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Journal Cover Electrocatalysis
  [SJR: 0.817]   [H-I: 17]   [2 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  [2353 journals]
  • Electrochemical Behavior of a Pd Thin Film Electrode in Concentrated
           Alkaline Media
    • Authors: K. Hubkowska; M. Soszko; M. Symonowicz; M. Łukaszewski; A. Czerwiński
      Pages: 295 - 300
      Abstract: Abstract Pd limited volume electrodes (LVE) were obtained electrochemically from the PdCl2 aqueous solution. Hydrogen absorption was performed using cyclic voltammetry and chronoamperometry in concentrated (6 M) alkaline solutions (KOH, NaOH, the mixture of 2M LiOH + 4M KOH) and results were compared with 0.5 M H2SO4. It was found that hydrogen pretreatment procedure is crucial for further examination of hydrogen absorption in Pd electrodes. After many cycles of hydrogen absorption/desorption in Pd, these processes become electrochemically more reversible—faster than in a freshly prepared electrode. Results obtained for Pd electrodes in different concentrated alkaline media subjected to hydrogen pretreatment procedure are comparable with those for an acidic solution (e.g., α→β phase transition potential equals to ca. 0.050 V vs. RHE). The continuous Pd electrode cycling does not affect significantly the amount of absorbed hydrogen (ca. 0.72–0.74). The surface roughness factor in basic solutions decreases after multiple hydrogen sorption as in case of an acidic solution. Graphical Abstract ᅟ
      PubDate: 2017-07-01
      DOI: 10.1007/s12678-017-0379-5
      Issue No: Vol. 8, No. 4 (2017)
  • Catalytic Duality of Platinum Surface Oxides in the Oxygen Reduction and
           Hydrogen Oxidation Reactions
    • Authors: Sadaf Tahmasebi; Ashley A. McMath; Julia van Drunen; Gregory Jerkiewicz
      Pages: 301 - 310
      Abstract: Abstract In polymer electrolyte membrane fuel cells (PEMFCs), the hydrogen oxidation reaction (HOR) and the oxygen reduction reaction (ORR) take place on the surface of platinum nanoparticles (Pt-NPs) residing on carbon support. Polycrystalline platinum (Pt(poly)) serves as a model polyoriented system due to its randomly oriented grains separated by grain boundaries, and research using Pt(poly) creates important background knowledge that is used to identify and understand electrochemical phenomena occurring in fuel cells. In this study, we report new results on the electrochemical behavior of Pt(poly) in 0.50 M H2SO4 aqueous solution saturated with reactive gases, namely O2(g) and H2(g). We analyze the influence of the potential scan rate over a broad range of values (1.00–50.0 mV s−1) on the cyclic voltammetry (CV) behavior of Pt(poly). A comparative analysis of the impact of dissolved O2 and H2 on the electrochemical behavior of Pt(poly) is performed using CV profiles and capacitance transients. Their analysis reveals the existence of new features that are observed in the potential range corresponding to the Pt surface oxide formation and reduction. The results indicate that the Pt surface oxide reveals catalytic duality because it acts both as an inhibitor and a catalyst in both the ORR and HOR. In the case of the ORR, the anodic-going transients reveal that the process becomes inhibited as the Pt surface oxide develops, while in the cathodic-going transients, the reduction of Pt surface oxide significantly (ca. 65%) increases the reaction rate. In the case of the HOR, the anodic-going transients also reveal that the process becomes inhibited as the Pt surface oxide develops, while in the cathodic-going transients, the reduction of Pt surface oxide increases (ca. 15%) the reaction rate. The catalytic effect can be attributed either to changes in the surface electronic structure that accompanies the surface oxide reduction or to short-lived increase in the electrochemically active surface area. Graphical Abstract ᅟ
      PubDate: 2017-07-01
      DOI: 10.1007/s12678-017-0372-z
      Issue No: Vol. 8, No. 4 (2017)
  • Electrospun Carbon Nanofibers as Supports for Bioelectrodes
    • Authors: Cenk Gumeci; Duyen Do; Scott Calabrese Barton
      Pages: 321 - 328
      Abstract: Abstract A wide range of carbon nanofiber (CNF) mats with controlled properties of fiber diameter, surface area, porosity, and conductivity were fabricated via a facile and economical electrospinning method. CNFs are used as supports for bioelectrodes to enhance enzyme utilization. This study employed glucose oxidase (GOx) in a redox hydrogel system, which mediates electron transfer via osmium metal center, to create a glucose bioelectrode. CNFs reduces the hydrogel thickness and enhances the electron transport. CNFs exhibit promising glucose oxidation current density reaching 10 mA cm−2 that is higher than those of commercial carbon materials such as multiwalled carbon nanotubes (MWCNT), Bucky paper, Pyrograf, and Toray paper. Graphical Abstract ᅟ
      PubDate: 2017-07-01
      DOI: 10.1007/s12678-017-0373-y
      Issue No: Vol. 8, No. 4 (2017)
  • Acetylene-Treated Titania Nanotube Arrays (TNAs) as Support for Oxygen
           Reduction Reaction (ORR) Platinum Thin Film Catalysts
    • Authors: Sebastian Proch; Shuhei Yoshino; Itaru Gunjishima; Satoru Kosaka; Naoko Takahashi; Naohiko Kato; Kensaku Kodama; Yu Morimoto
      Pages: 351 - 365
      Abstract: Abstract Platinum layers show higher specific oxygen reduction reaction (ORR) activities than nanoparticles, and smooth monolayers of platinum on polycrystalline gold have been achieved by electrodeposition from CO-saturated solutions. Since Pt monolayers are interesting catalytic systems, this methodology was attempted on acetylene-treated titania nanotubes (TNAs) with high conductivity. However, the investigation of the as-treated TNAs found that probably nanotubes with an oxygen-containing graphitic overlayer were formed. It was observed that deposition after partial oxidative removal of the overlayer led to very low ORR activities while deposition on the intact overlayer gave rise to the highest activities obtained in our research so far. This is attributed to a “tie-layer” effect, in which the carbon layer screens the negative effects of the underlying TiO2 layer. The interesting effects of the graphitic overlayer on the ORR activity of the Pt deposits on acetylene-treated TNAs offer a strategy to mitigate the unfavorable interactions of the Pt/TiO2 interface. However, the carbon layer in this study was found not to be stable upon potential cycling. Graphical Abstract Only Gold Lets Platinum be Platinum: Monolayer amounts of Pt, electrodeposited under CO termination, so far, only show specific activities comparable to polycrystalline platinum if deposited on polycrystalline gold. TiO2 modifications as supports facilitate higher activities only at enhanced conductivities, which usually sacrifice their stability.
      PubDate: 2017-07-01
      DOI: 10.1007/s12678-017-0377-7
      Issue No: Vol. 8, No. 4 (2017)
  • Theoretical Studies on the CO 2 Reduction to CH 3 OH on Cu(211)
    • Authors: Shan Ping Liu; Ming Zhao; Wang Gao; Qing Jiang; Timo Jacob
      Abstract: Abstract CO2 reduction has been pursued for decades as an effective way to produce useful fuels and to mitigate global warming at the same time. Methanol synthesis from CO2 hydrogenation over Cu-based catalysts plays an important role in the chemical and energy industries. However, fundamental questions regarding the reaction mechanism and key reaction intermediates of this process are still unclear. To address these issues, we studied the CO2 hydrogenation process using density functional theory (DFT) combined with van der Waals (vdW) force corrections, finding that the most effective pathway proceeds along the reaction series CO* → CHO* → CH2O* → CH2OH* → CH3OH* with the reactive intermediate CH2O*, which is consistent with experimental findings. Additionally, we find that water molecules play an inhibiting role in the reaction, while H bonds and vdW forces have an essential effect on the reaction mechanisms. These findings shed light on the reaction mechanism of CH3OH formation from CO2 hydrogenation and reveal the essence of H2O in this reaction, providing a useful basis for preceding studies. Graphical Abstract Adsorption configurations of COH on (a) bare Cu(211) and (b) on Cu(211) with a co-adsorbed H2O chain. The corresponding reaction pathways on these two surfaces (c and d) have been calculated using density functional theory combined with van der Waals force corrections. Based on these calculations we obtain the most promising pathway and reveal the drastic effect of water molecules.
      PubDate: 2017-08-01
      DOI: 10.1007/s12678-017-0403-9
  • Nanostructured Catalysts Synthesized by High-Energy Mechanical Alloying
           for Formic Acid Electrochemical Oxidation
    • Authors: A. Ezeta-Mejía; M. G. Montes de Oca-Yemha; E. M. Arce-Estrada; M. Romero-Romo; M. Palomar-Pardavé
      Abstract: Abstract Formic acid (FA) oxidation at Pd-X (where, X is cobalt or nickel) nanostructures synthesized by high-energy mechanical alloying (MA) was reported. The structure and morphology of Pd-X were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). It was found that Pd-Co was comprised mainly by the intermetallic Pd2Co formation while Pd-Ni by the alloy Ni0.525Pd0.475. Both catalysts exhibit lamellar agglomerates that were nanostructurated in nature (with crystallite sizes between 2 and 17 nm). The electrochemically active surface area of both catalysts was determined by CO stripping and the electrochemical results (cyclic voltammetry and chronoamperometry) demonstrated that Pd-Co and Pd-Ni displayed adequate catalytic activity towards FA oxidation reaction comparable to other systems reported in the literature including single metal, bimetallic, and trimetallic catalysts synthesized and supported differently. Graphical Abstract XRD characterization of the metal powders and of the resulting Ni-Pd alloy. TEM results for one nanoparticle of the said alloy. Electrochemical characterization of the Pd-Ni alloy through cyclic voltammetry and a comparison between the alloys obtained through chronoamperometry
      PubDate: 2017-07-31
      DOI: 10.1007/s12678-017-0404-8
  • CO-Terminated Pt/Au Codeposition on Titania Nanotube Arrays (TNAs)
    • Authors: Sebastian Proch; Shuhei Yoshino; Naoko Takahashi; Satoru Kosaka; Kensaku Kodama; Yu Morimoto
      Abstract: Abstract Forming platinum monolayers on less-expensive materials is an ingenious way to enhance the mass activities for oxygen reduction reaction (ORR) and decrease the amount of this scarce and precious metal in fuel cell technology. Previously, we observed low activities of Pt catalysts deposited directly on titania nanotube arrays (TNAs). Here, we propose a gold interlayer between Pt and TiO2. The synthesis is attempted by the codeposition of Pt and Au from CO-saturated solution. The activity of the Pt/Au codeposited catalyst is higher than in the case when Pt is deposited alone. This result suggests that Au is a promising way to enhance ORR activity. The activity of this catalyst, however, is still much lower than that of the Pt monolayer on bulk gold. This is explained by the negative effects of CO, disrupting the chance of monolayer formation by preadsorption to the TNA substrate. Graphical Abstract CO-terminated Pt/Au codeposition on titania nanotube arrays (TNAs)
      PubDate: 2017-07-31
      DOI: 10.1007/s12678-017-0405-7
  • Water Structure and Mechanisms of Proton Discharge on Platinum Electrodes:
           Empirical Valence Bond Molecular Dynamics Trajectory Studies
    • Authors: Johannes Wiebe; Eckhard Spohr
      Abstract: Abstract We present a comparative analysis of molecular dynamics trajectory studies of the influence of surface charge, ion strength, and ion adsorption on the interfacial water structure and the possible pathways of proton transport and discharge on negatively charged platinum(111) electrodes. The model used is a reactive force field based on a nine-state empirical valence bond model. It incorporates both proton transfer between water molecules and simultaneous electron and proton transfer to the metal (discharge). The interfacial water polarization is the result of the competition between the electrical field influence of the smooth surface charge and the point-like local charges of adsorbed positive or negative ions, which leads to variations of the prevalent proton discharge pathways depending on system composition. Graphical Abstract In trajectory calculations of proton adsorption and discharge from aqueous solutions onto charged platinum electrodes, the presence of electrolytes in the adsorbate layer influences proton discharge mechanisms via changes in water orientation and via exclusion of discharge sites through repulsive cation-proton interactions.
      PubDate: 2017-07-22
      DOI: 10.1007/s12678-017-0398-2
  • Electrochemical Dissolution of Platinum Electrode in
           Perfluoroalkylsulfonic Acid
    • Authors: Minoru Umeda; Yuuki Okuda; So Takizawa; Mitsuhiro Inoue; Akira Nakazawa
      Abstract: Abstract The electrochemical dissolution of Pt in perfluoroalkylsulfonic acid was investigated to understand the degradation of polymer electrolyte fuel cells. Trifluoromethanesulfonic acid (TFMSA) was used as the electrolyte solution. The results showed that a Pt electrode significantly dissolves by successive potential cycling between −0.26 and 2.0 V vs. Ag/Ag2SO4 in concentrated TFMSA solutions such as 10 mol dm−3. The anodic Pt dissolution is induced during the potential step conducted in the 10 mol dm−3 TFMSA. Chronopotentiometry revealed that the Pt anodically dissolved at 2.0 V vs. Ag/Ag2SO4 is Pt4+. From the double potential chronocoulometry, it was considered that the anodic Pt dissolution in the concentrated TFMSA involves the direct dissolution of the metallic Pt and the Pt dissolution due to the place exchange of the oxygen atoms in PtO and PtO2. Also, the local low pH caused by the H+ ions generated during the O2 evolution might accelerate the significant anodic Pt dissolution in the 10 mol dm−3 TFMSA. Graphical Abstract Significant anodic Pt dissolution in concentrated trifluoromethanesulfonic acid (TFMSA) contains the direct dissolution of the metallic Pt and the Pt dissolution due to the place exchange of the oxygen atoms in the Pt oxides.
      PubDate: 2017-07-21
      DOI: 10.1007/s12678-017-0400-z
  • The Catalytic Impact of Ethionine on the Multi-Step Electroreduction of
           Bi(III) Ions in Chlorates(VII) Solutions
    • Authors: Agnieszka Nosal-Wiercińska; Mariusz Grochowski
      Abstract: Abstract It was concluded that the presence and the protonation of the ethionine (Et) have effects on the rate of the multi-step process of Bi(III) electroreduction in the 2 mol dm−3 chlorates(VII). The catalytic activity of ethionine increases with increasing amounts of NaClO4 in the basic electrolyte solution. Increased amounts of HClO4 in chlorate(VII) solutions causes a decreased rate of the Bi(III) ion electroreduction process in the presence of ethionine. This confirms the assumption on the variety of active complexes mediating the passage of electrons. Graphical Abstract ᅟ
      PubDate: 2017-07-21
      DOI: 10.1007/s12678-017-0406-6
  • Electrodeposition of Electroactive Co–B and Co–B–C Alloys for Water
           Splitting Process in 8 M NaOH Solutions
    • Authors: Dawid Kutyła; Maciej Palarczyk; Karolina Kołczyk; Remigiusz Kowalik; Piotr Żabiński
      Abstract: Abstract The aim of this work was to determine parameters of obtaining Co–B and Co–B–C alloys characterized by low overpotential in hydrogen evolution reactions. There were tests performed to examine the influence of borax and arginine concentration changes as well as the value of cathodic current intensity on the composition, morphology, synthesis current efficiency, and effectiveness of hydrogen evolution. Carbon was added to Co–B alloys to improve its properties of water decomposition in 8 M NaOH solution at 90 °C. The results of the experiments confirmed a decrease in overpotential values from 48 mV/dec for Co–8.5B alloy to 33 mV/dec for Co–8.2B–9.6C alloy obtained at the highest concentration (0.1 M) of arginine in the electrolyte. It was observed that alloys of good catalytic properties featured an amorphous structure. The coatings were analyzed with the use of a scanning electron microscope (SEM) and X-ray diffraction (XRD). The content of boron was assessed based on the glow discharge spectroscopy (GDS) method, whereas carbon was analyzed with the method of adsorption spectroscopy of infrared radiation. Graphical Abstract ᅟ
      PubDate: 2017-07-19
      DOI: 10.1007/s12678-017-0401-y
  • Electrochemistry of Nanocrystalline La 0.5 Sr 0.5 MnO 3 Perovskite for the
           Oxygen Reduction Reaction in Alkaline Medium
    • Authors: Noureddine Khellaf; Abdelkrim Kahoul; Farid Naamoune; Nicolas Alonso-Vante
      Abstract: Abstract Nanocrystalline La0.5Sr0.5MnO3 (LSMO) perovskite-sized powders were successfully synthesized at heating low temperature and time using the Pechini method based on polyesterification between citric acid and ethylene glycol. The electroactivity of carbon-supported perovskite (LSMO/C) for the oxygen reduction reaction (ORR) was evaluated. The results showed that the electroactivity of LSMO/C largely depends on the calcination temperature, type of electrolyte, and mass loading. It increased remarkably with the calcination temperature in 0.1 M KOH. The ORR performance was examined in KOH, NaOH, and K2SO4. Higher electroactivity was recorded in KOH electrolyte, as compared to NaOH and K2SO4. Graphical Abstract Single-phase nanocrystalline La0.5Sr0.5MnO3 (LSMO) perovskite oxides were obtained via the Pechini method at 600 °C. The carbon-supported perovskite (LSMO/C) (heat treated at 700 °C) showed a pronounced oxygen reduction activity as compared to those heat treated at 500 and 600 °C.
      PubDate: 2017-07-19
      DOI: 10.1007/s12678-017-0397-3
  • Enhancement of Oxygen Reduction Reaction Activity of Pd Core-Pt Shell
           Structured Catalyst on a Potential Cycling Accelerated Durability Test
    • Authors: Naoya Aoki; Hideo Inoue; Takashi Okawa; Yuta Ikehata; Akira Shirai; Hideo Daimon; Takayuki Doi; Yuki Orikasa; Yoshiharu Uchimoto; Hiroshi Jinnai; Shin Inamoto; Yuji Otsuka; Minoru Inaba
      Abstract: Abstract Carbon-supported Pd core-Pt shell structured catalyst (Pt/Pd/C) was synthesized by a modified Cu under potential deposition/Pt displacement method without any precise potential control. The specific activity for oxygen reduction reaction (ORR) of the Pt/Pd/C catalyst increased by 5-fold after an accelerated durability test (ADT; rectangular wave potential cycling of 0.6 V (3 s)–1.0 V (3 s) performed in Ar-saturated 0.1 M HClO4 at 80 °C for 10,000 cycles), which enhanced ORR mass activity of the catalyst by 1.4-fold although its electrochemical surface area significantly decreased. TEM observation showed that the morphology of the catalyst particles changed into a spherical shape and the mean diameter decreased after the ADT. TEM-EDX compositional analysis revealed that the Pd core preferentially dissolved out and that the Pt shell was rearranged and thickened with the ADT. CV measurement using Bi3+ probe implied that the Pt(111) facet was partially formed on the Pt shell after the ADT. Furthermore, EXAFS analysis showed that the Pt–Pt bond distance of the Pt shell was shortened after the ADT. It was considered that the drastic enhancement in the ORR-specific activity of the catalyst after the ADT arises from the decrease in number of lowly coordinated surface Pt atoms, partially formed Pt(111) facet on the catalyst surface, and properly induced compressive strain in the Pt shell via the rearrangement of the Pt shell assisted by the preferential dissolution of the Pd core during the ADT. Graphical Abstract ᅟ
      PubDate: 2017-07-15
      DOI: 10.1007/s12678-017-0399-1
  • The Selective Electrochemical Detection of Dopamine Using a Sulfated
           β-Cyclodextrin Carbon Paste Electrode
    • Authors: Gama Theophile Gnahore; Trinidad Velasco-Torrijos; John Colleran
      Abstract: Abstract The present work describes a novel approach for the determination of dopamine (DA) using carbon paste electrodes modified with sulfated β-cyclodextrin (S-β-CDCPE). The electrodes show high affinity towards DA electrochemical oxidation. DA returned a concentration detection range 5 × 10−7 M to 5 × 10−4 M and a detection limit of 1.33 × 10−7 M. DA, ascorbic acid (AA), and serotonin (5-HT) in a solution mixture can be simultaneously oxidized at significantly different potentials in the presence of S-β-CDCPE, while the unmodified CPE returned an overlapping response. In particular, S-β-CD-modified carbon paste microelectrode exhibits clear peak potential separations of 0.161, 0.101, and 0.258 V (vs. Ag/AgCl) for AA/DA, DA/5-HT, and AA/5-HT, respectively, in artificial cerebrospinal fluid (aCSF). Graphical Abstract Schematic illustration of the electrochemical oxidation of DA in the presence of AA and 5-HT at mS-β- CDCPE.
      PubDate: 2017-07-15
      DOI: 10.1007/s12678-017-0402-x
  • Merging Empirical Valence Bond Theory with Quantum Chemistry to Model
           Proton Transfer Processes in Water
    • Authors: Sebastian Dohm; Eckhard Spohr; Martin Korth
      Abstract: Abstract Proton transfer processes in water are of fundamental importance for, among others, electrochemical proton discharge. Empirical valence bond (EVB) approaches were shown in the past to be a versatile tool for modeling complex phenomena such as proton discharge at metal electrodes. By replacing empirical fitting procedures with on-the-fly quantum chemistry (QC) calculations, we arrive at a transferable and systematically tunable description of proton transfer in water with EVB. Graphical Abstract ᅟ
      PubDate: 2017-07-13
      DOI: 10.1007/s12678-017-0396-4
  • Electrocatalytic Activity and Durability of Li x Ni 2-x O 2 /Ni Electrode
           Prepared by Oxidation with LiOH Melt for Alkaline Water Electrolysis
    • Authors: Sho Fujita; Ikuo Nagashima; Yoshio Sunada; Yoshinori Nishiki; Shigenori Mitsushima
      Abstract: Abstract Alkaline water electrolysis (AWE) is suitable for hydrogen production to develop a fluctuating and uneven-distributed renewable energy-based energy system, because hydrogen is a secondary energy which is suitable to large-scale storage and transportation, and the AWE has a simple configuration using low-cost materials. In this system, the anode typically using Ni and Ni alloys is degraded during the fluctuation of electricity from renewable energy. This degradation is related to the surface hydrous oxide layer which contains Ni(II) and Ni(III). During potential cycling, the hydrous oxide layer grows and increases the electronic resistance due to the redox of Ni(II)/Ni(III) and Ni(III)/Ni(IV). In order to improve the durability and catalytic activity by stabilization of the surface using an electroconductive oxide, a Li x Ni2-x O2/Ni has been developed. The surface oxide was prepared by the oxidation of Ni with a LiOH melt. The Li-doped amount for the surface oxide prepared at 1000 °C was homogeneous with a cubic crystalline structure. On the other hand, the crystalline structure prepared at 800 °C was a mixture of the trigonal and cubic Li-doped NiO phases, which has a high and low Li content, respectively. The oxide layer conductivity increased with the Li-doped amount. The excess Li-doped amount increased not only the conductivity of the oxide layer but also the deactivation of the oxygen evolution reaction (OER) electrocatalytic activity. The durability of the Li x Ni2-x O2/Ni under potential cycling was higher than that of Ni for both the OER activity and redox change of Ni(II)/Ni(III) and Ni(III)/Ni(IV). Graphical Abstract Alkaline water electrolysis (AWE) is suitable for hydrogen production to develop a fluctuating and uneven-distributed renewable energy-based energy system, because hydrogen is a secondary energy which is suitable to large-scale storage and transportation, and the AWE has a simple configuration using low-cost materials. In order to improve the durability and catalytic activity by stabilization of the surface using an electroconductive oxide, a Li x Ni2-x O2/Ni has been developed. The oxide layer conductivity increased with the Li-doped amount. The excess Li-doped amount increased not only the conductivity of the oxide layer but also the deactivation of the OER electrocatalytic activity (left). The durability of the Li x Ni2-x O2/Ni under potential cycling was higher than that of Ni for the OER activity (right).
      PubDate: 2017-07-03
      DOI: 10.1007/s12678-017-0390-x
  • Nickel Nanoparticles for the Efficient Electrocatalytic Oxidation of
           Methanol in an Alkaline Medium
    • Authors: Meisong Guo; Yanan Yu; Jingbo Hu
      Abstract: Abstract Nickel nanoparticles (NiNPs) are directly synthesized on an indium tin oxide electrode by ion implantation, which is a convenient, cost-effective, and environmentally friendly method. The morphology of the obtained electrode is characterized by scanning electron microscopy (SEM). The size of the nickel nanoparticles (NiNPs) is in the range of 50~125 nm based on SEM measurements. The general electrochemical behaviors of the modified electrode are characterized by electrochemical impedance spectroscopy (EIS). The electrocatalytic activity and stability are measured by cyclic voltammetry (CV) and chronoamperometry. The results confirm that the NiNPs/ITO electrode has substantial electrocatalytic activity towards the oxidation of methanol with good stability, indicating possible applications in direct methanol fuel cells. Graphical Abstract ᅟ
      PubDate: 2017-05-20
      DOI: 10.1007/s12678-017-0384-8
  • Effect of Magnetic Field on HER of Water Electrolysis on Ni–W Alloy
    • Authors: Liju Elias; A. Chitharanjan Hegde
      Abstract: Abstract Electroactive Ni–W alloy coating with a specific composition was developed as an efficient electrode material for hydrogen evolution reaction (HER) through electrodeposition technique. The high overvoltage towards HER at the electrode surface was reduced by an applied magnetic field during water electrolysis. The effect of introduced magnetic was studied under different applied magnetic field strengths (varying from 0.1 T to 0.4 T) to epitomize the HER efficiency. The enhancement in HER efficiency of the Ni–W alloy electrode in the presence of the applied magnetic field was established through electrochemical analysis and also by quantifying the amount of H2 gas evolved during the analysis. The improvement in HER efficiency of Ni–W alloy under induced magnetic field may be attributed to the magnetohydrodynamic (MHD) force-induced convection and H2 bubble disentanglement. The coating was characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) analyses. The magnetic field-induced efficient water electrolysis is explained with plausible mechanisms, and the results are discussed. Graphical Abstract Magnetic field-induced efficient hydrogen evolution reaction.
      PubDate: 2017-05-04
      DOI: 10.1007/s12678-017-0382-x
  • Synergistic Effects of Polypyrrole Nanofibers and Pd Nanoparticles for
           Improved Electrocatalytic Performance of Pd/PPy Nanocomposites for Ethanol
    • Authors: Srabanti Ghosh; Nimai Bhandary; Suddhasatwa Basu; Rajendra N. Basu
      Abstract: Abstract The development of advanced materials is a central issue to accelerate the implementation of fuel cell technology which constitutes immense potential to meet future power sources. In this work, a facile, one-pot synthesis of Pd nanoparticles (NPs)/polypyrrole (PPy) nanofiber composites has been reported using oxidative complexes as soft templates. Average size of Pd NPs within the PPy nanofibers was found to be in the range of 2.2–4 nm as measured from transmission electron microscopic (TEM) image. The NPs possess good degree of crystallinity as discernible from the lattice fringes in high-resolution transmission electron microscopy (HRTEM), and the cubic crystal phase was ascertained from the X-ray diffraction (XRD) pattern. Electrochemical measurements like cyclic voltammetry (CV) and chronoamperometry (CA) measurements demonstrate that the Pd NP-based polymer nanocomposites (PNCs) show superior electrocatalytic activity for ethanol oxidation and higher stability compared to the commercial Pd/C catalysts which suggest the significant advantages of polymer support over carbon support. The enhanced electrochemical performance attributed with low charge-transfer resistance of the composite catalyst facilitates an easier access of ethanol molecules to the catalytic sites. The mass activity of Pd/PPy nanocomposites is 7.5 and 78 times higher than that of commercial Pd/C and bulk Pd/PPy composites. The effective dispersion of the Pd NPs within the conducting polymer nanostructures allowed an enhancement of the catalytic activity. Our adopted method could be suitable for further development of advanced anode catalyst for alkaline fuel cell applications.
      PubDate: 2017-05-03
      DOI: 10.1007/s12678-017-0374-x
  • Best Practices and Testing Protocols for Benchmarking ORR Activities of
           Fuel Cell Electrocatalysts Using Rotating Disk Electrode
    • Authors: Shyam S. Kocha; Kazuma Shinozaki; Jason W. Zack; Deborah J. Myers; Nancy N. Kariuki; Tammi Nowicki; Vojislav Stamenkovic; Yijin Kang; Dongguo Li; Dimitrios Papageorgopoulos
      Abstract: Abstract Thin-film-rotating disk electrodes (TF-RDEs) are the half-cell electrochemical system of choice for rapid screening of oxygen reduction reaction (ORR) activity of novel Pt supported on carbon black supports (Pt/C) electrocatalysts. It has been shown that the magnitude of the measured ORR activity and reproducibility are highly dependent on the system cleanliness, evaluation protocols, and operating conditions as well as ink formulation, composition, film drying, and the resultant film thickness and uniformity. Accurate benchmarks of baseline Pt/C catalysts evaluated using standardized protocols and best practices are necessary to expedite ultra-low-platinum group metal (PGM) catalyst development that is crucial for the imminent commercialization of fuel cell vehicles. We report results of evaluation in three independent laboratories of Pt/C electrocatalysts provided by commercial fuel cell catalyst manufacturers (Johnson Matthey, Umicore, Tanaka Kikinzoku Kogyo—TKK). The studies were conducted using identical evaluation protocols/ink formulation/film fabrication albeit employing unique electrochemical cell designs specific to each laboratory. The ORR activities reported in this work provide a baseline and criteria for selection and scale-up of novel high activity ORR electrocatalysts for implementation in proton exchange membrane fuel cells (PEMFCs). Reproducibility of ORR mass activity for three Pt/C catalysts between three laboratories using best practices and standardized measurement protocols. Graphical Abstract
      PubDate: 2017-05-02
      DOI: 10.1007/s12678-017-0378-6
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