bluuebunny/crossref_metadata_2025_split huggingface dataset:
Decoration of Vanadium Pentoxide on Conductive Carbon Nanotube Framework As Electroactive Materials for Aqueous Supercapacitors
Authors: Lin Jeng-Yu , Lin Shih-Yu 
Published: February 2020

Supercapacitors (SCs) have been regarded as energy-storage devices that performance between conventional capacitors and batteries. They commonly have higher energy densities, deliver higher power densities, long cycling life and faster charge/discharge rates than conventional batteries. The charge storage mechanisms of SCs are generally divided into the following two types. The one is electric double-layer capacitors (EDLCs) which originates from the charge accumulation process at the electrode/electrolyte interface, and the other type is pseudocapacitors in which the charge storage mechanisms occurs through the faradic redox reactions.
Among the transition-metal oxides, vanadium pentoxide (V2O5) has layered structure, the satisfactory charge storage capacity, a modest electronic conductivity, unique advantages of high energy density and wide potential window arising from its various vanadium oxidation states. In this work, we successfully decorated V2O5 thin layer on the surface of conductive carbon nanotubes (CNTs), designated as CNT@V2O5, by using pulsed-mode electrodeposition. It was found that the as-deposited V2O5 thin film is with nano-crystalline nature and the surface of the CNTs is evenly deposited with it. The as-deposited CNT@V2O5 electrode can reveal an enhanced discharge capacitance of 198 F/g at current density of 1 A/g in 2 M NaNO3 aqueous electrolyte.
MnCo Layered Double Hydroxide Based Pseudocapacitor: Effect of Morphology and Electrochemical Cycling
Authors: Patil Dipali S. , Ryu Jongwon , Pawar Sachin A. , Shin Jae Cheol , Kim Hyo Jin 
Published: February 2020

Layered double hydroxides (LDHs) attract considerable attention for use in supercapacitors owing to their unique features such as good anion exchange abilities, high redox activities, easily tunable chemical compositions, high chemical stabilities, and large surface areas. Among the LDHs, MnCo-LDH, CoAl-LDH, and NiMn-LDH are very promising electrode materials for supercapacitors as a class of two-dimensional metal hydroxides. MnCo-LDH is the most desirable electrode material for energy storage applications in the LDH class, as cobalt can be introduced in the LDH to improve the conductivity of the electrode material; Co2+ can be oxidized to the conductive CoOOH during the electrochemical reactions. Similarly, the introduction of manganese helps improve the electrochemical activity owing to its multiple oxidation states.
We report a stepwise morphological evolution of MnCo-layered double hydroxide (LDH) cubes with the hydrothermal reaction time. The electrochemical performance of the fabricated electrode at each step was studied in detail. The obtained MnCo-LDH exhibited maximum areal capacitances of 3.17 Fcm-2 (at a scan rate of 5 mVs-1) and 3.78 Fcm-2 (at an applied current of 3 mA), good rate capability (74% at a scan rate of 100 mVs-1), and excellent energy efficiency (80% at an applied current of 4.5 mA). The electrochemical performances of all synthesized electrodes were enhanced during the electrochemical cycling, which led to morphological modifications. In addition, for practical applications, we fabricated a symmetric supercapacitor based on the MnCo-LDH electrode and studied its electrochemical performance in detail.

Keywords: MnCo, Layered double hydroxide, electrochemical cycling, pseudo-capacitor, hydrothermal.
On-Chip Microsupercapacitors Using Ultrathin Lipon Film
Authors: Sallaz Valentin , Oukassi Sami , Poulet Sylvain , Voiron Frédéric , Bedjaoui Messaoud , Salot Raphaël , Berardan David 
Published: February 2020

On-chip solid-state micro-supercapacitors (MSCs) have been the center of massive researches over the recent years due to their wide range of applications (wearables, IoT, etc.), and the unremitting need for miniaturization and high electrical performances1. Moreover, MSC are known to gather high power density and extremely long cycle life2. In particular, the use of stable solid-state electrolytes in MSC is required to overcome safety issues (electrochemical and temperature instabilities) and enable easy packaging for on-chip integration3.
Lithium phosphorous oxinitride (LiPON) solid-state electrolyte has aroused a growing interest for MSCs due to its well-known excellent electrochemical properties (ionic conductivity, potential and temperature stability, etc.)4. Furthermore, the recently proved feasibility of ultrathin and conformal films deposition5,6 makes LiPON a particularly interesting candidate for energy storage solutions with high aspect ratio architectures. To the best of our knowledge, no study has reported on the use of ALD LiPON for MSCs.
In this work, we propose a thorough study of a 2D-planar ultrathin LiPON film for inorganic solid-state on-chip MSC. We obtained an uniform and homogeneous 10nm thick LiPON from the LiOtBu-DEPA chemical reaction. The elemental composition of the as deposited LiPON is determined by X-ray Photoelectron Spectroscopy as Li1.75PO2.5N0.6. The associated ionic conductivity is calculated around 10-8 S/cm at 25°C, and an activation energy of 0.62 eV is extracted using Electrochemical Impedance Spectroscopy within 20-50°C range.
TiN/LiPON/Ti MIM structures have been considered to characterize our MSC. The fabricated device exhibits typical capacitance values as high as 100 µF/cm² for scan rates up to 1 V/s. The capacitive and faradaic dependences of MSC will be discussed. A good cycling ability (>103 cycles) within the 0 – 3V voltage range is also recorded by applying a constant current of 100 µA/cm². Rate dependence and voltage stability window of MSC will also be reported.
References:
1. F. Béguin, V. Presser, A. Balducci and E. Frackowiak, 2014, 2219–2251.
2. N. A. Kyeremateng, T. Brousse and D. Pech, Nat. Nanotechnol., 2016, 12, 7–15.
3. Y. Huang, Y. Huang, M. Zhu, W. Meng, Z. Pei, C. Liu, H. Hu and C. Zhi, ACS Nano, 2015, 9, 6242–6251.
4. L. Le Van-Jodin, F. Ducroquet, F. Sabary and I. Chevalier, Solid State Ionics, 2013, 253, 151–156.
5. T. Göhlert, P. F. Siles, T. Päßler, R. Sommer, S. Baunack, S. Oswald and O. G. Schmidt, Nano Energy, 2017, 33, 387–392.
6. A. J. Pearse, T. E. Schmitt, E. J. Fuller, F. El-Gabaly, C. F. Lin, K. Gerasopoulos, A. C. Kozen, A. A. Talin, G. Rubloff and K. E. Gregorczyk, Chem.
Mater., 2017, 29, 3740–3753.

Figure 1
Perforation Optimization of DMFC Anode Porous Medium
Authors: Alrashidi Abdullah , Liu Hongtan , Zhang Xu 
Published: February 2020

Carbon Dioxide management is essential to the development of Direct Methanol Fuel Cell Anode. CO2 bubbles evolution at the anode can create large mass transport loss and block the sites where the triple phase boundary occurs for the electrochemical reaction. The gas can be trapped in the Gas diffusion layer (GDL) and block the channels from the incoming fuel [1-2]. Researchers have studied the mechanism and the dynamics by visualizations of how CO2 bubbles evolve from the catalyst layers [3-5]. Some studies have been done to the anode structure to improve the performances by modifying the material, wettability, porosity and thickness [6-8]. However, disagreements have been confirmed from different design aspects to whether those modifications reduce the mass transport loss or not [9-11]. In this study, pathways/perforations were created by laser perforating the Gas Diffusion layer (GDL) to enhance the mass transport from and to the catalyst layer. Results have shown superiority of the perforated GDL over the conventional GDL. Further optimization of the perforation diameter, the spacing along the lateral and channel directions have been accomplished. First, the perforation diameter size was investigated with minimum number of holes, 16 holes, spaced with 2 millimeters in lateral and channel directions over the 1 cm^2 active area of the electrode, as can be seen in Figure 1A. The 60-micron diameter showed little improvement over the virgin GDL while further increase of the diameter caused massive mass transport loss. Secondly, further optimization of the spacing in the lateral and channel directions in Figure 1B, it was found that the 60-micron diameter with 1 millimeter in lateral spacing and 2 millimeter in channel spacing increased the maximum power density by roughly 30% compared to virgin GDL.
Figure1: A) Different perforation diameter ranging from 60-500 micron with 16 holes; B) Spacing optimization in lateral and channel directions.

Figure 1
Electrocatalytic Performance of Palladium-Based Electrocatalysts Supported on Carbon Nanotubes for Formic Acid Oxidation
Authors: Juárez-Marmolejo Leticia , Montes de Oca-Yemha Maria Guadalupe , Palomar-Pardavé Manuel , Romero-Romo Mario Alberto , Ezeta-Mejía Araceli , Arce-Estrada Elsa , Pérez-Rodríguez Sara , Lázaro Maria Jesus 
Published: February 2020

Recently, the study of carbon supports like carbon nanotubes (CNT) has intensified. The interaction between the support and nanoparticles improved the efficiency and durability of fuel cells (FCs), decreasing the electrocatalyst poisoning and in some cases it can modify the particle size. Palladium based nanostructured electrocatalysts, supported on glassy carbon [1], carbon black Vulcan [2] and CNT [3] are used in electrochemical energy storage devices such as FCs.
In the present work, Pd and PdFe nanoparticles supported on CNT with and without functionalization (CNT and CNTox) were used for Formic Acid Oxidation Reaction (FAOR) in acid media. Electrocatalysts were synthesized by the borohydride reduction method with a metal loading of 20 wt.%. The CNTs were synthesized by the methane catalytic decomposition, and subjected to an oxidation treatment with nitric acid, named as CNTox. The morphology, composition and structural properties were studied by Transmission Electron Microscopy (TEM), Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX) and X-Ray Diffraction (XRD). The FAOR was evaluated in acid media in a conventional three-electrode cell by means of cyclic voltammetry and chronoamperometry. From the steady state current density it was found that that Pd and PdFe supported at CNTox allowed improving the catalytic activity in comparison with the non-oxidized support as shown in Figure and Table 1.
Figure 1.Potentiostatic transients of the Pd base electrocatalysts supported at CNT and CNTox at 0.4 V for 900 seconds and Table 1. Comparison of steady-state current density of synthesized electrocatalysts to the potential of 0.4 V.

I.E. Espino-López, M. Romero-Romo, M.G. Montes de Oca-Yemha, P. Morales-Gil, M.T. Ramírez-Silva, J. Mostany, M. Palomar-Pardavé. Journal of The Electrochemical Society 166 (2019) D3205.

L. Juárez-Marmolejo, S. Pérez-Rodríguez, M.G. Montes de Oca-Yemha, M. Palomar-Pardavé, M. Romero-Romo, A. Ezeta-Mejía, P. Morales-Gil, M.V. Martínez-Huerta, M.J. Lázaro. International Journal of Hydrogen Energy 44 (2019) 1640.

H. Yan, Z. Bai, S. Chao, Q. Cui, L. Niu, L. Yang, J. Qiao, K. Jiang, Ionics 20 (2014) 259.

Figure 1
The First Durable Imidazolium-Based Radiation Grafted Anion Exchange Membranes for Alkaline Fuel Cells: The Impact of Water Management
Authors: Mahmoud Ahmed Mohamed Ahmed , Yoshimura Kimio , Hiroki Akihiro , Maekawa Yasunari 
Published: February 2020

Recently, Radiation grafted anion exchange membranes (AEM) gained increasing interest for alkaline fuel cell applications due to their high performance such as the highest power density ever reported for alkaline fuel cells (>2W/cm2). 1 However, their durability under operating fuel cell conditions still the biggest challenge.2 In our group, several radiation grafted AEMs, having several imidizalium-based graft-polymers consisting of N-vinyl (NVIm), 2-methyl-1-vinyl- (NVMIm), 2-methyl-4-vinyl- (4VMIm), and 2-(4-ethenylphenyl)-imidazolium (2StIm) graft-polymers, have been developed.3,4 In this work, the durability of the membrane-electrode-assembly (MEA) consisting imidazolium based radiation grafting AEMs under the supply of H2 and O2 at 60 °C was investigated in comparison to the MAE with common benzyl trimethylammonium (BTMA) based membranes. The core of this study is to investigate the effect of water management and specifically the dew point of the flow gas at anode and cathode sides on the performance and durability of imidazolium based membranes. For example, by tuning the due points for NVMIm-AEM the maximum power density increased from 115 to 200 mW/cm2. On the other hand, In spite of the low durability of 4VMIm membranes under in-situ alkaline durability in solution,5 the 4VMIm retained 75 % of the initial voltage after 240 h under fuel cell conditions, that was more durable than BTMA-based MEA (Figure 1). This study reveals the main role of water management of AEMs not only on the performance but also on the membrane durability. The study discloses an alternative durable AEMs for the new generation of alkaline fuel cells and other energy applications.
References:
1- L. Wang, M. Bellini, H. A. Miller, J. R. Varcoe J. Mater. Chem. A
2018, 6, 15404.
2- A. M. A. Mahmoud, K. Miyatake J. Mater. Chem. A.
2018,6, 15456.
3- K. Yoshimura, A. Hiroki, H-C. Yu, Y. Zhao, H. Shishitani, S. Yamaguchi, H. Tanaka, Y. Maekawa J. Memb. Sci.
2019, 573, 403-410.
4- Maekawa et.al, Soft Matter, 2018,14, 9118-9131.
5- Maekawa et. al, ECS Trans.
2017, 80, 8, 979-987.

Figure 1
Sol-Gel Assisted Synthesis of Encased Polymer Electrolyte Fuel Cell Cathode Catalysts
Authors: Farghaly Ahmed A. , Myers Deborah J. 
Published: February 2020

State-of-the-art polymer electrolyte fuel cell (PEFC) cathode catalyst layers (CCLs) are composites of proton-conducting perfluorosulfonic acid (PFSA) ionomer and platinum alloy catalyst particles. The PFSA is in the form of agglomerates dispersed throughout the CCL and also as a thin film coating the carbon support and platinum alloy particle surface.1 The thin PFSA film on the catalyst surface has been shown to both decrease oxygen reduction reaction (ORR) activity and cause high oxygen transport resistance.2-4 Such ionomer-catalyst surface interactions can negatively affect both PEFC performance and durability.

This talk will describe an approach to addressing the issues of ionomer poisoning of ORR activity, local oxygen transport resistance, and the lack of PEFC cathode performance durability by encasing Pt and Pt alloy catalyst particles in the cavity of a 3D porous inorganic framework. Platinum (Pt) and platinum alloys (PtxMy) encased in 3D porous inorganic nanocrystal catalysts have been prepared by a sol-gel process combined with chemical reduction. Catalysts with 5, 10 and 20 Pt/PtxMy wt% have been prepared and their ORR activity has been evaluated using the thin-film rotating disk electrode (TF-RDE) technique. The platinum content in the encased catalysts has been determined using inductively coupled plasma mass spectrometry (ICP-MS) and X-ray fluorescence (XRF). The morphology, crystal structure, and spatial distributed of the metal nanoparticles have been characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and energy-dispersive X-ray spectroscopy, respectively.
References

C. Cetinbas, R. K. Ahluwalia, N. N. Kariuki, and D.J. Myers, J. Electrochem. Soc.,
165(13), F1051 (2018).

Kongkanand and M. F. Mathias, J. Phys. Chem. Lett., 7, 1127 (2016).

Subbaraman, D. Strmcnik, A. P. Paulikas, V. R. Stamenkovic, and N. M. Markovic, Chemphyschem, 11, 2825 (2010).

Subbaraman, D. Strmcnik, V. Stamenkovic, and N. M. Markovic, J. Phys. Chem. C, 114 8414 (2010).

Acknowledgements
This work was supported by the United States Department of Energy, Energy Efficiency and Renewable Energy, Fuel Cell Technologies Office. Argonne is a U.S. Department of Energy Office of Science Laboratory operated under Contract No. DE-AC02-06CH11357 by UChicago Argonne, LLC.
Effect of Carbon Support on Fe-N3/C Model Active Site for the Oxygen Reduction Reaction
Authors: Fruehwald Holly M , Zenkina Olena V , Easton E. Bradley 
Published: February 2020

Non-precious metal catalysts for the oxygen reduction reaction (ORR) are of great interest for fuel cell technology due to their low cost and wide availability of materials. Development of these catalysts has been a constantly growing area. However, there have been very few literature reports that provide insights into the precise nature of the structure and geometry of the catalytically active sites formed in these materials.
In the current literature, the most commonly proposed catalytically active site(s) for ORR corresponds to Fe-N2+2/C geometry. This is typically produced through a high temperature pyrolysis step to obtain this desired configuration in the active sites[1]. However, the pyrolysis step is very disadvantageous due to the production of a distribution of nitrogen functional groups on the surface which can negatively affect the activity of the catalyst, since only nitrogen functionalities with specified geometry are considered to be the most active for ORR[2,3]. As well, high temperature treatments increase the cost of production, and can be quite energy demanding. Thus, high-temperature treatment makes it difficult to design a surface rich in a specific active site for the desired application.
The work presented here demonstrates a model system for a non-precious metal catalyst for the ORR achieved by covalently functionalizing a conventional carbon support with a nitrogen-rich ligand. The terpyridine ligand geometry allows the formation of well-defined active catalytic sites when covalently attaching an N3/C functionality to the carbon surface, leaving exposed the most active sites for the ORR. Room temperature metal-ligand coordination with Fe results in desired Fe-N3/C moieties on the surface. We demonstrate that this system can be prepared using mild reaction conditions and does not require high temperature treatment for improved activity, in fact heat treatment to this system was detrimental to the activity. The Fe-N3/C support was subjected to electrochemical studies in both acidic and basic aqueous media and demonstrates the potential of this system to be used as a model for an Fe-N3/C active site for ORR.

References

[1] M. Lefèvre, E. Proietti, F. Jaouen, J.-P. Dodelet, Science
2009, 324, 71-74.
[2] F. Charreteur, F. Jaouen, S. Ruggeri, J.-P. Dodelet, Electrochimica acta
2008, 53, 2925-2938.
[3] H. M. Fruehwald, I. I. Ebralidze, O. V. Zenkina, E. B. Easton, ChemElectroChem
2019, 6, 1350.

Figure 1
Understanding Electrochemical Degradation of Polymer Electrolyte Fuel Cell Catalysts Using Time-Resolved Measurements
Authors: Kariuki Nancy N. , Papadias Dionissios D. , Myers Deborah J. , Ahluwalia Rajesh 
Published: February 2020

The catalysts of choice in polymer electrolyte fuel cells (PEFCs) remain Pt-based nanoparticles on high-surface-area carbon support. One critical challenge facing commercialization of this fuel cell is the gradual decline in performance during operation, mainly caused by the loss of electrochemical surface area (ECA) of the Pt or Pt alloy nanoparticles at the cathode and, if an alloy, loss of the base metal alloying component (e.g., Co, Ni, or Fe). In this respect, the understanding of the dominant mechanisms of the loss of ECA and loss of oxygen reduction activity, such as the electrochemical dissolution of Pt or the base metal, is of vital importance. Several mechanisms for dissolution of platinum have been proposed including direct Pt dissolution and electrochemical oxidation of the Pt surface atoms followed by chemical dissolution of the resulting Pt surface oxide. Our previous measurements on PtCo catalyst showed that degradation of PtCo/C catalysts due to Pt dissolution is greatly accelerated by the reduction of PtOx species formed at potentials >0.9 V and that accelerated Co loss is also associated with reduction of the oxides formed at >0.9 V. 1

This presentation will outline effects of type of Pt alloy catalyst (e.g., solid solution, ordered intermetallic, shape-controlled) on Pt and alloying element dissolution rates as a function of number of accelerated stress test cycles. Studies are performed to quantify the amount of dissolved base metal and Pt during potentiodynamic conditions in an electrochemical flow cell system connected to an inductively-coupled plasma-mass spectrometer (ICP-MS) capable of detecting trace concentrations (<ppb) of dissolved elements in solution. The electrochemical data combined with the ICP-MS data are used to evaluate the influence of various factors such as potential, potentiodynamic profile parameters (e.g., scan rate, upper and lower potential limits), atomic structure, and base metal content on the dissolution processes of alloy catalysts in acidic electrolytes at room temperature. Fundamental models will be developed to explain the mechanisms of degradation process for the various catalyst types under various potential conditions.
References

K. Ahluwalia, D. D. Papadias, N. Kariuki, J. K. Peng, X. P. Wang, Y. Tsai, D. Graczyk, and D. J. Myers, J Electrochem Soc, 165, F3024 (2018)

This work was supported by the U.S. Department of Energy, Energy Efficiency and Renewable Energy, Fuel Cell Technologies Office under the auspices of the Fuel Cell Performance and Durability Consortium (FC-PAD). Argonne National Laboratory is managed for the U.S Department of Energy by the University of Chicago Argonne, LLC, also under contract DE-AC-02-06CH11357.
Theoretical Prediction of the Distribution of Spin Moment on Metal-N-C Catalyst Embedded in Truncated Graphene Sheets
Authors: Oguz Ismail Can , Jaouen Frederic , Mineva Tzonka 
Published: February 2020

As a pristine graphene nanostructure, zigzag graphene nanoribbons (ZGNRs) has received considerable interest over the past decade due to the presence of polarizable edge states1. It has also been employed as a model system for non-precious metal catalysts since it can host a variety of active sites2. Among various classes of catalysts, metal (Me) and nitrogen co-doped graphene has been emerging as promising electrocatalysts in oxygen reduction reaction (ORR). Furthermore, it has also been shown that porphyrin-like Me vacancy embedded in graphene is more stable at edges than far-away from the edges3. In the light of those recent studies, the change of spin states on the edge and in the bulk caused by Fe and N co-doping is an essential factor to tune the electronic and magnetic states on graphene. Therefore, unraveling spin interactions between co-doped metal-nitrogen complex and edge states (illustrated in Fig. 1) can control the electronic conductivity of doped graphene sheets and electron density at metal active sites, which is essential for their applications in electrocatalysts.
In this work, the effect of nitrogen-metal and vacancies in the bulk and edge configurations on the spin polarization on graphene materials will be presented as obtained from two computational methodologies: plane waves and atomic-centered Gaussian functions. There are some drawbacks on each DFT code regarding magnetic calculations. Sensitivity of the value of total magnetic moment in VASP obtained from Bravais lattice depends on k-point sampling, smearing parameters and stress applied to unit cell. On the other hand, the initial spin moment guess on each atom is not implemented on deMon2k to be able to obtain anti-ferromagnetic states of graphene.
Finally, the ORR reactivity as a function of (a) the metal location in graphene and (b) the edge truncations will be discussed.

Figure 1:

Suppression of spin polarization in edge modification by Fe
N4

Acknowledgement: This work is supported by the LabEx CheMISyst ANR-10-LABX-05-01.

References

Son, Y.-W.; Cohen, M. L.; Louie, S. G. Half-metallic graphene nanoribbons. Nature
2006, 444, 347

Zitolo, A. et al. Identification of catalytic sites for oxygen reduction in iron- and nitrogen-doped graphene materials. Nature Materials
2015,
14, 937–942

Holby, E. F.; Taylor, C. D. Control of graphene nanoribbon vacancies by Fe and N dopants: Implications for catalysis. Appl. Phys. Lett.
2012,
101, 064102

Figure 1