bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of MEAs with Pt/Mesoporous Carbon as a Cathode Catalyst
Authors: Minamida Yasuto , Noda Zhiyun , Hayashi Akari , Sasaki Kazunari 
Published: February 2020

Polymer electrolyte fuel cells (PEFCs) have recently been paid great attention owing to commercialization of fuel cell vehicles (FCVs) since 2015. However, PEFCs still have some problems to be overcome, such as improvement of cost and durability for the next generation. In our study, improvement on durability of electrocatalysts is targeted by reducing the mobility of Pt particles on the carbon support. Particularly, Pt particles are introduced into the nano-space of Mesoporous Carbon (MC), which has the nano-channel structure with a diameter of ca. 10 nm. Such encapsulation of Pt in the carbon nano-space leads to successfully reducing the mobility of Pt. MEAs have been prepared with such electrocatalysts as cathode materials, and the sufficient performance has been confirmed, so far. In this study, we have particularly focused on the triple phase boundary formed inside the carbon nano-space. The methods of Nafion introduction were controlled in order to study how they influence on IV performance and durability.
Electrocatalysts were synthesized from platinum (Ⅱ) acetylacetonate as a precursor by supporting ca. 30 wt% Pt on our original MC, and named as Pt/MC. Pt/MC was used only for the cathode. For the anode, a commercial Pt/Ketjen black catalyst (TEC10E50E, TKK Corp.) was in use. Then, MEAs were prepared by spraying the slurry of electrocatalysts and Nafion on the both sides of Nafion membrane, followed by hot-pressing. The solvents for introducing Nafion into carbon nano-space were controlled by ethanol or hexafluoropropanol.
Based on our previous research work, introduction of Nafion into carbon nano-space is known to depend on the kind of solvents[1]. Therefore, in this study, MEAs were made using hexafluoropropanol, which was thought to be more suitable for introduction of Nafion than regular ethanol. Besides the initial performance of MEAs, their durability was also evaluated, using the cycle test at the potential range where the dissolution and re-precipitation of Pt particles occurs[2]. As a result, the initial activity was higher for MEAs made with ethanol, whereas durability was higher for MEAs made with hexafluoropropanol. Successful formation of the triple phase boundary has led to the increase in durability. Further, we are now working on improving the initial activity by optimizing introduction methods of Nafion.
References
[1] A. Hayashi et al. J. Phys. Chem. C, 113(28), 12149 (2009).
[2] A. Ohma et al., ECS Trans, 41 (2011) 755.
SnO2 As an Effective Protection Layer of Electrospun Carbon Nanowires Based Catalyst for PEMFC Applications
Authors: Ercolano Giorgio , Marichy Catherine , Silva Ricardo Manuel , Caputo Gianvito , Jones Deborah J , Roziere Jacques , Cavaliere Sara , Pinna Nicola 
Published: February 2020

Proton exchange membrane fuel cells (PEMFC) can provide clean and long lasting electrical energy while being portable and operated at relatively low temperatures. However, a reduction of the fabrication costs and an improved durability are pivotal to a successful market introduction of this technology. A more effective utilisation of the highly priced Pt catalyst and the use of more durable materials for the catalyst supports are the core of the development of novel, market ready PEMFC. This could be achieved by moving away from the current standard based on Pt nanoparticles supported on amorphous carbon.
We propose a novel catalyst obtained combining electrospinning of carbon nanowires and microwave Pt synthesis with atomic layer deposition of a protective functional metal oxide layer. We studied the morphology and electrochemical properties of this novel structure and demonstrated that the addition of a thin SnO2 layer deposited by ALD increase the durability without reducing the Pt activity for the oxygen reduction and that synergistic utilisation of the oxide and Pt can increase the activity towards methanol and ethanol oxidation.
Pt Catalysts Supported on Polybenzimidazole-Grafted Graphene for PEMFCs
Authors: Li Zhe-Fei , Zhang Hangyu , Yang Fan , Stanciu Lia , Xie Jian 
Published: February 2020

The performance of a PEMFC is dominated by its catalyst performance, which depends on the size and distribution of the catalyst on the surface of the carbon support. A functionalized carbon support allows better dispersion of the catalyst nanoparticles, which can reduce the aggregation of metal nanoparticles and, consequently, improve the catalyst performance.1 Graphene is single-atomic-layer-thick carbon atoms arranged in a hexagonal lattice, which is the thinnest catalyst support for Pt catalyst nanoparticles. Graphene has many advantages over conventional carbon black catalyst support, like high electronic conductivity, surface area, mechanical strength, and excellent stability.2 All of these unique properties make the graphene as an ideal candidate for Pt catalyst support in polymer electrolyte fuel cells (PEFCs).3 In this work, covalently-functionalized graphene with polybenzimidazole (PBI) was employed as the catalyst support. The Pt nanoparticles were uniformed deposited onto graphene/PBI due to a strong interaction between PBI and Pt. Such Pt catalyst supported on the PBI grafted graphenes will benefit the MEA for PBI membrane based PEMFCs. The synthesized catalysts were characterized using rotating disk electrode (RDE) for their elctrocatalytic performance.
The Cyclic voltammetry (CV) curves of graphene/PBI supported Pt catalyst at a scan rate of 20 mV/s in N2-saturated 0.1 M HClO4 is shown in Figure 1. The electrochemical active surface area (ECSA) was calculated to be about 55 m2
Pt/gPt, which is comparable with that of commercial E-TEK Pt/C catalyst (58 m2
Pt/gPt). The high ECSA value suggests the uniform distribution of Pt on the surface of graphene/PBI. Accelerated degradation tests (ADT) were also evaluated by monitoring the changes in electrochemical surface area during voltage cycling between 0.6 V and 1.2 V at a scan rate of 20 mV/s in N2-saturated 0.1 M HClO4. After 1000 cycles, a relatively surface area loss of more than 81% was observed in commercial catalyst. In comparison, the relative surface area loss of graphene/PBI supported Pt catalyst was 57%. The increase in the stability of catalyst may result from the strong binding of Pt nanoparticles onto PBI-grafted graphene. In conclusion, the high ECSA and excellent durability of graphene/PBI supported Pt catalyst illustrates the advantage of polybenzimidazole-grafted graphene as a catalyst support in PEMFCs.
RuO2 Nanosheet Modified Pt-Based Catalysts as CO Tolerant PEFC Anode
Authors: Sugimoto Wataru , Takimoto Daisuke , Ohnishi Tomohiro 
Published: February 2020

PtRu/C are presently used as the anode catalyst for residential polymer electrolyte fuel cells. Anode catalysts with increased CO tolerance is desired since trace amounts of CO residing in reformates poisons the catalysts. In addition, catalyst degradation due to gradual loss of Ru is known to occur due to start/stop cycles. Thus efforts have been made to develop CO-tolerant electrocatalysts with high durability. The addition of nanostructured oxides has shown some promising results. In an earlier study, the authors showed that the addition of oxide nanosheets to carbon supported Pt-based catalysts can act as co-catalysts for the oxidation of adsorbed CO and enhance the durability [1-3]. Here we have studied catalyst activity and durability of PtxRuy/C catalysts modified with RuO2.1 nanosheets (RuO2.1ns) towards the hydrogen oxidation reaction in the presence of CO.
RuO2.1ns were derived from layered K0.2RuO2.1.nH2O [4]. Commercially available PtxRuy/C were modified with RuO2.1ns following previously described methods [5,6]. Catalytic activity was measured using rotating disk electrodes in 0.1 M HClO4 (25oC) in pure H2 (j(H2)) or 300 ppm CO/H2 (j(CO/H2)). Chronoamperometry was conducted at 20 mV vs RHE at 400 rpm.
The composite catalyst RuO2.1ns-Pt/C had the same ECSA and j(H2) value as Pt/C, indicating that RuO2.1ns does not impede H2 diffusion to the Pt surface. The j(CO/H2) value of RuO2.1ns-Pt/C was 18% higher than Pt/C.
The j(CO/H2) value of RuO2.1ns-PtRu/C after 1000 consecutive cycles between 0.05 and 0.4 V vs. RHE (v = 100 mV/s) was compared with Pt2Ru3/C. The initial j(CO/H2) of RuO2.1ns-PtRu/C was similar to PtRu/C and Pt2Ru3/C. After cycling, the j(CO/H2) of RuO2.1ns-PtRu/C was 20% higher than commercial catalysts.
This work was supported in part by the “Polymer Electrolyte Fuel Cell Program” from the New Energy and Industrial Technology Development Organization (NEDO), Japan.
[1] W. Sugimoto, T. Saida, Y. Takasu, Electrochem. Commun., 8, 411 (2006).
[2] T. Saida, W. Sugimoto, Electrochim. Acta, 55, 857 (2010).
[3] T. Saida, N. Ogiwara, Y. Takasu, W. Sugimoto, J. Phys. Chem. C, 114, 13390 (2010).
[4] W. Sugimoto, H. Iwata, Y. Yasunaga, Y. Murakami, Y. Takasu, Angew. Chem. Int. Ed.,42, 4092 (2003).
[5] D. Takimoto, C. Chauvin, W. Sugimoto, Electrochem. Commun, 33, 123 (2013).
[6] C. Chauvin, T. Saida W. Sugimoto, J. Electrochem. Soc., 161, F318 (2014).
Fabrication of Metal Nanowires Containing Highly Controllable Nanospaces
Authors: Sada Takao , Fujigaya Tsuyohiko , Nakashima Naotoshi 
Published: February 2020

Hollow nanostructures are of scientific and technological interest in the broad applications due to their ability to interact with other materials not only at their surfaces, to modulate refractive index, to improve the catalytic activity and to lower the density of nanostructures [1]. To prepare hollow structures, various methods such as versatile template methods based on the removal of sacrificial template [2] and simple templateless method [3] have been developed and enable to incorporate the void space or nanospaces into various nanostructures such as the nanosphene, nanocubes, nanorods and nanowires. Among these nanostructures, porous nanowires have much attention in the many field because they acquire the above advantages of hollow structures as well as the advantage of 1 D structures [4]. On the other hand, the precise control of pore size, volume and density in arbitrary structures is important because the size, volume and density directly determine the new ability depending on the nanospaces to provide the desired functions. Herein, we report the facile, high-throughput and novel route to fabricate the metal nanowires containing highly controllable nanospaces.
The metal nanowires containing highly controllable nanospaces were fabricated by the template method based on the removal of sacrificial template. We choose Nickel (Ni) as the metal and Silver (Ag) as the sacrificial template. We confirmed the Ni nanowires containing highly controllable Ag segment were fabricated by the pulsed electrodeposition in Anodic Aluminum oxide template. After etching the Ag segment, we clearly observed the Ni nanowires containing highly controllable nanospaces. By taking the advantage of the well controllability of the electroplating conditions such as the time of the deposition and the concentration of the plating solution, we found the size and the pitch of the hollowed segments were successfully controlled.
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2004, 304, 711.
[4] H. Jiang et al., Chemical Communications
2012, 48, 4465.
Enhancement of Electron Transfer Rates in Iodine/Iodide Ionic Liquid through Catalyzing the Chemical Step of I-I Bond Splitting: Development of Semi-Solid Redox Electrolyte Capable of Fast Charge Propagation
Authors: Rutkowska Iwona Agnieszka , Orlowska Justyna M. , Marks Diana , Kulesza Pawel J. 
Published: February 2020

The ability of platinum nanostructures to induce splitting of I-I bond in the iodine molecule is explored here to enhance electron transfers in the iodine/iodide redox couple and thus to accelerate charge transport in the respective room-temperature 1,3-dialkylimidazolium cation based ionic liquid. There has been growing recent interest in room-temperature ionic liquids, especially those with 1,3-dialkylimidazolium cations due to their such important features as negligible vapor pressure, high ionic conductivity and thermal stability, fairly wide electrochemical window, and ability to dissolve organic and inorganic solutes. The resulting redox-conducting electrolytes have several advantages: high conductivity, low vapor pressure, high iodide concentration and good electrochemical stability. Among disadvantages is their high viscosity that certainly contributes to the low diffusion coefficient of the oxidized form of the redox couple if the charge transport mechanism is truly physical. It was established that platinum induces electron transfers within the iodine/iodide redox system. Strong interactions of Pt or Pd with iodide or iodine were also postulated. Formation of the monolayer type coverages (on platinum or palladium) of strongly adsorbed monoatomic iodine together with weakly bound electroactive iodine/iodide was also postulated. By using solid-state voltammetric (both sandwich-type and microelectrode based) methodology, we demonstrate in the present work that effective (apparent) diffusion coefficients have significantly increased upon incorporation of the iodine-modified Pt or Pd nanoparticles and, in particular, the carbon-nanotube (multi-walled) supported iodine-modified Pt nanostructures. The Dye Sensitized Solar Cell utilizing the dye-covered TiO2 and the iodine/iodide ionic liquid electrolyte admixed with the iodine-modifed Pt based nanostructures has yielded reasonably higher efficiencies and better physicochemical parameters in comparison to the analogous Pt-free system.
In the present work, we explore the respective interfacial (electrocatalytic) phenomena on nanostructured platinum or palladium (namely Pt or Pd nanoparticles that three-dimensionally distributed in the electrolyte phase), and we utilize them to enhance iodine/iodide electron transfers and to develop systems capable of fast charge propagation. To further improve charge distribution within the redox-conducting electrolyte, we have also introduced multi-walled carbon nanotubes (as supports for dispersed iodine modified Pt nanoparticles) into our hybrid system.
Examining the Electrodeposition Mechanism of Manganese Dioxide Using In-Situ Small Angle X-ray Scattering
Authors: Donne Scott W , Dose Wesley M , Dupont Madeleine F 
Published: February 2020

Manganese dioxide thin films, produced by anodic electrodeposition, have been found to exhibit extremely high specific capacitance. However, their capacitive performance decreases markedly as the film thickness increases, so despite exhibiting specific capacitance values of up to 2000 F/g (for extremely thin films), their applications are limited due to their low volumetric capacitance.
The enhanced performance of thin films is largely due to their high specific surface area and conductivity, both of which decrease as the film thickness increases. Improving the performance of thicker films requires synthesis methods in which the morphology of the films can be tailored to optimise surface area and conductivity. To achieve this, the mechanism by which manganese dioxide is electrodeposited must be fully understood.
In this work, manganese dioxide was deposited onto a platinum electrode from a solution of MnSO4 in H2SO4. The deposition process was examined in-situ using small angle x-ray scattering (SAXS) using a synchrotron x-ray beam.
SAXS analysis was used characterise the material at different stages throughout the deposition. Features such as the pore size and particle size and shape were obtained from the data, showing how the morphology of the film changes as deposition is occurring. The deposition solution and deposition potential were varied in order to find the optimum deposition conditions required to create high performance thin film capacitors.
The performance of the thin films was analysed using standard electrochemical techniques including cyclic voltammetry and constant current charge discharge.
Electrochemical Study of the Interaction between Silicon n–type (100) and Hydroxyl Radicals
Authors: Muñoz Eduardo Carlo , Heyser Cristopher Alejandro , Hasse Ulrich , Scholz Fritz 
Published: February 2020

Semiconductor materials offer electronic properties that make them promising for being employed in the molecules detection in different environments. The present study proposes the analysis of changes in electrochemical responses of crystalline silicon (n–Si) after the interaction with hydroxyl radicals (•OH) in aqueous media.
In a first stage, the synthesis of hydroxyl radicals was done by means two procedures: (i) Fenton reaction and (ii) H2O2 photochemical decomposition using a UV digester for this purpose. Variables in these processes were time and hydrogen peroxide concentration in order to determine the dependence of these parameters on silicon–hydroxyl radical interaction.
After each immersion in radicals (separately both methods •OH of generation), it was performed a chemical cleaning treatment on silicon, which consisted: i) without further treatment; ii) HCl treatment or iii) HF treatment. This last was done to avoid the presence of silicon oxide (SiO2) on the semiconductor surface. Subsequently, n–Si was placed in a three electrodes cell: silicon as working electrode, Ag / AgCl, KCl (saturated) as a reference electrode (0.197 V vs SHE) and a platinum counter electrode. After were registered the corresponding voltammograms in a potassium chloride (KCl 0.1 M) solution at different pH values. In order to study the pH dependence on the interaction between substrate – reactive species (Si – •OH) were analyzed the current and the peak potential shift for each experimental conditions. Finally, Atomic Force Microscopy (AFM) was done to observe morphological changes in the substrate surface.
Ultrafast Anodic Growth of TiO2-Nanotubes with Semi-Metallic Properties
Authors: Hahn Robert , Schmuki P. , Kirchgeorg Robin 
Published: February 2020

Self organized nanotubular structures of transition metal oxides grown on their metallic substrates, especially titanium [1], have attracted great scientific and technological interest due to the possibility to exploit their functional properties (such in photo-catalysis, electro-catalysis, solar energy conversion and as host for Li storage) in a nanotubular morphology. In contrast to the conventional way to grow anodic TiO2 nanotubes, which is an optimized electrochemical treatment of Ti in fluoride containing electrolyte (for an overview see [2]) this work reports on the growth of nanotubes by so-called RBA (rapid breakdown anodization).[3] This nanotube growth-process is in comparison extremely fast (seconds instead of hours) and leads to surface coatings consisting of dense packed bundles of nanotubes with very high aspect ratios (tube length up to 50 micrometer, tube diameter of ~40 nanometer). In addition, this method provides a new route for an insitu electrochemical doping during the growth of TiO2 nanotubular layers with various transition metals to adjust i.e. the photocatalytic activity [4]. The second part of the presentation will demonstrate that alternatively the electronic and optical properties [5] of these TiO2 nanotubes can be significantly modified, showing semi-metallic behavior by a high temperature reduction treatment in acethylene or ammonia creating a suitable platform for highly conductive surface area electrodes which is important i.e. sensing applications. [6]

Literature:

[1] V. Zwilling, M. Aucouturier, E. Darque-Ceretti, Electrochim. Acta, 45, 921 (1999).
[2] S. Berger, R. Hahn, P. Roy, P. Schmuki Phys. Status Solidi B247, 10, 2424 (2010).
[3] R. Hahn, J. M. Macak, P. Schmuki, Electrochem. Commun.,9, 947 (2007).
[4] M. Stark, R. Hahn, M.S. Killian, P. Schmuki Catal. Sci. Technol., 3, 1765 (2013).
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Atomic-Layer Electroless Deposition on Noble Metal Powders
Authors: Robinson David B. , Cappillino Patrick J. , Buffleben George M. , Salloum Maher , Benson David M. , Stickney John Lewellen 
Published: February 2020

Palladium has important applications in an array of fields including hydrogen storage and sensing, chemical catalysis and fuel cells. It offers high volumetric power density in metal hydride batteries and pseudocapacitors. However, the rates of hydride formation and hydrogen release in such applications are often limited by the high stability of the surface hydride formed on Pd. Theoretical and experimental reports suggest that adlayers of metals that form weaker surface Pd-H interactions can destabilize the surface hydride, which should facilitate hydrogen transport.
We have developed a room-temperature electroless atomic layer deposition (ALD) technique in which we grow such layers on palladium powder. This is in contrast to electrochemical ALD, which requires applying a current to a substrate, and to gas-phase ALD, which requires elevated temperatures that can damage some substrates. Exposing a suspension of powder to dilute hydrogen/nitrogen gas mixtures causes a surface hydride to form. Subsequent addition of a solution containing noble metal salts displaces the surface hydride with the reduced metal in a surface-limited reaction. This process can be repeated, and the thickness of the surface coverage increases, as shown by X-ray photoelectron spectroscopy.
This technique requires no specialized equipment, and makes use of benign reagents. It is surface-limited in nature, but is not limited to an electrode. This confers important advantages of high scalability and compatibility with complex surface topologies; conductive substrates are not required. We believe that this versatile technique could be widely applied by synthetic chemists to take advantage of enhanced catalytic properties of near-surface alloys.
In addition to details on the preparation and characterization of Pd powder with adlayers of other noble metals, we will show evidence of enhanced hydrogen transport in these samples. A kinetic model for this process that includes gas flow, solid-state hydrogen diffusion and surface hydride formation will be presented.
Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND2013-8925A