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Journal Cover Electrocatalysis
  [SJR: 0.883]   [H-I: 10]   [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  [2334 journals]
  • Synthesis of Pt/C Fuel Cell Electrocatalysts: Residual Content of Chloride
           and Activity in Oxygen Reduction
    • Authors: Luděk Kaluža; Mikkel J. Larsen; Ignacio Jiménez Morales; Sara Cavaliere; Deborah J. Jones; Jacques Rozière; Anna Kallistová; Pavel Dytrych; Daniela Gulková; Madeleine Odgaard
      Pages: 269 - 275
      Abstract: Graphical Abstract Transmission electron micrographs (TEM), the corresponding Pt particle size distribution histograms, and chemical analysis for residual Cl content by instrumental neutron activation analysis (INAA) and X-ray photoelectron spectroscopy (XPS) of selected representative Pt/C fuel cell catalysts.
      PubDate: 2016-04-12
      DOI: 10.1007/s12678-016-0312-3
      Issue No: Vol. 7, No. 4 (2016)
  • Oscillatory Electro-oxidation of Methanol on Platinum Single Crystal
    • Authors: B. A. F. Previdello; P. S. Fernández; G. Tremiliosi-Filho; H. Varela
      Pages: 276 - 279
      PubDate: 2016-05-23
      DOI: 10.1007/s12678-016-0317-y
      Issue No: Vol. 7, No. 4 (2016)
  • Investigation of Electrochemical Properties of Model Lanthanum Strontium
           Cobalt Ferrite-Based Cathodes for Proton Ceramic Fuel Cells
    • Authors: Chung-Yul Yoo; Dae Sik Yun; Sun-Young Park; Jaeku Park; Jong Hoon Joo; Haein Park; Minseok Kwak; Ji Haeng Yu
      Pages: 280 - 286
      Abstract: The electrochemical properties of La0.6Sr0.4Co0.2Fe0.8O3-δ-based cathodes are studied as model electrodes for proton ceramic fuel cells. The electrochemical performance of symmetric cells with porous cathodes (La0.6Sr0.4Co0.2Fe0.8O3-δ, La0.6Sr0.4Co0.2Fe0.8O3-δ–BaCe0.9Y0.1O3-δ, and La0.6Sr0.4Co0.2Fe0.8O3-δ–BaZr0.8Y0.2O3-δ), investigated as a function of oxygen and water partial pressures, follows the order La0.6Sr0.4Co0.2Fe0.8O3-δ–BaCe0.9Y0.1O3-δ ≥ La0.6Sr0.4Co0.2Fe0.8O3-δ >> La0.6Sr0.4Co0.2Fe0.8O3-δ–BaZr0.8Y0.2O3-δ. The results indicate that the cathode performance of La0.6Sr0.4Co0.2Fe0.8O3-δ–BaCe0.9Y0.1O3-δ is enhanced mainly due to the extension of the effective triple phase boundary, whereas that of La0.6Sr0.4Co0.2Fe0.8O3-δ–BaZr0.8Y0.2O3-δ is lowered due to the poor proton conductivity along the percolated BaZr0.8Y0.2O3-δ particles. From the observed oxygen partial pressure dependence, the rate-determining step of the above cathode polarization reaction is principally ascribed to the oxygen reduction reaction. Graphical abstract Schematics of the cathode reaction mechanism at the surface of the LSCF, LSCF-BCY, and LSCFBZY cathodes
      PubDate: 2016-07-01
      DOI: 10.1007/s12678-016-0306-1
      Issue No: Vol. 7, No. 4 (2016)
  • The Effect of Platinum Loading and Surface Morphology on Oxygen Reduction
    • Authors: S. Taylor; E. Fabbri; P. Levecque; T. J. Schmidt; O. Conrad
      Pages: 287 - 296
      Abstract: Abstract The catalytic activity of Pt catalysts towards the oxygen reduction reaction (ORR) was investigated on a catalyst system developed by thermally induced chemical deposition of Pt on carbon. The use of this deposition method made it possible to prepare a practical catalyst system with various Pt loadings on the support. Increasing the Pt loading caused a change in the Pt surface morphology which was confirmed by transmission electron microscopy (TEM) and CO stripping voltammetry measurements. The occurrence of a low and high-potential CO oxidation peak suggested the presence of Pt agglomerates and Pt nanoparticles, respectively. An increase in Pt loading lead to a subsequent decrease in the electrochemical surface area (ECSA, m2 Pt/gPt) as the platinum surface transitioned from isolated platinum nanoparticles to platinum agglomerates. The specific activity was found to increase with increasing Pt loadings, while the mass activity decreased with loading. The mass and specific activity data from this study was found to follow a ‘master curve’ obtained by the comparison of normalised activities from various different studies in the literature. Pt selectivity was also affected by Pt loading and hence Pt surface morphology. At low Pt loadings, i.e. large interparticle distances, the amount of H2O2 produced was significantly higher than for high Pt loadings. This confirms the presence of a ‘series reaction pathway’ and highlights the importance of the H2O2 desorption-readsorption mechanism on Pt nanoparticles and the ultimate role of Pt interparticle distance on the ORR mechanism. Graphical Abstract Effect of platinum loading and surface morphology on oxygen reduction activity
      PubDate: 2016-07-01
      DOI: 10.1007/s12678-016-0304-3
      Issue No: Vol. 7, No. 4 (2016)
  • In Situ ATR-FTIR Studies of Ethanol Electro-oxidation in Alkaline Medium
           on PtRh/C Electrocatalyst Prepared by an Alcohol Reduction Process
    • Authors: E. H. Fontes; Sirlane G. da Silva; E. V. Spinace´; A. O. Neto; R. F. B. de Souza
      Pages: 297 - 304
      Abstract: Abstract Anion exchange membrane fuel cell is a new chance to produce a functional and portable fuel cell; however, the studies are still at an early stage with few reports regarding the AEMFC. PtRh/C electrocatalysts with different Pt:Rh atomic ratios were prepared by an alcohol reduction process. X-ray diffraction patterns for all PtRh/C materials indicated no shift in Pt(fcc) peaks showing that Rh did not incorporated into Pt lattice; however, the analysis of lattice parameter showed that some Pt atoms are added to Rh(fcc) structure. The mean particle sizes were in the range of 4–5 nm. Electrochemical experiments showed that PtRh/C electrocatalyst with Pt:Rh atomic ratio of 70:30 had superior performance exhibiting a current density of 5.0 mA mgmetal −1. From in situ ATR-FTIR experiments, it was observed that PtRh/C electrocatalyst with Pt:Rh atomic ratio of 70:30 produced more acetate ions than other ones, while the material prepared with Pt:Rh atomic ratio of 50:50 was more selective to CO2 as observed in acid media. Graphical Abstract Integrated acetaldehyde, carbonate, acetate, and CO2 band intensity as a function of the electrode potential for Pt/C, Rh/C, and PtRh/C electrocatalysts
      PubDate: 2016-07-01
      DOI: 10.1007/s12678-016-0308-z
      Issue No: Vol. 7, No. 4 (2016)
  • Evaluation of Oxygen Reduction Activity by the Thin-Film Rotating Disk
           Electrode Methodology: the Effects of Potentiodynamic Parameters
    • Authors: Guangyu Chen; Meng Li; Kurian A. Kuttiyiel; Kotaro Sasaki; Fanpeng Kong; Chunyu Du; Yunzhi Gao; Geping Yin; Radoslav R. Adzic
      Pages: 305 - 316
      Abstract: Abstract An accurate and efficient assessment of activity is critical for the research and development of electrocatalysts for oxygen reduction reaction (ORR). Currently, the methodology combining the thin-film rotating disk electrode (TF-RDE) and potentiodynamic polarization is the most commonly used to pre-evaluate ORR activity, acquire kinetic data (i.e., kinetic current, Tafel slope, etc.), and gain understanding of the ORR mechanism. However, it is often neglected that appropriate potentiodynamic parameters have to be chosen to obtain reliable results. We first evaluate the potentiodynamic and potentiostatic polarization measurements with TF-RDE to examine the ORR activity of Pt nanoelectrocatalyst. Furthermore, our results demonstrate that besides depending on the nature of electrocatalyst, the apparent ORR kinetics also strongly depends on the associated potentiodynamic parameters, such as scan rate and scan region, which have a great effect on the coverage of adsorbed OHad/Oad on Pt surface, thereby affecting the ORR activities of both nanosized and bulk Pt. However, the apparent Tafel slopes remained nearly the same, indicating that the ORR mechanism in all the measurements was not affected by different potentiodynamic parameters. Graphical Abstract CV response of bulk Pt under a programmed potential scan
      PubDate: 2016-04-11
      DOI: 10.1007/s12678-016-0309-y
      Issue No: Vol. 7, No. 4 (2016)
  • 3D π-Conjugated Poly(amic) Acid Polymer as Support Matrices for
           Ethanol Electro-Oxidation on Palladium and Platinum Catalysts
    • Authors: Victor M. Kariuki; Jing Zhang; Magdalena Parlinska; Omowunmi A. Sadik
      Pages: 317 - 325
      Abstract: Abstract The search for new catalyst support matrices to replace the conventional carbon black support has been an important research field for decades. Aromatic conducting polymer (ACP)-based matrices have been found as prospective candidates. Poly(amic) acid (PAA) is one such polymer. We hereby present the catalytic activity and stability of electrodeposited palladium (PdNPs) and platinum (PtNPs) nanoparticles stabilized with PAA. We fabricated four electrodes: Pd/GCE, PAA/Pd/GCE, Pt/GCE, and PAA/Pt/GCE. Cyclic voltammetry and chronoamperometry were employed to assess the ethanol oxidation reaction using PAA as support matrix. PAA was used as support to enhance the stability of PdNPs and PtNPs in basic and acidic media, respectively. The synthesized PAA was characterized using NMR and FTIR. Scanning electron microscopy and X-ray diffraction (XRD) were used for nanoparticle characterization. Test results revealed that the presence of PAA layer on the catalysts leads to sluggish electron transfer kinetics as deduced from higher forward and reverse current densities (5 and 11 mA/cm2) for PdNPs on glassy carbon (Pd/GCE) electrode compared to PAA-stabilized PdNPs (PAA/Pd/GCE) (0.6 and 1.2 mA/cm2), respectively. A similar trend was reported for PtNPs. However, in presence of PAA, both PtNPs and PdNPs were observed to provide stability at up to 900 and 150 cycles, respectively. Chronoamperometric results reinforced the catalyst stabilization effect of the polymer, with findings revealing that the steady-state current density of PAA/Pd/GCE was ∼2.5 times higher than the bare Pd/GCE. Graphical Abstract Poly (amic) acid (PAA)- a biodegradable, electroactive, conductive and π-conjugated polymer- was spin coated onto electrodeposited Pd and Pt nanoparticles and subsequently used for ethanol oxidation reaction in basic and acidic conditions respectively. The catalytic activity of Pd and Pt nanoparticles was retained and the catalyst stability enhanced in presence of PAA film.
      PubDate: 2016-04-11
      DOI: 10.1007/s12678-016-0307-0
      Issue No: Vol. 7, No. 4 (2016)
  • Study of Hypochlorite Reduction Related to the Sodium Chlorate Process
    • Authors: Kristoffer Hedenstedt; Adriano S. O. Gomes; Michael Busch; Elisabet Ahlberg
      Pages: 326 - 335
      Abstract: Abstract Reduction of hypochlorite is the most important side reaction in the sodium chlorate reactor leading to high energy losses. Today chromate is added to the reactor solution to minimize the hypochlorite reduction but a replacement is necessary due to health and environmental risks with chromate. In order to understand the effect of different substrates on the hypochlorite reduction, α-FeOOH, γ-FeOOH, Cr2O3 and CrOH3 were electrodeposited on titanium and subjected to electrochemical investigations. These substances are commonly found on cathodes in the chlorate process and can serve as model substances for the experimental investigation. The mechanism of hypochlorite reduction was also studied using DFT calculations in which the reaction at Fe(III) and Cr(III) surface sites were considered in order to single out the electrocatalytic properties. The experimental results clearly demonstrated that the chromium films completely block the reduction of hypochlorite, while for the iron oxyhydroxides the process can readily occur. Since the electrocatalytic properties per se were shown by the DFT calculations to be very similar for Fe(III) and Cr(III) sites in the oxide matrix, other explanations for the blocking ability of chromium films are addressed and discussed in the context of surface charging, reduction of anions and conduction in the deposited films. The main conclusion is that the combined effect of electronic properties and reduction of negatively charged ions can explain the reduction kinetics of hypochlorite and the effect of chromate in the chlorate process. Graphical Abstract Two dimensional test rig for hypochlorite reduction on transition metal sites embedded in an oxy-hydroxide matrix. The adsorption of Cl is used as descriptor for the reaction.
      PubDate: 2016-04-21
      DOI: 10.1007/s12678-016-0310-5
      Issue No: Vol. 7, No. 4 (2016)
  • Carbon-Supported Pt Hollow Nanospheres as a Highly Efficient
           Electrocatalyst for the Oxygen Reduction Reaction
    • Authors: Baizeng Fang; Blaise A. Pinaud; David P. Wilkinson
      Pages: 336 - 344
      Abstract: Abstract In this study, carbon black Vulcan XC-72R (VC)-supported Pt hollow nanospheres (HNSs) were prepared through a simple synthesis strategy using VC-supported Co nanoparticles (NPs) as the template combined with the replacement of Co by PtCl6 2− ions. The new modified synthesis method results in improved Pt distribution and performance compared to the previously reported conventional synthesis method. The as-developed Pt(20 wt%)HNS/VC catalyst has a homogenous Pt HNS particle size of ca. 18 nm and a uniform particle distribution on the VC support. Furthermore, the Pt HNSs are found to be composed of discrete Pt NPs with a crystallite size of ca. 2–3 nm. Due to the unique nanostructure and alloying with Co of the Pt HNS, the Pt(20 wt%)HNS/VC outperforms significantly a state-of-the-art Pt(20 wt%)NP/VC for the oxygen reduction reaction. Graphical Abstract Carbon black Vulcan XC-72R (VC) supported Pt hollow nanospheres (HNSs) were prepared through a simple synthesis strategy. Due to the unique nanostructure of the Pt HNS, the Pt(20 wt%) HNS/VC outperforms significantly a state-of-the-art Pt(20 wt%) NP/VC for the oxygen reduction reaction.
      PubDate: 2016-04-21
      DOI: 10.1007/s12678-016-0311-4
      Issue No: Vol. 7, No. 4 (2016)
  • Atomistic Mechanism of Pt Extraction at Oxidized Surfaces: Insights from
    • Authors: Mohammad J. Eslamibidgoli; Michael H. Eikerling
      Pages: 345 - 354
      Abstract: Abstract In this article, we propose a novel mechanism for the atomic-level processes that lead to oxide formation and eventually Pt dissolution at an oxidized Pt(111) surface. The mechanism involves a Pt extraction step followed by the substitution of chemisorbed oxygen to the subsurface. The energy diagrams of these processes have been generated using density functional theory and were analyzed to determine the critical coverages of chemisorbed oxygen for the Pt extraction and Oads substitution steps. The Pt extraction process depends on two essential conditions: (1) the local coordination of a Pt surface atom by three chemisorbed oxygen atoms at nearest-neighboring fcc adsorption sites; (2) the interaction of the buckled Pt atom with surface water molecules. Results are discussed in terms of surface charging effects caused by oxygen coverage, surface strain effects, as well the contribution from electronic interaction effects. The utility of the proposed mechanism for the understanding of Pt stability at bimetallic surfaces will be demonstrated by evaluating the energy diagram of a CuML/Pt(111) near-surface alloy. Graphical Abstract Atomistic mechanism of Pt extraction at oxidized surfaces
      PubDate: 2016-05-11
      DOI: 10.1007/s12678-016-0313-2
      Issue No: Vol. 7, No. 4 (2016)
  • Erratum to: 3D π-Conjugated Poly(amic) Acid Polymer as Support
           Matrices for Ethanol Electro-Oxidation on Palladium and Platinum Catalysts
    • Authors: Victor M. Kariuki; Jing Zhang; Magdalena Parlinska-Wojtan; Omowunmi A. Sadik
      Pages: 355 - 355
      PubDate: 2016-05-17
      DOI: 10.1007/s12678-016-0315-0
      Issue No: Vol. 7, No. 4 (2016)
  • Methanol Oxidation in Alkaline Medium Using PtIn/C Electrocatalysts
    • Authors: M. C. L. Santos; C. A. Ottoni; R. F. B. de Souza; S. G. da Silva; M. H. M. T. Assumpção; E. V. Spinacé; A. O. Neto
      Abstract: Abstract Pt/C and PtIn/C with atomic ratios of 90:10, 70:30, and 50:50 were investigated for methanol electro-oxidation in alkaline media by using cyclic voltammetry (CV), chronoamperometry (CA), and direct methanol alkaline fuel cell (DMAFC). All electrocatalysts were synthesized using sodium borohydride method with 20 wt% of metals loading on carbon. X-ray diffraction (XRD) analysis revealed that bimetallic PtIn had faced centered cubic structure and, also, confirmed alloy formation for PtIn/C nanoparticles. Transmission electron micrographs showed metal nanoparticles with average particle size between 3.0 and 5.0 nm; however, the particle size increases when the In content was increased in PtIn/C. In the CV experiments, the onset potential of methanol electro-oxidation shifted to lower values as the indium content increased. Chronoamperometry experiments and direct methanol alkaline fuel cell suggested PtIn/C (70:30) as the most promising material for methanol electro-oxidation: this result could be explained by the presence of Pt and In in close contact (electronic effect) as the occurrence of oxy-hydroxy interactions. Graphical Abstract Chronoamperometry curves for PtIn/C electrocatalysts at 25 °C.
      PubDate: 2016-08-17
      DOI: 10.1007/s12678-016-0324-z
  • Electrocatalysis of NADH on 3,5-Dinitrobenzoic Acid Encapsulated on
           Multiwalled Carbon Nanotube-Modified Electrode
    • Authors: R. Moscoso; E. Inostroza; S. Bollo; J. A. Squella
      Abstract: We report that glassy carbon electrode (GCE) modified with multiwalled carbon nanotubes (MWCNTs) can encapsulate or entrap 3,5-dinitrobenzoic acid (35DNB) generating a 35DNB-MWCNTGC electrode. After electrochemical reduction in situ of only one nitro group of 35DNB, it turns into the hydroxylamine derivative (R-NHOH), which can be further oxidized to the nitroso derivative (R-NO). Then, R-NO/R-NHOH redox couple was electrogenerated in situ by cycling the potential between 0.20 and −0.20 V vs Ag/AgCl. The very well-defined and persistent redox couple was characterized with a formal potential, E o ’ = −28 mV vs Ag/AgCl at a scan rate of 20 mV s−1. Using the Laviron’s plot, a transfer coefficient, α = 0.45, and an electron transfer rate constant, k s  = 10.5 s−1, for the electron transfer of the couple R-NO/R-NHOH, were calculated. This redox reaction results to be a very efficient mediator for electrocatalytic NADH oxidation. The 35DNB-MWCNTGC electrode efficiently catalyzes the oxidation of NADH with a decrease of more than 0.60 V vs Ag/AgCl in the overpotential compared to the bare GCE and a difference of 0.25 V vs Ag/AgCl with respect to the situation without mediator. The preparation of the electrode is very easy and not time-consuming. Graphical abstract The precursor 3,5-dinitrobenzoic acid entrapped on the MWCNTs three dimensional array generate the redox couple RNO/RNHOH capable to act as mediator in the oxidation of NADH.
      PubDate: 2016-08-15
      DOI: 10.1007/s12678-016-0323-0
  • OER Activity of Ir-Ta-Zr Composite Anode as a Counter Electrode for
           Electrohydrogenation of Toluene
    • Authors: Kohei Nagai; Kensaku Nagasawa; Shigenori Mitsushima
      Abstract: Abstract The organic chemical hydride method using the toluene (TL)/methylcyclohexane (MCH) system is one of the prospective energy carrier technologies for hydrogen storage and transportation. The direct electrohydrogenation of toluene with water decomposition using electric power is a highly efficient energy conversion process for the MCH synthesis. In this process, an IrO2-based directionally stable electrode® (DSE®) for the oxygen evolution reaction (OER) is used as the anode because of its good electrocatalytic activity and durability. However, further improvement in the activity is needed for practical applications. In this study, the effect of Zr addition substituted for Ta in IrO2-Ta2O5/Ti, which is a typical OER anode, on the electrocatalytic activity has been investigated in sulfuric acid with TL contamination. The activity of both the IrO2-Ta2O5/Ti and the IrO2-Ta2O5-ZrO2/Ti was higher and less affected by TL contamination than the IrO2/Ti. The activity of the IrO2-Ta2O5-ZrO2/Ti increased with the Zr content. The Zr addition increased the real surface area along with the increase in the double layer capacitance; on the other hand, the increase in activity was more than that of the surface area. Therefore, the Zr additive would affect not only the real surface area increase, but also the electrocatalytic activity. Graphical Abstract Schematic drawing of electrolyzer for direct electrohydrogenation of toluene with water decomposition (left). Oxygen evolution reaction current on Ir50Ta20Zr30-oxide/Ti, Ir50Ta50-oxide/Ti, and IrO2/Ti with (dash) and without (solid) toluene contamination as a function of the potential in 1 M H2SO4 at 60 oC (right).
      PubDate: 2016-08-11
      DOI: 10.1007/s12678-016-0325-y
  • Platinum Nanoparticles Supported on Nitrogen-Doped Graphene Nanosheets as
           Electrocatalysts for Oxygen Reduction Reaction
    • Authors: Kristel Jukk; Nadezda Kongi; Protima Rauwel; Leonard Matisen; Kaido Tammeveski
      Abstract: Abstract This paper deals with nitrogen-doped graphene nanosheets prepared using dicyandiamide precursor as a catalyst support for oxygen reduction reaction (ORR). Platinum nanoparticles supported on N-doped graphene nanosheets (Pt/NG) were studied as electrocatalysts for ORR in acid and alkaline solutions employing the rotating disk electrode (RDE) technique. Pt/NG nanomaterials were synthesised by chemical reduction of hexachloroplatinic acid using sodium borohydride or ethylene glycol as reducing agents. Surface morphology and composition of the prepared catalysts were examined by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The TEM images showed a high dispersion of Pt nanoparticles on N-doped graphene nanosheets due to strong interaction of Pt with nitrogen functionalities. The average nitrogen content was between 6 and 7 at.% according to the XPS analysis. In acidic solution, 20 wt% Pt/NG catalyst prepared by borohydride reduction showed the highest specific activity for O2 reduction from all the Pt/NG materials studied. Pt/NG nanomaterials exhibited excellent electrocatalytic activity in alkaline media, and their half-wave potentials were similar to that of commercial Pt/C catalyst. The RDE data analysis showed that the ORR on the Pt/NG catalysts proceeded via four-electron pathway. Graphical Abstract ᅟ
      PubDate: 2016-07-30
      DOI: 10.1007/s12678-016-0322-1
  • A Facile Synthesis of Size-Controllable IrO 2 and RuO 2 Nanoparticles for
           the Oxygen Evolution Reaction
    • Authors: Tam D. Nguyen; Günther G. Scherer; Zhichuan J. Xu
      Abstract: The efficiency of the water electrolysis process is restricted by the sluggish kinetics of the oxygen evolution reaction (OER). Developing efficient catalysts and their synthesis methods is highly desired to improve the kinetics of the OER and therefore the overall efficiency of the water electrolysis. In this report, we present a facile wet-chemical method for synthesizing IrO2 and RuO2 nanoparticles (NPs) for the OER. The nanoparticles were synthesized by reducing metal chlorides in ethylene glycol in the presence of polyvinylpyrrolidone, followed by annealing in air. The particle size was controlled by adjusting the annealing temperature. The activity of IrO2 and RuO2 NPs supported on carbon black was investigated by cyclic voltammetry (CV) in alkaline (0.1 M KOH) electrolyte. As-synthesized IrO2 and RuO2 NPs showed high OER activity. The IrO2 NPs exhibited a specific activity of up to 3.5 (±1.6) μA/cm2 oxide at 1.53 V (vs. RHE), while the RuO2 NPs achieved a value of 124.2 (±8) μA/cm2 oxide. Moreover, RuO2 NPs showed a mass activity for OER, up to 102.6 (±10.5) A/goxide at 1.53 V (vs. RHE), which represents the highest value reported in the literature to date. Graphical abstract A facile wet-chemical method for synthesizing IrO2 and RuO2 nanoparticles (NPs) is reported here. The nanoparticles were synthesized by reducing metal chlorides in ethylene glycol in the presence of polyvinylpyrrolidone, followed by annealing in air. The size of particles can be controlled by varying the annealing temperature and subsequently their OER activities are varied
      PubDate: 2016-06-30
      DOI: 10.1007/s12678-016-0321-2
  • Fabrication of β-Cyclodextrin-Functionalized Reduced Graphene Oxide
           and Its Application for Electrocatalytic Detection of Carbendazim
    • Authors: Tien Song Hiep Pham; Li Fu; Peter Mahon; Guosong Lai; Aimin Yu
      Abstract: Abstract We reported a graphene-based electrochemical sensor for sensitively measuring carbendazim, which is one of the effective benzimidazole fungicides popularly used in agriculture. The β-cyclodextrin-functionalized reduced graphene oxide (β-CD–RGO) nanocomposites were synthesized using hydrazine as the reducing agent at room temperature. The as-synthesized nanocomposites were characterized using different analytical methods including UV–visible spectroscopy and Fourier transform infrared spectroscopy. The nanocomposites with a combination of physicochemical properties of RGO and high molecular recognition capability of β-CD were used to modify the surface of a glassy carbon electrode for the electrochemical determination of the drug carbendazim using cyclic voltammetry and differential pulse voltammetry. The current responses of carbendazim on the β-CD–RGO-modified electrode were greatly enhanced compared to that on the bare electrode due to the electrocatalytic effect of β-CD–RGO. It was found that the peak currents increased linearly with the carbendazim concentration in the range between 0.1 and 40 μM. The obtained results suggest that β-CD–RGO composite could be a potential candidate for the preparation of effective electrochemical sensors for carbendazim or similar drugs in the future. Graphical Abstract A sensitive electrochemical sensor of carbendazim was developed based on the electro-catalysis of β-CD/reduced graphene oxide modified electrode.
      PubDate: 2016-06-22
      DOI: 10.1007/s12678-016-0320-3
  • Pt 3 M (M: Co, Ni and Fe) Bimetallic Alloy Nanoclusters as Support-Free
           Electrocatalysts with Improved Activity and Durability for Dioxygen
           Reduction in PEM Fuel Cells
    • Authors: B. Narayanamoorthy; V. Linkov; C. Sita; S. Pasupathi
      Abstract: Abstract Pt3M (M: Co, Ni and Fe) bimetallic alloy nanoclusters were synthesized by a novel and simple chemical reduction approach, and employed as the promising electrocatalyst to accelerate the kinetics of oxygen reduction reaction (ORR) for polymer electrolyte membrane fuel cells. From XRD, the positive shift of diffraction angle confirms the alloy formation between Pt and M and the elemental composition was confirmed by energy dispersive X-ray spectroscopy analysis. The nanocluster morphology and particle size was determined using scanning and transmission electron microscopy analysis. The ORR kinetic parameters for Pt-M electrocatalysts were calculated and compared with reported Pt/C catalysts. Among the Pt-M electrocatalysts, Pt-Co was found to be the most efficient catalyst having the higher mass and specific activity (at 0.9 V vs. RHE) of 0.44 mA/μg and 0.69 mA/cm2, respectively. The accelerated durability test reveals that the Pt-M bimetallic alloy nanoclusters retain appreciable surface area and mass activity after 8000 potential cycles confirms good long-term durability, and also competing with the reported benchmark ORR catalysts. Graphical Abstract TEM image of Pt3Co bimetallic alloy nanocluster with cyclic voltammograms of Pt3M (M: Co, Ni & Fe) electrocatalysts
      PubDate: 2016-06-10
      DOI: 10.1007/s12678-016-0318-x
  • Regulating the Product Distribution of CO Reduction by the Atomic-Level
           Structural Modification of the Cu Electrode Surface
    • Authors: Youn-Geun Kim; Alnald Javier; Jack H. Baricuatro; Manuel P. Soriaga
      Abstract: Abstract Cu catalyzes the electrochemical reduction of CO2 or CO to an assortment of products, a behavior that is a detriment when only one reduced compound is desired. The present article provides an example in which, through the atomic-level control of the structure of the Cu electrode surface, the yield distribution is regulated to generate only one product. The reaction investigated was the preferential reduction of CO to C2H5OH on Cu at a low overpotential in alkaline solution. Experimental measurements combined electrochemical scanning tunneling microscopy (ECSTM) and differential electrochemical mass spectrometry (DEMS). An atomically ordered Cu(100) surface, prepared from either a single crystal or by Cu(pc)-to-Cu(100) reconstruction, did not produce ethanol. When the surfaces were subjected to monolayer-limited Cu↔Cu2O cycles, only the reconstructed surface underwent an additional structural transformation that spawned the selective production of ethanol at a potential 645 mV lower than that which generates multiple products. Quasi-operando ECSTM indicated transformation to an ordered stepped surface, Cu(S) − [3(100) × (111)], or Cu(511). The non-selective, multiple-product Cu-catalyzed reduction of CO had thus been regulated to yield only one liquid fuel by an atomic-level structural modification of the electrode surface. Graphical Abstract TOC GRAPHIC
      PubDate: 2016-06-07
      DOI: 10.1007/s12678-016-0314-1
  • Co-sputtered Pt x Pd y Al z thin film electrocatalysts for the production
           of hydrogen via SO 2 (aq) electro-oxidation
    • Authors: A. Falch; V. A. Badets; C. Labrugère; R. J. Kriek
      Abstract: Abstract A co-sputtered PtxPdyAlz ternary system was investigated for potential use as anode catalyst for the electro-oxidation of aqueous sulphur dioxide (SO2), a key reaction in the hybrid sulphur (HyS) process for splitting water into hydrogen and oxygen. Combining the noble metals Pt and Pd with Al resulted in no significant improvement in onset potential; however, current output was improved for the majority of the electrocatalysts evaluated. Of these electrocatalysts, only a single ternary composition exhibited improved stability when compared to pure Pt. It was found that a combination of Pt40Pd57Al3 (annealed at 900 °C) exhibited superior performance when compared to pure Pt and the previously determined best binary electrocatalyst, i.e. Pt3Pd2. Current density ( Pt−1) increased from 108.11 to 181.21 and finally to 396.73 for Pt, Pt3Pd2 and Pt40Pd57Al3, respectively, indicating an increase in activity that correlates with a decrease in Pt content. Atomic force microscopy (AFM) revealed an increase in surface roughness for Pt, Pt3Pd2 and Pt40Pd57Al3, while the occurrence of metal interaction and certain degrees of Al migration (a result of annealing) was confirmed for Pt40Pd57Al3 by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction analysis (XRD). Graphical Abstract The electro-oxidation of aqueous SO2 is a key reaction in the hybrid sulphur (HyS) process for water-splitting. A sputtered PtxPdyAlz ternary system was investigated for potential use as anode catalyst. It was found that a combination of Pt40Pd57Al3 annealed at 900 °C, exhibited noteworthy performance when compared to pure Pt and the previously determined best binary electrocatalyst, i.e. Pt3Pd2. Current density ( Pt−1) increased from 108.11 to 181.21 and finally to 396.73 for Pt, Pt3Pd2, and Pt40Pd57Al3, respectively, indicating an increase in activity that correlates with a decrease in Pt content.
      PubDate: 2016-06-03
      DOI: 10.1007/s12678-016-0319-9
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