed sulfur species. For Pt, we estimate a surface sulfur coverage of 4 % based on the experimentally measured Tafel slope. In the case of Rh, the sulfur coverage was calculated to be approximately 1 %. The Tafel slopes obtained changed from 106 mV decade−1 for Rh and 80 mV decade−1 for Pt at potentials below 0.7 V vs. standard hydrogen electrode (SHE) to 210 mV decade−1 for Rh and 162 mV decade−1 for Pt at potentials above 0.7 V vs. SHE, suggesting a change in the reaction mechanism corresponding to a change in the surface of the electrocatalyst.
      PubDate: 2015-09-23
  • Photoelectrochemical Treatment of α,β-Unsaturated Ketones on TiO
           2 -RuO 2 /Ti Electrode
    • Abstract: Abstract The photoelectrochemical degradation of structurally similar α,β-unsaturated ketones such as 4-phenyl-3-buten-2-one (benzylideneacetone), 1-(p-totyl)-1-penten-3-one, 4-(p-totyl)-3-buten-2-one, and 4-mesityl-3-buten-2-one has been investigated. Their susceptibility to oxidation and reduction was determined on the basis of voltammetric measurements. It was found that the more methyl groups are attached to the aromatic ring, the oxidation and reduction occurs easier. Among electrodes with different molar ratio of TiO2 and RuO2 (also modified with transition metals oxides: Nb2O5, ZrO2, and Y2O3), TiO2 (70 %)-RuO2 (30 %)/Ti electrode was selected for photoelectrochemical reaction as the optimum one. The photocatalytic activity of the analyzed materials has been determined on the basis of the photocurrent generated in KCl and NaClO4 solutions. The highest mineralization was achieved for benzylideneacetone while the lowest was for 4-mesityl-3-buten-2-one using current intensity of 0.3 A and UV radiation with the wavelength of 254 nm during 120 min.
      PubDate: 2015-09-02
  • Overlayer Au-on-W Near-Surface Alloy for the Selective Electrochemical
           Reduction of CO 2 to Methanol: Empirical (DEMS) Corroboration of a
           Computational (DFT) Prediction
    • PubDate: 2015-08-27
  • The Synthesis of Metallic β-Sn Nanostructures for Use as a Novel Pt
           Catalyst Support and Evaluation of Their Activity Toward Methanol
    • Abstract: Abstract This study offers a unique insight into the use of high surface area metallic tin as support material for platinum catalysts for fuel cell application. We have synthesized high surface area metallic β-tin nanostructures (TNSs) in aqueous solutions by novel one-pot process and used it as a platinum catalyst support in methanol electrooxidation reaction. Rigorous study of parameters controlling the size and shape of TNSs was performed, including selected surfactant molecules at various concentrations, tin salts, and the addition of sodium citrate. Rod-shaped particles with a 50-nm diameter and 500-nm length were obtained from solutions of selected surfactant in concentrations of 1–20 mM by sodium borohydride reduction. These particles had a β-Sn crystalline core with a main lattice plane of (101) and were covered by a 4-nm oxide shell. A maximal surface area of 170 m2 g−1 was measured from a sample prepared by using low concentration of sodium dodecyl sulfate (SDS) (1 mM). This sample is composed of nanorods and nano semi-spherical shape tin particles. Addition of sodium citrate, which acts as a Sn2+ ion ligand, yields longer rods. Electrochemical oxidation of methanol on platinum catalyst, supported on metallic Sn nanostructure, exhibits a high activity, which is comparable to commercial carbon-supported platinum catalysts. In situ surface-enhanced Raman (SER), emphasizing the role of surface oxides on the methanol oxidation activity, further studied methanol oxidation on Pt/TNS, Pt/C, and Pt-Sn alloy catalyst.
      PubDate: 2015-08-27
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