bluuebunny/crossref_metadata_2025 huggingface dataset:
Nickel-Rare Earth (RE=Ce,Dy,Sm) Electrodes for H2O2 Reduction in Direct Borohydride Fuel Cells
Authors: Santos Diogo M.F. , Cardoso David , Sljukic Biljana , Sequeira Cesar A.C. , Macciò Daniele , Saccone Adriana
Published: February 2020

Direct borohydride/peroxide fuel cells (DBPFCs) use sodium borohydride (NaBH4) as an anodic fuel and hydrogen peroxide (H2O2) as the oxidant. DBPFCs show higher theoretical cell voltage and energy density than most low temperature fuel cells. Furthermore, the fact that both fuel and oxidant are liquids at room temperature simplifies their storage, handling, thermal management and internal processing [1]. For these reasons, DBPFCs are promising alternatives as power sources for space, underwater, and specific terrestrial applications where oxygen is not available.

To push forward the DBPFC, it is necessary to develop efficient electrocatalytic materials towards hydrogen peroxide reduction reaction (HPRR), at the lowest possible cost. Nickel (Ni) alloys were found to possess good catalytic activities for HPRR [2]. Recently, it was shown that Ni-rare earth (RE) alloys presented improved catalytic activity for hydrogen evolution reaction, at much lower cost [3]. However, nothing is known about the effects of RE elements on the electrocatalytic behavior of Ni towards the HPRR.

In this study, the HPRR is evaluated in six different Ni-RE intermetallic alloy electrodes, namely nickel-cerium (Ni-Ce), nickel dysprosium (Ni-Dy) and nickel-samarium (Ni-Sm) with 5 and 10 at.% of RE metal. The alloys were prepared by arc melting, starting from the stoichiometric amounts of the two parent metals, and analyzed by XRD and SEM coupled with EDS. The results were directly compared with single Ni electrode in the same experimental conditions.

Electrochemical experiments were performed using a standard three-electrode setup, using each of the Ni-RE alloys as a working electrode. The alloys were tested in 2 M NaOH + 0.05 M H2O2 aqueous electrolytes, at temperatures ranging from 25 to 45 ºC. Cyclic voltammetry (CV), linear scan voltammetry (LSV), chronoamperometry (CA), and chronopotentiometry (CP), were used to investigate the electrodes activity for HPRR reduction in alkaline media. CVs of the alloys presented a well-defined cathodic peak. Plots of peak currents and peak potentials as a function of the potential scan rate allowed calculation of the number of exchanged electrons and of the charge transfer coefficients for the studied temperature range. CA measurements demonstrated good stability of the tested systems.

References

1. D.M.F. Santos, C.A.C. Sequeira, Sodium borohydride as a fuel for the future, Renew. Sustain. Energy Rev. 15 (2011) 3980.

2. A.E. Sanli, A. Aytaç, Electrochemistry of The Nickel Electrode as a Cathode Catalyst In The Media Of Acidic Peroxide For Application of The Peroxide Fuel Cell. ECS Trans. 42 (2012) 3.

3. D.S.P. Cardoso, L. Amaral, D.M.F. Santos, B. Šljukić, C.A.C. Sequeira, D. Macciò, A. Saccone, Int. J. Hydrogen Energy 40 (2015) 4295.
Green Synthesis of Au-Based Nanomaterials Using an "All-in-One" Ionic Liquid and Their Electrocatalytic Properties for Glucose Electro-Oxidation
Authors: Pérez Covarrubias Luis A. , Romero-Soto Christian A. , Álvarez-Contreras Lorena , Guerra-Balcázar Minerva , Arriaga Luis Gerardo , Ledesma-García Janet , Arjona Noé
Published: February 2020

In a previous work, the ability of 2-hydroxyethylammonium formate ionic liquid to act as an “all-in-one” reaction medium was tested for Pd and Pd-NiO nanoparticles. In this work, the proof of its power to synthesize metallic nanoparticles was extended to the following materials: Au, AuPd, AuPt and AuCuO nanoparticles as well as Pd and CuO as controls. These materials were used as electrocatalysts for the glucose electro-oxidation reaction. According with XRD, crystallite sizes of 16.9, 11.8, 12.0, 12.6, 10.1 and 11 nm were obtained for Au/C, AuPd/C, AuPt/C, AuCuO/C, Pd/C and CuO/C, respectively. TEM micrographs showed nanoparticle sizes closed to crystallite sizes. For metallic mixtures, X-ray fluorescence revealed metallic compositions of Au60Pd40, Au90Pt10 and Au85CuO15. Moreover, thermogravimetric analyses showed metal mass contents between 24 to 32 wt. % (Vulcan carbon was used as support) for all materials except AuCuO which showed 4 wt. %. The electrocatalytic activity toward glucose electro-oxidation was tested as function of its concentration and temperature. All materials showed electrochemical response to the presence of glucose. For fuel cell applications, AuPt showed the most negative oxidation potential (-0.57 V vs. NHE at 40°C) and the highest peak current density (58.5 mA mg-1). For electrochemical non-enzymatic glucose detection, all materials showed good response to the successive addition of 1 mM glucose at short times (less than 10 seconds). However, due to its easiness to be synthesized, and its relative low cost, CuO/C can be an attractive option for non-enzymatic glucose sensors.
Electrochemical Performance of H2o-CO2 Co-Electrolysis with a Tubular Solid-Oxide Co-Electrolysis (SOC) Cell
Authors: Lim Tak-Hyoung , Lee Jong-Won , Lee Seung-Bok , Park Seok-Joo , Song Rak-Hyun
Published: February 2020

The H2O-CO2 electrochemical conversion process in solid-oxide co-electrolysis (SOC) cells may be one of the most efficient ways to reduce CO2 emissions and to store renewable power simultaneously. In this study, a tubular solid-oxide co-electrolysis (SOC) cell based on a general electrode support solid-oxide fuel cell was fabricated and investigated. For this purpose, we fabricated tubular electrode support tubes through an extrusion process, and after which the essential SOC cell components, i.e., the electrolyte and the electrode, were coated onto the surface of the ceramic support consecutively using a vacuum slurry and dip-coating method. The cell was operated while varying the operating temperature, cathode gas flow rate, and the supplied amount of H2O. The results demonstrate that the fabricated tubular SOC cell is a promising candidate for many practical applications, such as technology to mitigate climate change and power fluctuations associated with renewable energy.
High-Temperature Transport and Thermoelectric Properties of Ca3
-XSmxCo4O9
Authors: Park Kyeongsoon , Cha J. S. , Hakeem D. A.
Published: February 2020

Ca3Co4O9 ceramic has attracted considerable attention for its practical applications in thermoelectric devices. The thermoelectric properties of Ca3Co4O9–based ceramics can be improved by controlling its composition, microstructure, and carrier conduction. We fabricated Ca3
-xSmxCo4O9+δ
by spark plasma sintering process in combination with Ca3
-xSmxCo4O9+δ powders prepared by sol–gel method. The electrical conductivity and the Seebeck coefficient were simultaneously measured over a temperature range of 500-800 °C. The thermal conductivity was obtained by measuring thermal diffusivity and specific heat capacity. XRD patterns showed that all the samples were single monoclinic phase, and no secondary phase was detected. The substituting ions of Sm3
+ did not change the crystal structure. The degree of crystallographic anisotropy was evaluated in terms of the Lotgering factor. The electrical conductivity significantly increased with the incorporation of Sm3
+. The Seebeck coefficient showed a positive value over the measured temperature range, indicating p-type conduction. In this work, the temperature dependent thermoelectric properties of Ca3
-xSmxCo4O9+δ were systematically investigated.
Nano-Composite Barium Strontium Cobalt Iron Oxide - Gadolinium Doped Ceria Solid Oxide Fuelcell Cathodes
Authors: Bocklund Brandon J. , Nicholas Jason D.
Published: February 2020

Symmetrical Solid Oxide Fuel Cell Nano-Composite Cathodes (NCCs) were fabricated by infiltrating Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) precursor nitrate solutions containing glycine and Triton-X 100 into porous Ce0.9Gd0.1O1.95 (GDC) cathode scaffolds. X-ray diffraction indicated that in all cases the BSCF infiltrate was >90% phase pure. NCCs produced using CaCl2 desiccation exhibited improved performance compared to conventionally infiltrated NCCs. The observed performance trends were interpreted in terms of scanning electron microscopy-measured BSCF nanoparticle sizes and Simple Infiltrated Microstructure Polarization Loss Estimation (SIMPLE) modelling.
(Invited) Combined Experimental-Numerical Approaches for Transport Characterization in Nano and Micron-Sized Multi-Component and Multi-Functional Materials
Authors: Haussener Sophia
Published: February 2020

Porous and heterogeneous materials are core components in energy conversion and storage devices such as batteries, fuel cells and electrolyzers, or photoelectrochemical fuel generators. The heterogeneity and structural complexity of these components are a result of three main drivers: i) The multi-functional nature of the applications requiring the presence of various functional materials in close vicinity, ii) nano- and micron-scale structuring of the material required to overcome the bulk material transport limitations, and iii) cheap and simple synthesis methods resulting in stochastic and complex morphologies. Consequently, understanding of the multi-physical transport phenomena and optimization of the component for enhanced performance, requires an accurate modelling and prediction of the transport properties, which heavily rely on the complex nano to micron-scale morphology.

In this presentation, I will show how a previously developed combined experimental-numerical approach1 can be used for the accurate numerical characterization of the heterogeneous components’ transport properties. The methodology consists of (i) the experimental characterization of the material’s exact microstructure via non-intervening, non-destructive imaging techniques, and the subsequent use of this data in (ii) the discrete-scale numerical determination of the medium’s effective transport properties in conjunction with continuum-scale theory. This approach can be extended by using digital image processing on the structure data2,3 to allow for artificial changes in the morphological characteristics – corresponding to real variations in the fabrication process – and subsequent investigation of the changes in the material’s transport properties.  

I will show results from the application of the combined experimental-computational methodology to three morphologically complex components at very different length-scales and in three different applications: (i) nano-structured multi-component photoelectrodes for the production of solar fuels, (ii) nano-structured porous electrodes in high-temperature electrolysis, and (iii) porous ceramic receivers for the production of concentrated solar power. The approach allowed to quantify for the first time morphological and transport properties of nano-structured photoelectrodes (example i), to characterize novel transport properties such as permeability for porous electrodes in high-temperature electrolysis (example ii), and to propose pore-scale engineering design guidelines for optimized structures of solar receivers (example iii). 

1   J. Petrasch, Ph.D. thesis, ETH Zurich, 2007.

2   S. Haussener, and A. Steinfeld, Materials, 2012, 5, 192–209.

3   S. Suter, A. Steinfeld, and S. Haussener, Int. J. of Heat and Mass Transfer, 2014, 78, 688-698.

4   S. Suter, and S. Haussener, JOM, 2013, 65, 1702-1709.
Soft-Templated Mesoporous Graphitic Carbon Nitride and Their Cobalt Composites for Energy Storage Application
Authors: Palani Raja Jothi , Shanthi Kannan
Published: February 2020

Non-precious electrocatalysts with high activity and low cost are desirable candidates for many state-of-the renewable energy devices, such as energy storage and conversion. However, the design and formation of such materials remain a signiﬁcant challenge. In this study, a facile soft-templated route is designed for the synthesis of mesoporous graphitic carbon nitride (meso g-C3N4) and cobalt modified g-C3N4 composites. Once the meso g-C3N4 modified with cobalt (Co) source, the morphology slowly changed to aggregated nanoballs like morphology at a particular Co composition (3 wt.%). The mesoporous architecture and morphology were confirmed by using N2-sorption and high resolution transmission electron microscopy studies, respectively. The effects of Co concentration on the nanostructures and electrochemical performances of the composites for supercapacitor application are investigated. The obtained mesoporous Co/g-C3N4 nanoballs showed excellent electrochemical performance related to high specific capacitance, good rate capability, and greater cyclic stability than other samples (mesoporous g-C3N4 nanoflakes and non-porous analogue). The exceptional electrochemical performance of mesoporous Co/g-C3N4 nanoballs for supercapacitor could be attributed to an effective integration of g-C3N4 nanoflakes and cobalt that maximizes the synergistic interaction between them. Detailed synthetic procedure and electrochemical properties of these nanostructures will be discussed in the meeting with reference to the physicochemical properties.
Development of Ionic Liquid-Tagged Carbohydrate Building Block for Electrochemical Glycosylation
Authors: Nokami Toshiki , Sasaki Norihiko , Isoda Yuta , Itoh Toshiyuki
Published: February 2020

Recently we have developed an electrochemical method for oligosaccharide synthesis based on the automated electrochemical assembly (AEA) of carbohydrate building blocks. This method enables us to access fully protected oligosaccharides rapidly in a preparative scale; however, the assembly of building blocks is one of the steps of oligosaccharide synthesis. In order to increase efficiency of the entire process, it is important to introduce a strategy which facilitates separation and purification of oligosaccharides thus-obtained.

Separation tags are small molecules which are covalently attached to the substrates to make the separation step easier and faster. There are several tags including a fluorous tag, an ionic liquid tag, and others which have already been introduced into oligosaccharide synthesis. In this study, we introduced an ionic liquid tag to the building block for electrochemical glycosylation, because we presume that an ionic liquid tag works not only as a separation tag but also as an electrolyte and a reservoir of the counter anion for the reactive intermediate of glycosylation. Here we report the development of a novel ionic liquid tag and its application for electrochemical glycosylation.

The developed benzyl ether-type ionic liquid tags were prepared from the corresponding precursors that can be prepared in a single step by the reaction of tertiary amines and introduced to a thioglycoside building block also in a single step with high yields. Electrochemical glycosylation of the thioglycoside equipped with the ionic liquid tag affords the corresponding disaccharides which can be purified easily by washing with water and organic solvent sequentially. In the presence of palladium carbon under the hydrogen gas atmosphere, removal of the tag and benzyl protecting groups of hydroxyl groups can be performed to obtain the fully deprotected disaccharides.
Synthesis of 1,5-Diaminonaphthalene Via Electrochemical C,H-Amination of Naphthalene
Authors: Möhle Sabine , Herold Sebastian , Richter Frank , Nefzger Hartmut , Waldvogel Siegfried R.
Published: February 2020

Since their invention in 1937, polyurethanes (PUR) have found numerous applications in our daily life.[1] A key building block for high performance polyurethanes (Vulkollan®) is 1,5-naphthalene diisocyanate, made from 1,5-diamino naphthalene. The latter is currently made by a rather laborious multistep process. Therefore, a direct and sustainable access to 1,5-naphthalene diisocyanate or the precursor diamine would be of interest. In 2013 Yoshida et al. reported a promising process for the electrochemical C,H amination of electron-rich arenes.[2,3] Through anodic pyridination at a carbon felt anode (graphite) N-arylpyridinium ions are obtained. Aminolysis with piperidine yields the corresponding primary amines. Overoxidation and the introduction of a second amino moiety are suppressed because of the positive charge of the pyridinium intermediates.

We successfully demonstrated the twofold, electrochemical C,H amination of naphthalene by employing boron-doped diamond anodes. This innovative electrode material shows a higher performance at more positive potentials.[4] The second amino functionality is, due to electrostatics, regioselectively introduced at position 5. Upon work-up 1,5-diaminonaphthalene and 1-aminonaphthalene are obtained. Currently, the reaction is optimized regarding e.g. current density and electrolyte. It is envisioned, that the positive charge of 1-pyridiniumnaphthalene can be effectively shielded through an appropriate choice of supporting electrolyte (-concentration). Thus, the second oxidation should be facilitated. Furthermore, the scope of the reaction is expanded to other polycyclic aromatic hydrocarbons, as well as other nitrogen-based nucleophiles.

References:

[1]   a) O. Bayer, W. Siefken, H. Rinke, L. Orthner, H. Schild (IG Farben), DRP 728981, 1937; b) H.W. Engels, H. G. Pirkl, R. Albers, R. W. Albach, J. Krause, A. Hoffmann, H. Casselmann, J. Dormish, Angew. Chem. Int. Ed.
2013; 52, 9422–9441, Angew. Chem. 2013, 125, 9596–9616.

[2]   T. Morofuji, A. Shimizu, J. I. Yoshida, J. Am. Chem. Soc. 2013, 135, 5000–5003

[3]   S. R. Waldvogel, S. Möhle, Angew.
Chem. Int. Ed.
2015, 54, 6398–6399; Angew. Chem. 2015, 127, 6496–6497.

[4]   B. Elsler, D. Schollmeyer, K. M. Dyballa, R. Franke, S. R. Waldvogel, Angew.
Chem. Int. Ed. 2014, 53, 5210─5213; Angew.
Chem.
2014, 126, 5311─5314.

Figure 1
Electropolymerization of EDOT on Wireless Electrodes Toward Polymer Microfiber Networks
Authors: Inagi Shinsuke , Koizumi Yuki , Ohira Masato , Nishiyama Hiroki , Tomita Ikuyoshi
Published: February 2020

Recently we reported the site-selective electroplating of metals such as Au and Pt on a conductive object used as a bipolar electrode (BPE).1 The application of alternating current (AC) voltage between the driving electrodes was found to be effective for the precise modification of the BPEs.

   We report here the electropolymerization of 3,4-ethylenedioxythiophene (EDOT) and its derivatives by AC-bipolar electrolysis with the sacrificial reduction of benzoquinone.2 Poly(3,4-ethylenedioxythiophene) (PEDOT) derivatives were found to propagate as a fiber form from the ends of Au wires used as BPEs parallel to an external electric field, without the use of templates. The effects of applied frequency and of the solvent on the morphology, growth rate and degree of branching of these PEDOT fibers were investigated. In addition, a chain-growth model for the formation of conductive material networks was also demonstrated.

References

1. Y. Koizumi, N. Shida, I. Tomita, S. Inagi, Chem. Lett.
2014, 43, 1245.

2. Y. Koizumi, N. Shida, M. Ohira, H. Nishiyama, I. Tomita, S. Inagi, Submitted.

Figure 1
Molecular Tailoring for Efficient Conversion of Near-Infrared Light in Dye-Sensitized Solar Cellsoral
Authors: Novelli Vittoria , Barbero Nadia , Magistris Claudio , Barolo Claudia , Sauvage Frédéric
Published: February 2020

Dye-sensitized solar cells (DSCs) stand actually as a promising alternative to conventional silicon photovoltaic devices owing to lower production cost, low environmental footprint and unique properties to convert efficiently low light intensities and diffuse day light.(
1
) Today more than 14 % power conversion efficiency (PCE) has been achieved by optimizing a cocktail of organic dye in conjunction with a Co+III/+IItris(1,10-phenanthroline) redox couple.(
2
) So far, the current chemistry developed for DSC still present a lack in absorbing and converting substantially low-lying energy photons greater than λ >750 nm. With the aim to continue improving light harvesting capability of DSC for approaching closer to silicon standards, two important breakthroughs are needed: (i) reducing the internal energy loss arising from energy mismatch for electron injection and for dye regeneration (ii) extending light harvesting towards the NIR by the development of a new class of efficient sensitizers energetically well-coupled with the electronic properties of anatase TiO2 semi-conductor and electrolyte redox couple.

We have developed a series of new efficient organic sensitizers based on squaraine core-units, croconines or cyanines which are able to shift towards the red the light absorption from ca. 520 nm from the current ruthenium polypyridil-based sensitizers to as high as 830 nm. These new sensitizers not only show NIR absorption but also exhibit significantly higher molar extinction coefficients (100 000 - 320 000 mol-1cm-1) while being cost competitive.

This communication will describe these new efficient sensitizers converting up to 20% IPCE until 950 nm. Their light-to-electricity performances have been optimized by using highly diluted dye solution to promote aggregate-free self-assembled monolayer and carefully chosen electrolyte composition. Finally, the relationship between dye structure, electrolyte composition and the kinetic of charge transfers will be discussed on the basis of complementary set of techniques such as electrochemical impedance spectroscopy, time-correlated single photon-counting and ultra-fast pump-probe transient absorption spectroscopy.

1.            B. O'Regan and M. Gratzel, Nature, 1991, 353, 737-740.

2.            K. Kakiage, Y. Aoyama, T. Yano, K. Oya, J.-i. Fujisawa and M. Hanaya, Chem. Commun., 2015, 51, 15894-15897.
Electrochemical Characterization of Novel Organoborohydride Compounds
Authors: Cardoso David , Sequeira Cesar A.C. , Abbey Eric , Santos Diogo M.F. , Barker Josh , Bateman Chris
Published: February 2020

Sodium borohydride (NaBH4) is a solid white powder that finds wide application as a reducing agent in organic and inorganic synthesis [1]. This compound possesses relatively mild reducing abilities, but certain applications call for reducing powers greater than NaBH4, while others require the reducing powers to be attenuated. Organic chemists have successfully tuned the reducing power of NaBH4by attaching organic electron donating or withdrawing groups to the boron center, which can also drive regio- and stereoselectivity.

These organoborohydrides have received much recent attention for their role in frustrated Lewis pair systems [2], as well as in hydrogen fuel carriers. Computational methods have established the tuning power of different organic substituents on the boron center, but experimentally quantifying reducing power remains difficult [3]. The present study seeks to quantify reducing power using electrochemical methods and elucidate the relationship between organic tuning group and reducing ability.

In this work, benzylborohydride (C7H7BH3Na) was prepared by reduction of potassium benzyltrifluoroborate with a metal hydride. The compound structure was further characterized by multinuclear NMR and FTIR. Whereas, the electrochemical characterization was carried out using a standard three-electrode setup, by cyclic voltammetry (CV) in static conditions and by linear scan voltammetry (LSV) using a rotating ring-disk electrode (RRDE) system. Platinum and gold disk macroelectrodes and microelectrodes were used to study the electrooxidation of these compounds. The organoborohydrides were tested in DMSO + 0.03 M C7H7BH3Na at temperatures ranging from 25 to 65 ºC. The results were directly compared with NaBH4solutions in the same experimental conditions.

The main electrochemical parameters were calculated, including number of exchanged electrons, charge transfer coefficient, reaction rate constant, and diffusion coefficient for the selected range of temperatures. Moreover, the activation energy for the benzylborohydride oxidation reaction was calculated assuming Arrhenius behavior.

The formation of intermediate compounds was checked by RRDE studies, elucidating the possible steps involved in the oxidation mechanism. Several other organoborohydride compounds are planned to be studied and that will allow finding a direct relationship between organic substituents and the reducing power of the borohydride center.

1. H.O. House, Modern synthesis reactions, Benjamin, W.A., Menlo Park, CA, 1972.

2. J. Paradies, Metal-free hydrogenation of unsaturated hydrocarbons employing molecular hydrogen, Angew. Chem. Int. Ed. 53 (2014) 3552.

3. Z.M Heiden, A.P. Lathem, Establishing the hydride donor abilities of main group hydrides, Organometallics 34 (2015) 1818.
Hybrid Electrocatalytic Nanomaterials for Isopropanol Oxidation
Authors: Miecznikowski Krzysztof , Adamczyk Lidia , Cox James A. , Kulesza Pawel J
Published: February 2020

Recently, there has been growing interest in development of electrochemical energy conversion systems utilizing small organic molecules as alternative technologies to hydrogen based fuel cells. Such organic molecules as methanol, ethanol or isopropanol can be ideally oxidized to carbon dioxide.  But realistically the reactions are rather slow at ambient conditions. Obviously, there is a need to develop novel electrocatalytic materials.

Platinum has been recognized as the most active catalytic metal towards oxidation of alcohols at low and moderate temperatures. But Pt anodes are readily poisoned by the strongly adsorbed intermediates, namely by CO-type species, requiring fairly high overpotentials for their removal. Up to now lot of materials have been tested as electrocatalysts for small organic molecules in acidic media, such as Pt, its alloys Pt–M (M= Ru, Sn, Rh, Pb, Ir, W or Mo) in binary or ternary form and even different methods to prepare Pt thin film electrodes. Complete oxidation of alcohols into CO2 via C–C bond cleavage is mechanistically difficult at ambient (low) temperature, and the surface of catalytic platinum readily undergoes poisoning with intermediates of the alcohols oxidation. This problem may be partially solved by applying bifunctional electrocatalysts. In general, metals, like ruthenium, tin or rod are oxophilic, which provide oxygen at low potentials and mitigates the poisoning effect by oxidizing the metastable intermediates with adsorbed water fragments.

In order to increase the overall kinetic of electrooxidation of isopropanol, we have utilized as carriers (matrices) carbon nanotubes (CNTs) modified with the cesium salt of Keggin-type heteropolyacids of molybdenum and tungsten (Cs2.5H0.5PMo12O40, Cs2.5H0.5PW12O40) or metal oxide (MoO3, ZrO2, CeO2, IrO2). The presence of metals oxide and cesium salt are capable of generating of interfacial reactive hydroxy groups on the surfaces and also increase the catalytic surface. Remarkable increases of electrocatalytic currents measured under voltammetric and chronoamperometric conditions have been observed. Electrochemical diagnostic experiments have been supported with microscopic monitoring of morphology using transmission electron microscopy (TEM) and ATR-FTIR measurements.
Photochemical Degradation of Diclofenac Sodium By Nanophotocatalyst ZnO Doped C, N, S in Aqueous Solution Using UV Irradiation
Authors: Giahi Masoud , Taghvi Hajar
Published: February 2020

Novel C, N, and S-doped ZnO nanoparticles were prepared by a solid phase reaction. The catalyst was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results showed that crystallite size of synthesized C, N, and S-doped ZnO were in nanoscale.  The degradation was studied under different conditions such as the catalyst concentration, concentration of drug, initial pH value and presence of electron acceptor. The results showed that photocatalytic degradation of drug was strongly influenced by these parameters. The best conditions for the photocatalytic degradation of diclofenac sodium were obtained. The optimum concentrations of N, S, C -ZnO was found to be 0.44g/L. The photodegradation efficiency of diclofenac sodium decreased with an increase in the initial concentration of diclofenac sodium. In acidic solutions, photocatalytic degradation efficiency was higher than in alkaline solutions. The photodegradation efficiency of diclofenac sodium was accelerated by addition of a small amount of K2S2O8 and H2O2.

Figure 1
Underpotential Deposition of Nickel on Cu2o Films and Its Effects on Reactivity and Stability of Cu2o Films
Authors: Fillinger Akiko , DeHority Kaitlyn , Budin Noah
Published: February 2020

Our studies on crystal facet and reactivity relationship suggest that the (111) face of Cu2O films electrodeposited from pH 12 cupric lactate solution is a preferred surface for photogeneration of H2 from water, owing to its polar O2--termination.  In order to prevent photodecomposition of this Cu2O surface, which is initiated by interaction of the terminal O2- and H+ (Cu2O  + 2H+  + 2e-  --> 2Cu0 + H2O), while maintaining the attraction of H+ to the surface and potentially catalyzing H2 generation, we have attempted to deposit a monolayer of nickel via underpotential deposition (UPD).  Underpotential deposition on oxides has not been explored much unlike the underpotential deposition on metals as a monolayer deposition method.

Nickel was deposited on Cu2O films from a 0.08 M nickel acetate solution by applying various potentials for 1 min at room temperature.  The Cu2O films with nickel deposited were dissolved in HNO3, and then the quantities of the deposited nickel at the various potentials were determined with atomic absorption spectrometry (AAS).  The AAS results indicate that the underpotential deposition at -0.2 V vs. SCE (the calculated Nernst potential of the nickel solution is  -0.49 V vs. SCE) deposited nickel that is equivalent to a 23 % monolayer coverage, corresponding to 60 kJ stronger interaction of Ni2+(aq) with O2- at Cu2O surface than with bulk Ni surface, as predicted for the polar Cu2O (111) face.    For the estimate of the 100 % coverage of Cu2O surface, the atomic radius of Ni (124 pm) was used as well as the surface roughness of 1.09 obtained by atomic force microscopy measurements.  At -0.3 V vs. SCE, more than a monolayer of nickel (205 %) was deposited.

According to the x-ray photoelectron spectroscopy (XPS), the binding energy (BE) of Ni 2p3/2 electron changed from 855 eV for -0.2 V vs. SCE UPD sample to 851 eV for -0.3 V vs. SCE UPD sample.  Since the BEs of 854.6 eV and 852.6 eV have been assigned for Ni2+ and Ni0, respectively, the XPS data indicate that the full reduction of nickel at the Cu2O surface occurs at potentials more negative than -0.2 V vs. SCE. 

The effects of underpotentially deposited nickel on the activity and stability of Cu2O films will be compared with respect to the deposition potential.
Solar Driven Processes at Semiconducting Metal Oxide Electrodes, Assisted By Non-Noble Metal Catalysts
Authors: Solarska Renata , Bienkowski Krzysztof , Sarnowska Marta , Augustynski Jan
Published: February 2020

Attempts to improve performance of the semiconductor photo-electrodes used either for oxidation or reduction of species present in the electrolyte very often require presence of a catalysts However, identification of new molecular catalysts, active in often highly corrosive media or under unfavourable band energetics is a challenge.  N-type mesoporous tungsten trioxide, WO3, is one of few stable semiconductor materials able to photo-electrochemically split water under solar light irradiation but it’s operational acidic environment restricts use of any catalyst to the precious metal based oxygen-evolution electrocatalysts.  In an attempt to overcome this limitation, an addition to the acidic electrolyte of Keggin-type polyoxometalates (POMs) species was investigated in function of their electrocatalytic capabilities to drive oxygen evolution. The presence of this catalyst in the electrolyte makes it particularly efficient for use with nanoporous structure allowing deep penetration of the catalyst dissolved in the electrolyte. Moreover, moderate doping with metal cations of WO3 has been found to enhance visible blue light absorption of tungsten trioxide and, consequently, its photocurrent conversion efficiency. Combination of those two effects allowed achieving of record high water photooxidation currents attained under simulated solar AM 1.5G irradiation. The enhancement of anodic photocurrents will be discussed in the frame of functionalization of different mixed metal oxides with the POMs and correlated with the measurements of the amounts of oxygen evolved at the modified electrodes.
Nanodot Formation of Ferrocene-Terminated Self-Assembled Monolayers
Authors: Ikeda Katsuyoshi
Published: February 2020

Self-assembly of molecular monolayers is a very useful technique for fabricating chemically modified electrodes with various functions.  This technique enables to form a uniform molecular monolayer on a metal surface without guidance from outside.  On the other hand, it is still difficult for this technique to fabricate patterned monolayers or to integrate multiple functionality within a monolayer.  Although soft-lithography of self-assembled monolayers such as microcontact printing has already been reported, further advancement in forming nanoscale features of molecular monolayers is awaited for creation of multifunctional electrodes.  In this study, molecular nanodots are formed on Au(111) surfaces using a novel electrochemical nanolithographic method combining reductive desorption of thiols with AuNP-assisted local stabilization of the monolayers. 

The left panel of the figure shows a topographic image and I-V curves measured on nanopatterned monolayers of 4-methylbenzenethiols on Au(111) using current-AFM.  As a result of the local removal of the molecular monolayers, the exposed surface showed metallic conductivity.  On the other hand, the other area showed rather low conductivity with the exponential profile, indicating that the molecular layers remained with nanoscale domains.  The right panel shows that average molecular nanodot sizes was controllable by alternating the size of AuNP template or by changing the ionic strength for reductive desorption.  Electrochemical responses of ferrocene-terminated monolayer nanodots will be also demonstrated in the talk.

Figure (left) I-V curves measured on molecular nanodots and on the exposed Au(111) (right) Average sizes of molecular nanodots vs. sizes of AuNP templates.

Figure 1
Fabrication of Different Crystalline Diamond Films and Their Application As Anodes for the Oxidation of Human Urine
Authors: Li Zhongjian , Li Hao , Zhang Xingwang , Lei Lecheng , Yang Bin
Published: February 2020

Diamond shows several extreme outstanding properties, such as high Young's modulus, low surface roughness and chemical inertness et al. Thus, it has been used extensively in many fields including microelectromechanical systems, electron ﬁeld emitters and electrochemistry. The diamond film will be conductive after boron-doping, and therefore it can be used as a popular candidate anode for the electrochemical oxidation of organic containments in aqueous solution since it shows a wide potential window, low background current, high electrochemical stability and corrosion resistance. Water recycling would be the most realistic and economical way for human being in confined space station where it is cut off from the atmosphere for a long time.

In our work, hot filament chemical vapor deposition (HFCVD) method was employed to fabricate microcrystalline and nanocrystalline diamond films using only hydrogen and methane as precursor. Different factors such as methane concentration, substrate temperature and reaction pressure were studied and it reveals that methane concentration is the major contribution on the morphology change. The resulted morphology of diamond films changed from microcrystalline to nanocrystalline when the methane concentration increased from 2% to 10%. Boron-doped microcrystalline and nanocrystalline diamond films were both used as anodes for the electrochemical degradation of human urine. They show comparable efficiency on the degradation of organic compounds on both electrodes, and while show a small difference on the oxidation of chlorine ions and ammonia ions. However, the nanocrystalline diamond anode shows a longer lifetime due to the lower surface roughness in comparison with the microcrystalline diamond anode. Herein, the nanocrystalline diamond anode is promising for the industrial applications in the electrochemical oxidation of wastewater in the future.
Voltammetric Determination of Mercury in Biological Samples Using Crown Ether/Multiwalled Carbon Nanotube-Based Sensor
Authors: Hassan Rabeay , Kamel Manal , N.A. Hassan Hassan , Khaled Elmorsy
Published: February 2020

An electrochemical assay for sensitive and selective determination of mercury was suggested. Preparation, characterization, and testing the electro-catalytic activity of Crown-ether/multi-walled carbon nanotubes (MWCNTs) / CPEs were performed.  The voltammetric responses of modified electrodes with various sensing elements and nanomaterials were carefully investigated. Consequently, improving the sensitivity and selectivity were achieved using a combination of 12-crwon-4- ether and MWCNTs (10% w/w for each). A linear response was observed from 5 -110 µg/ml, with the detection limit (S/N=3) of 0.25 µg/ml. The method was interference free from many species and successfully applied for the determination of mercury in blood, urine or tab-water samples with a high accuracy and precision comparable with the reference method (Atomic Absorption Spectroscopy AAS).

Figure 1
The Electrochemical Behaviour of Some Composite Coatings Obtained By Electrodeposition on Metallic Substrate
Authors: Branzoi Florina , Branzoi Viorel , Pacuretu Catalina , Pahom Zoia
Published: February 2020

Nanocomposite films based on 3,4 ethylen-dioxythiophene and 3-methylthiophene with functionalized single-walled carbon nanotubes (SWANTs- polyaminobenzene sulfonic acid - CNT-PABS, SWANTs- with carboxylic acids functionalized - CNT-COOH) and different large anionic surfactants as dopants (1-dodecane sulfonic acid sodium salt, sodium dioctyl sulfosuccinate - AOT and sodium dodecylbenzenesulfonate - SDBS) were studied. It was fabricated by a simple oxidative electropolimerization method.

All the obtained composites showed improved mechanical integrity, higher electronic and ionic conductivity and exhibited larger electrode specific capacitance than the polymer alone. These nanoporous composite films were grown electrochemically from aqueous solutions such that constituents were deposited simultaneously onto substrate electrode.

The synthetic, morphological and electrical properties of the obtained nanocomposite films were compared. Scanning electron microscopy (SEM) revealed that the composite films consisted of nanoporous networks of SWCNTS (single-walled carbon nanotubes) coated with polymeric film. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) demonstrated that these composite films had similar electrochemical response rates to pure polymeric films but a lower resistance and much improved mechanical integrity. The large anionic surfactants served as dopant during the electropolymerization to synthesize polymer/CNTSF composite films. The electrochemical and physical properties of the resulting composites were evaluated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and FT-IR spectroscopy techniques.The improved properties of the electrodes were obtained by using these composite films. The specific electrochemical capacitance of the composite films is a significantly greater value than that for pure polymer films prepared similarly. All of the composite films were a very promising electrode material for application in supercapacitor.
Photochemical Degradation of an Anionic Surfactant By TiO2 nanoparticle Doped with C, N in Aqueous Solution
Authors: Giahi Masoud , Zamiri Marzieh
Published: February 2020

In this work, We synthesized  a novel C, N-doped TiO2 nanoparticles by sol-gel method. The catalyst was characterized by X-ray powder diffractometer (XRD), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). The results showed that crystallite size of synthesized C, N-doped TiO2 particles were in nanoscale. UV light photocatalytic studies were carried out using sodium naphthalene sulfonate formaldehyde (SNF) as pollutant. The effects of initial concentration of surfactant, catalyst amount, pH, addition of oxidant on the reaction rate were ascertained and optimum conditions for maximum degradation was determined. The results indicated that for a solution of 20 mg/L of sodium naphthalene sulfonate formaldehyde, almost 98.7% were removed, in pH around 4.0, 0.44 g/L photocatalyst, 1 mM K2S2O8 irradiated for 90 min. The kinetics process was studied and the photodegradation rate of SNF was found to obey pseudo-first-order kinetics equation represented by the Langmuir–Hinshelwood model.
Synthesis and Investigation of Poly(N-Isopropylacrylamide-co-N-vinylcarbazole) Hydrogels Morphological, Fluorescence and Electrical Properties
Authors: Gokceoren Argun T , Alveroglu Esra
Published: February 2020

In this study, poly(N-Isopropylacrylamide-co-N-vinylcarbazole) gels were prepared and characterized with Fourier Transform Infrared Spectroscopy, Photoluminescence Spectroscopy, Scanning Electron Microscopy, Differential Scanning Calorimetry and DC conductivity methods. The synthesis and characterization results showed that the presence of NVCz moieties affected the thermal characteristics, topological properties and conductivity of the gels. The obtained NIPA hydrogel was found to swell in aqueous media for up to 80%, while the 50 wt/v% NVCz incorporated sample (S5) swells up to 40%. Here we report that the fluorescence emission and electrical conductivity results attest the opportunity to manufacture a tunable biomedical materials.  Since, the maximum peak at 350 nm red shifted to 385nm, whilst a second peak appeared at 425 nm by the presence of the conductive PNVCz moieties allowing the possibility to control the fluorescence character of the gel. For instance an in-vivo drug release system tracking in a Fluorescence Image-Guided Surgery (FIGS) in which resolution deepness is essential in the visible wavelength could be extended when excited by means of a fluorophore compound.
Co Doped Pt3 Co Intermetallic Compound As an Efficient Catalyst for Oxygen Reduction Reaction
Authors: Zhao Yige , Liu Jingjun , Wang Feng , Li Zhilin , Ji Jing , Dou Meiling
Published: February 2020

Abstract: The oxygen reduction reaction (ORR) is a significant cathodic reaction for renewable source applications such as fuel cells and metal-air batteries. However, the slow kinetics of ORR has become the major impediment for the commercial applications. Therefore, catalysts for the ORR are needed to lower the electrochemical over-potential. Although platinum supported on carbon (Pt/C) catalyst is now developed as the commercial catalyst, its low durability and high cost still limit the application. Thus, developing high performance catalysts with superior activity and durability is still an essential task to replace the traditional Pt/C catalyst.

Alloying Pt with a non-precious metal not only decreases the cost but also improves the catalytic performance as a result of synergistic effect between the two elements. Pt-Co system has been paid broad attention because of its relatively high activity and stability.[1] Although the state of the art Pt-Co randomly mixed alloy may exhibit high activity resulted from the so-called ligand effect,[2] its stability remains a troublesome problem owing to the severe agglomeration and dissolution during the ORR process.[3] Recently, Pt-based intermetallic compound has attracted wide interest due to its constant composition and ordered structure, and it has been demonstrated to be a desirable catalyst with excellent stability and anti-poison when compared with the randomly mixed alloy. Nevertheless, a great challenge for the practical application still exists on account of the low activity of pure intermetallic. Thus, synthesizing Pt-based catalysts with concurrently high activity and durability is still a tough problem.

This abstract mainly focuses on a new class of Co doped Pt3Co intermetallic compound as an efficient catalyst by doping a small number of Co atoms into ordered intermetallic Pt3Co phase. The obtained catalyst has the special structure with Pt3Co intermetallic as solvent and Co as solute. The electrochemical tests indicate that the gained catalyst exhibits both higher activity and durability than the commercial Pt/C catalysts, which can be attributed to the unique electronic structure of Co-doped Pt3Co intermetallic compound. This research may provide a promisingly new idea to synthesize next-generation catalysts for ORR.

References

[1]  D. Wang, H. L. Xin, R. Hovden, H. Wang, Y. Yu, D. A. Muller, F. J. DiSalvo and H. D. Abruña, Nat. Mater., 2013, 12, 81-87.

[2] M. Bele, P. Jovanovič, A. Pavlišič, B. Jozinović, M. Zorko, A. Rečnik, E. Chernyshova, S. Hočevar, N. Hodnik and M. Gaberšček, Chem. Commun., 2014, 50, 13124-13126.

[3]   L. Su, S. Shrestha, Z. Zhang, W. Mustain and Y. Lei, J. Mater. Chem. A, 2013, 1, 12293-12301.

Figure 1
Ultrasonic-Assisted Galvanic Replacement Synthesis for the Platinum Deposition on Palladium to Prepare Pd-Pt/MWCNT Electrocatalysts for ORR
Authors: Zapata-Fernandez Jesus Raymundo , Reynoso-Soto Edgar Alonso , Paraguay-Delgado Francisco , Gochi Yadira , Perez-Sicairos Sergio , Lin-Ho Shui Wai , Garcia-Tapia Karelid , Félix-Navarro Rosa María
Published: February 2020

In this work a simple two step method for preparing bimetallic Pd-Pt/MWCNT electrocatalysts via ultrasonic-assisted galvanic-replacement is presented. Firstly, Pd nanoparticles were deposited over MWCNT by micro-emulsion method to synthesize Pd/MWCNT. In a second step the Pd/MWCNT electrocatalyst is immersed in an ultrasonic bath of an aqueous solution containing different Pt concentrations to form a bimetallic Pd-Pt/MWCNT electrocatalyst by galvanic replacement reaction. It is worth to mention that any additive reagent was added during this reaction. The effects of galvanic replacement time, temperature and agitation were investigated. Three different amounts of Pd content were tested: 5, 10 and 20% wt. The catalysts were characterized by TEM, EDS and electrochemical methods. The results showed that bimetallic nanoparticle composition can be tuned up through the galvanic replacement conditions, where the Pt concentration of solution has a very important role. The ultrasound conditions allowed a great performance of the galvanic replacement reaction which leads to achieve the best electrocatalyst in two hour reaction time at room temperature. The electrocatalyst prepared with 10% wt of initial Pd content, 2 hour of reaction time, Pt concentration of 1.25 mM and final composition of Pd:Pt 1:2 showed the highest catalytic activity of all synthesized catalysts. These results showed a simple, efficient an environmental friendly route to synthesized bimetallic electrocatalysts for fuel cell applications.