bluuebunny/crossref_metadata_2025_split huggingface dataset:
Progress in Electrochemical CO2 Reduction in Gas Phase – Design of Efficient Co-Electrolyser Systems
Authors: Patru Alexandra , Binninger Tobias , Schmidt Thomas J. 
Published: February 2020

The electrochemical CO2 reduction reaction (CO2RR) is a complex reaction which must be carried out in a highly selective and efficient manner. Many efforts are being taken to develop catalysts with improved reaction selectivity and efficiency and significant progress has been made in this area of research [1]. However, CO2RR kinetics, product identification and quantification are mostly carried out in half-cell configurations using liquid electrolytes. This fundamental approach of studying CO2RR is limited by the low solubility of CO2 in water, the maximum CO2 reduction current reported in the literature is in the range of 0.01- 0.02 A/cm2 [2]. In order to overcome the solubility problem and to reach higher operating current densities, CO2 reduction can be carried out in a co-electrolysis system where pure or diluted gaseous CO2 is used. Our research efforts were focused on the design of an electrochemical cell for co-elecrolysis operating at high-current densities with good product selectivity.
The most promising results were obtained when a bipolar membrane was used as the electrolyte. The experiments were conducted in a membrane electrolyzer-like configuration setup. Various gold type cathode electrode materials were tested. IrTiO2 was used as an anode material to catalyse the oxygen evolution reaction. The reaction products were analysed by on-line mass spectroscopy. The co-electrolyser performance and the selectivities of the various MEAs are examined in detail.

References

[1] J. Herranz, J. Durst, E. Fabbri, A. Patru, X. Cheng, A.A. Permyakova, T.J. Schmidt, Nano Energy
2016, 29, 4.
[2] J. Durst, A. Rudnev, A. Dutta, Y. Fu, J. Herranz, V. Kaliginedi, A. Kuzume, A.A. Permyakova, Y. Paratcha, P. Broekmann, T.J. Schmidt, Chimia
2015, 12, 69.

Acknowledgements

Financial support of this work by the Commission of Technology and Innovation Switzerland (CTI) and the Swiss Competence Center for Energy Research Heat and Electricity Storage are greatly acknowledged.
Theoretical Characterization of the Electronic and Optical Properties of Beryllium and Nitrogen Co-Doped Graphene: A Proposed P-Type Semiconductor for Nanoelectronic and Optoelectronic Applications
Authors: Olaniyan Okikiola , Mapasha Edwin R , Khaleed Abubakar Abubakar , Emmanuel Igumbor , Manyala Ncholu 
Published: February 2020

Ab-initio calculations within the framework of density functional (DFT) have been performed to study the electronic and optical properties of Be and N co-doped graphene. The results have been compared with that of Be-doped, N-doped, and pristine graphene. The effect of doping and isomerization on the electronic and the optical properties of these systems have been studied by varying the impurity concentrations of Be-doped and N-doped graphene systems from 3.13% through 12.5%, whereas for Be and N co-doped graphene, the concentration has been varied from 6.25% through 25.0 % impurity concentration.
The formation energies of the systems with different impurity configurations were calculated to examine their relative stabilities. It was found that for Be-N co-doped graphene, the configuration of which N and Be coexisting as the nearest neighbors is energetically the most favorable configuration. Moreover, at the same impurities concentration, Be-N co-doped graphene was observed to be more stable than Be-doped graphene due to its lower formation energy. Thus these results reveal that it is much easier to synthesize Be-N co-doped graphene than to synthesize Be-doped graphene. Hence, the relatively high formation energy of Be-doped graphene could be the reason why the system is yet to be synthesis experimentally despite a recent theoretical report on it.
The results of the electronic structure calculations reveal that Be-N co-doped and Be-doped graphene are p-type semiconductors while N-doped graphene has been verified to be an n-type semiconductor. For all the doped systems considered in this study, it was observed that the size of the band gap increases with impurity concentration with respect to the aforementioned energetically most favorable isomer. At impurity concentration of 3.13%, a minimum band gap of 0.44 eV and 0.21eV was realized for Be-doped and N-doped graphene respectively while at 12.5 % corresponding maximum gap of 1.41 eV and 0.6 eV were observed. Besides, Be-N co-doped graphene was found to have a minimum band gap of 0.43 eV at 6.25% and a maximum gap of 1.54 eV at 25.0% impurities concentration.
The dielectric matrices of the doped systems were calculated using first-order time-dependent perturbation theory in the simple dipole approximation. It was found that all the systems investigated were transparent within the frequency interval of 7.0eV-10eV for parallel EM polarization. In general, we observed that the optical properties of the doped systems investigated respond to doping concentration differently across the EM spectrum with respect to the anisotropic signature of the host system.
The results of our study demonstrate that the band gap of graphene can be tailored to meet the requirements of specific applications in nanoelectronic and optoelectronic devices.
Broadband Sum-frequency Generation Spectroscopy Study of Electrochemical Surface Processes
Authors: Huang-Fu Zhi-Chao , He Yu-Han , Zhou Zhi-You , Wang Zhao-Hui , Sun Shi-Gang 
Published: February 2020

As a second order nonlinear technique, sum-frequency generation (SFG) spectroscopy is forbidden, under the electric-dipole approximation, in the bulk of a medium with inversion symmetry and then generate only at the surface of such media where the symmetry is broken and appear to be highly surface-specific for interfaces between the centrosymmetric media. So far, many studies of electrochemical processes at various interfaces have been performed by using SFG, and molecular level insight like the molecular adsorption, orientation, packing, and dynamics has been obtained.
We have developed broadband sum-frequency generation (BB-SFG) spectroscopy. It enables us to obtain information on in situ electrochemical systems. One of the electrochemical processes is the CO2 reduction on a polycrystalline copper and polycrystalline gold electrode. The antisymmetric C−H stretching modes of methyl group and antisymmetric C−H stretching modes of methylene group were observed on copper electrode surface, no adsorbed CO intermediate was observed. As for the process on gold electrode surface, the adsorbed CO was the main intermediate detected, and CO was observed at a relative high potential (-0.5V vs SCE). In addition, we present some other examples that investigate the electrochemical interface with SFG techniques, such as the potential-dependent nonresonant (NR) SFG.
Figure 1 (a)(b) Potential-dependent BB-SFG spectra of 0.1M CO2-saturated NaHCO3 solution at poly-Cu electrode (C-H region) and poly-Au electrode (CO region). (c) Variations of the wavenumbers (black) and intensities (red) of the CO peak in (b) from the fitting data.

Acknowledgement: This work was financially supported by NSFC (21327901 and 21621091).

Figure 1
(Keynote) Redox Catalysis for Redox Flow Lithium-Oxygen Battery
Authors: Wang Qing 
Published: February 2020

Batteries are often the heaviest, costliest and the least-green component of electronic devices, and are currently the bottleneck in the large-scale deployment of stationary energy storage for smart grid and automotive energy storage for electric vehicles. Among various battery technologies, Li-O2 battery possesses the highest theoretical energy density and is regarded as the “Holy Grail” for next generation electrochemical energy storage. While numerous profound studies have been done to understand the battery chemistry, challenges relating to surface passivation and pore clogging by Li2O2 precipitation on the gas diffusion cathode remain. This severely impairs the round-trip energy efficiency and limits the achievable capacity of the cell. In this talk, a conceptually new and implementable solution — redox flow lithium-oxygen battery (RFLOB) [1] will be introduced, to address these critical issues confronted by Li-O2 battery. This novel device was devised based on reversible redox targeting of battery materials, and the recent advancement of redox flow lithium-ion batteries [2]. As demonstrated here, RFLOB combines great system flexibility of the redox flow battery with the extremely high energy density of the Li-O2 batteries, revealing significant advantages over other state-of-the-art electrochemical energy storage devices [3,4].
References:
[1] Y. G. Zhu, C. Jia, J. Yang, F. Pan, Q. Huang, and Q. Wang, Chem. Comm., 2015, 51, 9451-9454.
[2] C. Jia, F. Pan, Y. G. Zhu, Q. Huang, L. Lu, and Q. Wang, Science Advances, 2015, 1, e1500886.
[3] Y. G. Zhu, X. Wang, C. Jia, J. Yang, and Q. Wang, ACS Catalysis, 2016, 6, 6191–6197.
[4] Y. G. Zhu, et al., Nat. Commun., 2017, 8, 14308.
Sodium Superionic Conductor-Type Sodium Vanadium Fluorophosphates for Rechargeable Sodium-Ion Batteries
Authors: Hung Tai-Feng , Yeh Yu-Wen , Yang Chang-Chung , Chang Wen-Sheng , Hsueh Kan-Lin 
Published: February 2020

Owing to the increasing demand for the electrochemical energy storage devices with sufficient capacity, high reliability and low cost, rechargeable sodium-ion batteries (SIBs) have recently regarded as alternative candidates to lithium-ion batteries (LIBs) because of their benefits on material abundance, cost-effectiveness and electrochemical similarities. However, the energy density delivered from the current SIBs is still not comparable with that of the LIBs, which was ascribed to the lower cell voltage. Therefore, developing the cathode materials with higher redox potentials is eagerly anticipated. As one of the most promising cathode materials, carbon-coated sodium vanadium fluorophosphates (Na3V2(PO4)2F3/C) nanocomposites have been extensively investigated due to the merits of their sodium superionic conductor (NASICON) structures for facile ionic transportations, high voltage and high capacity. In this study, the Na3V2(PO4)2F3/C nanoparticles were synthesized using a wet-chemistry route, followed by calcination in an argon atmosphere. The resulting powders were characterized by powder X-ray diffractometer, electron microscopes and thermogravimetric analyzer to confirm their crystalline structure, morphologies and amount of carbon loading, respectively. Benefiting from the nanostructures and continuous carbon coatings, the outstanding reversible capacity (128 mAh/g@0.1 A/g), rate capability (106 mAh/g@1.0 A/g) and capacity retention (98.2 %@100 cycles@1.0 A/g) were achieved as demonstrated by galvanostatic testing. Given the improved electrochemical properties, the NASICON-type Na3V2(PO4)2F3/C nanoparticles synthesized in the present study were anticipated to function as efficient cathode materials for SIBs.
Acknowledgement: We gratefully acknowledge financial support from the Bureau of Energy (BOE), Ministry of Economy Affair (MOEA), Taiwan.
Physicochemical Properties of Dialkyl Ethers
Authors: Nambu Noritoshi , Suzuki Shohei , Ogasawara Masaru 
Published: February 2020

Ethylene glycol diethyl ether (1,2-diethoxyethane: DEE) is dialkyl ethers of ethylene glycol. The solubility of lithium salts in DEE is much less than that in ethylene glycol dimethyl ether (1,2-dimethoxyethane: DME) and ethylene glycol ethyl methyl ether (1-ethoxy-2-methoxyethane: EME). Partial fluorination of DEE increases the polarity. We have investigated the effect of the partial fluorination on the physical and electrochemical properties of DEE in some detail. The mass densities decreased in the order of decreasing the molar mass: tetrafluorinated DEE (FETFEE) > trifluorinated DEE (ETFEE) > monofluorinated DEE (EFEE) (≈ diethyl carbonate (DEC)) > DEE. The molar concentration of FETFEE was higher than that of ETFEE in spite of the large molar size: DEC > EFEE > DEE > FETFEE > ETFEE. The relative permittivity and viscosity of FETFEE were higher than those of ETFEE and EFEE: FETFEE > ETFEE ≈ EFEE > DEE > DEC for the relative permittivity and FETFEE > EFEE > ETFEE > DEC > DEE for the viscosity. The kinematic viscosity of ETFEE was as low as that of DEE above 50 °C. The partial fluorination of DEE improved the solubility of LiPF6. The electrolytic conductivity of 1 mol dm−3 LiPF6/FETFEE was lower than that of 1 mol dm−3 LiPF6/EFEE, but higher than that of 1 mol dm−3 LiPF6/ETFEE. The partial fluorination can increase the ability of the solvent molecules to form hydrogen bonds. The fluoromethyl group may serve as an anion-attracting group. The use of an EC−FETFEE equimolar binary mixture suppressed the discharge capacity fading at high cycle numbers.
Hybrid Battery System to Achieve High Power and High Energy for Automotive Applications
Authors: Kim Huiseok , Jung Seunghun 
Published: February 2020

Although lithium-ion batteries (LiBs) have superior power and energy density than the other type of batteries, generally, a LiB is specially customized to achieve its specific requirements such as long-range mileage for EV or high power for HEV. This is because it is difficult to meet both high power and high energy density with a single type of battery. For example, high energy batteries for EVs that have thick electrodes may undergo charging problem such as lithium metal plating at low temperature. Accordingly, several studies were conducted to simultaneously improve both power and energy performance of LiBs. Using altered composition of electrode materials, electrolyte, and separator, LiBs could have improved energy retention or power performance [1-3]. But, preceding studies could not achieve both energy and power performance for vehicle applications at the same time. In order to resolve this problem, Kotz et al. [4] proposed a concept of a hybridized battery which combined a high energy battery with a high power capacitor within a single system. They reported that the internal parallel hybridization of those two components could achieve higher power and higher energy than each component operates independently.
In the present study, we propose a new concept of battery system to achieve both high power and high energy at once by externally hybridizing a high power LiB with a high energy LiB in a single system, so called “hybrid battery (HB)”. To investigate the feasibility of the concept, we construct a mathematical model of a HB system as shown in figure 1. Three LiBs are connected in parallel. Two of them are high power LiBs and the other is high energy LiB. Conducting computational simulations with the developed model, basics characterization (OCV, resistance, C-rate performance) of the hybrid battery system is investigated for the first time. Then, we examine the performance of the hybrid battery under various operating conditions. Also, charging/discharging interactions among LiB members are monitored. To validate the present HB concept with the developed mathematical model, an actual hybrid battery system is constructed by using three automotive LiBs. Basic characterization and simulated driving test shows a good agreement with the theoretically predicted result. Through the present study we confirm the validity of the HB concept for automotive applications.

References

[1] Zonghai Chen, W.Q. Lu, J. Liu, K. Amine, Electrochemica Acta 51 (2006) 3322-3326
[2] Norio Takami, Hiroki Inagaki, Yoshinao Tatebayashi, Hidesato Saruwatari, Keizoh Honda, Shun Egusa, J Power Sources 244 (2013) 469-475
[3] Won-Kyung Shin, Ji-Hyun Yoo, Dong-Won Kim, J Power Sources 279 (2015) 737-744
[4] Dario Cericola, Petr Novak, Alexander Wokaun, Rudiger Kotz 196 (2011) 10305-10313

Figure 1
Amorphous Iron-Nickel (oxo)Hydroxide Nano-Particles Immobilized on SnO2 Nanotube Arrays As an Integrate Anode for Oxygen-Evolution Reaction
Authors: Xiang Rui , Wei Zidong 
Published: February 2020

Key words: Oxygen evolution, Nanotube arrays, electro-catalysis
Development of efficient and earth abundant electro-catalysts for oxygen evolution reaction (OER) greatly hampered the realistic large scale production of hydrogen by electrolysers.[1] Bimetal iron/nickel (oxo)hydroxide represents a promising OER catalyst for its high intrinsic activity and stability.[2] To enhance its conductivity and density of active sits, we rationally immobilized amorphous FexNi(1-x)OOH nano-particles on SnO2 nanotube arrays by a mild all solution process. The SnO2 layer does not only function as a conductive matrix, but also guarantee the successful in-situ decoration of FexNi(1-x)OOH species instead of oxidative corrosion of the Nickel foam substrate by FeCl3 in the solution. Multiple physical characterizations confirmed the successful construction of the tubular architecture of SnO2 and the even dispersing of FexNi(1-x)OOH particles (SEM, TEM, XPS and Raman etc.). Its outstanding catalytic activity in basic solution in terms of a quite low overpotential of 250 mV at 50 mA cm-2 was demonstrated by electrochemical measurements (fig.1-h), and was ensured benefiting from the amorphous nature of FexNi(1-x)OOH nano-particles and the elegant tubular array micromorphology feature.
Fig. 1. SEM image (a, b) and element mapping (c, d, e, f and g) of NixFe(1-x)OOH/SnO2 nanotube arrays; (h) Linear Sweep Voltammetry (LSV) curves of NixFe(1-x)OOH@SnO2 NTA/Ni foam (purple), NiOOH@SnO2 NTA/Ni foam (blue), FeOOH@SnO2 NP/Ni foam (green), SnO2 NTA/Ni foam (red line) and bare Ni foam (black line) in alkaline solution. Dash line shows the LSV curve of NixFe(1-x)OOH@SnO2 NTA/Ni foam in the same solution with 70% iR compensation,. Condition: 1.0 M KOH. Scan rate 5 mV s-1.

Reference:

[1]. Nian-Tzu Suen, Sung-Fu Hung, Quan Quan, Nan Zhang, Yi-Jun Xu, Hao Ming Chen, Chem. Soc. Rev., 2017, 46, 337—365.
[2]. Shihui Zou, Michaela S. Burke, Matthew G. Kast, Jie Fan, Nemanja Danilovic, Shannon W. Boettcher, Chem. Mater. 2015, 27, 8011−8020.

Figure 1
(Invited) Lithium-Ion Capacitor Utilizing 3-D Current Collector with Bis(fluorosulfonyl)Imide-Based Electrolyte
Authors: Ishikawa Masashi , Hirota Naoya , Uchida Satoshi , Yamagata Masaki , Okuno Kazuki , Majima Masatoshi , Hosoe Akihisa 
Published: February 2020

The lithium-ion capacitor (LIC) is a new storage device that combines an electric double-layer capacitor (EDLC) with a lithium-ion battery (LIB). Although LIC features an excellent power density like EDLC, the energy density of LIC is lower than that of LIB. Therefore, improvement of energy density is required for LIC. In the present study, to achieve high energy density of LIC, a porous 3-dimensinal (3-D) current collector is applied to LIC electrodes. This 3-D current collector can increase the packing density of active material. It is, however, expected that diffusion of ionic carriers is limited when we use a conventional organic electrolyte because an electrode based on a 3-D current collector should be massive and hence too long ionic diffusion pathways. As a result, LIC using a 3-D current collector may deliver limited power. Here ionic liquids (ILs) that have a high carrier density would be useful as an electrolyte for LIC to maintain power. The purpose of this study is applying IL-based electrolytes to LICs with the porous 3-D current collector.
We assembled a three-electrode cell. A positive electrode using an aluminum 3-D current collector was composed of activated carbon, acetylene black (AB) and polyvinylidene di-fruoride (PVdF). A negative electrode using a copper 3-D current collector was composed of hard carbon, AB and PVdF. A lithium foil was used as a counter electrode as well as reference electrode. We used lithium bis(fluorosulfonyl)imide/1-ethyl-3-methylimidazorium bis(fluorosulfonyl)imide (LiFSI/EMImFSI) as an IL-based electrolyte. The cell was charged and discharged for 3000 cycles at 1.0 C-rate in a voltage range of 2.0 – 3.8 V. We also evaluated rate performance of the LIC cells by rapid charging and discharging test up to 30 C-rate.
When we observed the potential profiles of the positive and negative electrodes during charge and discharge at the 2nd, 1000th and 3000th cycles, it was found that the LIC cell containing our FSI-based IL electrolyte can be charged and discharged reversibly as well as stably. Even though we applied long-term cycling such as 3000 cycles to the LIC cell, the capacity has not significantly degraded. We compared rate performance among the IL electrolyte and conventional organic electrolytes. Although the IL has a relatively high viscosity, it was shown that the FSI-based IL electrolyte has high rate performance comparable to that of a LiPF6-based organic electrolyte. This may be due to a high carrier density of the IL. These results suggest that application of the FSI-based IL electrolyte to LIC electrodes with the porous 3-D current collector is promising to keep or enhance energy and power capability.
A Step Potential Electrochemical Spectroscopy Analysis of Capacitance Fade with Increasing Film Thickness in Anodically Electrodeposited Thin Films of Manganese Dioxide
Authors: Gibson Andrew J , Donne Scott W 
Published: February 2020

Manganese oxides (MnO2, MnOOH) are promising materials for electrochemical capacitors due to their low cost and toxicity, coupled with their attractive energy storage properties, and as such are well represented in the literature [1]. Thin films of MnO2 prepared by electrodeposition are capable of achieving high values for gravimetric specific capacitance (>2000 F/g) [2], however this rapidly decreases with increasing film thickness. Material activity, as well as material morphology play an important role in determining the capacitive behaviour of a material [3]. Recently, a new method for using step potential electrochemical spectroscopy to separate double layer and faradaic capacitance has been developed [4].
In this presentation, the change in both the double layer and faradaic capacitance with increasing film thickness of anodically prepared deposits will be discussed. With increasing film thickness the gravimetric double layer capacitance increases; however, this is significantly offset by a degradation in material activity, leading to an overall decay in material capacitance. The proposed structural and morphological reasons for these changes will be discussed.
1. Wei, W., et al., Manganese oxide-based materials as electrochemical supercapacitor electrodes. Chemical Society Reviews, 2011(40): p. 1697 - 1721.
2. Cross, A., et al., Enhanced Manganese Dioxide Supercapacitor Electrodes Produced by Electrodeposition. Journal of Power Sources, 2011. 196: p. 7847 - 7853.
3. Conway, B.E., Electrochemical Supercapacitors: Scientific Fundamentals and Technological Applications. 1999, New York: Springer.
4. Dupont, M.F. and S.W. Donne, A Step Potential Electrochemical Spectroscopy Analysis of Electrochemical Capacitor Electrode Performance. Electrochimica Acta, 2015. 167: p. 268 -277.