bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhancing the Performance of a Zinc-Iodide Redox Flow Battery
Authors: Shakeri Hosseinabad Fatemeh , Roesler Roland , Roberts Edward P.L. 
Published: May 2020

A very high energy density has been reported for the zinc-iodide flow battery [1]. In order to enhance the performance of a zinc-iodide flow battery, an iodide-based complexing agent (1-cyanomethyl-1-methylpyrrolidinium iodide) was added to a 3.0 M ZnI2 electrolyte system. An optimized flow field design for uniform distribution of the electrolyte is desirable for the redox flow battery systems. The impact of flow field design on the performance of the battery was investigated.
Charge-discharge characteristics were carried out to investigate cyclability and efficiency of the zinc-iodide battery with and without the presence of complexing agent. The flow cell used graphite felt electrodes, a Nafion membrane, and had an active area of 5 cm2. In this study, the influence of a flow through design, and a flow-by design on the performance of the zinc-iodide flow battery was evaluated. Electrochemical characterization methods, including cyclic voltammetry (CV) and rotating disk electrode (RDE) studies, with and without the presence of complexing agent were performed to evaluate redox potential, diffusion coefficient and electrochemical reversibility of the electrolyte system. The deposited material on the positive and negative electrodes and stability of the electrode material were studied by SEM, EDX, XRD and Raman.
[1]- Li, Bin, Zimin Nie, M. Vijayakumar, Guosheng Li, Jun Liu, Vincent Sprenkle, and Wei Wang. "Ambipolar zinc-polyiodide electrolyte for a high-energy density aqueous redox flow battery." Nature communications 6 (2015): 6303.
Thin Membranes for PEM Water Electrolysis and the Challenge to Reduce Hydrogen Permeation
Authors: Stähler Markus , Stähler Andrea , Scheepers Fabian , Lehnert Werner , Carmo Marcelo 
Published: May 2020

In order to reach the system efficiency targets for PEM water electrolysis of more than 70%LHV at current densities of up to 3 A/cm², thin membranes are indispensable. It is known that the use of thin membranes leads to the disadvantage that they additionally have to be stabilized mechanically and chemically for cell operation. Furthermore, it is known that during pressure operation, a large amount of gas permeates through the thin membrane. This can result in forming explosive gas mixtures of oxygen and hydrogen at the anode, especially at low current densities, which prevents a safe electrolysis operation. However, little research has been done so far that, when using thin membranes, additional effects can arise which significantly increase the gas permeation. These effects lead to safety-relevant hydrogen concentrations at the anode, not only for small but also for larger current densities of a few amperes per square centimeter.
It is demonstrated that, without an intensive comparison of material and cell operating parameters, a comparison of different investigations with respect to the measured permeation values in PEM water electrolysis can hardly be made. Important parameters are discussed which have to be taken into account in cell assemblies when thin membranes are used.
The presented experimental results show a correlation in the PEM water electrolysis MEA which can significantly increase the hydrogen permeation through a 50 μm thin N212 membrane under ambient pressure. At the same time, it is demonstrated how the hydrogen content in the anode gas can be reduced to very low levels using the identified correlation.
Voltammetric Biosensor Based on Silver Nanowires and Tyrosinase for the Electrochemical Detection of Catechol
Authors: Salvo-Comino Coral , Rodriguez-Valentin Javier , Gonzalez-Gil Alfonso , Garcia-Cabezon Cristina , Rodriguez-Mendez Maria Luz 
Published: May 2020

An enzymatic electrochemical biosensor for catechol detection based on silver nanowires (AgNWs), has been developed. The employment of AgNWs was essential to improve the electron transfer in comparison with that offered by an ITO substrate. AgNWs’ electrocatalytic properties and high affinity with biomolecules make them desirable for constructing biosensors. Combining nanomaterials with enzymes reduces insulating effects, due to the high-efficient electrical activity from the active site of the enzyme to the electrode. Moreover, the employment of these proteins increases the specificity of the sensor.
Among the variety of processes available to synthesize AgNWs [1,2], polyol process has been selected, because of the simplicity and reliability it offers. The employed method consisted in a silver precursor (AgNO3) reduction in presence of Ethylene glycol as a solvent and polyvynilpyrrolidone, which is a surfactant that facilitates the AgNWs dispersion. The developed biosensor results from the immobilization of tyrosinase (TYR) on the top of the AgNWs deposited by spin coating in a different concentration ratio. FTIR, UV-vis, DRX and AFM have confirmed the proposed structure and cyclic voltammetry has shown the amplification caused by the combination of the nanomaterial and the enzyme in the film denoting their excellent performance, sensitivity and reproducibility. Moreover it has been demonstrated that the concentration of AgNWs employed in the development of the biosensors is crucial in terms of reproducibility, in addition to being excellent electronic mediators.

Figure 1. Voltametric response of ITO-Tyr (red) and ITO-AgNWs-TYR (black) onto ITO surface to 10-4M catechol in phosphate buffer 10-2M.

[1] Xu, L. et al. Anal. Methods 7, 5649-5653 (2015), [2] Kumar-Krishnan, S. et al. RSC Adv. 6, 20102–20108 (2016)

Acknowledgments: Financial support by MINECO and FEDER (RTI2018-097990-B-100 and BES-2016-077825) and the Junta de Castilla y León-FEDER (VA-275P18) is gratefully acknowledged.

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Bio-Sourced, Potentially Biodegradable Materials for Fast Response Moisture Sensors
Authors: Gouda Abdelaziz , Reali Manuel , Santato Clara 
Published: May 2020

Humidity is a very important physical parameter that plays an imperative role in technology and human activity. Researchers are paying more attention to develop moisture-responsive materials with outstanding characteristics such as high sensitivity, wide humidity detection range, fast response and short recovery times to keep pace with the on-going development in technology. Abundant, bio-sourced and biodegradable organic materials, such as melanin, are needed to enable the development of eco-designed technologies that alleviate the environmental footprint of the electronics sector. Melanin is a ubiquitous biomacromolecule with diverse functions including hydration dependent electrical response [1], photoresponse [2], antioxidant [3] , metal chelation [4], and free radical scavenging [5]. Melanin originates from the oxidative polymerization of (5,6)-dihydroxindole (DHI) and (5,6)-dihydroxindole 2-carboxyl acid (DHICA) building blocks [6]. Natural melanin is expected to contain up to 70% of DHI in molecular ratio [7]. Due to the absence of the carboxyl group in the molecular structure, DHI-melanin features a ordered, conjugated structure thus expected to show better electrical conductivity with respect to DHICA-melanin [5]. Herein, we investigate DHI-melanin and DHI-DHICA melanin thin films (7:3 weight ratio), spin coated and polymerized on technologically relevant and potentially biodegradable substrates, as active layers for fast response moisture sensors.

References

[1] Wünsche J, Deng Y, Kumar P, Di Mauro E, Josberger E, Sayago J, Pezzella A, Soavi F, Cicoira F and Rolandi M 2015 Protonic and electronic transport in hydrated thin films of the pigment eumelanin Chem. Mater.
27 436-42
[2] Mostert A B, Rienecker S B, Noble C, Hanson G R and Meredith P 2018 The photoreactive free radical in eumelanin Science advances
4 eaaq1293
[3] Tu Y-g, Sun Y-z, Tian Y-g, Xie M-y and Chen J 2009 Physicochemical characterisation and antioxidant activity of melanin from the muscles of Taihe Black-bone silky fowl (Gallus gallus domesticus Brisson) Food Chem.
114 1345-50
[4] Hong L and Simon J D 2007 Current understanding of the binding sites, capacity, affinity, and biological significance of metals in melanin. ACS Publications)
[5] Panzella L, Gentile G, D'Errico G, Della Vecchia N F, Errico M E, Napolitano A, Carfagna C and d'Ischia M 2013 Atypical structural and π‐electron features of a melanin polymer that lead to superior free‐radical‐scavenging properties Angew. Chem. Int. Ed.
52 12684-7
[6] Meredith P and Sarna T 2006 The physical and chemical properties of eumelanin Pigment cell research
19 572-94
[7] Pezzella A, d'Ischia M, Napolitano A, Palumbo A and Prota G 1997 An integrated approach to the structure of Sepia melanin. Evidence for a high proportion of degraded 5, 6-dihydroxyindole-2-carboxylic acid units in the pigment backbone Tetrahedron
53 8281-6
Preparing DNA SAM Electrochemical Sensors Using Potential Assisted Deposition Methods. Controlling the Coverage and Local Organization of the DNA in the SAM.
Authors: Bizzotto Dan , Leung Kaylyn , Yu Hua-Zhong 
Published: May 2020

Typically, DNA SAMs used for electrochemical based sensing are prepared without controlling the gold electrode potential[1]. Applying a potential during DNA deposition enables control over the coverage and DNA organization[2-4]. These characteristics are determined by the composition of the immobilization buffer, the immersion time, the DNA concentration, the extent of backfilling with a small alkylthiol and whether deposition occurs on a bare or alkythiol coverage gold surface[3-4]. Few studies have explored the influence of the underlying surface crystallography. Here, we show the possibilities of using electrochemical potential control to manipulate the characteristics of the DNA SAM. Moreover, the use of a single crystal gold bead electrode, coupled with the use of a fluorophore tagged DNA and fluorescence microscopy, enables examination of the influence of the underlying surface crystallography on the DNA SAM prepared. Various constant potentials were used as well as using a square-wave potential perturbation during deposition. There are significant differences in the DNA SAM produced under these conditions. In some cases, the DNA coverage was low on the <111> surfaces, higher on more open or atomically rough regions. In other cases, the coverage was higher on the <100> surfaces as compared to the other regions. The use of constant positive or negative potentials (vs SCE) resulted in significant differences in the relative coverages among regions of different atomic arrangements (Fig 1). In addition, a significant difference was observed between immobilization buffers that contain Cl and those that are Cl free. Also, the use of constant or square-wave potential perturbations resulted in significantly different local organizations of DNA in the SAM. Examples of these types of DNA SAM surfaces will be presented with some conclusions on the implications for use on polycrystalline planar gold surfaces.
References:
[1] Xiao, Y.; Lai, R. Y.; Plaxco, K. W. Preparation of Electrode-Immobilized, Redox-Modified Oligonucleotides for Electrochemical DNA and Aptamer-Based Sensing. Nat. Protoc.
2007, 2 (11), 2875–2880.
[2] Jambrec, D.; Kayran, Y. U.; Schuhmann, W. Controlling DNA/Surface Interactions for Potential Pulse‐Assisted Preparation of Multi‐Probe DNA Microarrays. Electroanal.
2019, 410, 3.
[3] Leung, K. K.; Gaxiola, A. D.; Yu, H. Z.; Bizzotto, D. Tailoring the DNA SAM Surface Density on Different Surface Crystallographic Features Using Potential Assisted Thiol Exchange. Electrochim. Acta
2018, 261, 188–197.
[4] Leung, K. K.; Yu, H. Z.; Bizzotto, D. Electrodepositing DNA Self-Assembled Monolayers on Au: Detailing the Influence of Electrical Potential Perturbation and Surface Crystallography. ACS Sens.
2019, 4 (2), 513–520.
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(Invited) Steps Towards a Mechanistic Understanding of Electrocatalytic Phenomena in Solid Oxide Cells
Authors: Fleig Juergen 
Published: May 2020

Solid oxide fuel or electrolysis cells are based on electrochemical reactions such as oxygen reduction and evolution, hydrogen oxidation or water splitting and the corresponding cell performance depends crucially on the kinetics of these electrode reactions. High reaction rates at low driving forces (overpotentials) as well as low degradation rates are aimed at. This leads to much interest in reaction mechanisms of the corresponding reactions. In a first step, often the relevant reaction pathway (via triple phase boundaries or via the electrode bulk) is identified and the most resistive region within the predominant pathway is localized (e.g. a certain interface or the electrode bulk). In a next step, it is desirable to obtain an atomistic understanding of the resistive or electrocatalytic processes. Here, exact surface species or point defects and phenomena such as dissociation or ionization come into play, and despite strong research activities many questions remained unsolved so far.
This talk presents our recent progress on this topic: Established electrochemical approaches (e.g. Butler-Volmer equation) do no longer hold for describing such reactions and a novel model was thus developed, which allows a proper interpretation of p(O2) dependences and current-voltage curves. It is discussed, how composite electrodes can improve the reaction rate by a kind of “job sharing”. Exsolution-based composites are considered at the fuel side (Fe on LSF) and it is discussed, what happens during electrochemical switching of their electrocatalytic activity by an overpotential. Moreover, it is illustrated how nano-particles of Pt on (La,Sr)FeO3 (LSF) thin film electrodes strongly improve the reaction rate and also completely change the reaction mechanism (see figure) and the p(O2) dependence. Finally, the topic of active sites and electrode degradation is considered, with special emphasis on (La,Sr)CoO3 (LSC) and LSF. Extraordinarily high oxygen reduction activity of pristine films is shown, different reasons for degradation are discussed, and surprising defect chemical phenomena are displayed for oxygen evolution from LSC thin films.

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Electrolysis of O2-Containing Low Concentration CO2 in Solid Oxide Electrolysis Cells with La-Based Hexaaluminate Cathode for Syngas Production
Authors: Sun Xueyan , Zhao Wei , Zhu Liangliang , Shui Ziyi , Chen Xi , Zhu Yanyan 
Published: May 2020

Excessive emission of CO2, the primary greenhouse gas, has been widely believed to be the main contributor to global warming. Recently, direct-air-capture (DAC) of CO2 is emerging as a promising technique to mitigate the greenhouse problem. In this work, a new technology is developed where the CO2/air mixture captured by DAC1 is directly converted into high value-added syngas using solid oxide electrolysis cells (SOECs)2. In this new system, H2O and O2-containing CO2 (CO2/air mixture) are co-electrolyzed for syngas production in the cathode of SOECs, and in the anode, methane is partially oxidized into syngas to decrease the overpotential and electricity consumption.
The cathode materials of SOECs need to keep stable under the condition of strong reduction and high humidity. meanwhile CO2 directly captured from ambient air is mixed with oxygen in the cathode, which poses a challenge to prevent the oxidation of cathode materials. Hexaaluminate3 (AAl12O19-δ or AAl12O17-δ), as a kind of composite metal oxides, is considered as one of the most promising high-temperature catalytic materials due to its unique layered crystal structure. Besides, Al3+ in its structure can be partially or completely substituted by transition metal ions, and the valence state and proportion of its elements and content of oxygen vacancy can be adjusted in a large range. Therefore, hexaaluminate catalysts with high catalytic activity can be designed by means of chemical tailoring according to the characteristics of chemical reactions and requirements for catalysts.
In this work, La-hexaaluminate is employed as the cathode material for co-electrolyzing H2O and CO2/air mixture to produce syngas. A series of characterization methods are used to evaluate the basic physical properties of hexaaluminate, including phase structure, oxygen vacancy concentration, thermal stability, thermal expansion coefficient and chemical compatibility with electrolyte materials. Moreover, the stability of electrolytic cell in various operating conditions was investigated, the morphology of cathode and anode materials before and after the operation of the electrolytic cell were compared. The reason of performance attenuation of the electrolytic cell was preliminarily analyzed. The new scheme developed in the present work, provides a way for the effective utilization of O2-containing low concentration CO2 captured by DAC, which is not only useful for alleviating the greenhouse effect, but also gains extra fuels with the help of renewable energy.

References:

1. J. Song, J. Liu, W. Zhao, Y. Chen, H. Xiao, X. Shi, Y. Liu, and X. Chen, Ind Eng Chem Res, 57, 4941 (2018).
2. Y. Song, X. Zhang, K. Xie, G. Wang, and X. Bao, Adv Mater (2019).
3. M. Tian, X. Wang, and T. Zhang, Catal Sci Technol, 6, 1984 (2016).
Composite Solid Oxide Cell Electrodes Based on Ruddlesden-Popper Nickelates and Co-Doped Ceria
Authors: Tsai Chen-Yu , Skinner Stephen J. 
Published: May 2020

Significant interest has been directed towards the development of high performance air electrodes for solid oxide electrolysis cells, with a wide variety of potential materials considered. Much of the effort has been directed towards modification of conventional solid oxide fuel cell electrode materials, such as La1-xSrxCo1-yFeyO3-d (LSCF) and related perovskites with few studies directed toward new materials. The layered perovskites of the Ruddlesden-Popper (RP) family, Ln2NiO4+d where Ln = rare earth, have begun to receive some attention for this application, but the thermodynamic stability of these phases has precluded their widespread adoption. However the common degradation product of the Ln2NiO4 phases is the relatively high electronic conducting higher order RP materials such as Ln4Ni3O10-d. With the high electronic conductivity and stability in the SOC operating temperature window (600-900oC) these phases where Ln = La, Pr are promising candidates for solid oxide electrolyser application. However the uncertain ionic conductivity of these phases leads to consideration of composite materials exploiting an electrolytic material as the oxide ion conducting phase.
In this work we consider the Pr4Ni3O10-d (PNO) -Ce1-x-yPrxGdyO2-d (CGPO) composite phases evaluating the phase compatibility, percolation of the phases and electrode performance characterised using impedance spectroscopy. From evaluation of the impedance responses we find that the optimum performance of the composite electrode was obtained at an operating temperature of 710oC with a 50:50 wt% mixture. The area specific resistance of the electrode was determined to be 0.18 Ωcm2 at 710oC, with a minimum value of 0.08Ωcm2 at 784oC, Figure 1. Further, we evaluate the limiting processes of the cells, finding that at low electrolyte content the composite electrode performance is diffusion limited, whilst at higher electrolyte content the limiting process gradually changes to surface exchange. This work highlights the potential of this composite electrode and the considerable scope for device development based on these new materials.

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(Invited) Electrolyzer Development and Process Optimization: Paving the Road for Industrial Carbon-Dioxide Electroreduction
Authors: Endrodi Balazs , Kecsenovity Egon , Jones Richard , Janáky Csaba 
Published: May 2020

Electrochemical reduction of CO2 is a promising method for converting a greenhouse gas into value-added products, utilizing renewable energy. Novel catalysts, electrode assemblies, and cell configurations are all necessary to achieve economically appealing performance. In this talk, I am going to present a zero gap electrolyzer cell, which converts gas phase CO2 to products without the need for any liquid catholyte. This is the first report of a CO2 electrolyzer cell, where multiple stacks are connected, thus scaling up the electrolysis process. The operation of the cell was validated using both silver nanoparticle and copper nanocube catalysts, and the first was employed for the optimization of the electrolysis conditions. Upon this, CO formation with partial current densities above 250 mA cm−2 were achieved routinely, which was further increased to 300 mA cm−2 (with ~95 % Faradaic efficiency) by pressurizing the CO2 inlet. Evenly distributing the CO2 gas among the stacks (parallel connection), the operation of the multi-stack cell was identical to the sum of multiple single-stack cells. When passing the CO2 gas through the stacks one after the other (serial gas connection), the CO2 conversion efficiency was increased remarkably. Importantly, the presented electrolyzer simultaneously provides high partial current density, low cell voltage (−3.0 V), high conversion efficiency (up to 40 %), and high selectivity for CO production; while operating at up to 10 bar differential pressure.
In the second part of the talk I will show how the cell can operate with pure water feed on the anode side, therefore avoiding the use of alkaline anolyte. A carefully designed activation protocol will be presented, which allows the cell to operate at high current density, using pure water feed. The effect of temperature and flow rate on the operation will also be presented. Finally, the nature of ion-transport through the anion exchange membrane as a function of the operational conditions will be discussed.
Integrating Materials Design and Operando Spectroscopy for the Development of Next Generation CO2 Reduction and Biomass Valorization Catalytic Systems
Authors: Kornienko Nikolay 
Published: May 2020

Electrochemical conversion of abundant feedstocks to fuels and value-added chemicals is rapidly gaining significance as a promising method to harness renewable electricity. Specific reactions within this context that my research group is focused on are the reduction of CO2 and oxidation of waste biomass. Because the design of new catalytic systems is inherently linked to a precise understanding of how these reactions proceed on heterogeneous surfaces, we put considerable efforts in developing methodology for opernado probing with Raman spectroscopy CO2 reduction and biomass valorization. This talk will detail our efforts in the design, electrochemical characterization, and spectroscopic investigation of
1) Composite systems of metallic nanoparticles decorated with functional organic ligands with steer CO2 reduction reactions down a select pathway on their surface
2) Tandem CO2 catalysis at the material-Metal Organic Framework (MOF) interface
3) Electrochemical oxidationof 5-hydroxymethylfurfural (HMF) on gold and transition metal oxide surface
In all, I show how using opernado Raman spectroscopy provides the mechanistic information on surface reaction mechanisms that enhance our understanding of functional hybrid interfaces and provides avenues for future materials design within the context of electrosynthesis of fuels and chemicals.

Figure 1