bluuebunny/crossref_metadata_2025_split huggingface dataset:
Glucose Oxidase Affects Laccase and Bilirubin Oxidase Direct Bioelectrocatalytic Cathodes
Authors: Milton Ross D , Giroud Fabien , Thumser Alfred E , Minteer Shelley D. , Slade Robert CT 
Published: February 2020

Glucose oxidase (GOx) is commonly incorporated into glucose-oxidising/oxygen-reducing enzymatic biological fuel cells (EBFCs), as the anodic biocatalyst. The flavin adenine dinucleotide (FAD) cofactor of GOx is tightly bound, and possesses an associated favourable low redox potential allowing the use of a wide range of electron mediators, which in turn increases the theoretical maximum open-circuit potential (OCP) of EBFCs. Furthermore, GOx is highly specific to glucose and offers high catalytic activity, making it a good choice for futuristic implantable EBFCs. GOx-based anodes do, however, exhibit a major significant drawback; electron transfer to the electrode following the enzymatic oxidation of glucose competes with the natural electron acceptor of GOx: oxygen. The reduction of oxygen by GOx can dramatically lower the dissolved oxygen concentration of a solution, whilst simultaneously producing hydrogen peroxide.
Laccase and bilirubin oxidase (BOd) can undergo the enzymatic 4-electron reduction of dissolved oxygen to water, and efficient direct electron transfer (DET) has been established for both enzymes. The inhibition of laccase and BOd by halides (primarily fluoride and chloride ions) is well documented; it is reported that BOd exhibits greater resistance to halide inhibition. Nevertheless, DET can also instil a degree of resistance to chloride inhibition. Lastly, BOd can efficiently reduce oxygen to water at near-neutral and physiological pH, making it a favourable choice of biocatalyst in implantable devices.
The research presented within this paper investigates the effect of the parasitic reduction of oxygen to hydrogen peroxide by GOx, on laccase and BOd direct bioelectrocatalytic cathodes. We report that GOx can produce significant quantities of hydrogen peroxide and thereby significantly affect laccase and BOd cathodes (albeit by different mechanisms), even when DET is established (a mode previously used to remediate chloride inhibition). Furthermore, we compare and contrast the performance of laccase and BOd when GOx is replaced with “oxygen-insensitive” FAD-dependent glucose dehydrogenase (FAD-GDH).
This research has implications for the future design of EBFCs.
This research is funded by the UK SuperGen Biological Fuel Cells Consortium (Contract: EP/H019480/1), National Science Foundation Grant #105797 and the Air Force Office of Scientific Research (AFOSR).
The Carbon/Iodide Interface in Protic Ionic Liquid Medium for Application in Supercapacitors
Authors: Béguin François , Skowron Piotr , Anouti Mérièm , Frackowiak Elzbieta 
Published: February 2020

Among various energy storage systems, great interest is focused on electrochemical capacitors (ECs) because of their high power and long cycle life. The most typical devices operate through the charge/discharge of the electrical double-layer at the electrode/electrolyte interface in aqueous or organic medium and as well as in ionic liquid. The capacitance can be significantly enhanced by quick redox reactions originating from the electrolyte species at the electrode/electrolyte interface, for example by using iodide salt aqueous solutions [1]. However, in the later case, the voltage of the system is limited to 1 V due do the low thermodynamic window of water. Therefore, we propose to investigate a possible extension of this window by using solutions of iodide salt in ionic liquids (ILs).
The ILs selected were triethylammonium bis(tetrafluoromethylsulfonyl)imide [Et3NH]-[TFSI] and 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide [Emim]-[FSI]. Two iodides, triethylammonium iodide [Et3NH]-[I] or tetraethylammonium iodide [Et4N]-[I], were introduced in the ionic liquid at a concentration of 0.25 mol L-1. The electrochemical experiments as cyclic voltammetry, galvanostatic charge/discharge and impedance spectroscopy were conducted using a two-electrode cell construction. In some experiments, a silver wire was added as pseudo-reference to monitor the potential of individual electrodes. Activated carbon (AC) with high microporosity coated on aluminum foil from Batscap (France) was used as working and counter electrode. Glass microfiber paper (Whatman) was utilized as separator. Galvanostatic (0.2 A·g-1) cycling up to 1.8 V in two-electrode cell (Figure 1B) demonstrates a remarkable increase of capacitance when [Et3NH]-[I] is added to [Et3NH]-[TFSI], from 78 to 157 F·g-1. The voltammogram of figure 1A shows clearly that the increase of capacitance is caused by the positive electrode where faradaic processes occur.

Acknowledgements:The Foundation for Polish Science is acknowledged for supporting the ECOLCAP Project realized within the WELCOME Program, co-financed from European Union Regional Development Fund.
[1] G. Lota, E. Frąckowiak, Electrochemistry Communication, 11 (2009) 87-90
Probes Based on Silica Sol-Gels for Voltammetry in the Absence of Electrolyte in the Sample Phase
Authors: Cox James A. , Miecznikowski Krzysztof , Steinecker William H. , Pacey Gilbert E. 
Published: February 2020

Silica sol-gels that are processed at room temperature contain residual solute. By selection of salts that have the properties of a humidistat in the sol, the resulting gel will contain a controlled amount of water, thereby making the resistance of the sol-gel independent of humidity of a contacting gas phase. Further, when the processing conditions result in a mesoporous sol-gel, diffusion coefficients of electroactive species that are encapsulated therein are in the 10-6 cm2s-1 range. The latter is illustrated by the cyclic voltammetry of hexacyanoferrate when a solid-state cell is fabricated to incorporate three electrodes in the silica matrix. This design is extended to the voltammetry of gas-phase species by extending the working electrode beyond the sol-gel so that a three-phase boundary is formed. In this manner the detection of carbon monoxide, hydrazine, and hydrogen peroxide by amperometry is achieved.
This cell design was evaluated as an amperometric detector for gas chromatography. Initial experiments were in the flow injection mode with He flowed at 0.63 mL min-1 as the carrier gas and100- µL injections of H2 comprised the sample. Wirh a Pt working electrode at 0.5 V vs. a Pt quasi-reference electrode, linear response to concentration over range 1.7 x 10-6 g to 7.6 x 10-6 g was observed. Extensions to 1,2-ethandithiol, phenol, p-cresol, and thioanisole yielded detection limits of 4, 1, 3, and 70 ppmv (k = 3 criterion), respectively, when operating the working electrode at 800 mV. Application to aqueous samples in the absence of supporting electrolyte also were achieved; however, a problem is that leaching of the electrolyte from the sol-gel cell was a limitation. To address this problem, the sol-gel matrix is being modified to contain a macromolar cation (anion) of a size that is greater than the ca. 0.5 nm pore size of the silica. An example is to immobilize 3,4- ethyelenedioxythiophene (EDOT) in the sol-gel and oxidize it to the polymeric form, PEDOT. Results on the polymerization process will be shown, and the efficacy of the resulting composite as a matrix for a probe to determine various species in water in the absence of supporting electrolyte will be presented.
High Pressure NMR Investigation of 3M Fuel Cell Ionomers
Authors: Pilar Kartik , Farrington Jaime , Rua Armando , Cuffari David , Ostrovskiy Eugene , Suarez Sophia , Stallworth PE , Greenbaum Steve 
Published: February 2020

Nuclear Magnetic Resonance (NMR) measurements were obtained for polymer electrolyte membranes (PEM) provided by 3M Corp. through the courtesy of Dr. Steve Hamrock. These membranes have potential for use within PEM Fuel Cells (PEMFCs) and can operate at somewhat lower relative humidity than NAFION. NMR spin-lattice relaxation (T1) and static gradient self-diffusion measurements were obtained as a function of applied hydrostatic pressure for three different equivalent weight (EW) membranes at several values of water content. T1 measurements allow us to study the rotational molecular motion of water within the membranes, whereas diffusion directly probes translational motion (1). By measuring both T1 and self-diffusion, possible relationships between rotational and translational motion within the membranes can be observed and effects due to water content or EW can be found.
The membranes studied had EWs of 700, 825, and 1000, and each was prepared with both 10% and 20% water content (wt. %). Measurements were conducted at several temperatures. For T1 measurements, we used deuteron NMR in membranes equilibrated with D2O because of the high sensitivity of nuclear quadrupole relaxation to rotational motions (2). In order to measure diffusion (using proton NMR on samples equilibrated with H2O) in samples contained within a high pressure Cu/Be cell, it was necessary to use a spin-echo pulse sequence in the static gradient in the fringe field of a 7.3 T superconducting magnet. Figure 1 displays isothermal variable pressure T1 results obtained for the 700 EW membrane with 20 wt. % D2O. It can be seen that T1 values increase with temperature and decrease with pressure.
The results for different membranes also suggest that values for T1 increase with higher membrane EW and with higher D2O content. It is found that there is an increase in activation volume, Δv, with lower water content and lower temperatures, which was calculated using
Δv = -kT[lnT1/P]T [1]

Table 1 displays the activation volume of each membrane at various temperatures with 20 wt. % D2O.
Measurements of water self-diffusion as a function of pressure for each sample at different water content are underway. Diffusion activation volumes will thus be obtained and compared with those for deuteron spin-lattice relaxation. Such comparison will shed light on the relationship between water translational and rotational motion inside the ionomer, and hopefully lead to insight into the proton transport mechanism.
REFERENCES
1. Jayakody, JRP, Stallworth, PE, Mananga, ES, Farrington-Zapata, J, and Greenbaum, SG. J. Phys. Chem. B
108, 4260 (2004).
2. Fontanella, JJ, Wintersgill, MC, Chen, RS, Wu, Y, and Greenbaum, SG. Electrochimica Acta
40, 2321 (1995).
This work was supported by the Office of Naval Research.
Invited Presentation: Mathematical Modeling of Diffusion-Induced Stress and Other Coupled Physics in Li-Ion Batteries
Authors: Christensen Jake 
Published: February 2020

The pursuit of high-energy-density, low-cost electrochemical energy storage systems for electric vehicles inevitably requires careful examination of the coupling between mechanics, electrochemistry, thermodynamics, and mass transport in batteries. High-capacity Li battery materials such as Li alloys and Li metal undergo large volume changes during battery cycling, and the stress induced by these volume changes must be accommodated at the material, composite, or device level in order to reduce the rate of battery degradation. Here we review some early work in the modeling of diffusion-induced stress in Li-ion insertion materials,[1,2] showcase other examples of multiscale, multidomain battery models,[3,4] and discuss future research directions in the field of battery modeling.
1. J. Christensen and J. Newman, "Stress generation and fracture in lithium insertion materials,"
Journal of Solid State Electrochemistry, 2006. 10(5): p. 293-319.
2. J. Christensen and J. Newman, "A Mathematical Model of Stress Generation and Fracture in Lithium Manganese Oxide," Journal of the Electrochemical Society, 2006. 153(6): p. A1019-A1030.
3. J. Christensen, D. Cook, and P. Albertus, "An Efficient Parallelizable 3D Thermoelectrochemical Model of a Li-Ion Cell," Journal of The Electrochemical Society, 2013. 160(11): p. A2258-A2267.
4. S. Patnaik, An Electrical Network Model for Computing Current Distribution in a Spirally Wound Lithium Ion Cell, MS Thesis, Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology: Cambridge, MA (2012).
Characterization of Mechanical Degradation in Lithium Ion Battery Electrodes
Authors: Barai Pallab , Mukherjee Partha P. 
Published: February 2020

Active particles inside Lithium Ion Battery electrodes are responsible for hosting Li ions during operation. Li ions intercalate and deintercalate in the host material through diffusion process. This induces significant amount of diffusion induced stress, which may lead to mechanical degradation in terms of formation of microcracks in the active particles [1]. Nucleation of these microcracks results in formation of spanning cracks which eventually leads to catastrophic failure of the material.
We have demonstrated a random lattice spring based methodology to characterize the development of microscopic damage and their subsequent nucleation to form crack fronts [2]. According to the lattice spring method, breaking of each bond is simulated by solving the equilibrium equation. Initially, evolution of fracture happens in a diffused manner (see Fig. 1(a)). Once the stress concentration at a microcrack tip starts to dominate over the disorder term, the material fails to sustain any more loads and a spanning crack develops (see Fig. 1(b)). In lattice spring model, when a bond breaks, the strain energy associated with that spring gets released (see Fig. 1(a)).
In acoustic emission experiments, released energy waves associated with cracking of materials are detected [3]. Figure 1(c) shows the formation of microscopic damage and cracks inside an active particle during the discharge process. Figure 1(d) shows that the amount of mechanical degradation saturates after 4 – 5 discharge/charge cycles. The goal of this research is to develop a computational scheme to capture the experimentally observed energy release during Li intercalation inside active particles.

References

[1] S. Kalnaus, K. Rhodes, and C. Daniel, J Power Sources,
196(19), 8116-8124 (2011).
[2] P. Barai and P. P. Mukherjee, J Electrochem Soc,
160(6), A955-A967 (2013).
[3] K. Rhodes, M. Kirkham, R. Meisner, C. M. Parish, N. Dudney, and C. Daniel, Rev Sci Instrum,
82 (7), (2011)
Invited Presentation: Chemo-Mechanical Stress and Its Impact on the Stability and Reliability of Solid Oxide Fuel Cells
Authors: Kawada Tatsuya 
Published: February 2020

As a device of ceramic multilayers, solid oxide fuel cell has a risk of having mechanical failures when material selection is not appropriate. It may cause a fatal damage of a cell and the whole stack. Thermo-mechanical properties, i.e. thermal expansion mismatch between the materials or temperature gradient inside a cell is the primary cause of a mechanical failure. In addition, chemical strain can also lead to a serious problem if a nonstoichiometric compound is used as a major component of the cell stack, which is the case of most SOFCs under development. The chemical strain is a function of local temperature and oxygen potential which is determined by mass, charge, and heat transport in the materials and at the interfaces. Thus, the chemo-mechanical or electro-chemo-mechanical aspects of the materials should be carefully taken into consideration in designing and operating the cells.
Impact of the chemical strain on the reliability is highest when electrolyte itself shows oxygen nonstoichiometry, and is used in an electrolyte-support type configuration. Doped ceria is an example as pointed out by several researchers. Transition metal doped lanthanum gallate also shows significant chemical stress when used as an electrolyte. The valence state of cobalt changes from 4+ to 2+ depending the local oxygen potential, the oxygen vacancy concentration changes significantly. The stress distribution was calculated under open circuit, operation, and short-circuited conditions for the flat- constrained and partially constrained situations. Large tensile stress is anticipated on the cathode side. Temperature distribution also enhances the development of the stress. Similarly as the electrolyte material, oxide interconnects such as lanthanum chromite based materials can also causes chemical stress in the cell. On the other hand, electrode material such as lanthanum cobaltite or cobalt ferrite has less effect of chemical expansion under normal operation conditions even though chemical strain is large when oxygen partial pressure decreases. Although overpotential at the electrode locally reduces the cathode material, the thickness of the electrochemically active layer is around or less than 10 micrometer in air. Together with the high porosity of the electrode, those materials are safely used in actual cell stacks. However, under accidental conditions such as stoppage of air flow, the large chemical expansion of the mixed conductor cathode causes fatal failure in a cell.
In contrast to the significance of chemical to mechanical coupling in SOFC materials, effects of mechanical stress on the chemical properties are not well understood, and expected to be negligible in a practical SOFCs. Direct effect of stress on the oxygen nonstoichiometry was found negligible by using electromotive force measurements.
Synthesis and Photophysical Studies of Hydrophilic Zinc Phthalocyanine Dendrimers
Authors: Setaro Francesca , Torres Tomas , de la Escosura Andres , Hahn Uwe , Nonell Santiago , Ruiz Gonzalez Ruben 
Published: February 2020

Phthalocyanines (Pc) and their metalloderivatives (MPc) are two-dimensional 18 π-electron aromatic porphyrin synthetic analogues1. Due to their excellent photochemical and photophysical properties, together with their chemical versatility, Pcs are perfectly suited for their application as photosensitizers (PS) in photodynamic therapy (PDT).
Pcs exhibit a strong absorption band in the visible region of the UV/vis spectrum from 630 to 750 nm and, in the presence of an appropriate central atom, they yield long-lived triplet excited states and high singlet oxygen photo-production2. Yet, although several Pcs disclose their capability to act as photosensitizing agents3, not many of them are soluble in aqueous media4.
In this communication, we report the synthesis, photochemical and photophysical characterization of a series of new metallodendrimers built around a zinc phthalocyanine core. Within the last step of the synthetic route, the terminal esters were hydrolyzed, giving rise to a dramatic change in polarity upon formation of multiply charged species that are very soluble in aqueous media.
Through photochemical and photophysical studies, we corroborated the capacity of these water-soluble species to produce singlet oxygen in air-saturated solution. Moreover, along with increasing dendritic shell, a significant increase in the generation of singlet oxygen was observed. These highly hydrophilic Pc dendrimers may thus be advantageous for the purpose of producing 1O2 in biological media by photosensitization.

References

[1] a) G. de la Torre, C.G. Claessens, T. Torres Chem. Commun 2000 (2010); b) G. de la Torre, G. Bottari, U. Hahn, T. Torres Struct. Bond
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[2] a) C.G. Claessens, U. Hahn, T. Torres, Chem. Rec.
8, 75 (2008); b) L.M. Moreira, F.V. dos Santos, J.P. Lyon, M. Maftoum-Costa, C. Pacheco-Soares, N.S. da Silva, Aust. J. Chem. 61, 741 (2008); c) Handbook of Porphyrin Science, K.M. Kadish, K.M. Smith, R. Guilard (Eds.) vol. 4. World Scientific: Singapore, 2010.
[3] a) J.W. Hofman, F. van Zeeland, S. Turker, H. Talsma, S. A. G. Lambrechts, D. V. Sakharov, W. E. Hennink, C. F. van Nostrum, J. Med. Chem.
50, 1485 (2007); b) X.J. Jiang, S. L. Yeung, P. C. Lo,W.P. Fong, D. K. P. Ng, J. Med. Chem.
54, 320 (2011); c) J.T.F. Lau, X.J. Jiang, D.K.P. Ng, P.C. Lo, Chem. Commun. 49, 4274 (2013).
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61, 327 (2009); b) U. Hahn, F. Setaro, X. Ragàs, S. Nonell, A. Gray-Weale, T. Torres, Phys. Chem. Chem. Phys.
13, 3385 (2011); c) M. Nishida, H. Horiuchi, A. Momotake, Y. Nishimura, H. Hiratsuka, T. Arai, J. Porphyrins Phthalocyanines
15, 47 (2011); d) T.L. Doane, C.H. Chuang, A. Chomas, C. Burda, ChemPhysChem
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Controlling Molecular Alignment on Highly Ordered Pyrolitic Graphite of Porphyrin-Tb(III) Double-Decker Single Molecular Magnets
Authors: Inose Tomoko , Tanaka Daisuke , Tanaka Horfumi , Ivasenko Oleksandr , Nagata Toshi , De Feyter Steven , Ishikawa Naoto , Ogawa Takuji 
Published: February 2020

Single molecular magnets (SMMs) that show slow magnetic relaxation properties at low temperatures have great potential for use as nanoscale memory devices or quantum computers. In our study, we focused on porphyrin-Tb(III) double-decker complexes and their magnetic properties.1,2 Our goal was to control the molecular alignment of SMMs on highly ordered pyrolitic graphite (HOPG) by a self-assembling process. We synthesized protonated, anionic, and radical forms of octaethylporphyrin (OEP)-Tb(III) double-decker complexes and observed the molecular alignment of each molecule on HOPG using scanning tunneling microscopy (STM). The STM observations demonstrated that all OEP-Tb(III) double-decker complexes had similar pseudo-hexagonal packing structure stability on HOPG, regardless of differences in the electronic structure (Figure 1). In particular, the lattice parameters of protonated form 1 (a = 1.41 ± 0.03 nm, b = 1.46 ± 0.05 nm) showed almost the same values as anionic form 2 (a = 1.34 ± 0.01 nm, b = 1.42 ± 0.01 nm) and radical form 3 (a = 1.39 ± 0.04 nm, b= 1.45 ± 0.06 nm).
We also prepared and observed the molecular alignment of a protonated 5,15-bisdodecylporphyrin (BDP)-Tb(III) double-decker complex. This complex showed a lamellar packing structure on HOPG (Figure 2). Herein, we succeeded in isolating stable 2D supramolecular structures of all the OEP-Tb(III) double-decker complexes on HOPG. Control of molecular alignment was also realized by changing the substituents.

References:

1) A. Candini et al., Nano Lett.
2011, 11(7), 2634.

2) D. Tanaka, T. Inose, T. Ogawa et al., Chem. Commun.
2012, 48, 7796.