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Journal Cover Electrocatalysis
  [SJR: 0.817]   [H-I: 17]   [1 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  [2345 journals]
  • Magnetically Induced Electrodeposition of Ni-Mo Alloy for Hydrogen
           Evolution Reaction
    • Authors: Sandhya Shetty; Ampar Chitharanjan Hegde
      Pages: 179 - 188
      Abstract: The electrocatalytic activity of Ni-Mo alloy coatings for hydrogen evolution reaction (HER) was tried to increase by inducing the magnetic field (B), perpendicular to the process of deposition. The electrocatalytic activity of Ni-Mo alloys were studied by cyclic voltammetry (CV) and chronopotentiometry (CP) measurements in 1.0 M KOH medium. Ni-Mo alloy coatings developed at c.d. = 1.0 A dm−2 and B = 0.4 T was found to exhibit highest electrocatalytic activity for HER (with highest cathodic peak c.d. of −0.274 A cm−2 and least onset potential of −1.24 V and highest volume of H2 liberated, 14.0 mL), demonstrated by CV and CP experiments. The stability factor of Ni-Mo alloy coatings were evaluated through corrosion study. The experimental results showed that Ni-Mo alloy, electrodeposited in the presence of B, is more corrosion resistant than its conventional alloy, when tested in the same alkaline medium. The increase in the electrocatalytic activity of Ni-Mo alloy coatings, developed under induced B, is attributed to the structural and morphological changes, caused by an increase of Ni content in the alloy, evident from X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. Graphical ᅟ
      PubDate: 2017-05-01
      DOI: 10.1007/s12678-017-0350-5
      Issue No: Vol. 8, No. 3 (2017)
  • Synthesis and Characterization of ZrO 2 /C as Electrocatalyst for Oxygen
           Reduction to H 2 O 2
    • Authors: Jussara F. Carneiro; Leandro C. Trevelin; Alex S. Lima; Gabriel N. Meloni; Mauro Bertotti; Peter Hammer; Rodnei Bertazzoli; Marcos R. V. Lanza
      Pages: 189 - 195
      Abstract: Electrogeneration of hydrogen peroxide (H2O2) has potential application in advanced oxidation processes. Amorphous carbon is well known as catalyst for oxygen reduction reaction (ORR) through two-electron pathway. However, modification of the carbon can improve its selectivity for the H2O2 electrogeneration. In the present study, we investigated the properties of ZrO2 nanoparticles supported on carbon black (Printex L6) as electrocatalyst for H2O2 production in acidic medium. The catalytic activity of ZrO2/C for oxygen reduction to H2O2 is higher than the catalytic activity of treated carbon black. The highest selectivity of the ZrO2/C catalyst for H2O2 production is attributable to the presence of oxygenated functional groups on its surface and consequently increase of the surface hydrophilicity in comparison with treated carbon black. This surface effect leads to highest H2O2 electrogeneration, which is shown as a high current efficiency (I(H2O2)%). In fact, increased H2O2 yields from 74.5 to 84.2% were observed for the treated carbon black and ZrO2/C catalysts, respectively, whereas the I(H2O2)% for the unmodified carbon black was 65.3%. Furthermore, the modification of carbon by ZrO2 nanoparticles shifted the ORR half-wave potential towards ca. 137 mV, indicating lower energy consumption for producing H2O2. Thus, the ZrO2/C nanoparticles are shown to be promising electrocatalysts for environmental applications. Graphical Zirconium oxides on carbon black improved significantly the selectivity of the substrate to H2O2 electrogeneration.
      PubDate: 2017-05-01
      DOI: 10.1007/s12678-017-0355-0
      Issue No: Vol. 8, No. 3 (2017)
  • Conducting Polymer-Layered Carbon Nanotube as Sensor Interface for
           Electrochemical Detection of Dacarbazine In-Vitro
    • Authors: M. Satyanarayana; K. Yugender Goud; K. Koteshwara Reddy; K. Vengatajalabathy Gobi
      Pages: 214 - 223
      Abstract: A reusable electrochemical sensor ensembling carbon nanotubes and a conducting polymer together is fabricated for the detection of an important anti-cancer drug, dacarbazine (DTIC). A thin film of a conducting polymer, poly(2-amino-1,3,4-thiadiazole) (poly-ATD), is formed on the carbon nanotube paste electrode (CNPE) by employing a potentiodynamic polymerization technique. The fabricated sensor surface has been characterized by FTIR spectroscopy and scanning electron microscopy (SEM) for the structural and chemical properties of the electrode system. The electrochemical capability of the fabricated poly-ATD/CNPE composite electrode for the detection of DTIC is examined by cyclic voltammetry (CV) and electrochemical impedance spectroscopic analysis (EIS), and the poly-ATD/CNPE electrode is found to be efficient for electrocatalytic oxidation of DTIC. Optimization and evaluation of the sensor system are examined by differential pulse voltammetry (DPV). A linear relationship of DTIC concentration over the peak current of DPVs is exhibited over a wide concentration range of 0.05–24.0 μM with a low detection limit (3σ/b) of 35 nM. Steady state current–time analysis experiments under hydrodynamic conditions exhibited a low detection limit of 20 nM, and the analysis time is as low as 10 s. Practical utility of the fabricated poly-ATD/CNPE biosensor for the detection of DTIC directly from artificial urine and pharmaceutical formulations has been demonstrated with very good recovery limits. Graphical
      PubDate: 2017-05-01
      DOI: 10.1007/s12678-017-0357-y
      Issue No: Vol. 8, No. 3 (2017)
  • PtRu Nanoparticles Supported on Phosphorous-Doped Carbon as
           Electrocatalysts for Methanol Electro-Oxidation
    • Authors: Viviane Santos Pereira; Julio C. M. da Silva; Almir Oliveira Neto; Estevam V. Spinacé
      Pages: 245 - 251
      Abstract: P-doped carbon was prepared by thermal treatment of commercial carbon Vulcan XC72 with H3PO4 at 800 °C. PtRu nanoparticles were supported on carbon Vulcan XC72 (C) and on P-doped carbon (P-C) using an alcohol reduction process. The obtained materials were characterized by energy-dispersive X-ray spectroscopy, Raman spectroscopy, X-ray diffraction, transmission electron microscopy, and cyclic voltammetry. The performance of the electrocatalyst was evaluated for methanol electro-oxidation. The intensities of D-band and G-band of Raman spectra were different for P-doped carbon and carbon Vulcan XC72. X-ray diffraction of PtRu/C electrocatalyst showed that Pt face-centered cubic phase and Ru amorphous phase coexist in this material, while for PtRu/P-C electrocatalyst, it was observed the presence of PtRu alloy and Ru hexagonal close-packed phases. The use of P-doped carbon as support for PtRu nanoparticles improves the methanol electro-oxidation. This increase of activity could be attributed to a decrease of average nanoparticle sizes and/or more active Pt and Ru species resulting from metal-support interactions. Graphical
      PubDate: 2017-05-01
      DOI: 10.1007/s12678-017-0360-3
      Issue No: Vol. 8, No. 3 (2017)
  • Enhancement of Ethanol Oxidation Reaction on Pt (PtSn)-Activated Nickel
           Foam Through In situ Formation of Nickel Oxy-Hydroxide Layer
    • Authors: Boguslaw Pierozynski; Tomasz Mikolajczyk
      Pages: 252 - 260
      Abstract: The present paper reports on a significant enhancement of ethanol oxidation reaction (EOR), investigated on Pt and PtSn-modified nickel foam electrodes, realized via in situ formation of surface nickel oxy-hydroxide layer in 0.1 M NaOH solution. In the presence of ethanol in electrolyte, adsorbed C2H5OH molecules (and/or its oxidation intermediates) prevent Pt (PtSn) sites from their extensive dissolution upon prolonged surface electrooxidation of Ni foam electrode. The above was elucidated through cyclic voltammetry examinations and a.c. impedance-derived charge transfer resistance parameter values. Surface topography and the presence of catalytic additives were revealed from the combined scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX) analyses. Graphical Enhanced EOR kinetics on electrooxidized Pt/PtSn Ni foam. Surface-adsorbed ethanol/oxidation intermediates prevent Pt/PtSn catalyst sites. Pt/PtSn-modified Ni foam—introductory anode for alkaline direct ethanol fuel cell.
      PubDate: 2017-05-01
      DOI: 10.1007/s12678-017-0362-1
      Issue No: Vol. 8, No. 3 (2017)
  • Oxygen Reduction Reaction Catalyzed by Small Gold Cluster on h-BN/Au(111)
    • Authors: Andrey Lyalin; Kohei Uosaki; Tetsuya Taketsugu
      Abstract: The catalytic activity for the oxygen reduction reaction (ORR) of a hexagonal boron nitride (h-BN) monolayer deposited on a Au(111) surface and decorated by a small planar Au8 cluster has been studied theoretically using density-functional theory. It is shown that gold nanoparticles (Au-NP) deposited on the h-BN/Au(111) surface can provide catalytically active sites for effective ORR at the perimeter interface with the support. Stabilization of oxygen at the perimeter interface between Au-NP and h-BN/Au(111) support promotes OOH* dissociation opening effective 4-electron pathway of ORR with formation of H2O. It is suggested that increase in the perimeter interface area between the supported Au-NP and the surface would result in increase of the ORR activity. Such increase in the perimeter interface area can be achieved by decreasing the size of Au-NP. Our calculations demonstrate the principal ability to functionalize inert materials such as stand-alone h-BN monolayer or Au surface for the ORR and open new way to design effective Pt-free catalysts for fuel cell technology. Graphical ?
      PubDate: 2017-06-21
      DOI: 10.1007/s12678-017-0395-5
  • Sonochemical Synthesis of PdAg/RGO Nanocomposite as an Efficient
           Electrocatalyst for Both Ethanol Oxidation and Oxygen Reduction Reaction
           with High CO Tolerance
    • Authors: Lakshmanan Karuppasamy; Sambandam Anandan; Chin-Yi Chen; Jerry J. Wu
      Abstract: Controlled size of nanoparticles and rational tuning of the composition could precisely and effectively change the catalytic properties of Pd-based materials, enhancing the electrocatalytic performance and stability. In this article, we reported a rapid and facile synthesis of reduced graphene oxide (RGO) nanosheet-supported alloys of bimetallic PdAg nanoparticles, which were directly prepared by using simultaneous ultrasonic probe irradiation method. The as-synthesized alloys of nanoparticles exhibit excellent electrocatalytic activities for ethanol oxidation and oxygen reduction reaction (ORR) in alkaline medium, including high mass (3138 mA mg−1 Pd) and specific (1.26 mA cm−2) activity on the basis of Pd mass in ethanol oxidation reaction, high electron transferred number (3.94), larger kinetic current density (5.05 mA cm−2), excellent CO tolerance, and long-term stability and durability. The physicochemical and electrochemical characterization of as-prepared electrocatalyst materials was studied by using various tools, such as FE-SEM, HR-TEM, XRD, XPS, FT-IR, CV, CA, EIS, CO-stripping, and LSV-RDE. The developed electrocatalyst is expected to open up a novel class of anode and cathode materials with excellent durability and stability for direct ethanol fuel cell. Graphical Bifunctional electrocatalytic ethanol oxidation and oxygen reduction of PdAg/RGO electrocatalyst
      PubDate: 2017-06-21
      DOI: 10.1007/s12678-017-0391-9
  • Dynamics of the Interaction of Formic Acid with a Polycrystalline Pt Film
           Electrode: a Time-Resolved ATR-FTIR Spectroscopy Study at Low Potentials
           and Temperatures
    • Authors: Z. Jusys; R. J. Behm
      Abstract: Aiming at more insights into the interaction of formic acid with a Pt electrode, we have studied the dynamics of formic acid interaction with a polycrystalline Pt film electrode in the potential range around the onset of the reaction, from 0.0 to 0.4 V (reversible hydrogen electrode (RHE)), by a combination of electrochemical and in situ IR spectroscopy transient measurements. The measurements were performed under well-defined mass transport conditions; IR spectra were acquired in an attenuated total reflection (ATR) configuration with a time resolution of up to 25 ms (rapid scan mode). To slow down the reaction kinetics and thus stabilize short-living adsorbed intermediates, measurements were performed at ambient and low reaction temperatures (3 °C). Kinetic H/D isotope effects, introduced by using deuterated formic acid, were explored to learn more about the contribution of C–H bond splitting in the rate-determining step in formic acid dehydration (COad formation). Rapid scan ATR-FTIRS measurements show no measurable time delay between the appearance of the bands related to adsorbed bridge-bonded formate species and adsorbed CO at higher potentials (>0.1 V) and no detectable formate signals at low potentials (≤0.1 V), although COad is still formed even at 0.0 V. Adsorption of HCOOH species at low potentials (0.0–0.1 VRHE) is indicated by a band developing at around 1720 cm−1, which is isotope shifted upon deuteration of the C–H bond. Consequences of these and other observations, including the observation of a bell-shaped potential dependence of the initial rate for COad formation in the potential range 0.0–0.4 V or distinct kinetic H/D isotope effects in the rate constants for COad formation, on the mechanistic understanding of the formic acid–Pt interaction are discussed. Graphical ᅟ
      PubDate: 2017-06-17
      DOI: 10.1007/s12678-017-0392-8
  • Elementary Reaction Steps in Electrocatalysis: Theory Meets Experiment
    • Authors: Axel Groß; Ludwig A. Kibler
      PubDate: 2017-06-08
      DOI: 10.1007/s12678-017-0389-3
  • Electrodeposition of Ag Overlayers onto Pt(111): Structural,
           Electrochemical and Electrocatalytic Properties
    • Authors: Ludwig A. Kibler; Khaled A. Soliman; Alan Plumer; Christopher S. Wildi; Eric Bringley; Jonathan E. Mueller; Timo Jacob
      Abstract: Epitaxially grown Ag overlayers have been fabricated by electrochemical deposition onto Pt(111). The electrochemical behaviour of these Ag overlayers has been studied by cyclic voltammetry, and their adsorption properties are significantly influenced by the underlying Pt(111) substrate and markedly different from those of Ag(111). A characteristic voltammetric peak for OH adsorption on pseudomorphic Ag islands has been observed for alkaline solution. A deposition–dissolution hysteresis in the underpotential deposition region for the Ag bilayer suggests exchange processes between subsurface Ag and Pt atoms. Theoretical DFT calculations confirm the stability of a pseudomorphic Ag monolayer. However, it is shown for two and three Ag layers that the formation of sandwich structures is theoretically favoured, i.e. Ag layers tend to be separated by single Pt layers. While Ag displaces hydrogen adsorbed in the underpotential region, the activity of Ag monolayers for the hydrogen evolution reaction (HER) is very close to that of Pt(111). Also, Tafel slopes for HER on the first pseudomorphic Ag monolayer on Pt(111) and for blank Pt(111) are almost identical, whereas thicker overlayers are more Ag-like. It is shown by theoretical calculations for the case of an Ag monolayer on Pt(111) that hydrogen can be adsorbed on the Pt subsurface layer. Graphical ᅟ
      PubDate: 2017-06-03
      DOI: 10.1007/s12678-017-0386-6
  • Design and Development of Instrumentations for the Preparation of Platinum
           Single Crystals for Electrochemistry and Electrocatalysis Research. Part
           2: Orientation, Cutting, and Annealing
    • Authors: Nakkiran Arulmozhi; Gregory Jerkiewicz
      Abstract: In this contribution, which is the second paper in a series, we report on the design and development of several pieces of equipment, which facilitate the preparation of a hemispherical single crystal with a desired crystallographic surface structure starting with a spherical Pt single crystal. The pieces of equipment include a dual, high-resolution charge-coupled device (CCD)-based camera for acquiring Laue X-ray back-scattering patterns to orient spherical single crystals, a precision custom-designed jig for cutting and polishing pre-oriented single crystals, and an induction annealing system with controlled gaseous atmosphere for obtaining well-ordered and defect-free single crystal surfaces. Firstly, the paper describes the dual CCD camera setup, which allows acquiring, processing, and analyzing Laue back-scattering patterns in a digital format. The single crystal holder comprising a goniometer, the CCD-based detection system, and an optomechanical system together allow simple, adaptable, quick, and accurate single crystal orientation. Secondly, the paper presents details of a high-precision jig used in the cutting and polishing of single crystals. The jig setup includes a goniometer supporting a holder in which a single crystal is mounted and two micrometers. It maintains the desired single crystal surface parallel to the polishing disk on which abrasive materials are dispersed and polishing cloths are mounted. The micrometers allow monitoring the polishing rate and maintaining the desired single crystal surface exactly parallel to the polishing disk. Thirdly, the paper describes details of the annealing system. It consists of an induction-annealing furnace with a custom-made coil, a custom-designed quartz cell that facilitates single crystal annealing under controlled atmosphere conditions. Optimization of the induction annealing parameters and conditions, which determine the final quality of single crystal surfaces, is described in detail. Finally, the paper explains the unique aspects of this setup and methodically describes the operating procedures required to obtain a hemispherical single crystal with an atomically flat surface. Graphical Visual representation of (111) Oriented Pt spherical single crystal and fcc(111) surface structure with their corresponding simulated and experimentally observed Laue diffraction pattern
      PubDate: 2017-05-26
      DOI: 10.1007/s12678-017-0385-7
  • Electrochemical Kinetics: a Surface Science-Supported Picture of Hydrogen
           Electrochemistry on Ru(0001) and Pt/Ru(0001)
    • Authors: M.P. Mercer; H.E. Hoster
      Abstract: In this short review, we compare the kinetics of hydrogen desorption in vacuum to those involved in the electrochemical hydrogen evolution/oxidation reactions (HER/HOR) at two types of atomically smooth model surfaces: bare Ru(0001) and the same surface covered by a 1.1 atomic layer thick Pt film. Low/high H2 (D2) desorption rates at room temperature in vacuum quantitatively correspond to low/high exchange current densities for the HOR/HER in electrochemistry. In view of the “volcano plot” concept, these represent two surfaces that adsorb hydrogen atoms, Had, too strongly and too weakly, respectively. Atomically smooth, vacuum annealed model surfaces are the closest approximation to the idealized slab geometries typically studied by density functional theory (DFT). A predictive volcano plot based on DFT-based adsorption energies for the Had intermediates agrees well with the experiments if two things are considered: (i) the steady-state coverage of Had intermediates and (ii) local variations in film thickness. The sluggish HER/HOR kinetics of Ru(0001) allows for excellent visibility of cyclic voltammetry (CV) features even in H2-saturated solution. The CV switches between a Had- and a OHad-/Oad-dominated regime, but the presence of H2 in the electrolyte increases the Had-dominated potential window by a factor of two. Whereas in plain electrolyte two electrochemical adsorption processes compete in forming adlayers, it is one electrochemical and one chemical one in the case of H2-saturated electrolyte. We demonstrate and quantitatively explain that dissociative H2 adsorption is more important than H+ discharge for Had formation in the low potential regime on Ru(0001). Graphical Left: Cyclic voltammograms of Ru(0001) in 0.1 M HClO4, with and without H2 present in solution. Left inset: atomic resolution scanning tunnelling microscope (STM) images of Ru(0001). Centre: volcano plot showing the theoretically predicted hydrogen evolution/oxidation (HER/HOR) current densities on Ru(0001), with variable Had coverage in the adlayer. These values are compared with the exchange current densities for the HER/HOR on Pt(111) and pseudomorphic overlayers of Pt on Ru(0001), where the Pt overlayer thickness is indicated. Temperature programmed desorption (TPD) spectra of D2 on Ru(0001) (upper left) and Pt/Ru(0001) (upper right) are shown along with the respective adsorbate coverage obtained at 300 K. Right: STM image of Pt/Ru(0001). The line indicated how the Pt overlayer thickness varies across the surface, as illustrated at the bottom.
      PubDate: 2017-05-24
      DOI: 10.1007/s12678-017-0381-y
  • Nickel Nanoparticles for the Efficient Electrocatalytic Oxidation of
           Methanol in an Alkaline Medium
    • Authors: Meisong Guo; Yanan Yu; Jingbo Hu
      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 ᅟ
      PubDate: 2017-05-20
      DOI: 10.1007/s12678-017-0384-8
  • Influence on the Electrocatalytic Water Oxidation of M 2+ /M 3+ Cation
           Arrangement in NiFe LDH: Experimental and Theoretical DFT Evidences
    • Authors: Ariel Guzmán-Vargas; Juvencio Vazquez-Samperio; Miguel A. Oliver-Tolentino; Guadalupe Ramos-Sánchez; Jorge L. Flores-Moreno; Edilso Reguera
      Abstract: This contribution reports the effect of the iron content and M2+/M3+ ratio cation arrangement-distribution on the oxygen evolution reaction (OER) catalyzed by layered double hydroxides. The electrocatalysts, containing variable contents of Ni and Fe, were successfully prepared through a homogeneous precipitation method. The formation of LDH structure was verified by powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Other properties were determined such as specific surface area, electrical conductivity, and surface basicity. First-principles DFT+U calculations complemented and supported the electrochemical results. According to both the electrochemical and simulation results, the increase of the catalytic activity for the OER on the presence of Fe3+ is closely related with the configuration and distribution of Fe and Ni cations in the brucite layer structure. The effect of iron is indirect, favoring the electron hopping on the Ni sites for certain local configuration. Graphical ᅟ
      PubDate: 2017-05-16
      DOI: 10.1007/s12678-017-0383-9
  • Electrocatalytic Oxidation of Formate and Formic Acid on Platinum and
           Gold: Study of pH Dependence with Phosphate Buffers
    • Authors: Areeg Abdelrahman; Johannes M. Hermann; Ludwig A. Kibler
      Abstract: The effect of electrolyte pH on the electrooxidation of formic acid/formate is studied using cyclic voltammetry on polycrystalline rotating disk and single-crystalline Pt and Au electrodes in phosphate-based solutions over a wide range of pH (1–12). A non-linear relationship between oxidation current and pH at constant overpotential is identified for both metals. Surface structure influences the reaction for both Pt and Au electrodes. The results in terms of pH dependence are in agreement with those reported in literature. However, experimental evidence shows that adsorbed phosphates cause dramatic changes in the behaviour of the oxidation of formic acid on Pt and Au electrodes due to site blocking and competitive adsorption. The pH dependence on the catalytic activity for formic acid oxidation on Pt is more complex, due to the poisoning of the electrodes by adsorbed CO in addition to intricate anion adsorption effects. The role of the phosphates in the electrocatalyzed reaction is more than maintaining the pH of the system. Rather, various phosphate anions strongly adsorb on the surface, block reactive surface sites and quantitatively decrease oxidation currents. The blocking effect of the phosphate anions increases with increasing pH value. A more considerable blocking effect is established for Au. In addition, a strong pH dependence on overpotential is identified for Pt. In general, oxidation kinetics of formic acid depends strongly on pH, the nature of the adsorbed phosphate species and the electrode potential. Graphical ᅟ
      PubDate: 2017-05-05
      DOI: 10.1007/s12678-017-0380-z
  • Effect of Magnetic Field on HER of Water Electrolysis on Ni–W Alloy
    • Authors: Liju Elias; A. Chitharanjan Hegde
      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 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: 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: 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
      PubDate: 2017-05-02
      DOI: 10.1007/s12678-017-0378-6
  • Direct Butane Utilization on Ni-(Y 2 O 3 ) 0.08 (ZrO 2 ) 0.92 -(Ce 0.9 Gd
    • Authors: Hirofumi Sumi; Toshiaki Yamaguchi; Hiroyuki Shimada; Koichi Hamamoto; Toshio Suzuki; Scott A. Barnett
      Abstract: Nickel-yttria-stabilized zirconia-gadolinia-doped ceria (Ni-YSZGDC) composite anodes were investigated to use butane directly for microtubular solid oxide fuel cells (SOFCs). It was confirmed that mechanical mixing and sintering at 1400 °C for the YSZGDC composites resulted in the formation of a YSZ-GDC solid solution. The n-butane conversion for the cells with Ni-YSZGDC composite anodes was higher than that with Ni-YSZ anode. However, carbon deposition was observed on the Ni-YSZGDC composite anodes after durability test in n-butane. On the other hand, the performance was stable for the cell with the Ni-GDC anode in n-butane due to no carbon deposition. The Ni-GDC anode has a high electrochemical activity of carbon oxidation. Graphical ᅟ
      PubDate: 2017-03-15
      DOI: 10.1007/s12678-017-0369-7
  • Electrochemical Reactions of Sodium 2-Ethylhexyl Sulfate Salt
    • Authors: Aleksandra Perek-Dlugosz; Adam Socha; Jacek Rynkowski
      Abstract: The electrochemical reactions of sodium 2-ethylhexyl sulfate (EHS) and its effect on the Zn2+ electroreduction have been investigated at a mercury electrode using cyclic voltammetry. It has been shown that the reduction takes place in two steps. The presence of EHS in the solution containing Zn2+ ions moves slightly the potential of zinc reduction towards more negative potentials and causes a slight increase in current density. The differential capacity-potential and differential capacity-time measurements indicate strong adsorption in a wide potential range on the electrode surface. In the potential range −0.46 to −0.86 V vs. saturated calomel electrode and at the concentration lower than the critical micelle concentration (CMC), adsorption for the longer time is hardly reversible. At the concentration higher than the CMC, the formation of hemispherical surface micelles is observed. The theoretical maximum degree of electrode coverage computed with the use of quantum-chemical calculations is equal to 3.53 × 1014 particles cm−2, and it is larger than the value determined experimentally from cyclic voltammograms. In the case of electrochemical reaction, at a current of 0.3 A, during 180 min, the obtained mineralization of EHS is only 3%. Graphical
      PubDate: 2017-03-01
      DOI: 10.1007/s12678-017-0356-z
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