bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ionic Functionalization of Polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene via Friedel-Crafts Bromoalkylation and Its Application for Anion Exchange Membranes
Authors: Jeon Jong Yeob , Mohanty Angela D , Tian Ding , Bae Chulsung 
Published: February 2020

A new post-functionalization method of polystyrene (PS) block of polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) is presented. Due to good chemical stability of backbone in alkaline condition, elastic mechanical property, nanoscale phase separation morphology, and commercial availability, SEBS is a promising candidate for preparation of anion exchange membranes (AEMs). Chloromethylation, the most frequently used reaction for AEM synthesis, of the PS block in SEBS generally results in low levels of functionalization or gelation.1, 2 To overcome these limitations our group has reported functionalization of SEBS for AEM applications using transition metal-catalyzed C-H borylation and Suzuki coupling reactions.3

Herein, we report another method “bromoalkylation” of aromatic rings at SEBS via the acid-catalyzed Friedel-Crafts alkylation of a tertiary alcohol. Compared to our previous report, this new synthetic route is much simple and does not require noble transition metals, affording the synthetic process more economical and scalable. Bromoalkylated tertiary alcohol is converted to a tertiary carbocation, which readily reacts with p electrons of the aromatic rings at PS block under acidic condition. Quaternary ammonium (QA) functionality and tether length between polymer backbone and cationic head groups were conveniently tunable by changing the structure of brominated tertiaryalcohols. A maximum of 80 mol. % of PS block could be functionalized.
A series of SEBS-based AEMs were prepared with different QA concentrations and tether lengths. The properties of membrane samples were investigated by comparing ion-exchange capacity (IEC), water uptake, OH- conductivity and morphology. Among them, SEBS-C3-TMA-0.8 (tether length, n=3; 80% of PS functionalization) has the highest IEC (1.62 mequiv g-1), and OH- conductivity of 93 mS cm-1 at 80 °C in water. Moreover, the IEC and OH-conductivity of all membranes were preserved after immersing them in 1 M NaOH at 80°C for 500 h.
1. Q. H. Zeng, Q. L. Liu, I. Broadwell, A. M. Zhu, Y. Xiong and X. P. Tu, J. Membr. Sci. 2010, 349, 237-243.
2. L. Sun, J. Guo, J. Zhou, Q. Xu, D. Chu and R. Chen, J. Power Sources 2012, 202, 70-77.
3. A. D. Mohanty, C. Y. Ryu, Y. S. Kim and C. Bae, Macromolecules 2015, 48, 7085-7095.

Figure 1
(Invited) Structured Electrochemical Materials Fabricated from Directed Self-Assembly of Block Copolymers and Advanced Lithography
Authors: Zhang Le , Cao Chi , Yakimov Alexandrina , Arges Christopher George 
Published: February 2020

In this first part of the talk, the process of directed self-assembly will be presented for controlling the microphase separated structure in block copolymer electrolytes (BCEs) with astonishing fidelity. Key results highlight that ionic conductivity of BCEs followed an exponential growth curve with respect to ionic domain connectivity. Conversely, small amounts of terminal defects of the ionic domains rendered no advantage in ionic conductivity for microphase separated systems over non-phase separated systems. Ionic domain alignment to electrode surfaces with a tortuosity of 1 yielded a 4 order of magnitude improvement in ionic conduction over anti-aligned ionic domains. The results suggest that ‘perfect’, long-range ordered structures are necessary for maximizing BCE ionic conductivity.
The second part of the talk presents our work on structured electrochemical interfaces for fuel cell and water electrolysis applications. The structured interfaces were prepared by conventional micropatterning and advanced block copolymer lithography. Patterned electrochemical interfaces provide greater interfacial area values that reduce charge-transfer resistances. However, increasing the interfacial area by patterning deeper into electrochemical materials (e.g., into the polymer electrolyte membrane) gave rise to large mass transfer related resistances that eventually offset gains from reduction in charge-transfer resistances. The talk will highlight appropriate design heuristics for fabricating patterned electrochemical interfaces that optimize fuel cell and electrolyzer thermodynamic performance.
(Invited) Kinetic Modeling of the Borohydride Oxidation Reaction (BOR) at Gold and Platinum Electrodes
Authors: Olu Pierre-Yves , Braesch Guillaume , Bonnefont Antoine , Savinova Elena R. , Chatenet Marian 
Published: February 2020

Due to their high theoretical energy density, direct borohydride fuel cells (DBFCs) are a promising alternative to proton exchange membrane fuel cells for mobile applications. However, the energy conversion efficiency of DBFCs is impeded by the hydrogen generation and escape from the anode upon operation. The hydrogen escape characteristics during the BOR depend strongly on the type of metal chosen as anode electrocatalyst, on the architecture of the catalyst layer and on the concentration of NaBH4 [1-4]. This shows the importance for further understanding of the BOR mechanism with regards to the influence of the experimental conditions on the reaction.
In this presentation, the results of recent experimental studies about the BOR on gold and platinum electrodes will be presented and discussed with the help of microkinetic modeling. The proposed kinetic model is able to reproduce the main features of electrochemical (rotating (ring-)disk electrode, RRDE) and differential electrochemical mass-spectrometry (DEMS) measurements for various concentrations of NaBH4 (5, 50 and 500 mM), and is in agreement with the results of DFT calculations and FTIR measurements [5-8]. These experimental findings enable to compare and discuss the BOR mechanism between Pt and Au surfaces accounting for the differences in hydrogen generation/oxidation during the BOR but also for the poisoning of the electrodes with adsorbed BOR intermediates.

This work was supported by the French ANR (project ANR-16-CE05-0009).

References

(1) Jusys, Z.; Behm, R. J. Electrochem. Commun.
2015, 60, 9.
(2) Freitas, K. S.; Concha, B. M.; Ticianelli, E. A.; Chatenet, M. Catal. Today
2011, 170, 110.
(3) Olu, P.-Y.; Job, N.; Chatenet, M. J. Power Sources
2016, 327, 235.
(4) Olu, P. Y.; Bonnefont, A.; Rouhet, M.; Bozdech, S.; Job, N.; Chatenet, M.; Savinova, E.Electrochim. Acta
2015,
179, 637.
(5) G. Rostamikia, M.J. Janik, J. Electrochem. Soc., 2009, 156 B86.
(6) G. Rostamikia, M.J. Janik, Electrochim. Acta,
2010, 55, 1175.
(7) B. Molina Concha, M. Chatenet, F. Maillard, E.A. Ticianelli, F.H.B. Lima, R.B. de Lima,Phys. Chem. Chem. Phys.,
2010, 12, 11507.
(8) B. Molina Concha, M. Chatenet, E.A. Ticianelli, F.H.B. Lima, J. Phys. Chem. C,
2011, 115 12439.
Hierarchical Titanium Nitride Nanostructures As Catalyst Scaffold for PEMFC Technology
Authors: Perego Andrea , Giuffredi Giorgio , Casalegno Andrea , DiFonzo Fabio 
Published: February 2020

To overcome the high cost of the catalyst in Direct Methanol Fuel Cell (DMFC) technology, research is moving towards the reduction in the Pt loading in the electrodes by increasing the electrochemical surface area. To date, the state of the art of catalyst supports is dominated by mesoporous carbon. It shows high conductivity but suffer from stability issues especially on long term operation. As shown in the literature, titanium nitride (TiN) has a metal-like conductivity with an outstanding chemical stability [1], and moreover, it is reported to be functional towards the oxidation of adsorbate CO on platinum active sites [2].
In this contribution, we report about TiN catalysts support with self-assembled, hierarchical mesoporous nanostructure, grown by Pulsed Laser Deposition. This approach controls the gas dynamics of the nanoclusters-inseminated supersonic jet to differentiate the resulting impaction deposition, affecting the growth of the film. Platinum is deposited by means of pulsed electrodeposition and it shows a peculiar lamellar structure, most likely due to the strong electric field on the nanostructures.
Electrochemical and physical characterization are performed, showing performances towards both methanol oxidation and oxygen reduction, and revealing information about the interaction between catalyst, scaffold and reactants.
We demonstrate that it is possible to obtain a catalyst support with large surface area whose morphology can be controlled at the nanoscale. Such as a support could be ideal for the highest platinum utilization, and for the metal loading reduction, since it has similar effects with respect to the metallic Ru in commercial DMFC catalysts with a much lower cost. Stability at high potential is also investigated, and so is the possibility to use the same material as a cathode exploiting the stability of the TiN.
These results show the potential of a PVD based technique that opens the doors of the nanoscale to the fabrication of high performing electrodes whose morphological and electrical properties are easily tuned. This approach holds promises for a consistent reduction in the metal loading in DMFC technology.
[1] M. Wittmer, B.Studer and H.Melchior, Journal of Applied Physics, 52, 5722 (1981)
[2] M. Roca-Ayats, G. Garcia, J.L. Galante, M.A. Peña and M.V. Martinez-Huerta, Journal of Physical Chemistry C 117, 20769-20777 (2013)

Figure 1
Improved Anode Catalyst for Formic Acid Fuel Cells
Authors: Pemberton Kailey D , Rice Cynthia A. 
Published: February 2020

The use of direct formic acid fuel cells (DFAFCs) in portable electronic devices can improve available power density and convenience, compared to today’s rechargeable batteries. Unfortunately, current DFAFC anode catalysts either have high parasitic overpotentials and/or deactivate over time. This deactivation causes a decrease in sustained performance of the catalyst over time.[1] A typical anode catalyst used in these DFAFC consists of carbon supported platinum nanoparticles with a sub-monolayer of bismuth (Pt/C-Bi).[2] Over time, bismuth is oxidized and lost from surface resulting in deactivation of the catalyst nanoparticles, which leads to the DFAFC losing performance.[3]
Bismuth at moderate Pt surface coverages promotes formic acid adsorption in the CH-down orientation through a combination of the third-body (steric) and electronic effects. When formic acid adsorbs in the CH-down orientation the direct reaction pathway is promoted bypassing the formation of strongly adsorbed reaction intermediates. The overpotentials associated with the direct reaction pathway are minimal, thereby elevating the power output of the DFAFCs.
The goal of this project is to explore stable alternative adsorbates to replace bismuth in order to maximize power density and durability of DFAFCs. Three-electrode electrochemical studies are performed on a polycrystalline Pt disk working electrode in 0.1M HClO4. Initial studies with citrate have demonstrated strong surface adsorption to Pt. The cyclic voltammograms in Figure 1 demonstrate that citrate blocks hydrogen adsorption/desorption sites on Pt and coverage is tailorable to that of a submonolayer of citrate. Linear sweep voltammetry in formic acid shows minimal electro-oxidation performance on pure Pt and a full monolayer of citrate. However, for a submonolayer of citrate the activation overpotential is reduced to 0.2 V vs. RHE due to the significant contribution to the direct reaction pathway.
References:
1. X. Yu and P.G. Pickup, Journal of Power Sources, 182, 124, (2008).
2. A.S. Bauskar and C.A. Rice, Electrochimica Acta, 93, 152, (2013).
3. A.O. Pistono, C.S. Burke, J.W. Cisco, C. Wilson, B.G. Adams, and C.A. Rice, ECS Electrochemistry Letters, 3, F65, (2014).

Figure 1
Porous Silver/Indium and Gold/Indium Electrocatalysts for Electrochemical Conversion of Carbon Dioxide
Authors: Lee Hyunju , Kim Hyenki , Ahn Sang Hyun 
Published: February 2020

As the use of fossil fuels increased, the global warming is becoming much serious problem by huge emission of CO2 to atmosphere. Thus, tremendous efforts have been conducted to reduce the concentration of CO2 in atmosphere. As one of the promising technologies, the electrochemical conversion of CO2 to useful products has been received a great attention because these products are able to be utilized in various industrial fields. Among the products, the production of CO is known to have an economical benefit because the market price of CO is relatively higher than other products. As the electrocatalysts, the silver and gold-based metals are commonly used to produce CO from the electrochemical reduction of CO2. However, the cost is an important criterion for CO2 conversion although these noble metals are highly active and selective for CO production. In this study, the porous copper foam was fabricated by two-step galvanostatic electrodeposition in order to obtain a large electrochemical surface area, and then indium electrodeposition was carried out on the top of copper foam to suppress the hydrogen evolution reaction which is known as competitive reaction with electrochemical CO2 reduction. Then porous indium was immersed in the electrolytes which contained noble metals precursor in order to decrease the amount of noble metal usage. The fabricated porous silver/indium and gold/indium were used as electrocatalysts for the CO2 conversion reaction. The obtained CO Faradaic efficiency was varied by the material properties of silver/indium and gold/indium catalysts such as morphology, roughness and surface composition.
(Invited) Tuning the Structure and Property of Electrode Materials of Lithium Battery
Authors: Li Jun-Tao , Huang Ling , Sun Shi-Gang 
Published: February 2020

Along with fast development of compact mobile electronic devices, electric vehicles and large scale electricity storage for renewable energies, the demand on lithium batteries for increasing their energy, power, safety and lowering their cost of become a focal issue in today’s society and R&D communities. It is well recognized that the performances of lithium battery depend strongly on electrode materials, and the structure, especially the surface structure, of electrode determines the density of active sites for Li conversion reaction and the channels for Li+ intercalation/deintercalation. Therefore, it is of crucial importance in controlling the transport kinetics of lithium ions and promoting the performances of lithium battery through tuning the structure of electrode materials.
This communication reports our recent progresses in tuning the surface structure and property of electrode materials. Different materials including nanostructured metal oxides, habit-tuned LNMO nanoplates, NCM hexagonal nanobricks, graphene-based sulfur and RuO2/MnO2 nanorods were designed and control-synthesized, and served as electrodes in lithium ion battery, lithium-sulfur battery and lithium-air battery. The results demonstrated clearly the significant enhancement of electrochemical performances of specific capacity, cycleability and rate property of the as-prepared electrode materials with well-defined structure. Besides the active materials of electrode, the guar gum binder that is a low-cost, environmentally friendly and multi-functional binder for the next generation lithium-ion batteries with high energy density has been developed and applied in both anode and cathode of lithium ion batteries.
Acknowledgements: This work was supported by NSFC (21621091,1373008).
References:
1. G. Z. Wei, X. Lu, F. S. Ke, L. Huang, J. T. Li, Z. X. Wang, Z. Y. Zhou, S. G. Sun, Adv. Mater., 2010, 22(39), 4364.
2. F. Fu, G.L. Xu, Q. Wang, Y.P. Deng, X. Li, J.T. Li, L. Huang, S.G. Sun, 2013, 1, 3860.
3. G.L. Xu, Y.F. Xu, J.C. Fang, F. Fu, H. Sun, L. Huang, S. Yang, S.G. Sun, ACS Applied Materials & Interface, 2013, 5, 6316-6323
4. G.L. Xu, Q. Wang, J.C. Fang, Y.F. Xu, J.T. Li, L. Huang, S.G. Sun, J. Mater. Chem. A, 2014, 2,19941.
5. J. Liu, Q. Zhang, T Zhang, J.T. Li, L. Huang, S.G. Sun, Adv. Funct. Mater. 2015, 25, 3599.
6. T. Zhang, J.T. Li, J. Liu, Y.P. Deng, Z.G.Wu, Z.W. Yin, D. Guo, L. Huang, S.G. Sun, Chem. Commun. 2016, 52, 4683.
7. Y.Q, Lu, J.T. Li, X.X. Peng, T Zhang, Y.P. Deng, Z.Y. Wu, L. Huang, X.D. Zhou, S.G. Sun, Electrochem. Commun. 2016, 72, 79.
8. Y.F. Xu, Y. Chen, G.L. Xu, X.R. Zhang, Z. Chen, J.T. Li, L. Huang, K. Amine, S.G. Sun, Nano Energy, 2016, 28, 63.
Chemical and Electrochemical Properties of La0.58Sr0.4Fe0.8Co0.2O3-
δ (LSCF) Thin Films upon Oxygen Reduction and Evolution Reactions
Authors: Pitscheider Simon , Machala Michael , Guan Zixuan , Chen Di , Hjelm Johan , Jacobsen Torben , Chueh William C , Mogensen Mogens Bjerg , Chatzichristodoulou Christodoulos 
Published: February 2020

The Oxygen Evolution and Oxygen Reduction Reactions (OER/ORR), occurring at the oxygen electrode of Solid Oxide Cells (SOCs) in the two possible ways of operation, require substantial overpotentials, therefore lowering the operating efficiency of the cells. The reaction mechanisms occurring at these electrodesare still not completely understood due to their complexity and localized character at the interfaces between different materials or between the gas atmosphere and the electrocatalyst, and need in situ techniques with very high chemical sensitivity, with the additional difficulty of probing the materials as close as possible to their realistic operating conditions.
In addition, the properties of LSCF are, despite numerous studies, still unclear in many aspects, despite LSCF being one of the state-of-the-art electrocatalysts used for SOCs. It is understood that the surface chemical composition deviates from the nominal bulk composition, and that secondary phases can segregate at the surfaces and interfaces during operation. Furthermore, the electrochemical properties such as Area Specific Resistance (ASR), oxygen exchange coefficient (kex), ASR activation energy (Ea) and pO2exponents for LSCF reported in the literature vary considerably.
This study aims to better understand the properties of LSCF, by combining the results of Electrochemical Impedance Spectroscopy (EIS) and Near-Ambient Pressure X-ray Photoelectron Spectroscopy (NAP-XPS) on model electrodes, both in polarized and unpolarized conditions. In particular, NAP-XPS studies of the surface chemistry evolution under operation, as well as the correlation between surface potential changes in relation to the applied overpotential are addressed, in an attempt to determine the real driving force for the oxygen reactions.
For this purpose, thin films of LSCF are deposited by Pulsed Laser Deposition (PLD) through shadow masks, in order to obtain well-defined electrode geometries with low risk of contamination, and subsequently tested both in highly clean EIS measuring setups and at the synchrotron beamline. The results of both kinds of experiments are correlated, the goal being a better understanding of the material’s properties under operation, as well as possible degradation phenomena.

Acknowledgements:

We gratefully acknowledge financial support from ECoProbe (DFF – 4005-00129) funded by the Danish Independent Research Council, Otto Mønsteds Fond (17-70-0196) and SUNCAT in collaboration with the Danish Agency for Science and Higher Education (7032-00001B)
Fabrication and Testing of Anode Supported Protonic Ceramic Fuel Cells in Biogas
Authors: Nasani Narendar , Pukazh Selvan D , Fagg Duncan Paul 
Published: February 2020

Protonic Ceramic fuel cells (PCFCs) offer a low-pollution technology to generate electricity electrochemically with high efficiency when compared to that of combustion engines [1]. PCFCs also offer the advantage of keeping fuel electrode (anode) undiluted, with the water formation taking place at the air electrode (cathode) side. Thin electrolyte membranes are preferred, to reduce the ohmic losses during the fuel cell test [2], with the most common electrolyte materials being alkaline earth doped cerates, zirconates and their solid solutions, due to high proton conductivity and low activation energy. Nonetheless, the chemical instability of BaCeO3 in acidic atmospheres and the high sintering temperature and resistive grain boundaries of BaZrO3 are the main problems currently limiting their application in PCFCs [3]. As a compromise, the composition 40% Ce substituted Ba (Zr, Y) O3-δ, lying in the solid solution between the zirconate and cerate materials, has been received great attention due to improving the chemical stability of the cerate, while maintaining high total protonic conductivity[4][5].
In the present work, anode (Ni-BaCe(1-x)Zr(x-y)Y(1-x-y)O3-δ) supported thin electrolyte membrane (~6µm thickness) protonic cells were developed by a spin coating technique, with a triple conducting cathode (H+/O2-/e-) is deposited on this electrolyte/anode half-cell, figure 1. The performance of the complete PCFC cell is tested in biogas, an important feedstock from bio-waste mainly consisting of CH4 and CO2. The behavior of the triple conducting cathode, fuel utilization, carbon deposition and overall performance (I-V-P) comparison results will be discussed in detail.

Acknowledgments

The authors gratefully acknowledge funding from the FCT, POPH, PTDC/CTM/100412/2008, FCT Investigator Programme, IF/01344/2014/CP1222/CT0001, PTDC/CTM-ENE/6319/2014, QREN, FEDER and COMPETE Portugal and the European Social Fund, European Union.

References

[1] W.G. Coors, J. Power Sources. 118 (2003) 150–156.
[2] E.D. Wachsman, K.T. Lee, Science. 334 (2011) 935–9..
[3] E. Fabbri, D. Pergolesi, E. Traversa, Chem. Soc. Rev. 39 (2010) 4355–69.
[4] L. Bi, E. Fabbri, E. Traversa, Electrochem. Commun. 16 (2012) 37–40.
[5] N. Narendar, P.A.N. Dias, J.A. Saraiva, D.P. Fagg, Int. J. Hydrogen Energy. 38 (2013) 8461.

Figure 1
Materials Design and Synthetic Strategies to Enhance Electron Transport in Composite Materials
Authors: Takeuchi Kenneth J , Takeuchi Esther S , Marschilok Amy C 
Published: February 2020

Electroactive materials are typically incorporated into batteries through the fabrication of composite electrodes including additives to enhance conductivity and to mechanically bind the components. These structures provide an opportunity to decrease inert material content if multifunctional materials can be designed and employed. For example, redox active materials that incorporate silver cation (Ag+) demonstrate the possibility for in-situ generation of an electrically conductive percolation network of Ag0 metallic nanoparticles through a reduction displacement reaction. This paradigm has been demonstrated with silver vanadium phosphorous oxide (Ag2VO2PO4) where the electrical conductivity increased 15,000-fold upon lithiation.
This presentation provides new strategies for the deliberate design of composite materials taking advantage of the opportunity for in-situ reduction displacement to form conductive networks. Several new approaches will be described. These include a one pot synthetic approach for the direct formation of a composite where one component is silver ion containing and the second is not. Additionally, surface modification approaches to generate conductive surface coatings will be introduced. These methods can significantly benefit the electrochemistry compared to composites formed by mechanical mixing alone, as will be illustrated in this presentation.