bluuebunny/crossref_metadata_2025_split huggingface dataset:
Striped Nanorods for Photocatalytic Hydrogen Production
Authors: Teo Gladys Y , Riley Jason D , Ryan Mary P 
Published: February 2020

Photovoltaic modules are under active consideration as a major contributor to future energy requirements. Coupled with an electrolyzer, this energy system converts energy harvested from the sun into chemical power. As the demand for a sustainable yet efficient and cost effective approach of producing hydrogen increases, researchers are seeking ways to improve the technology of forming solar fuel. Mimicking the idea of how nature collects and stores solar energy in chemicals bonds through photosynthesis, economically viable water splitting cells capable of splitting water directly at the semiconductor surface are being developed. The catalytic semiconductor is designed to be both a light absorber and an energy converter to store solar energy in the simplest chemical bond, H2, thereby eradicating significant fabrication and system costs involved with the use of separate electrolyzers wired to photovoltaic cells.
In this work, water splitting cells have been designed to consist of multi-component nanorods of titanium dioxide and platinum with well-defined nanostructures to function as photocatalytic cell for hydrogen production. As the TiO2-Pt nanorods are irradiated with light in the presence of a water source, oxygen and hydrogen are evolved at the anode TiO2 and cathode Pt segments of the nanorods respectively. The alternating segments of TiO2 semiconductor and Pt metal enable the control of the direction of charge movement and light absorption pathways in the material, thereby presenting a solution to improving the overall efficiency of photocatalytic hydrogen production.
By employing templated electrodeposition, homogeneous multi-segmented TiO2/Pt nanorods have been successfully fabricated. This simple method of synthesis permits an easier control of the position and composition of TiO2 and Pt along the length of the nanorods, which allows for a customizable and highly reproducible method of obtaining segmented rods with uniformly distributed active sites for efficient catalytic activity. The UV absorption properties of these multi-segmented TiO2/Pt nanorods are then compared to single segmented nanorods consisting of only TiO2.
Low-Voltage Electroreduction of CO2: A Lesson from Geoelectrochemistry in the Seabed
Authors: Nakamura Ryuhei 
Published: February 2020

To date, most research on heterogeneous CO2 electroreduction has been aimed at decreasing the large overpotential required for hydrocarbon synthesis. Specifically, most scientists have focused on reducing the external voltage to as low as 1.24 V, as this value represents the thermodynamic limit for producing organic compounds via CO2 reduction coupled with water oxidation [CO2 + H2O to (CH2O) + O2, where (CH2O) represents a carbohydrate].
As an alternative approach, it may be possible to exploit the highly active geoelectrochemical reactions mediated by microorganisms living in deep-sea hydrothermal environments. In such environments, chemolithoautotrophs, as opposed to photoautotrophs, primarily contribute to biomass production through the utilization of geochemical energy sources, such as H2S and H2, emitted from hydrothermal vents. Chemolithoautotrophic bacteria are able to utilize these energy-rich compounds for the production of hydrocarbons at rates that are one order of magnitude higher than that of photosynthesis, and several species can synthesize hydrocarbons using Fe2+ ions as a sole electron source for CO2 reduction. It is worth noting that Fe-oxidizing bacteria utilize the proton-motive force (PMF) generated by the reduction of O2 to H2O to elevate the energy of electrons obtained from Fe2+ oxidation by ~ 1 eV. Thus, although the reversible potential of the Fe3+/Fe2+ redox couple (0.77 V vs SHE) is more positive than that of NAD(P)/NAD(P)H (−0.32 V at pH 7), Fe-oxidizing bacteria are capable of generating NAD(P)H as a source of reductive energy for CO2fixation.
By harnessing the ability of Fe-oxidizing bacteria to elevate intracellular electrons into a higher energetic state, it may be possible to construct an integrated bioelectrochemical process in which the bacteria function not only as effective CO2 reduction catalysts, but also as voltage-multiplier circuits. In this system, CO2 reduction would occur at an external voltage that is one order of magnitude lower than that of conventional heterogeneous electrocatalytic systems. The thermodynamic limit of the external voltage required for the simultaneous reduction and oxidation of CO2 and H2O, respectively, is determined by the difference between the reversible potentials of E(O2/H2O) and E(Fe3+/Fe2+). Thus, the thermodynamic limit of the external voltage is estimated to be 0.035 V at pH 7 if 0.77 V is adopted as the redox potential of the Fe3+/Fe2+ couple. Based on these estimated values, the integrated bioelectrochemical process mediated by Fe-oxidizing bacteria can potentially proceed at an external voltage lower than 1.24 V, and thus provide an approach for utilizing the low-voltage electricity generated from hydro, solar, wind, and geothermal sources for the electrochemical conversion of CO2 to chemical fuels.
Effect of Operation Conditions during Fuel Starvation on Ruthenium Migration from Pt/Ru Anode Catalysts
Authors: Nedellec Yannig , Zaton Marta , Jones Deborah , Geymayer Martin , Hacker Viktor , Aarhaug Thor , Moller-Holst Steffen 
Published: February 2020

Membrane electrode assemblies developed for use with reformate and containing Pt/Ru (1:1) anode catalysts, have been submitted to a fuel starvation accelerated stress test (AST) protocol in combination with a range of different operation conditions The fuel-starved MEAs were aged under conditions enabling investigation of the effect of temperature (65, 85 °C), current density (200, 400 mA/cm2), relative humidity (40, 80% RH) and number of starvation/recovery cycles (up to 875 cycles). The MEAs were characterized following the AST using scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). This characterization has proven to be particularly useful in understanding the mechanism of degradation leading to performance loss of fuel-starved MEAs, and in correlating the observed extent of MEA modification in terms of migration of catalyst species, to the electrochemical parameters observed in situ.
The results show different trends in the evolution of the Ru/Pt ratio at the anode inlet and outlet regions, which is not unexpected given the greater degree of fuel starvation to the MEA at the anode outlet region, than at the anode inlet. At the anode outlet, the Ru/Pt ratio is <1 in the catalyst layer under all AST conditions, indicating that Ru has been lost due to electrochemical corrosion and leaching. Further, the extent of this depletion appears to be strong, and similar in all cases (0.26-0.39). At the anode inlet, the Ru/Pt ratio in the used MEAs ranged from 1 (i.e. unchanged compared with the pristine MEA) to 0.48, and the exact ratio within this range depended closely on the applied AST conditions. Correlation was also observed between the anode catalyst layer thickness and the extent of Ru loss.
The research leading to these results has received funding from the European Community’s Seventh Framework Programme (FP7/2010-2013) for the Fuel Cells and Hydrogen Joint Undertaking under grant agreement KEEPEMALIVE no. 245113.
Electrolysis of Trichlomethylated Compound Under Aerobic Condition Catalyzed by B12 Model Complex
Authors: Shimakoshi Hisashi , Inaba Takuya , Hisaeda Yoshio 
Published: February 2020

Reductive dehalogenation reactions are presently of great interest, primary because of their potential use in the treatment of halogenated solvent wastes as well as in remedial approaches to remove such chemicals from contaminated soils. A Co(I) species of cobalamin emerged in the active site of B12-dependent enzyme is a supernucleophile and reacts with an alkyl halide to form an alkylated complex with dehalogenation. Thus, the superior ability of cobalamin for reductive dehalogenation prompted us to investigate the catalysis of a cobalamin derivative for degradation of various halogenated compounds such as 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT), perchloroethelene (PCE), chloroform and so on.
Electrolysis of such organic halides mediated by cobalt complex usually achieved in anaerobic condition to avoid loss of reactive Co(I) species by autooxidation. Carbon center radical formed by homolysis of cobalt-carbon bond in alkylated complex generally coupled to form dimerized compound or abstract hydrogen to form simply reduced product. Here we reported electrolysis of organic halide under aerobic condition and conducted the reaction of in-situ generated substrate radical with oxygen to form more valuable compound such as ester.
Electrolysis of trichloromethyl benzene at -0.9 V vs. Ag/AgCl in the presence of heptamethyl cobyrinate perchlorate (1) in ethanol under anaerobic condition using undivided cell equiped with Pt mesh cathode and Zn plate anode to yield Z and E forms of 1,2-dichlorostilbene with 49% and 7%, respectively. In contrast, the same reaction was carried out in an aerobic condition, ethyl benzoate was selectively produced in 61 % yield based on initial concentartion of substrate. When the electrolysis was carried out in methanol or isopropano, methyl benzoate and isopropyl benzoate were formed, respectively. As for mechanism, primary formed radical species from homolysis of alkylated complex may reacts with oxygen to form peroxy species. Homolysis of O-O bond of peroxy species should produce oxyl radical. Following disproportionation and isomerization may produce benzoyl chloride as key intermediate in this reaction. Reactive benzoyl chloride could reacts with solvent ethanol to yield ethyl benzoate. Application of this aerobic electrolysis with colalamin derivative toward various trichloromethylated compounds will be reported.
Vanadium Flow Battery Performance Improvement through Electrode Modification
Authors: Brooker R. Paul , Bell Curtis , Bonville Leonard J. , Kunz H. Russell , Fenton James M. 
Published: February 2020

Flow battery performance has recently been significantly improved through the use of carbon papers, adopting a so-called “zero-gap” architecture.[1] The benefits of the carbon paper, as opposed to carbon felt, are increased rigidity for reduced contact resistance, high surface area, and low compression. These combinations lead to an improved flow through the high surface area electrode, and enhanced high current performance through increased mass transport.
Much attention has been devoted to improving the V(IV)-V(V) couple at the positive electrode.[2] However, a need exists to increase the reversibility of the vanadium reactions at the negative electrode. For example, Aaron et al. have demonstrated[3] that on discharge, V(II) oxidation appears to have slower kinetics than V(V) reduction, resulting in high overpotentials at the negative electrode. Therefore, in addition to the improvements gained by the use of carbon paper, increased performance may be obtained through increasing the oxidation kinetics of the negative electrode. This paper will demonstrate some efforts aimed at reducing the discharge overpotentials at the negative electrode through electro-deposition of metals.
An all-vanadium cell was utilized in these tests, with single-carbon papers used as electrodes. For all tests, a fresh carbon paper was utilized at the positive electrode, while the negative electrode was either plain carbon paper, or metal-coated carbon paper. The results indicate that performance of the cell improved dramatically by adding metal to the surface of the negative electrode.
This presentation will discuss the approach employed herein for improved performance, as well as its limitations.
[1] D.S. Aaron, Q. Liu, Z. Tang, G.M. Grim, A.B. Papandrew, A. Turhan, T.A. Zawodzinski, M.M. Mench, J Power Sources, 206 (2012) 4-4.
[2] C. Flox, M. Skoumal, J. Rubio-Garcia, T. Andreu, J.R. Morante, Appl Energ, 109 (2013) 344-351.
[3] D. Aaron, C.N. Sun, M. Bright, A.B. Papandrew, M.M. Mench, T.A. Zawodzinski, Ecs Electrochem Lett, 2 (2013) A29-A31.
Phase Stability of Li-Mn-O Oxides As Cathode Materials for Li Ion Batteries
Authors: Longo Roberto C , Kong Fantai , KC Santosh , Park Min-Sik , Yoon Jaegu , Yeon Dong-Hee , Park Jin-Hwan , Doo Seok-Kwang , Cho Kyeongjae 
Published: February 2020

The over-lithiated-oxides (OLOs) are a composite material of layered structures of Li2MnO3 and LiMO2 (M = Mn, Fe, Co, Ni). Their main advantage over current layered oxides is that they show much higher storage capacity as cathode material for Li-ion batteries, due to the presence of Li2MnO3 phase. However, experimental results indicate that Li2MnO3 is an almost inert material from an electrochemical point of view, and that it partially transforms into layered LiMnO2 after the first charge/discharge cycle, thus forming a phase that is a mixture of both Li2MnO3 and LiMnO2. During the subsequent charging cycles, OLO capacity is known to reduce gradually in connection with Mn spinel phase formation. To improve the OLO cathode material performance, it is desirable to suppress such spinel phase formation. In order to address the stability of Mn layered oxides, we have examined the phase diagram of the Li-Mn-O system on both physical and chemical (as a function of two chemical potentials, μ(Li) and μ(O)) potential space, using ab initio density-functional theory (DFT) simulations. These DFT findings will provide conceptual guidance in the experimental search for the mechanisms driving the structural transformation into the spinel phase, in an attempt to solve such structural instability problem and, thus, improving the performance of the OLO cathode materials.
This work was supported by Samsung GRO project.
Electrochemical Analysis and Interfacial Stability of Carbon-Overlay LiNi0.5Mn1.5O4 Cathode Material for High Potential Lithium Ion Battery
Authors: Jin Yi-Chun , Duh Jenq-Gong 
Published: February 2020

Recently, researches in lithium ion battery have focused on interfacial properties of various cathode materials. The interfacial reaction on the electrode material greatly dominates its electrochemical performances and thermal stability, especially manganese-type spinels. The deteriorated cyclability of LiNi0.5Mn1.5O4cathode at elevated temperature greatly hinders its realistic applications. One of the reasons is that the high surface reactivity with the electrolyte at an ultimate operating voltage around 4.7V, associating with the dissolution of Mn and the formation of SEI layer.
A proper SEI-layer can not only facilitate lithium intercalations but also provides a good protection from the undesired electrolyte invasion. This study demonstrates the carbon-overlay on the surface of LiNi0.5Mn1.5O4 electrode through atmosphere-controlled sputter techniques. The advantage of sputtered carbon layer on the electrode surface is without the degrading of pristine spinel structure. The carbon-overlay with the appropriated thickness was found to extend the cycle life and suppress the swelling behavior of LiNi0.5Mn1.5O4 cathode material. The essential beneﬁts of carbon-overlay is to stable the SEI layer on LiNi0.5Mn1.5O4 cathodes, retarding the severe capacity decay at elevated temperatures. Charge transfer kinetics and failure mechanisms involving the high-voltage oxidation and high temperature degradation are also detailed discussed.
Nitrogen-Doped Graphene-Wrapped Mn3O4 Nanoparticles As High-Performance Anode Materials for Lithium Ion Batteries
Authors: Park Seung-Keun , Piao Yuanzhe 
Published: February 2020

Lithium ion battery (LIB) is one of the most important power sources due to its high energy density [1]. To meet the increasing demands associated with the use of LIB in hybrid electric vehicles, many researches are focused on improving their electrochemical properties in term of materials. Graphite is commonly used as an anode material in commercial LIB. However, as it deliver a low specific capacity, its application in LIB is limited
Graphene has awakened a tremendous interest due to its very large surface area (~2600 m2 g-1), excellent electronic conductivity and stability. These properties allow graphene a promising electrode material for LIB. However, graphene exhibits rapid capacity decay during cycling.
Nitrogen doping of carbon materials has been studied as an effective way to solve the limitations and improve the electrochemical properties. Actually, nitrogen doping of graphene allows for enhanced interaction with lithium ions and the formation of a greater number of active sites through modulation of the band structure of graphene [2]. However, very few studies have been reported on the use of nitrogen-doped graphene/Mn3O4composite as the LIB anode material.
In this study, we have developed a simple hydrothermal method for the well-deposition of Mn3O4 nanoparticles onto nitrogen-doped graphene. Hydrazine plays an important role in the formation of such nanocomposites since it can act as both a nitrogen source and a reducing agent. In the SEM and TEM images, we have confirmed that highly crystalline Mn3O4 nanoparticles are well-dispersed on the N-doped graphene. The Mn3O4/N-doped grapheme nanocomposites show excellent electrochemical performance, including outstanding cycling stability, high reversible specific capacity and improved rate capability. The enhancement in the electrochemical properties of the material can be attributed to N-doped graphene, which acts as both a conductive substrate and a volume buffer layer, and also nitrogen doping allows for the fast electron moving and ion transfer by decreasing the energy barrier.

Reference

[1] M. Winter, R.J. Brodd, Chem. Rev., 104,4245 (2004).
[2] H.B. Wang, C.J. Zhang, Z.H. Liu, L. Wang, P.X. Han, H.X. Xu, K.J. Zhang, S.M. Dong, J.H. Yao, G.L. Cui, J. Mater. Chem. 21, 5430 (2011).

Acknowledgement

This work was supported by the Center for Integrated Smart Sensors funded by the Ministry of Science, ICT & Future Planningas Global Frontier Project (CISS-2012M3A6A6054193) and partial support from the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (no. 2013-053595)
Novel Co-Precipitation Method for Synthesis of Carbon-Free LiFePO4
Authors: Feng Hai , Milev Adriyan S , Kannangara G.S. Kamali 
Published: February 2020

Lithium iron phosphate (LiFePO4) is an important alternative cathode material to LiCoO2, which applications are limited by resource availability and safety issues. However, the full potential of the material is sometimes difficult to achieve due to its limited electrical conductivity and low rate of Li+ ion diffusion that together may limit the battery performance. One strategy is to manufacture LiFePO4 particles coated with a conductive phase, such as carbon, which improves the electronic contact between the LiFePO4 particles. However, the carbon seems to modulate not only the electric conductivity but also the reduce crystallite sizes and thus reduces the distance for Li+ transport in the LiFePO4 structure. Furthermore, carbon may improve the phase purity of the final product because during high temperature synthesis, carbon acts as a reducing agent and thus minimizes the likelihood of oxidation of Fe2+ to Fe3+. Despite these advantages, the role of different forms of carbon on the synthesis of LiFePO4 and the electrochemical performance of the materials is yet to be fully understood. This could be because the synthetic methods reported in the literature employ carbon containing precursors or solvents and therefore the LiFePO4 product always contain some form of residual carbon. This complicates the analysis of the effect of a specific carbon type on the electrochemical performance of the cathode material.
Carbon-free LiFePO4 material has been synthesised by a novel single-step co-precipitation method from aqueous solutions of LiOH∙H2O, NH4H2PO4 and FeSO4.7H2O precursors. The precipitation sequence and methodology, reaction atmosphere and the role of intermediate phases on the purity of LiFePO4 product has been investigated. The mechanism of formation of phase-pure carbon free LiFePO4 is also investigated and the role of synthesis atmosphere on the phase transformations and the effect of evolving gaseous species on the likelihood of oxidation of Fe2+ to Fe3+ are discussed. The lowest temperature to synthesise phase pure carbon-free LiFePO4 is 550 oC which remains phase pure during further heating up to 750 oC. The novel carbon-free method is suitable for investigation of the effect various forms of carbon (carbon black, nanotubes, meso-porous carbons, etc.) on the electrochemical performance of the cathodes containing LiFePO4.
All Polythiophene Redox Flow Battery
Authors: Yang Jung Hoon , Jeon Jae-Deok , Shim Joonmok 
Published: February 2020

Surge in demand for electrical energy has been a common phenomenon around world. In addition, greenhouse gas emission is another challenge. As a solution to these problems, large-capacity energy storage system have been proposed. This energy storage system can manage the increasing energy demand more efficiently in conjunction with renewable energy and smart grid.
Among various large energy storage systems, the redox flow battery (RFB) is one of the most viable alternatives. In particular, RFB in the range of 10 kW-10 MW is the most competitive in terms of cost, flexibility, rapid response and safety over other secondary batteries such as lithium ion and sodium sulfur batteries [1].
RFB can be simply classified into aqueous and organic redox flow batteries. Of the aqueous RFBs, all vanadium RFB and zinc/bromine RFB are the most representative ones. Many companies have been considering the commercialization of those flow batteries based on their high energy density and low cost. However, the aqueous redox flow battery is limited by water electrolysis which prevents from increasing the cell potential out of the hydrogen or oxygen evolution voltage.
Organic redox flow battery, which is free from the water electrolysis problem, has been studied extensively. Organic molecules can be synthesized from low-cost, lightweight, widely available materials. In addition, their electrochemical properties can be easily adjusted using the well-established knowledge of organic chemistry [2]. By taking these attributes of organic materials, it may be possible to make a redox flow battery with very high energy densities and power densities.
Polythiophene is a representative conjugated polymer. It has received a lot of attention due to its various availability as nonlinear optics and electronic device [3].
In this study, we investigated the possibility of polythiophene as a redox couple in organic redox flow battery. Polythiophene shows electrochemical redox activities at two different potentials of about -2.0 V and +0.5 V versus Ag/Ag+ (figure 1). The polythiophene is reduced at -2.0 V (n-doping) and oxidized at +0.5 V (p-doping). To investigate the charge-discharge characteristics, a single cell with the active electrode area of 7.0 cm úI 5.0 cm was used.

References

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2. S.E. Burkhardt, M.A. Lowe, S. Conte, W. Zhou, H. Qian, G.G. Rodriguez-Calero, J. Gao, R.G. Hennig, and H.D. Abruna, Energy Environ. Sci., 5, 7176 (2012).
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