bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pt Acts As a Catalyst to Activate RuO2: The Active Sites of RuO2 Co-Catalyst for the CO Oxidation
Authors: Sugimoto Wataru , Olu Pierre-Yves , Mochizuki Dai 
Published: February 2020

RuO2 has been suggested to act as stable co-catalysts for CO oxidation on Pt. However, little is known on how the oxide functions to oxidize nearby CO. In this work, we use model rotating disk electrodes composed of RuO2 nanosheets (RuO2(ns)) deposited on the surface of polycrystalline Pt, polycrystalline Au and glassy carbon. A new co-catalytic mechanism regarding the Pt/RuO2 interface towards the electro-oxidation of CO is proposed. Two distinct synergetic effects were identified, decreasing the bulk CO electro-oxidation onset potential compared to bare Pt by 50 mV (the ‘high potential’ synergetic effect at 0.85 V vs. RHE) and 250 mV (the ‘low potential’ synergetic effect at 0.65 V vs. RHE). We discuss the later with a new mechanism, involving an activated surface of RuO2(ns) generated by a partial reduction catalyzed by Pt.
The peculiar ‘low potential’ synergetic effect decays upon potential cycling in CO-saturated electrolyte where Pt is poisoned with COad, but can be reactivated by COad-free Pt in HUPD potential region. These results were resolved considering the formation of ‘Ru metal-like’ sites on RuO2(ns) which are generated from a partial reduction of the RuO2(ns) surface catalyzed by a Pt surface that is not poisoned by CO (spill-over hydrogen). Therefore, this ‘low potential’ synergetic effect interestingly differs from the customary bifunctional mechanism and shows a highly interdependent relationship where Pt-catalyzed activated surface of RuO2(ns) provides oxygenated species for the removal of CO adsorbed on Pt.
Acknowledgments
This work was supported in part by the ‘Polymer Electrolyte Fuel Cell Program’ from the New Energy and Industrial Technology Development Organization (NEDO), Japan.
(Keynote) Synthetic Protection Matrices for Integration of Redox Proteins in Fuel Cells and Photovoltaic Cells
Authors: Plumeré Nicolas 
Published: February 2020

Various redox proteins such as hydrogenases or photosynthetic proteins can be integrated in devices to produce electricity or chemical fuels. Redox hydrogels are among the best strategies to immobilize and electronically contact proteins to electrodes. The redox potentials and the solvation properties of viologen or Os-complex modified polymeric matrices can be tuned to enable benchmark current densities (300 μA cm-2 for photosystem 1 [1] and up to 400 μA cm-2 for photosystem 2 [2]) at low overpotential [3]. However, deactivation process of photosystems [4] and hydrogenases [5] limit their technological applications. We proposed the use of redox matrices for the protection of hydrogenases [6, 7] to open the possibility of utilizing these highly active but also highly sensitive enzymes in devices for energy conversion. The mechanism of protection relies on the redox buffering capacity of the matrix and the film properties can be adjusted to protect hydrogenases quasi-infinitely [8]. The main limitations are (i) the overpotential imposed by mediated electron transfer within the hydrogel, (ii) the film thickness required for protection which implies the need for a significant amount of enzyme that is not involved in the bioelectrocatalytic process and (iii) the inefficiency of the protection when the bioelectrodes are operated in a cathodic mode such as H2 production. However, recent progresses in bioelectrode and redox hydrogel design, in particular with respect to electron transfer properties, mitigate the compromise between protection and performance in hydrogenase based energy conversion.
[1] T. Kothe, S. Pöller, F. Zhao, P. Fortgang, M. Rögner, W. Schuhmann, N. Plumeré Chem. Eur. J.,
2014, 20, 11029 – 11034.
[2] K. Sokol, D. Mersch, V. Hartmann, J. Z. Zhang, M. M. Nowaczyk, M. Rögner, A. Ruff, W. Schuhmann, N. Plumeré, E. Reisner. Energy Environ. Sci., 2016, 9, 3698-3709.
[3] V. Hartmann, T. Kothe, S. Pöller, E. El-Mohsnawy, M. M. Nowaczyk, N. Plumeré, W. Schuhmann, M. Rögner Phys.
Chem. Chem. Phys., 2014, 16, 11936 - 11941.
[4] M. M. Nowaczyk, N. Plumeré. Nature Chemical Biology
2016, 12, 990-991.
[5] A. Kubas, C. Orain, D. De Sancho, L. Saujet, M. Sensi, C. Gauquelin, I. Meynial-Salles, P. Soucaille, H. Bottin, C. Baffert, V. Fourmond, R. Best, J. Blumberger, C. Leger, Nature Chem.
2017, 9, 88-95.
[6] N. Plumeré, O. Rüdiger, A.A. Oughli, R. Williams, J. Vivekananthan, S. Pöller, W. Schuhmann, W. Lubitz, Nature Chem. 2014, 6, 822.
[7] A. A. Oughli, F. Conzuelo, M. Winkler, T. Happe, W. Lubitz, W. Schuhmann, O. Rüdiger, N. Plumeré, Angew. Chem. Int. Ed.
2015, 54, 12329.
[8] Fourmond, V.; Stapf, S.; Li, H.; Buesen, D.; Birrell, J.; Rüdiger, O.; Lubitz, W.; Schuhmann, W.; Plumeré, N.; Léger, C. J. Am.
Chem. Soc.,
2015, 137, 5494

Acknowledgement. Financial support by the Cluster of Excellence RESOLV (EXC 1069) and by the ERC Starting grant REDOX SHIELDS is gratefully acknowledged.
(Invited) Lithium Ion Conductors – between Model Systems and Battery Materials
Authors: Heitjans Paul 
Published: February 2020

Lithium ion conductors continue to attract huge attention mainly due to the need for improved Li ion batteries, although “post-Li” energy storage systems are also being explored. In any case, basic research dealing with, e.g., the elementary ion jump process, the dimensionality of diffusion or the influence of structural disorder – besides being a field in its own right – is indispensable for those applications, too.
Here, exemplary results of our group on Li ion conductors are reviewed. Interestingly, materials used as model systems for basic questions quite often are also potential battery materials, i.e. solid electrolytes or electrodes, and vice versa.
An early example of a cathode material has been the intercalation compound LixTiS2 which turned out to be a model system for two-dimensional Li diffusion, involving a unique jump process over many decades, as was proven by a combination of nuclear magnetic resonance (NMR) techniques. Besides the layer-structured also the cubic modification as well as nanocrystalline and amorphous forms were examined with respect to dimensionality and disorder effects.. Anode materials studied by us primarily from a fundamental point of view have been Li
x
C6 (0<x≤1), Li4+x
Ti5O12 (0<x<3) and, as one of the silicides, Li12Si7. In Li12Si7 very fast quasi one-dimensional Li diffusion was detected. Among the potential electrolytes for all-solid-state Li ion batteries, Li7La3Zr2O12 was investigated in some detail also with respect to the influence of doping and defects on Li diffusivity.
The examples to be presented extensively involve NMR, which now is an established materials science method for Li ion dynamics [1, 2], but also impedance spectroscopy [3], mass spectrometry [4] and neutron reflectometry [5] have been applied in the Li ion transport studies.
[1] C. V. Chandran, P. Heitjans, Solid-State NMR Studies of Lithium Ion Dynamics Across Materials Classes, Annual Reports on NMR Spectroscopy 89 (2016) 1-102.
[2] K. Volgmann, V. Epp, J. Langer, B. Stanje, J. Heine, S. Nakhal, M. Lerch, M. Wilkening, P. Heitjans, Solid-State NMR to Study Translational Li Ion Dynamics in Solids with Low-Dimensional Diffusion Pathways, Z. Phys. Chem. 231 (2017) 1215–1241.
[3] J. Rahn, E. Hüger, L. Dörrer, B. Ruprecht, P. Heitjans, H. Schmid, Li Self-Diffusion in Lithium Niobate Single Crystals at Low Temperatures, Phys. Chem. Chem. Phys. 116 (2012) 2427–2433.
[4] A.-M. Welsch, H. Behrens, I. Horn, S. Roß, P. Heitjans, Self-Diffusion of Lithium in LiAlSi2O6 Glasses Studied Using Mass Spectrometry, J. Phys. Chem. A 116 (2012) 309–318.
[5] F. Strauß, E. Hüger, P. Heitjans, T. Geue, J. Stahn, H. Schmidt, Li Permeation through Thin Lithium-Silicon Films for Battery Applications Investigated by Neutron Reflectometry, Energy Technology 12 (2016) 1582–1587.
(Invited) Electrocatalytic Activity Towards ORR and Stability of Binary and Ternary Catalysts Based on Pt and Cu
Authors: Coutanceau Christophe , Lankiang Styven , Baranton Stève 
Published: February 2020

The catalytic activity of platinum can be enhanced by modifying Pt-NPs with transition metal atoms such as Ni, Fe, Co, Cr, Cu [1,2]. But, it has also been proposed that the addition of non-noble transition metals could involve a lower stability than pure platinum due to their dissolution [3,4] leading further to a loss of performances in PEMFC. Other authors have shown that the dealloying of the nanoparticle surface, leading to a core-shell structure having a Pt rich surface, could enhance the catalytic activity of binary or ternary Pt-based systems.
On the one hand, gold was proposed to prevent platinum dissolution by raising the Pt oxidation potential [5,6], a property which could be interesting to enhance the stability of core-shell Pt-based catalysts with Pt rich surface. Moreover, it has also been shown that PtAu-based catalysts could exhibit similar or even higher catalytic activity towards ORR than pure platinum [7–9]. On the other hand, recent DFT calculation identified that copper containing Pt-based catalysts, such as PtAuCu core-shell structures, as displaying high expected ORR activity and also a stabilizing effect from the Au-Cu interaction [10].
For these reasons, PtxCu1-x/C and ternary PtxAuyCuz/C catalysts were synthesized by a microemulsion method and characterized by TGA, TEM, XRD, AAS, XPS and cyclic voltammetry in order to assess their metal loading, their microstructure and their bulk and surface compositions. The electrocatalytic activity towards ORR, the selectivity and the stability of catalysts were studied in acidic electrolyte using the rotating disc and the rotating ring disc electrode techniques.

Acknowledgement:

The financial support of the European Commission under the FP7 Fuel Cells and Hydrogen Joint Technology Initiative grant agreement FP7-2012-JTI-FCH-325327 for the SMARTCat project is gratefully acknowledged.

References:

1- T. Toda, H. Igarashi, H. Uchida, M. Watanabe, J. Electrochem. Soc. 146 (1999) 3750–3756.
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7- P. Hernández-Fernández, S. Rojas, P. Ocón, J.L.G. Fuente, J.S. Fabián, J. Sanza, M. A. Peña, F.J. Carcía-García, P. Terreros, J.L.G. Fierro, J. Phys. Chem. C 111 (2007) 2913–2923.
8- D.F. Yancey, E.V. Carino, R.M. Crooks, J. Am. Chem. Soc. 132 (2010) 10988–10989.
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Heterogeneous Iron-Containing Carbon Gels As Catalysts for Oxygen and Carbon Dioxide Electroreductions – Rotating Ring-Disk Voltammetric Studies
Authors: Dembinska Beata , Kiciński Wojciech , Kulesza Pawel J 
Published: February 2020

There has been growing interest in the development of highly active catalysts for electroreduction of oxygen that could be effectively utilized in low-temperature fuel cells. The important practical issue is related to the need of lowering costs of catalysts by substituting the noble metals with inexpensive abundant elements. In this respect materials containing metallic moieties coordinated by nitrogen atoms embedded in the carbon matrix (M-N-C) are recognized as most suitable candidates to replace platinum catalysts. More recently, the approach of using such biomimetic centers has been considered for the carbon dioxide reduction, the reaction which permits generation of carbon-based chemicals, fuels or syngas. Since both reactions (O2 and CO2 reductions) are characterized by slow kinetics and may proceed through different pathways producing various products, their efficiency and selectivity still remain fundamental problems for practical applications.
It is well established that the best performing M-N-C catalysts (with high specific surface area and large fraction of micropores) are produced from nitrogen-containing polymeric precursors. In these study we present a new type of self-supporting M-N-C materials, namely nitrogen and sulfur co-doped iron containing highly porous carbon gels (obtained through pyrolysis of organic gels) as efficient non-precious metal catalysts for both the oxygen and carbon dioxide electroreductions. The precursors of the catalysts were prepared via the sol-gel polycondensation (induced with iron(III) cations) of resorcinol together with the mixture of two heterocyclic aldehydes containing nitrogen and sulfur. The role of S is to produce carbon gels with high specific surface areas (e.g. when compared to carbon gels containing solely N heteroatom).
It is commonly accepted that rotating ring(platinum)-disk(glassy carbon) electrode voltammetry can be effective diagnostic tool for elucidation of the performance and selectivity (towards water or hydrogen peroxide) of the oxygen electroreduction. We are going to demonstrate that a combination of the rotating ring-disk electrode methodology and stripping type voltammetry (at platinum ring) can be also used for the determination of the reaction mechanism, competitive formation (evolution) of hydrogen, and determination of CO-type adsorbates generated at the catalyst during the CO2 electroreduction.
(Invited) Light Metal Hydride Nanocomposites As Room Temperature Solid Electrolytes
Authors: de Jongh Petra E. , Ngene Peter , Blanchard Didier 
Published: February 2020

A central goal in current battery research is to increase the safety and energy density of Li-ion batteries. Electrolytes nowadays typically consist of lithium salts dissolved in organic solvents. Solid electrolytes could facilitate safer batteries with higher capacities, as they are compatible with Li metal anodes, prevent Li dendrite formation and sulphur shuttling, and eliminate risks associated with flammable organic solvents. Less than 10 years ago, LiBH4 was proposed as a solid state electrolyte. It showed a high ionic conductivity, but only at elevated temperatures. Since then strategies have been developed to extend the high ionic conductivity of LiBH4 down to room temperature, and other light metal hydrides have been explored as solid electrolytes [1].
Using LiBH4 as an example we will discuss how the properties of solid electrolytes can be modified by forming nanocomposites with metal oxides, leading to an enhancement of the room temperature ionic conductivity of more than three orders of magnitude[2]. DSC measurements combined with solid state NMR allow to identify how the nanoconfinement and presence of interfaces modify the phase stability and the Li+ mobility [3]. Systematic studies show how the ionic conductivity can be optimized by tuning the nanostructure and interfaces in these nanocomposites. Finally, promising results have been obtained in using these materials as solid-state electrolytes in next generation all-solid state lithium-sulphur batteries. [4]
[1] de Jongh et al. J. Appl. Phys. A (2016), 122:251.
[2] Blanchard et al., Adv. Funct. Mater. 25 (2015), 182.
[3] Verkuijlen et al., J. Phys. Chem. C 116 (2012) 22169.
[4] Blanchard et al, J. Electrochem. Soc. (2016).
Enhanced Capacitive Deionization of Graphene Nanoplatelet/Activated Carbon Composite Electrode
Authors: Ham Kahyun , Lee Jae Kwang , Lee Jaeyoung 
Published: February 2020

Water treatment is an essential technology. Especially, some nations demand appropriate technology to produce fresh water with a low cost. Capacitive deionization (CDI) with low-energy consumption and no secondary waste is emerging as an innovative desalination technology. [1] It removes salts in the water by adsorbing ions onto electric double layer in surface of electrode. Hence, carbon with high surface area as well as high conductivity and chemical stability against corrosion is one of the candidates for CDI electrode material. [2]

Electrosorption ability of CDI electrode is related with such textural characteristics as the pore structure, size and the ratio of mesopore to micropore. [3] In the recent study, the micropore with size less than 1nm showed an anomalous increase in carbon capacitance for the electric double layer capacitor. [4] Meanwhile, the well-connected pore channels are accessible for ion mobility in pore structure, formed by ample micropore and mesopore via intercalation. Therefore, it is utmost approach to develop micro/mesoporous carbon structures to enhance electrosorption capacity and construct facile ion transfer pathway.
In this work, we reported the development of meporous/microporous carbon composite for fast ion infiltration with high electrosorption capacity using different ratio of graphene nanoplatelet to activated carbon as CDI electrode. The electrode was characterized by SEM, XRD, BET and contact angle. To confirm electrochemical performance, cyclic voltammetry and electrochemical impedance spectroscopy was investigated. Also, the fabricated electrode was conducted Langmuir isotherm adsorption experiment to compare adsorption kinetics among the electrodes and CDI performance test. We found that the composite electrode had the improved process efficiency, attributed to the high conductivity and adsorption kinetics of graphene nanoplatelet compared with the electrode exploiting only activated carbon.
[1] S. Seo, Investigation on removal of hardness ions by capacitive deionization (CDI) for water softening applications, Water Research, 2010, 44, 2267
[2] S. Porada, Direct prediction of the desalination performance of porous carbon electrodes for capacitive deionization, Energy Environ. Sci., 2013, 6, 3700
[3] P.M. Biesheuvel, Dynamic adsorption/desorption process model for capacitive deionization, Journal of Physical Chemistry C, 2009, 113, 5636
[4] J. Chmiola, Anomalous increase in carbon capacitance at pore sizes less than 1 nanometer, Science, 2006, 313, 1760
Bi-Metal Deposits within Nanostructured Silicon with Respect to Permanent Nanomagnets
Authors: Rumpf Klemens , Granitzer Petra , Gonzalez-Rodriguez Roberto , Coffer Jeffery , Poelt Peter , Michor Herwig 
Published: February 2020

The purpose of this work is to fabricate nanostructured silicon with two different materials of embedded magnetic nanostructures to exploit the magnetic properties of both metals and gain control of the exchange coupling between the two metals especially with respect to their volume ratio. Furthermore a variation of the structure size and the proximity of the metal deposits modifies the exchange coupling and thus the energy product. Finally nanocomposits with an energy product as high as possible are achieved to give rise to on-chip applications using permanent nanomagnets, especially arranged in arrays.
In this work magnetic nanostructures of two different metals are deposited within nanostructured silicon to control the magnetic switching behavior of the silicon/metal nanocomposite. Two different templates, porous silicon and porous silicon nanotubes are utilized to achieve such nanocomposites. The morphology (pore diameter, tube diameter) of the two systems is comparable. In the case of the utilization of porous silicon templates a mesoporous morphology with average pore diameters of 50 nm are used and these oriented and separated pores are filled with two different metals, namely Ni and Co. The two metals are deposited alternatingly by electrodeposition. A further approach is the chemical growth of Co nanoparticles within porous silicon nanotubes (SiNTs) and the additional deposition of a Ni layer on the outer surface of the tubes. The inner diameter of the silicon tubes is around 50 nm and the wall thickness is about 10 nm. Since the silicon wall of the tubes offers a porous structure the Co particles, which are localized near the pore surface on the wall of a given nanotube, can touch the Ni layer. An alternative structure involves the deposition of an additional Si layer (after the growth of Co particles inside the tubes) as a spacer before the Ni deposition.
The morphology of the deposited bi-metal Ni/Co structures is figured out by SEM and EDX. Figure 1 shows an EDX-map of a cross-section of a porous silicon sample filled with Ni and Co.
In the presented work the dependence of the magnetic properties of a nanostructured silicon/bi-metal nanocomposite on the volume ratio of the metals, on the proximity of the nanostructures and also on the size of the metal deposits has been figured out. If the distance between the deposited bi-metal structures is small enough magnetic exchange coupling between them is present which could be observed. By tuning the bi-metal deposition an optimized energy product is achieved which gives rise to self-assembled nanocomposite systems containing permanent nanomagnets and arrays of them, respectively for on-chip applications.
Figure 1: EDX mapping of a cross-section of a porous silicon sample with deposited Ni-Co structures showing the ratio between Ni and Co (Ni …yellow, Co … Red).

Figure 1
Highly Sensitive Acetylcholinesterase Biosensor Based on Shaped Controlled ZnO Nanostructure for Paraoxon Pesticide Detection
Authors: Fallatah Ahmad , Kuperus Nicolas , Almomtan Mohammed , Padalkar Sonal 
Published: February 2020

Zinc oxide (ZnO) is an attractive material that finds applications in areas ranging from transistors, varistors, solar cells, photocatalysts and biosensors. Here we report the electrodeposition of ZnO nanostructured thin films in the presence of various capping agents like potassium chloride, ammonium fluoride and ethylenediamine to form different morphologies of ZnO. These ZnO nanostructures were used as biosensing platforms for the immobilization of acetylcholinesterase (AChE) and detection of the pesticide paraoxon. The electrodeposition of ZnO nanostructures was performed on carbon paper and carbon fabric substrate by using a zinc nitrate (Zn(NO3)2) precursor at 70 °C temperature with an applied potential of -1.0 V and 30 min reaction time. Many different morphologies of ZnO such as nanorods, nanoneedles, nanoplatelets, nanoflowers were successfully synthesized and characterized using scanning electron microscopy (SEM). Further the ZnO nanostructures were characterized by X-ray diffraction (XRD), UV-Vis spectroscopy, Raman spectroscopy and electrochemical impedance spectroscopy (EIS). An amperometric current response for the detection of paraoxon was recorded. The biosensor shows a detection limit to paraoxon in the range of 1nM–5µM . The developed biosensor shows high sensitivity, stability and low cost.
[PS[E1]Detection limit should be 1 nM. Let us not write a range. It can be confusing.
[PS[E2]You have written the abstract very well. Good job!