bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nitrogen and Sulfur Co-Doped MWCNT/Rgo Composite As Highly Active Electrocatalyst for Oxygen Reduction Reaction in Alkaline Fuel Cell
Authors: Kruusenberg Ivar , Šutka Andris , Shainyan Bagrat A. , Käämbre Tanel , Villemson Karl Markus , Wang Pangpang 
Published: February 2020

Recently a major effort in fuel cell research and development have been undertaken to displace platinum with platinum-free or even better, totally metal free catalyst materials. With the possibility of using heteroatom doped carbon-based materials as electrocatalysts for oxygen reduction reaction (ORR) instead of Pt, anion exchange membrane fuel cells (AEMFCs) have big advantage over other low-temperature fuel cells. Beside other carbon nanomaterials, carbon nanotubes and graphene have shown good electrocatalytic and catalyst supporting properties for different fuel cell cathode catalysts. Graphene and/or carbon nanotubtube doping with heteroatoms is a common strategy to increase the electrocatalytic activity of these materials towards the ORR [1]. Different heteroatoms, such as nitrogen, phosphorous, sulfur and boron have been studied as promising dopants to prepare electrocatalysts for ORR in alkaline media [2].
In this work the electrocatalytic activity of nitrogen and sulfur co-doped MWCNT/rGO was studied towards the ORR in alkaline media (0.1 M KOH) using the rotating disc electrode (RDE) method. The catalyst materials were prepared by doping of MWCNT/rGO with N and S via simple one-pot synthesis method using high-temperature pyrolysis in inert gas atmosphere. The resulting catalyst material exhibited excellent electrocatalytic activity towards the ORR in alkaline media. Catalyst samples were characterized also by transmission electron microscopy, X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy methods. Fuel cell experiments were carried out using Fumatech Fumapem® FAA anion-exchange membrane and FAA ionomer. Methanol tolerance and long-term stability tests were performed.
The results revealed remarkable catalytic activity of nitrogen and sulfur co-doped carbon towards the ORR in alkaline media, as well good methanol tolerance. Composition analysis with different physical characterization methods confirmed that nitrogen and sulfur have been grafted onto the carbon support. RDE tests demonstrated highly improved catalytic activity in comparison with undoped MWCNT/rGO and fuel cell tests showed a great potential of N and S doped carbon as alternative cathode catalyst and catalyst carrier for anion exchange membrane fuel cells.

References

[1] S. Ratso, I. Kruusenberg, U. Joost, R. Saar, K. Tammeveski, Enhanced oxygen reduction reaction activity of nitrogen-doped graphene/multi-walled carbon nanotube catalysts in alkaline media, International Journal of Hydrogen Energy 41 (2016) 22510.
[2] J.-C. Li, P.-X. Hou, C. Liu, Small 13 (2017) 1702002.

Figure 1
Alkaline Stable Sustainion® Anion Exchange Membrane for Fuel Cells
Authors: Liu Zengcai , Sajjad Syed D. , Yang Hongzhou , Zhu Liang , Masel Richard I. 
Published: February 2020

Anion exchange membrane fuel cells are of interest since they allow to use non-precious metal catalyst for both anode and cathode reaction. More than 2000 articles have been published on alkaline membrane fuel cells(1). There is one previous report indicating initial power densities of 1W/cm² but with no long term data(2). The best long term data shows a cell voltage decrease by about 25% over 800hr at a current density of 400mA/cm2 and 60°C.
Presently, Sustainion® 37 anion exchange membranes have demonstrate excellent stability in anion exchange membrane carbon dioxide (CO2) and water electrolyzer(3-6). Carbon dioxide electrolyzer runs at pH 6-8 with 10mM KHCO3 in anode(3), while water electrolyzer runs at pH close to 14 with circulating 1M KOH at both anode and cathode at 60C(4-6). Both alkaline CO2 and water electrolyzers have demonstrated 4000hr runs with only 1-6µV/hr increase in the cell voltage(3, 5).
Here we report our preliminary results for fuel cells with Sustainion® 43 anion exchange membranes as shown in Figure 1. In this data, Pt/C catalysts were used as both cathode and anode, and humidified H2 and O2 were fed to anode and cathode, respectively. The cell operated at 60 °C with back pressure of 1 atm. The maximum power density was 0.44W/cm² and the maximum current density was 2A/cm². These initial results suggest that Sustainion® 43 membranes could be useful for alkaline membrane fuel cells.
Figure 1 Cell voltage and power density as function of current density of the fuel cell with Sustanion anion exchange membrane and Pt/C for both anode and cathode. Back pressure: 1 atm; cell temperature at 60°C.

D. R. Dekel, Journal of Power Sources, 375, 158 (2018).

L. Wang, E. Magliocca, E. L. Cunningham, W. E. Mustain, S. D. Poynton, R. Escudero-Cid, M. M. Nasef, J. Ponce-Gonzalez, R. Bance-Souahli, R. C. T. Slade, D. K. Whelligan and J. R. Varcoe, Green Chemistry, 19, 831 (2017).

R. B. Kutz, Q. Chen, H. Yang, S. D. Sajjad, Z. Liu and I. R. Masel, Energy Technology, 5, 929 (2017).

Z. Liu, S. D. Sajjad, Y. Gao, J. Kaczur and R. Masel, ECS Transactions, 77, 71 (2017).

Z. C. Liu, S. D. Sajjad, Y. Gao, H. Z. Yang, J. J. Kaczur and R. I. Masel, International Journal of Hydrogen Energy, 42, 29661 (2017).

R. I. Masel, Z. Liu and S. Sajjad, ECS Transactions, 75, 1143 (2016).

Figure 1
Operand AFM Observation of Electrodeposited Lithium Metal
Authors: Sano Hikaru , Kitta Mitsunori , Shikano Masahiro 
Published: February 2020

Lithium metal anode is attractive due to its very negative potential and high capacity density, and however, secondary batteries with lithium metal anode are not practically used. One of the biggest obstacle against the wide spread in the market is dendrite formation at the anode during charging.[1] Many researches have been carried out where the mechanism of the dendrite formation of lithium metal were investigated in order to suppress the dendrite formation. Particularly the nano-scale and/or initial behavior of dendrite formation is of importance to elucidate the mechanism. Recently, peakforce-tapping mode AFM (atomic force microscopy) has been commercialized, where the damage to the sample surface from the AFM tip is much smaller than the damage in other conventional mode of AFM.[2] In this study, peakforce-tapping mode AFM was utilized to investigate the initial behavior of lithium electrodeposition in nano-scale in operand.
Lithium wire was cut in the electrolyte and was used as working electrode. Lithium wire was used as a counter electrode, and 0.1 M LiPF6/PC was used as electrolyte solution. Lithium was electrodeposited on working electrode with current density of 2.5 mA cm-2. The working electrode surface was observed by using peakforce-tapping mode AFM in operand. The height and adhesion mapping images were simultaneously obtained.
Two types of protrusions were observed in the series of height mapping images. One type of protrusions increased in size during electrodeposition, while the other type of protrusions kept their size. A series of adhesion mapping images indicate that the former type of protrusions had less adhesive surface than the latter type of protrusions. Furthermore, once the electrodeposition was stopped, the adhesion force of former type of protrusions increases and became the similar adhesion force of latter type of protrusions.[3] In PC solutions, the lithium surface is considered to be coated by surface film. The results may indicate that the surface film on the growing deposits is different from that of static-state deposits. In the case where dendrites had been suppressed, the deposits had been widely and uniformly spread and there had been no contrast at the adhesion images. The AFM technique can be used to detect the dendrite formation even at the very initial state of electrodeposition.

References:

[1] D. Aurbach et al., Solid State Ionics, 148, 405 (2002).
[2] https://www.bruker.com/fileadmin/user_upload/8-PDF-Docs/SurfaceAnalysis/AFM/ApplicationNotes/Introduction_to_Brukers_ScanAsyst_and_PeakForce_Tapping_Atomic_Force_Microscopy_Technology_AFM_AN133.pdf.
[3] M. Kitta and H. Sano, Langmuir, 33, 1861 (2017).

Acknowledgement:

This work was partly supported by the Japan Science and Technology Agency (JST) - Advanced Low Carbon Technology Research and Development Program, “Specially Promoted Research for Innovative Next Generation Batteries (ALCA-SPRING)”.
Surface-Oxidized Titanium Sulfide Nanoparticles As a Conductive Polysulfide Scavenger for a High Performance Lithium-Sulfur Battery
Authors: Jeon Jaebeom , Jung Yeon Sik 
Published: February 2020

Theoretically, a solid redox pair of Li and S can be used for energy storage devices with high specific capacity and energy density using low-cost sulfur as the active material, making it one of the most promising candidates to replace conventional lithium ion batteries. However, the practical use of Li-S battery is hindered by persistent issues regarding the formation of soluble polysulfides (PS) during electrochemical cycles and their shuttling effect. In order to minimize the irreversible loss of the active material from the cathode and its subsequent deposition on the anode, a few noteworthy efforts have been reported, including insertion of a protection layer or addition of a functional agent that can adsorb PS on the cathode side.
In this work, we report conductive titanium(III) sulfide (Ti2S3) nanoparticles, synthesized using a simple radio frequency (RF)-powered induction thermal plasma method, as a bifunctional material to be used in the S cathode. Ti2S3 nanoparticles can provide electrical conductivity to the electrode with a smaller volume compared to conventional conducting agent carbon, while simultaneously having PS adsorption adequate to mitigate the diffusion of PS from the cathode and reduce accompanying problems. We prepared Ti2S3 nanoparticles agent with improved PS adsorptivity by applying simple defect chemistry. The synthesized Ti2S3 was first exposed to air to be oxidized and form S defect on its surface. The surface-oxidized Ti2S3 proposed in this work shows both sufficient adsorption property to PS and electronic conductivity, and thus enhance the cyclability and areal energy density of the Li-S battery. The cyclic performance of our Li-S cell was achieved up to ~800 mAh gS
-1 even after 100 cycles at relatively high S loading of 3.0 mgS cm-2.
A Nature-Inspired Molecular Catalyst for Sustainable and Efficient Lithium-Oxygen Batteries
Authors: Lee Jun-Seo , Lee Cheolmin , Lee Jae Yun , Ryu Jungki , Ryu Won-Hee 
Published: February 2020

Lithium-oxygen (Li-O2) batteries employing a lightweight and gaseous oxygen cathode have been spotlighted because of their exceptional high-energy density (practically 2~3 times higher than lithium-ion cells).[1-2] However, their poor efficiency and cyclability originating from the sluggish kinetics for the formation and decomposition of lithium oxide products (i.e., LiO2, Li2O2) necessitate utilization of efficient catalysts. Although loading of the solid catalysts on the electrode effectively facilitates the Li-O2 cell reactions, they are quickly deactivated upon cycling due to accumulating product residues.[3-4]

Incorporation of soluble redox molecules into an electrolyte has been considered an effective alternative strategy to address the deactivation issues.[5] Their redox properties enable rapid electron transfer from/to the electrode through their self-diffusion and subsequent redox reactions instead of a slow electron movement through the insulating discharge products. Development of potential redox catalysts for Li-O2 cells should meet the following requirements: (i) high mobility in electrolyte; (ii) reversible redox properties for fast electron transfer; (iii) robust stability; and (iv) environmental friendliness.
In this work, we report a class of nature-inspired molecules as an efficient and stable redox catalyst for Li-O2 batteries. Interestingly, the catalyst molecules exhibits catalytic activity for both oxygen evolution and reduction reactions under a certain condition when it forms a stable dispersion of molecular aggregates, which can be controlled by types of electrolyte solvents and exposure to light. As a result of the optimized catalytic activity, the Li-O2 cells facilitated by redox reactions successfully achieve improved efficiency and a longer cycle life compared to reference cells. The reversibility of the Li-O2 reactions in the presence of the molecular catalysts is confirmed by ex-situ characterizations.
[1] Ryu, W. H.; Yoon, T. H.; Song, S. H.; Jeon, S.; Park, Y. J.; Kim, I. D. Nano Lett
2013, 13, 4190-7.
[2] Gittleson, F. S.; Yao, K. P. C.; Kwabi, D. G.; Sayed; Ryu, W.-H.; Shao-Horn, Y.; Taylor, A. D., ChemElectroChem
2015, 2, 1446-1457.
[3] Ryu, W. H.; Gittleson, F. S.; Schwab, M.; Goh, T.; Taylor, A. D., Nano Lett
2015,
15, 434-441
[4] Ryu, W. H.; Gittleson, F. S.; Li, J.; Tong, X.; Taylor, A. D., Nano Lett
2016, 16, 4799-4806
[5] Ryu, W. H.; Gittleson, F. S.; Thomsen, J.; Li, J.; Schwab, M.; Brudvig, G.; Taylor, A. D., Nature Commun., 2016, 7, 12925.
Feasibility of Electrochemical Mg Extraction from MgMn2O4 Cathodes for Mg Rechargeable Batteries
Authors: Hatakeyama Takuya , Shimokawa Kohei , Li Hongyi , Nakao Aiko , Uchimoto Yoshiharu , Ichitsubo Tetsu 
Published: February 2020

Mg rechargeable batteries (MRBs) have attracted much attention as a post Li-ion battery owing to high capacity, low electrode potential, and safety of Mg metal anode. However, it is generally a laborious task to seek suitable cathode materials for MRBs. According to the previous report [1], Mg insertion into several kinds of spinel oxide cathodes, Mg(TM)2O4 (TM = Co, Mn, etc), occurs at about 2-3 V vs Mg2+/Mg, which causes the spinel-to-rocksalt transition. In addition, it is noteworthy that Mg extraction from MgMn2O4 has been shown to occur at intermediate temperatures (around 150 ℃), but the detailed mechanism (such as structure change, electrochemical reaction, valence change, etc) has been still unclarified. In this study, we aim to investigate the feasibility of electrochemical extraction of Mg cations from MgMn2O4 to seek a better cathode material delivering a higher voltage.
MgMn2O4 was synthesized by the Pechini method [2] and calcined at 425 °C in air. After mixed with carbon black and binder, MgMn2O4 was coated on Al foil. Electrochemical experiments were conducted in three-electrode cells at 150 ℃, where Li reference electrode was employed to compare with the Li-extraction potential from the same material; the Li reference electrode was well separated from the ionic liquid Mg0.1Cs0.9-TFSA bulk electrolytes with ceramic filters. Compositions and crystal structures of MgMn2O4 cathodes after electrochemical experiments were investigated by ICP, XRD, and XPS analyses.
Compositions of MgMn2O4 cathodes after charge (Mg extraction from spinel) and also discharge (Mg insertion into spinel) processes are shown in Fig. 1. The Mg composition is decreased to 0.73 at charge amount equivalent to 139 mAh/g and to 0.58 at 346 mAh/g from the initial composition (x~1.04), which indicates that Mg cations can be certainly extracted from MgMn2O4, however, accompanying by some degree of electrolyte decomposition. To grasp the electrochemical equilibrium properties of Mg-extraction from MgMn2O4, galvanostatic intermittent titration technique (GITT) was employed. Figure 2 shows that the overpotential of Mg extraction is increased on charging, the open circuit potential reaches 3.9 V vs Li+/Li, and it is substantially unchanged till the end of the measurement. The plateau potential indicates that two-phase equilibrium reaction occurs during the Mg extraction process. Synchrotron XRD measurement reveals that the charged samples consist of the original spinel phase and a cubic spinel phase, and XPS measurement also suggests that the valence state of Mn is shifted to a higher (binding energy) from the initial state after charge.

Figure 1
Phosphorus Decorated Electrospun Carbon Anodes for Highly Efficient Lithium and Sodium Ion Batteries
Authors: Liberale Francesco , Fiore Michele , Ruffo Riccardo , Bernasconi Roberto , Shiratori Seimei , Magagnin Luca 
Published: February 2020

Electrospinning has recently attracted considerable attention as a powerful and versatile technique to produce efficient, specifically tailored and high-added value anodes for lithium ion batteries (LIBs) and sodium ion ones (SIBs) [1]. Carbon electrospun nanofibers (CNFs), obtained via polymer electrospinning and subsequent carbonization, provide faster intercalation kinetics with respect to commonly employed powder material thanks to the high surface to volume ratio and to the shorter diffusion paths for ions and electrons transport. They offer a large number of ions insertion sites and the charge-transfer resistance at the electrolyte/active material interface is therefore reduced [2].
Recently, red phosphorus has been considered as one of the most promising anode materials for LIBs and SIBs alternative to the C-based ones [3] but its widespread and easy application has been prevented due to its low conductivity and large volume expansion during cycling, leading to low cyclability and poor rate performances. For this reason, red phosphorus cannot be used alone, but it must be combined with other anode materials able to accommodate its expansion and to increase its conductivity.
Here we suggest a simple double-step procedure to obtain high-capacity electrospun carbon nanofibers anodes and to enhance their electrochemical performances with the insertion of red phosphorus in the matrix. In particular, we propose a simple drop-casting method to confine micro- and nanosized amorphous red P within the carbon mat, thus obtaining an highly efficient, self-standing, binder- and collector-free anode. Red P insertion in the CNFs net has been demonstrated by SEM and TEM analysis and the resulting material has been used to manufacture anodes for LIBs and SIBs. The reversible specific capacity and the rate capability of the obtained composite anodes have been significantly improved with respect to the electrospun carbon mat alone. The outstanding electrochemical performances for both LIBs and SIBs can be accounted to the synergic action of high-capacity red P clusters with the fast transport properties of the carbon fiber mat, acting also as an accommodation-volume matrix for the significant phosphorus expansion during charging/discharging.
[1] Wang, H. G., Yuan, S., Ma, D. L., Zhang, X. B. & Yan, J. M. Electrospun materials for lithium and sodium rechargeable batteries: from structure evolution to electrochemical performance. Energy Environ. Sci. 8, 1660–1681 (2015)
[2] Kim, C. et al. Fabrication of electrospinning‐derived carbon nanofiber webs for the anode material of lithium‐ion secondary batteries. Adv. Funct. Mater. 16, 2393–2397 (2006)
[3] Qian, J., Wu, X., Cao, Y., Ai, X. & Yang, H. High capacity and rate capability of amorphous phosphorus for sodium ion batteries. Angew. Chemie 125, 4731–4734 (2013)
The Micro-Optical Ring Electrode: A Sensor for Multiple Actinide Ions Monitoring
Authors: Linnett Gary , Andrieux Fabrice 
Published: February 2020

We present on the development of the Micro-Optical Ring Electrode (MORE) for the analysis of trans-uranium elements in aqueous mixtures. The MORE is a photo-electrochemical device based on a ring microelectrode that uses the insulator interior to the ring as a light guide. This single device exploits the unique photophysical and electrochemical properties of multiple analytes present in mixtures to quantify them. Our study aims to develop a protocol for the analysis of ions of uranium, neptunium and plutonium, which are most relevant to the nuclear industry, especially in the areas of decommissioning and fuel-reprocessing, where speedy and safe identification of radioactive contaminants is essential.
The technique offers a number of advantages over traditional methods in the area of radiochemical analysis such as real time monitoring in-situ, reduced radiation dose impact to the analyst as a result of greatly reduced sample handling and preparation, improved analysis times allowing quick decision making and a much reduced cost (e.g. compared to ICP-MS and Scintillation counting).
Here we present results of our study on successfully generating photocurrents from uranium containing solutions, and describe the response of the sensor as a function of wavelength of illumination, concentration of sensitizer and scavenger species, and include a discussion of limits of detection and interference from additional analytes. The effect of the MORE’s surface finish on photocurrents will also be discussed.
Electrochemistry of SmCl3 and SmF3 in Molten NaCl-KCl
Authors: Stulov Yuriy V. , Kuznetsov Sergey A. 
Published: February 2020

Lanthanide elements, which are present in spent fuel from fast nuclear reactors, can be converted into molten salts by anodic dissolution. Electrolysis of molten salts is promising for separation of lanthanides and actinides. To solve this problem, it is necessary to have experimental data on the electrochemical behavior of various lanthanides in molten salts.
The aim of this study is determine the influence of the first coordination sphere composition of samarium complexes on its electrochemistry in molten equimolar mixture NaCl-KCl.
Electrochemical investigations were carried out in a temperature range of 973-1173 K by cyclic voltammetry using an AUTOLAB PGSTAT 20 potentiostat with a package of application programs GPES (version 4.4.). The melt container was a glassy carbon crucible of SU-2000 brand, which also served as an auxiliary electrode. Tungsten wire was used as working electrode and Pt wire was utilized as a quasi-reference electrode.
In the NaCl-KCl-SmCl3 melt it was found that peak current of the recharge process of Sm(III) to Sm(II) is directly proportional to the square root of the polarization rate, while the peak potential does not depend on the polarization rate up to v=0.1 V s-1. According to the theory of linear sweep voltammetry, up to the polarization rate 0.1 V s-1, the electrode process is reversible. However, in the NaCl-KCl-SmF3 molten system the recharge process was reversible up to the scan rate 1.0 V s-1.
Diffusion coefficients of Sm(III) in chloride and chloride-fluoride melts were determined by cyclic voltammetry using the Randels–Sevchik equation.
The quasi-reversible process for the Sm(III)/Sm(II) redox couple was determined in NaCl-KCl-SmCl3 melt at a sweep rate 0.1<v<0.3 V s-1. This mechanism is clearly evidenced by the deviation of the experimental points from linearity in the IC

p vs. v
1/2 plot, by the dependence EC

p on v and by the magnitude of the difference between EA

p and EC

p, which is larger than is required for a reversible process. A transition from a reversible to a quasi–reversible process was found at v > 1.0 V s-1 in the NaCl-KCl-SmF3 melt.
The standard rate constants of charge transfer (k
s) of the Sm(III)/Sm(II) redox couple were determined by cyclic voltammetry both in NaCl-KCl-SmCl3 and NaCl-KCl-SmF3 molten salts using the Nicholson’s equation, which is valid for quasi-reversible processes. The higher values of k
s were obtained in chloride melt than in chloride-fluoride molten system.