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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  [2335 journals]
  • The Effect of Platinum Loading and Surface Morphology on Oxygen Reduction
    • 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
  • In Situ ATR-FTIR Studies of Ethanol Electro-oxidation in Alkaline Medium
           on PtRh/C Electrocatalyst Prepared by an Alcohol Reduction Process
    • 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
  • Investigation of Electrochemical Properties of Model Lanthanum Strontium
           Cobalt Ferrite-Based Cathodes for Proton Ceramic Fuel Cells
    • 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
  • A Facile Synthesis of Size-Controllable IrO 2 and RuO 2 Nanoparticles for
           the Oxygen Evolution Reaction
    • 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
  • Fabrication of β-Cyclodextrin-Functionalized Reduced Graphene Oxide
           and Its Application for Electrocatalytic Detection of Carbendazim
    • 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
  • 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
    • 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
  • Regulating the Product Distribution of CO Reduction by the Atomic-Level
           Structural Modification of the Cu Electrode Surface
    • 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
  • Co-sputtered Pt x Pd y Al z thin film electrocatalysts for the production
           of hydrogen via SO 2 (aq) electro-oxidation
    • 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
  • Oscillatory Electro-oxidation of Methanol on Platinum Single Crystal
    • PubDate: 2016-05-23
  • CO-Terminated Platinum Electrodeposition on Nb-Doped Bulk Rutile TiO 2
    • Abstract: Abstract Nanoparticulate platinum on carbon as oxygen reduction electrocatalyst suffers from two major drawbacks, namely, low specific activity of the Pt particles and corrosion instability of the carbon support under hydrogen starvation conditions (reverse current degradation). Both issues can be tackled by Pt thin films on TiO2 support. Platinum films were synthesized on commercially available Nb-doped bulk TiO2 electrodes via electrodeposition from Ar- (bulk amounts) and CO-saturated solutions (monolayer amounts). The platinized electrodes were tested for ORR activity in a voltammetric fashion, and the field-free semiconductor properties were evaluated by a combination of X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry (SE), photoelectron yield spectroscopy (PYS), electrochemical impedance spectroscopy (EIS), and bulk conductivity measurements. The deposition of bulk amounts of Pt leads to a situation where the catalytic activity is directly correlated to the conductivity of the electrode. Raising the majority carrier density in the Nb-doped TiO2, via proton intercalation in aqueous HClO4 or glycol, drastically increased the activity. In case of monolayer deposits (CO-terminated deposition), intercalation has practically no effect on activity. Thus, the hypothesis is formed that unfavorable electronic interaction of the TiO2 support with small amounts of platinum drastically reduces ORR activity, an effect which is not observed for monolayer amounts of Pt deposited on gold. Graphical Abstract Too Much Interaction: The oxygen reduction activity of bulk amounts of Pt, deposited on Nb-doped TiO2, can be significantly improved by raising the carrier density (via proton intercalation). Such treatment has no effect if monolayer amounts are deposited. This observation is attributed to unfavorable Pt/TiO2 interactions for minute amounts of Pt.
      PubDate: 2016-05-19
  • Erratum to: 3D π-Conjugated Poly(amic) Acid Polymer as Support
           Matrices for Ethanol Electro-Oxidation on Palladium and Platinum Catalysts
    • PubDate: 2016-05-17
  • Atomistic Mechanism of Pt Extraction at Oxidized Surfaces: Insights from
    • 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
  • Influence of Halide Ions on Anodic Oxidation of Ethanol on Palladium
    • Abstract: Abstract Ethanol oxidation on polycrystalline palladium electrodes in alkaline media was studied in the presence of halide ions. Addition of halide ions decreased the ethanol oxidation peak current monotonically as a function of increasing halide concentration. The extent of poisoning was found to be in the order I− > Br− > Cl−. Thus, Cl− ions show appreciable inhibition of ethanol oxidation peak current at [Cl−] ~ 10−3 M, whereas Br− and I− inhibit ethanol oxidation even at [Br−] or [I−] ~ 10−6 M. The potential of the ethanol oxidation peak shifted positive with increasing halide ion concentration. The extent of the shift was found to be in the order I− > Br− > Cl−. This study is relevant due to the widespread use of palladium halide complexes in the production of Pd electrocatalysts for ethanol oxidation and other electrocatalytic reactions.
      PubDate: 2016-05-01
  • Study of Hypochlorite Reduction Related to the Sodium Chlorate Process
    • 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
  • Carbon-Supported Pt Hollow Nanospheres as a Highly Efficient
           Electrocatalyst for the Oxygen Reduction Reaction
    • 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
  • Synthesis of Pt/C Fuel Cell Electrocatalysts: Residual Content of Chloride
           and Activity in Oxygen Reduction
    • 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
  • Evaluation of Oxygen Reduction Activity by the Thin-Film Rotating Disk
           Electrode Methodology: the Effects of Potentiodynamic Parameters
    • 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
  • 3D π-Conjugated Poly(amic) Acid Polymer as Support Matrices for
           Ethanol Electro-Oxidation on Palladium and Platinum Catalysts
    • 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
  • Comparison of FePt and Pt Nanostructures for Oxygen Reduction Reaction in
           Basic Medium
    • Abstract: Abstract FePt nanoparticles (NPs) and colloidal nanoparticle clusters (CNCs) have been synthesized by the reduction of platinum acetylacetonate (Pt(acac)2) combined with thermal decomposition of iron pentacarbonyl (Fe(CO)5) and compared to pure Pt NPs and CNCs for the catalytic activity of the oxygen reduction (ORR). The formation of NPs and CNCs has been carried out controlling injection temperature of the precursors and the surfactants during the synthesis. The size of the NPs and the CNCs formed is around 3 and 38 nm, respectively. High electrocatalytic performance of the FePt CNCs in comparison with that of nanoparticles and nanocluster of platinum has been obtained for the reduction reaction (ORR) in basic medium. The ORR is carried out by a four-electron charge transfer. The increase in the activity of the CNC structures formed by FePt nanoparticles can be attributed to the alloy formation that produces surface and electronic changes of the Pt atoms and to the structure of the CNCs obtained. Graphical Abstract Polarization curves of (a) CNCs FePt, (b) NPs FePt, (c) CNCs Pt, and (d) NPs Pt and their morphology.
      PubDate: 2016-03-14
  • Spontaneous Deposition of Iridium onto Nickel Substrates for the Oxygen
           Evolution Reaction
    • Abstract: Abstract Spontaneous deposition of Ir onto Ni substrates was investigated as a method to produce electrocatalytic layers for the oxygen evolution reaction in 30 % KOH solution. UV/Vis spectroscopy, cyclic voltammetry and other electrochemical methods are used to investigate the deposition process and the activity of the electrocatalytic coating towards the oxygen evolution reaction. From three solutions (IrCl3+HCl, H2IrCl6+HCl and H2IrCl6), H2IrCl6 is shown to give the most active and stable coating, with deposition times of 45 min at 60∘C enough to increase the activity of the Ni substrate for the oxygen evolution reaction. It is proposed that Ir deposition can occur via the reduction of the Ir precursor coupled to Ni oxidation, as well as the hydrolysis and localised precipitation of the Ir precursor due to the increase in surface pH during Ni dissolution.
      PubDate: 2016-02-05
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