bluuebunny/crossref_metadata_2025 huggingface dataset:
Rational Design of High Energy Sulfur Cathodes for Lithium-Sulfur Batteries
Authors: Lu Dongping , Shi Lili , Baranovskiy Arthur , Xiao Jie , Zhang Ji-Guang , Liu Jun
Published: February 2020

Deployment of Lithium-sulfur (Li-S) battery has been hindered by the low practically achievable energy and limited cycle life, although significant advances have been demonstrated in material development and fundamental understandings.1 There are still challenges in pursuing high energy Li-S battery lacking of high energy cathodes, stable anodes and electrolytes, particularly scientific knowledge bridging fundamental research and practical deployment. Sulfur cathodes host active materials for Li+ storage and thus determine the total capacity of the system. However, specific energy of the Li-S battery is highly dependent on the whole weight of the system, of which electrolyte takes a largest weight fraction but contributes nothing to energy. So rational electrode architecture design is of significant importance to not only realize the high sulfur mass loading but also decrease the electrolyte uptake to a very limited level.2 This is very challenging but the only pathway to the target of high energy Li-S battery for practical applications. In an attempt to addressing the key challenges in achieving high energy Li-S battery, our efforts are focused on the understanding of fundamental reasons that affect sulfur utilization in high loading electrodes and with lean amount electrolytes. Based on our understanding, rational cathode design including electrode materials, binders and electrode architectures has been proposed and demonstrated for high loading electrode preparation. At the meeting, we will present our recent progresses on the fundamental understanding and practical demonstration of high energy Li-S batteries.

References

(1) Manthiram A., Fu Y., Chung S.-H., Zu C.,Su Y.-S., Chem. Rev. (Washington, DC, U. S.)
2014, 114, 11751-11787.

(2) Lv D., Zheng J., Li Q., Xie X., Ferrara S., Nie Z., Mehdi L. B., Browning N. D., Zhang J. G.,Graff G. L., Adv. Energy Mater.
2015, 5, 1402290.
Ion-selective Polymer Electrolyte Membrane Based on Sulfonated Silica and Sulfonated Poly(Phenylene Oxide) for Redox Flow Battery
Authors: Roh Sung-Hee , Jung Ho-Young
Published: February 2020

Polymer electrolyte membrane (PEM) based on sulfonated poly (phenylene oxide) (sPPO) and sulfonated silica (sSiO2) is synthesized for the application of redox flow battery (RFB). Synthesis of PEM based on sPPO and sSiO2 is confirmed by Fourier Transform Infrared Spectroscopy (FT-IR). Proton conductivity (0.077 S cm-1) of PEM based on sPPO and sSiO2 is comparable to Nafion (0.078 S cm-1). This is due to the incorporation of sSiO2 having –SO3H functional group. Increased –SO3H functional groups in sPPO and sSiO2 can increase the ion exchange capacity (IEC) of the membrane. It can lead to high proton conductivity because of the well-organized cluster network structure. In addition, sSiO2 can play a role of barrier for the suppression of vanadium cross-over through the membrane. Therefore, the permeability of PEM (4.76 x 10-9 cm2 min-1) based on sPPO and sSiO2 is much lower than that of Nafion membrane (2.22 x 10-7cm2 min-1). It means that the selectivity of PEM based on sPPO and sSiO2 is much better than that of Nafion membrane. As a result of our study, it is found that our ion-selective PEM based on sPPO and sSiO2 can be a promising candidate for energy device and water treatment system.
Ordered Mesoporous Titanium Nitride As a Promising Carbon-Free Cathode for Aprotic Li-O2 Batteries
Authors: Kim Byung Gon
Published: February 2020

Despite the extraordinary gravimetric energy densities, Li-O2 batteries are still facing a technological challenge;[1] limited round trip efficiency leading to insufficient cycle life. Recently, carbonaceous electrode materials were found to be one of the primary origins of the limited cycle life,[2] as they produce irreversible side products during discharge. A few investigations based on noncarbonaceous materials have demonstrated largely suppressed accumulation of irreversible side products,[3] but such studies have focused mainly on the materials themselves rather than delicate morphology control. As such, here, we report the synthesis of mesoporous titanium nitride (m-TiN) with a 2D hexagonal structure and large pores (>30 nm), which was templated by a block copolymer with tunable chain lengths, and introduce it as a stable air-cathode backbone. Due to the well-aligned pore structure and decent electric conductivity of TiN, the battery reaction was quite reversible, resulting in robust cycling performance for over 100 cycles under a voltage cutoff condition. Furthermore, by protecting the Li metal with a poreless polyurethane separator[4] and engaging a lithium iodide redox mediator[3], the original capacity was retained for 280 cycles under a consistent capacity condition (430 mAh/g). This study reveals that when the appropriate structure and material choice of the air-cathode are coupled with an advanced separator and an effective solution-phase redox mediator, the cycle lives of Li-O2 batteries can be enhanced dramatically.

Reference
s
:

[1] J. W. Choi, D. Aurbach, Nat. Rev. Mater. 1 (2016) 16013.

[2] M.M. Ottakam Thotiyl, S.A. Freunberger, Z. Peng, P.G. Bruce, J. Am. Chem. Soc.135 (2013) 494−500.

[3] N. Feng, P. He, H. Zhou, Adv. Energy Mater. 6 (2016) 1502303.

[4] B.G. Kim, J. Kim, J. Min, Y. Lee, J.H. Choi, M.C. Jang, S.A. Freunberger, J.W. Choi, Adv. Funct. Mater. 26 (2016) 1747-1756.

Figure 1
Nitrogen and Phosphorous Co-Doped Carbon Felt for Enhancing VO2+/VO2
+ Redox Reaction for Vanadium Redox Flow Battery
Authors: Suharto Yustian , Kim Ki Jae
Published: February 2020

Nitrogen (N) and phosphorous (P) co-doped carbon felt is proposed as a promising electrode for enhancing VO2+/VO2
+ redox reactions. Nitrogen and phosphorous can be simultaneously incorporated onto the carbon felt through straightforward synthesis method using aniline and triphenylphosphine as N and P source. The successful incorporation of nitrogen and phosphorous functional groups onto the carbon felt surface can be confirmed by X-ray photoelectron spectroscopy analysis. Compared to the carbon felt electrode doped solely with nitrogen or phosphorous functional groups on its surface, the electrochemical activity of the proposed carbon felt electrode towards slow redox reactions of VO2+/VO2
+ can be greatly enhanced owing to the synergistic effects of the nitrogen and phosphorous functional groups. Consequently, VRFB cell assembled with N, P co-doped carbon felt electrode exhibits much stable cycle performance accompanied by highly improved energy efficiencies of 84.94 and 84.33% in the 1st and 50th cycle, respectively.
Insight into the Relationship between Transition Metal and Anionic Redox As Found in Simple Li-Rich CuO-Li2O Composite Cathode Materials
Authors: Papp Joseph K , McCloskey Bryan D.
Published: February 2020

Conventional lithium ion battery cathode materials derive their capacity exclusively from transition metal cation redox. Many recent studies on novel Li-rich cathode materials have found substantial reversible anionic redox that shows promise to greatly enhance battery capacity. Unfortunately, this anionic (oxygen) redox contribution to the charge compensation of lithium extraction and insertion typically results in cathode degradation and oxygen gas release. While previous studies have emphasized methods such as the doping of 4d or 5d transition metals to stabilize the formation of peroxo-like species, the mechanism of anionic redox in relation to the transition metals present is still largely unknown.

This study employs simple Li-rich cathode materials as a model for further understanding of the mechanism of anionic redox. Here we have synthesized a number of materials including simple 3d transition metal (e.g., Cu) doped lithium oxide to more closely examine the relationship between oxygen redox and the transition metal present in the cathode material. The materials studied contain a high ratio of lithium to transition metal to probe the maximum anionic redox activity. We will discuss our results in which galvanostatic measurements are combined with quantitative gas evolution analysis, in addition to ex-situ resonant inelastic X-ray scattering and X-ray photoelectron spectroscopy on cycled electrodes, to continue to clarify the required conditions for anionic redox in lithium ion battery cathode materials.
Carbothermal Shock Synthesis of Multimetallic, Solid Solution Electrocatalysts for Air-Based Batteries
Authors: Lacey Steven David , Yao Yonggang , Xu Shaomao , Hu Liangbing
Published: February 2020

Multicomponent nanomaterials are extremely difficult to synthesize by conventional methods. Accordingly, nanoparticles composed of immiscible elemental combinations tend to phase-separate rather than form singe-phase solid solutions, which limits the compositional space. A synthetic technique that facilitates kinetic control over thermodynamic mixing regimes is therefore advantageous and offers untold scientific and technological opportunities.

Here, we present a general route to alloy up to eight dissimilar elements into high entropy alloy nanoparticles (HEA-NPs) through a facile and tunable synthesis method: carbothermal shock (CTS).1 CTS employs flash heating and cooling of metal precursors on carbon to produce multimetallic nanoparticles with tailored elemental compositions, particle sizes, and structural complexity. Uniform mixing of nearly any metallic combination is achieved through high temperature exposure (~2000 K) during the thermal shock (55 ms) process, while rapid quenching (~105 K/s) retains this high-entropy state to form single-phase solid solutions.

This new synthetic technique promotes materials discovery and design for a wide range of applications, including catalysis and energy storage. Inspired by the performance of quinary HEA-NPs as ammonia oxidation catalysts, novel solid solution nanoparticles (with 2 or more metallic elements) are synthesized and evaluated as electrocatalysts in air-based batteries, such as lithium-oxygen (Li-O2) and Li-CO2. In this way, HEA-NPs composed of catalytically active elements may impart synergistic electrocatalytic effects to improve overall battery performance. This talk will describe the process and underlying mechanism to synthesize HEA-NPs, the overall capabilities of the CTS method, and recent results on electrocatalyst development towards Li-air battery applications.

References:

Y Yao*, Z Huang*, P Xie*, SD Lacey*, RJ Jacob, H Xie, F Chen, A Nie, T Pu, M Rehwoldt, D Yu, MR Zachariah, C Wang, R Shahbazian-Yassar, J Lu and L Hu, “Carbothermal shock synthesis of high-entropy-alloy nanoparticles,” Science, 359 (6383), pp. 1489-1494 (2018).
Intercalation Host Using Defective FePO4-Carbon Composite for Magnesium Rechargeable Battery Cathode
Authors: Orikasa Yuki , Kisu Kazuaki , Iwama Etsuro , Naoi Wako , Yamaguchi Yusuke , Munesada Toshiyuki , Hattori Masashi , Yamamoto Kentaro , Rozier Patrick , Simon Patrice , Naoi Katsuhiko
Published: February 2020

Magnesium rechargeable batteries are expected as one of candidates for next generation rechargeable batteries. The advantages of magnesium metal anode are the high theoretical capacity, high reserve amount of magnesium metal, and no dendrite formation. However, divalent magnesium ions are hard to diffuse in solid electrodes, and intercalation hosts that can operate at room temperature are limited to Chevrel type structures at present[1].

In this study, we investigated the applicability of FePO4-carbon composite prepared by ultracentrifugation (UC) method as magnesium-ion host structure. For nano-hybrid capacitor electrode, the electrode materials prepared by the UC method reported so far are capable of ultrafast lithium-ion insertion and extraction reaction[2]. Therefore, magnesium-ions could diffuse in the structure with a moderate condition. Since the irreversible magnesium ion insertion-extraction reaction in crystalline olivine type FePO4 has been reported[3], in this study, non-crystalline FePO4 with carbon composite was used.

FePO4-carbon composite was prepared by UC process[2]. The composite was mixed with PTFE. with the weight ratio of 9:1. The electrodes were charged using 1M LiPF6 in a 3:7 volume ratio of ethylene carbonate and diethyl carbonate. The charged electrodes were washed with DME and then, three-electrode cell with an Ag+/Ag double junction reference electrode was assembled. The counter electrode was an active carbon, and the electrolyte was 0.5 M magnesium bis(trifluoromethanesulfonyl)imide in acetonitrile. Charge-discharge measurements were performed at 25oC. The valence state of Fe in the charged / discharged electrodes were examined by X-ray absorption spectroscopy, which was measured in a transmission mode.

Reversible charge / discharge capacity was observed after the first discharge. In operation at 25oC and a rate of 1/20 C, a capacity of apploximately 150 mAh/g and the potential of about 2 V versus magnesium metal are observed. From the TEM-EDX measurements, the structure of FePO4 particles embedded in carbon and the intensity of magnesium is observed only in regions where FePO4 particles exist. X-ray absorption edge at Fe K-edge shifts downward in energy for the discharge reaction, reflecting the reduction of iron ions to maintain electrical neutrality upon magnesium-ion insertion in the discharge reaction.

Reference
s
:

[1] D. Aurbach, Z. Lu, A. Schechter, Y. Gofer, H. Gizbar, R. Turgeman, Y. Cohen, M. Moshkovich, E. Levi, Nature
407, 724-727 (2000).

[2] K. Naoi, K. Kisu, E. Iwama, S. Nakashima, Y. Sakai, Y. Orikasa, P. Leone, N. Dupre, T. Brousse, P. Rozier, W. Naoi, P. Simon, Energy Environ. Sci.
9, 2143-2151 (2016).

[3] R. Zhang, C. Ling, ACS Appl. Mater. Interfaces
8, 18018-18026 (2016).
Development of Carbon-Based Cathodes for Aluminium-Ion Batteries
Authors: McKerracher Rachel , Holland Alex , Wills Richard , Cruden Andy
Published: February 2020

The aluminium-ion battery is one of several promising post-lithium technologies under development to combat issues with lithium-ion batteries such as insecure lithium supplies, environmental impact and safety concerns associated with thermal runaway. [1,2]
Aluminium is an abundant material with an energy density of 1060 Wh.kg-1.[3] The limiting factor for the battery performance is the capacity of the cathode towards the intercalation of [AlCl4]- or Al3+ ions. Although several different cathode materials have been studied throughout the past few years, there have been few studies that compare the capacities of different cathode morphologies. Graphitic carbon materials have many features that make them ideal for aluminium-ion intercalation cathodes: they are electrically conductive, easily expandable, low density and low-cost, and are commercially available in a wide variety of morphologies.

In this work, the capacity of four forms of graphitised carbon are compared as aluminium-ion cathodes: pyrolytic graphite, carbon paper, carbon cloth and carbon felt. The materials differ in terms of their physical properties, and thus have different properties as aluminium-intercalating agents. Of all the materials examined, carbon paper had the highest energy density at 122 Wh.kg-1, and had an [AlCl4]- capacity of 70 mAh.g-1. Carbon paper had superior stability compared to pyrolytic graphite, particularly as the C-rate of cycling was increased. It undergoes no change in crystallographic structure even after cycling up to the 20C rate.

Additionally, the optimum distance between electrodes and electrolyte volume in an aluminium-ion cell was studied, and was found to be 1-2 mm in order to avoid shorting caused by eventual growth of aluminium nodules. In ionic liquid, the cell could only be charged to 2.45 V for repeated cycling, but experiments in a separator-less sealed cell showed that if the cell could be charged to 2.75 V, the capacity could be tripled.

References

M. Lin, M. Gong, B. Yu, Y. Wu, D.Y.Wang, M. Guan, M. Angell, C. Chen, J. Yang, B.J. Hwang, H. Dai, Nature, 520, 2015, 324-328.

N. Jayaprakash, S.K. Das, L.A. Archer, Chem. Commun., 47, 2011, 12610-12612.

National Laboratory, Oak Ridge, “Aluminiun-Ion Battery to Transform 21st Century Energy Storage” (pdf), retrieved 30 October 2014.

Figure 1
(Invited) Strategies to Improve Photostabilities of Visible-Emitting Nanophosphors
Authors: Isobe Tetsuhiko , Iso Yoshiki
Published: February 2020

Nanophosphors have attracted much interest in applications to wide color gamut displays and micro LEDs. Since nanophosphors have a large ratio of surface area to volume, they are sensitive to surrounding environment such as oxygen and water, particularly under irradiation by excitation light. We therefore focus on photostabilities of doped nanosphosphors of YAG:Ce3+ [1–3], YVO4:Bi3+,Eu3+ [4–6], and Y2O3: Bi3+,Eu3+ [7,8], and those of undoped nanophosphors of quantum dots of CuInS2/ZnS [9], InP/ZnS [10], and CsPbX3 (X = Cl, Br, I) [11]. In this talk, we mainly introduce our research on strategies to improve photostabilities of visible-emitting nanophosphors.

[1] Y. Kamiyama et al., J. Electrochem. Soc., 157, J149 (2010). [2] T. Isobe, ECS J. Solid State Sci. Technol., 2, R3012 (2013). [3] Y. Sasaki et al., ECS J. Solid State Sci. Technol., 5, R3049 (2016). [4] S. Takeshita et al., J. Electrochem. Soc., 157, J74 (2010). [5] S. Takeshita et al., Opt. Mater., 33, 323 (2011). [6] H. Hara et al., Mater. Sci. Eng. B, 178, 311 (2013). [7] T. Matsunaga et al., J. Lumin., 165, 62 (2015). [8] T. Watanabe et al., RSC Adv., 7, 14107 (2017). [9] C. Wada et al., RSC Adv., 7, 7936 (2017). [10] T. Watanabe et al., ECS J. Solid State Sci. Technol., 6, R75 (2017). [11] Y. Iso et al., ECS J. Solid State Sci. Technol., 7, R3040 (2018).
(Invited) d3 Electron Configuration: Basic Properties and Main Misconceptions
Authors: Brik Mikhail , Srivastava Alok M
Published: February 2020

Transition metal ions with the 3d3 electronic configuration (such as V2+, Cr3+, Mn4+, Fe5+) are widely used in various optical applications. In particular, the Mn4+ ions play a major role in red phosphors used in white light emitting diodes. Increased interest to these systems is justified by growing number of publications focused on the Mn4+ -based phosphors. However, quite often their spectroscopic properties are misinterpreted and physically incorrect statements can be met in the literature. Therefore, there is an urge need in a detailed and thorough review of the basic properties of the 3d3 electronic configuration, which would include the origin of the electronic energy levels, their degeneracy, symmetry, splitting patterns in crystal fields etc. This is the main goal of this presentation: to tutorize the fundamental optical properties of the 3d3 electronic configuration and to clear up some common misconceptions that we have encountered in the archival literature that pertains to the spectroscopic properties of the ions with the same electron configuration. The methods to properly describe the optical spectra of these systems are given. It is hoped that such systematic presentation of spectroscopic properties of the d3 ions and their variation from the free state to the crystalline solids will be useful for many researchers – mainly experimentalists – actively working in the field and will help them avoiding many mistakes when presenting their experimental results.
(Invited) A Quantum Electrodynamics Formulation of Energy Transfer Via Electric Dipole-Magnetic Dipole and Magnetic Dipole-Magnetic Dipole Interaction of Two Optically Active Ions
Authors: Collins John , Mishra Kailash C
Published: February 2020

The nonradiative electron transfer process between optically active ions in luminescent materials via electric dipole (ED)-magnetic dipole (MD) and magnetic dipole-magnetic dipole interaction has been investigated using a molecular quantum electrodynamics (QED) approach. The QED approach provides an intuitively simple but rigorous method of calculating the energy transfer probability through multipolar interactions such as the ED-MD and MD-MD interactions considered in this work. More details of this approach and its application to resonant energy transfer between molecules through the ED-ED interaction can be obtained from Craig and Thirunamachandran [1] and references therein.

The energy transfer process between two ions in the present study is shown schematically in Figure 1.

While the energy levels have been considered to be discrete within the QED formulation for calculating the transition probabilities, the broadening of the energy levels in solids has been processed using the spectral line shape functions without using the special normalization in the energy space used by Dexter [2]. The transition probabilities have been simplified further using experimentally observable spectroscopic parameters such radiative lifetime and absorption cross section. The final expressions for transition probability includes additional periodic functions that are meaningful only in the short wavelength regime of the electromagnetic radiation.

In this presentation, we will consider two classes of Feynman diagrams to calculate the transition rates for the energy transfer process through ED-MD and MD-MD interactions. In all the cases, the interaction between two ions is mediated by photons. In one class of diagrams, the photon is emitted first by ion A, and then absorbed by ion B at a later time. In other class of diagram, the photon is absorbed by ion B first and then emitted by ion A. The second class pertains to emission and absorption of a virtual photon. The theoretical details of calculating the transition probabilities and their significance will be presented. It will also be shown how this approach could be used in other luminescence processes to determine their plausibility and the transition rates.

[1] D. P. Craig and T. Thirunamachandran, Molecular Quantum Electrodynamics, Dover Publications, Mineola, New York (1998).

[2] D. L. Dexter, J. Chem. Phys. 21, 836 (1953).

Figure 1. A schematic diagram of energy transfer from ion A to ion B. The associated eigenstates and eigenenergies for each of these ions are indicated. The wavy line indicates transfer of energy from the ion A and B while the solid arrows indicate the electronic transitions each ion is going through simultaneously.

Figure 1
Rotating Disk Slurry Electrodeposition (RoDSE) Technique for Fuel Cell Catalysts Development
Authors: Velez Carlos A , Betancourt Luis E , Vega Melissa , Cabrera Carlos R
Published: February 2020

The Rotating Disk Slurry Electrodeposition (RoDSE) technique is a novel method which can electrochemically deposit metal nanoparticles on a given conductive support and produce a powder catalyst for diverse applications, e.g. ethanol oxidation reaction (EOR). This technique was used to electrodeposit Pd nanoparticles on carbon Vulcan XC–72R nanoflakes at three different applied potentials (0.0, 0.4, and 0.7 V vs. RHE). The potentials were chosen to represent different thermodynamic and kinetic regions of Pd electrodeposition. Each Pd /Vulcan catalyst was characterized through different spectroscopic, microscopic, and electrochemical techniques. Powder X–ray diffraction and transmission electron microscopy studies verified the Pd crystallinity and particle size, respectively. The Pd particle size decreased with a more positive applied electrodeposition potential at carbon Vulcan XC–72R nanoflakes. X-ray photoelectron spectroscopy determined that the applied potential affected, both, the final palladium and carbon oxidation states. Finally, cyclic voltammetry was used to characterize the electrocatalytic activity of each Pd / Vulcan catalyst in 0.1M KOH and for the EOR. It was found that, for Pd electrodeposition using RoDSE, an applied potential of 0.4 V vs. RHE provided considerable harmony between a mass transport and kinetically controlled deposition thereby providing the optimal conditions for a better EOR catalyst.

Figure 1
Intermediate Hopping on Flexible Cascade Surface with Electrostatic Channeling
Authors: Liu Yuanchao , Calabrese Barton Scott
Published: February 2020

Tandem bio-catalysis is able to fully utilize the bond energy stored in complex molecule by using sequential active sites. This results in an enhanced efficiency in electrocatalytic devices, enabling biofuel cells with higher energy density and biosensors with high sensitivity. Mass transport of reaction intermediate molecules is a key factor impacting the overall kinetics, which in nature is facilitated by substrate channeling, where intermediates are directly shuttled to the next active site instead of diffusing into the bulk.1

Electrostatic channeling represents one such mechanism, where charged intermediates are transported along an oppositely charged pathway. Natural electrostatic cascades have been studied for decades, and in 2017 we reported the first cascade with artificially introduced electrostatic channeling.2 This finding highlighted a surface diffusion mechanism on a 1D channeling bridge. However, intermediate transport between the bridge and the downstream enzyme binding site occurs on a flexible 2D surface exhibiting a range of interactions with the intermediate and potentially greater leakage. This process is of great significance to further explore the channeling kinetics and also make optimization for cascade design. Here, we are going to further map the channeling pathway between the bridge and intermediate active site. Enhanced sampling methods is used to elucidate the intermediate’s ergodicity in this process. Finally, kinetic Monte Carlo method is used to quantify the overall kinetics, from which the leaking contribution from each channeling region can be evaluated.

REFERENCE

I. Wheeldon, S. D. Minteer, S. Banta, S. C. Barton, P. Atanassov and M. Sigman, "Substrate channelling as an approach to cascade reactions", Nature Chemistry, 8, 299–309 (2016). doi:10.1038/nchem.2459.

Y. Liu, D. P. Hickey, J.-Y. Guo, E. Earl, S. Abdellaoui, R. D. Milton, M. S. Sigman, S. D. Minteer and S. Calabrese Barton, "Substrate Channeling in an Artificial Metabolon: A Molecular Dynamics Blueprint for an Experimental Peptide Bridge", ACS Catalysis, 7, 2486–2493 (2017). doi:10.1021/acscatal.6b03440.

Figure 1
Microkinetic Rate Theory:Formalization, Current Limitations, Prospects As Basis for Continuum Rate Theory
Authors: Francis Michael F
Published: February 2020

Microkinetic Rate Theory (MRT) has been an important part of chemical kinetics, being taught in undergraduate physics and chemistry courses, and forming the basis of modern descriptor theory used widely in research. In spite of MRT’s ubiquitous importance, it has remain unformalized and ungeneralized. In this talk, MRT is formalized and generalized. MRT is cast as an algebraic expansion and those matrix elements forming the coefficients of the generalization defined in terms of reaction rate constants, which are in turn connect to statistical mechanics. A transport formulation of MRT is given and it shown that Fickian diffusion is a subset of MRT. MRT is shown to deviate from direct kMC simulations in a certain rate regime which is attributed to phenomenologically distinct stochastic and deterministic rate regimes, similar to diffusion and continuum fluid mechanics, but relevant to chemical and complex kinetics.
Nickel Oxide Thin Film Photoelectrodes Prepared By RF Magnetron Sputtering
Authors: Valdemarsson Kim , Wang Kaiying
Published: February 2020

Out of several different promising first-row transition metals (Ni, Co, Mn and Fe) to be used for the Oxygen Evolution Reaction (OER) in a water splitting system, Nickel Oxide (NiO) turns out to be the most promising of them all, with the highest catalytic activity [1-2]. One of the key limitations on water electrolysis is that it is thermodynamically unfavorable due to demanding a significant amount of energy to make the reaction happen at an appreciable rate [2]. This further pushes the need for an efficient catalyst material to be used for anode in a photoelectrochemical (PEC) cell.

In this work, a thin film of nickel oxide (NiO) is deposited with RF magnetron sputtering technique on quartz, glass and indium tin oxide (ITO) substrates in pure argon atmosphere respectively. The thin films are characterized by Ultraviolet-visible spectroscopy (Uv-Vis), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDX), X-Ray Diffraction (XRD) analysis and 4-probe resistivity measurements. Typical UV-Vis and X-ray diffraction patterns (Fig. 1a-b) show that thin film NiO are successfully fabricated on these substrates. It can be seen from Figure 1b that increase in temperature significantly increases the material crystallinity, with some peaks becoming clearly more visible. From Table 1 we can deduct that the increase in power increase oxygen in the compound. The electrical properties are to be measured at probe stations for low temperatures (5K) up to room temperature. In summary, the phase transition of thin film NiO as well as light absorption from 220 to 850 nm have been investigated on these substrates.

References

[1] P. C. K. Vesborg, B. Seger, I. Chorkendorff, Recent development in Hydrogen Evolution Reaction Catalysts and their Practical Implementation, The Journal of Physical Chemistry Letters (2015). DOI: 10.1021/acs.jpclett.5b00306

[2] Y. Cheng, S. P. Jiang, Advances in electrocatalysts for oxygen evolution reaction of water electrolysis-from metal oxides to carbon nanotubes, Progress in Natural Science: Materials International (2015), DOI: 10.1016/j.pnsc.2015.11.008

Figure 1
Kinetic of Metal Extraction at the Water|1,2-Dichoroethane Interface
Authors: Pérez-Zúñiga Jared A , Amador-Hernández Judith , Sánchez-Muñoz Cervando , Colunga Urbina Edith M , de la Garza Rodríguez Iliana M , Velazquez-Manzanares Miguel
Published: February 2020

The electrochemical techniques are useful tools for the extraction of heavy metals from aqueous effluents. Between them, studies at the interface of two immiscible electrolyte solutions (ITIES) allow to understand the fundamentals that regulate the process of ionic metal extraction through hydrophobic barriers, owing to it is possible to control the equilibrium of the metal ion across the interface by applying an electrical potential. In the present work, it was studied the kinetic process of the facilitated ionic metal transfer by dibenzo-18-Crown-6 and diciclohexane-18-Crown-6 at the water/1,2-dioclhoroetane (1,2-DCE) interface

The electrochemical experiments were carried out in a 4-electrode cell (two references and two counterelectrodes) and the interface was polarized by cyclic voltammetry (CV). The rate constant (k) for the facilitated metal transfer at the water/1,2-DCE interface was evaluated from CV data through the procedure proposed by Nicholson. The peak-to-peak separation (DEp) of the transfer from the aqueous to the organic phase and from organic to the aqueous phase wave, as well as the diffusion coefficient, were considered for the calculus of k. The results showed that k is in the range of 10-3 cms-1, which is according to the values previously obtained for ion transfers at the liquid-liquid interface.
(Invited) Metal Production in CaCl2-Based Melts
Authors: Suzuki Ryosuke O. , Noguchi Hiromi , Haraguchi Yasushi , Natsui Shungo , Kikuchi Tatsuya
Published: February 2020

Left-side elements in periodic table are stable in oxide state. In order to produce their metals from the oxides, the molten CaCl2 is useful as the media where CaO is dissolved. By applying 3.0 V above melting temperature of CaCl2 (1045 K), CaO in CaCl2 melt electrochemically decomposes into metallic Ca and oxygen. The deposited Ca at cathode can work as reductant for the stable oxides. Because of strong reducing ability of Ca, Ti can be produced directly from TiO2. This calciothermic reduction forms a lot of CaO at the cathode, but it dissolves in CaCl2 and decomposes again by electrolysis. This OS process could be applied to TiO2 or other oxides. Even if electric insulators such as Al2O3 were used, metallic Al could be obtained. V2O5 and Bi2O3 are molten oxides, but they could be reduced to metallic state. It is noted that Al and Bi are liquid metals at the operating temperature.

The trials to decrease the residual oxygen in Ti are introduced from TiO2 and CaTiO3. By optimizing the cathodic structure, CaO content in the bath, H2O removal and cooling procedures, 1500 mass ppm oxygen could be achieved.

Oxygen anions at carbon anode form CO and CO2 gas bubbles. If gas bubbles do not leave from the anodic surface, CO2 gas forms CO3
2-. Carbonate ions are reduced by Ca to carbon, or electrochemically deposite carbon on cathode. These parasite reactions decrease the current efficiency. Quick removal of CO2 gas bubbles from anode is a key.

By applying TiS2 or V3S4 as the starting materials, good quality of metallic Ti or V, respectively, could be realized because they do not form solid solution with sulfur. The sulfur gas deposited at the cold parts of reaction vessel, and can be used for sulfide formation.
Interaction of Neodymium Containing Chloride Melts with Oxygen Species
Authors: Shchetinskiy Andrey V. , Dedyukhin Alexander S. , Volkovich Vladimir A. , Kaychenkova Regina Yu. , Maltsev Dmitry S. , Polovov Ilya B. , Chukin Andrey V.
Published: February 2020

Alkali chloride based melts can be employed as working media in spent nuclear fuels pyrochemical reprocessing. Oxygen is on of common impurities in technology and oxygen species can seriously influence speciation of metals in molten electrolytes. From the other hand, one of the possible ways of separating uranium from rare earth fission products by selective precipitation of uranium oxide. The present work was aimed at studying reactions taking place in chloride melts containing neodymium (III) and uranium (III and IV) ions upon addition of oxygen species. In particular, reactions with oxygen and oxide ions (introduced in form of lithium oxide) were considered.

Thermodynamic modeling of possible reactions was first performed to estimate the possibility of separating uranium from rare earths. The experiments were then conducted in the melts based on LiCl–KCl eutectic, NaCl–KCl equimolar mixture and individual LiCl at 550 oC (for LiCl–KCl) and 750 oC for all the melts). Reaction of the melts containing NdCl3, UCl3 or UCl4 with Li2O (at various O2– to Nd3+ (U3+, U4+) mole ratios) and with O2 was investigated.

High temperature electronic absorption spectroscopy was employed to determine the kinetics of the reactions taking place. Phase composition of the solid phases was characterized by X-ray powder diffraction analysis. Size of the particles in the precipitates formed at various conditions was also determined to assess the feasibility of subsequent separation of the solids from the technological melts.
Diethylmethylamine-Based Protic Ionic Liquids and Their Binary Mixtures with Water As Fuel Cell Electrolyte
Authors: Miran Muhammed Shah , Saikat Md. Shahriar Hasan
Published: February 2020

Protic ionic liquids (PILs) have attracted much attention as a designer material for manifold applications but most promising used as fuel cell electrolytes due to containing active proton in the cationic structure. However, ultimate product of the fuel cell reaction is water, thus, it is very interesting to investigate the effect of water on the properties of PILs for applying as fuel cell electrolytes. In this study, PILs were synthesized through neutralization of a tertiary amine, diethylmethylamine (dema) with sulphuric acid (H2SO4) and trifluoroacetic acid (CF3COOH). Binary mixtures of these PILs and water were prepared with a wide range of composition. The physicochemical and electrochemical properties of these PILs and their binary mixtures, such as density, viscosity, conductivity, thermal properties, ATR-FTIR, NIR, theoretical calculation and cyclic voltammetry (CV), have been studied in detail. The excess molar volume and excess viscosities were derived from density and viscosity and fitted to Redlich-Kister polynomial equation to confirm the presence and nature of interactions between PILs and water binary system. Analysis of FTIR-ATR and NIR spectra for the binary mixtures of [dema]CF3COO and water also indicated that there is a strong interaction between ionic species and water. From quantum chemical calculations using density functional theory (DFT), the electron density distribution around the ion pair of [dema]CF3COO is made and confirmed that there is a strong interaction between cation and anion not only due to strong hydrogen bond but also coulombic interaction. Conductivity of pure [dema]HSO4 was lower than [dema]CF3COO, however, conductivity of [dema]HSO4 and water binary mixtures was higher than the binary mixtures of [dema]CF3COO at room temperature when mole fraction of water was 0.90. From Walden plot (log Λ vs logη-1), it was revealed that [dema]HSO4 and its binary mixtures resemble good PILs, on the other hand, [dema]CF3COO and its binary mixtures are poor PILs, presumably due to high ΔpK
a of [dema]HSO4. Finally, electrochemical properties of PILs and their binary mixtures have been analyzed by CV measurements. It is found that there is a strong effect of water on the OCP of PILs. However, these PILs and binary mixtures could be useful as fuel cell electrolytes.
The Effects of Excess Protic Species on Oxygen Reduction in Protic Ionic Liquids and Implications for the Use of Ionic-Liquid Electrolytes in Fuel Cells
Authors: Walsh Darren Anthony , Goodwin Sean , Smith Daniel
Published: February 2020

The conventional polymer-electrolyte membranes used in low-temperature fuel cells are limited to operating temperatures below about 120 ºC, as they must be fully hydrated to facilitate proton transport. Protic ionic liquids (PILs) are ionic liquids formed by transferring protons from Brønsted acids to Brønsted bases, and it has recently been shown that some ammonium-based PILs inherently exhibit high proton conductivities. Consequently, PILs have been proposed for use as electrolytes in non-humidified fuel cells that can operate above 120 ºC (at intermediate temperatures). However, while they nominally consist entirely of ions, PILs can often contain a significant quantity of neutral species (either molecules or ion clusters) that can affect the physicochemical properties of the liquids.

In this contribution, we first describe an electroanalytical method for detecting and quantifying residual Brønsted acids in a series of ammonium-based PILs. Ultramicroelectrode voltammetry reveals that some of the accepted methods for synthesizing PILs can readily result in the formation of nonstoichiometric PILs containing up to 230 mmol dm−3 residual acid. We will then show that residual acid in PILs can have a drastic effect on the electrocatalytic oxygen reduction reaction (ORR; O2 + 4e−+ 4H+→ 2H2O) in the PILs. For example, the potential at which the ORR occurs at Pt in the PIL diethylmethylammonium trifluoromethanesulfonate, [dema][TfO], decreases linearly as the strength of the proton donor in the liquid decreases. In “pure” [dema][TfO], in which the proton donors during the ORR are the [dema]+ cations of the PIL (pK
a = 10), the onset potential of the ORR is the same as that of the hydrogen oxidation reaction (HOR) in the PIL. These observations have significant implications for the use of PILs as electrolytes in fuel cells and indicate that the best PILs are highly "acidic" liquids that can support oxygen reduction at high potentials.
Enhanced Performance and Durability of Polymer Electrolyte Membrane Fuel Cell By Infiltration of Cerium Oxide
Authors: Lee Jae Hyeok , Koo Junmo , Kim Jun Woo , Choi Hyung Jong , Shim Joon Hyung
Published: February 2020

Polymer Electrolyte Membrane Fuel Cells (PEMFCs) has been drown much attentions due to its high energy density, pollution-free electricity generation. Because of its versatile advantages, PEMFCs are considered as next-generation transportation system, which is used for power system of fuel cell electronic vehicle (FCEV). However, the usage of Pt catalyst hinders the widespread application of PEMFC because of high price of Pt. In order to utilize Pt in cost-effective way, various researches have been conducted to maximize the performance and long-term stability of Pt catalyst. Recently, many researches of Pt-metal oxide/C catalyst in PEMFCs have been investigated due to improvement of adsorption characteristics for oxygen at the surface of Pt by adding metal oxide. Especially, Cerium oxide has superior oxygen storage capability originated from easy redox between Ce3+ and Ce4+. Also, Pt-CeOx interact regions increase active sites where oxygen and Pt catalyst could meet together. In this study, we treated PEMFC cathode by cerium oxide with infiltration process, which enables uniform distribution of added materials with cost-effective way. We investigated the performance of PEMFC membrane-electrode assembly (MEA) with cerium oxide treated cathode. PEMFC performance was evaluated by current-voltage measurement and cyclic voltammetry. Also, the long term stability of cerium oxide treated PEMFC MEA has been analyzed with electrocatalyst accelerated degradation protocol proposed by Department of Energy (DOE). In brief, performance and long term stability enhancement of PEMFC MEA has been observed in cerium oxide treated samples. In our presentation, detail process of experiment and PEMFC performance analysis will be introduced.
Picomolar Detection of Epinephrine Using Aptamer Based Organic Electrochemical Transistor
Authors: Saraf Nileshi , Woods Eric R. , Peppler Madison , Seal Sudipta
Published: February 2020

Determination and quantification of small biomolecules is of immense importance in the world of biodiagnostic and health care industry. Among the different sensor technologies, organic electrochemical transistor (OECT) has shown tremendous potential owing to their low operating voltages and signal amplification. They have significant advantages such as miniaturization, feasibility, high throughput sensing and portability which given them an edge over other techniques. In the present study, an aptamer based OECT device has been developed to detect the presence of epinephrine. Epinephrine is a catecholamine which is responsible for flight or fight response of the body. The abnormalities in the level of Epinephrine is a direct indication of some disease such as pulmonary edema, Takotsubo cardiomyopathy, myocardial infarction and arrhythmias. The detection of epinephrine has been done using various techniques such as liquid chromatography, spectrophotometry, flow injection analysis, electrophoresis etc. All these methods are time consuming and require skilled labor and high-end instruments. As an alternative, aptamer based OECT device not only provides simple and compact approach but also provides a means for on-site testing in a timely and efficient manner. Upon addition of epinephrine in the OECT, the device showed a constant decrease in current which is observed in both transfer as well as current-time curve. The decrease was due to the oxidation of epinephrine in the vicinity of gate electrode which decreases the gate potential. A range of interfering species such as dopamine, ascorbic acid, DOPAC etc were also tested and no response was seen, which indicates high specificity of the approach. The present approach exhibited a detection limit of 90 pM with a response time in seconds which is by far the lowest detection limit achieved by any technique. The optimized aptamer based OECT sensor can be used to detect other biomolecules such as viral proteins, nucleotides, bacteria etc by designing the aptamer for the specific entity.
Beta-Cyclodextrin Mediated Synthesis of Graphene Supported Gold Nanoparticles for Application in a Hydrogen Generation Reaction
Authors: Abdel-Fattah Tarek M , Long Julia Madeline , Beveridge Connor , Price Brain , Osborne Justin
Published: February 2020

The fast-paced economic climate of the world today has prompted a more thorough investigation into the field of alternative fuels. Increasing energy demands coupled with the crippling environmental and economic costs of carbon-based fuels, has aided in bringing this issue to a global level.1 Hydrogen gas is among the most favorable of candidates being pursued in the search for a viable alternative to gasoline. Hydrogen is renewable in nature and produces no harmful emissions.2 Current methods of hydrogen generation are limited in their efficiency due to the difficulties of harnessing and storing pressurized gas. Solid chemical storage in the form of metal hydrides, known for their hydrogen releasing capabilities, have been proposed as an alternative to these methods.3 Sodium borohydride (NaBH4) is among the most favorable of metal hydrides for its high hydrogen content (10.8% wt) and superior energy density.1-4 When coupled with water, sodium borohydride can generate up to 4 moles of dihydrogen gas per mole of NaBH4 via a hydrolysis reaction. However, the oxidation of aqueous sodium borohydride is a slow process and the use of a catalyst is necessary for the reaction to procced at an appreciable rate. Transition metal catalysts, in particular Au, have been implemented in this reaction however, many suffer from oxidation degradation, therefore, the use of a support system is necessary.5 For this experiment, gold nanoparticles coupled with graphene and graphene oxide supports were used as the catalytic material for hydrogen evolution reactions. Overall, gold nanoparticles showed the highest reaction rate of 0.0018 mol-1 sec-1 at a standard concentration of NaBH4, standard pH 7 and an increased temperature at 30°C.

References

Dunn, S. Hydrogen futures: toward a sustainable energy system. International Journal of Hydrogen Energy 2002, 27, 235–264.

Haryanto, A.; Fernando, S.; Murali, N.; Adhikari, S. Current Status of Hydrogen Production Techniques by Steam Reforming of Ethanol: A Review. Energy Fuels 2005, 19, 2098–2106.

Dicks, A.L. Hydrogen generation from natural gas for the fuel cell systems of tomorrow. J. Power Sources 1996, 61, 113-124.

Huff, C.; Dushatinski, T.; Barzanjii, A.; Abdel-Fattah, N.; Barzanjii, K.; Abdel-Fattah, T.M. Pretreatment of gold nanoparticle multi-walled carbon nanotube composites for catalytic activity toward hydrogen generation reaction. ECS J Solid State Sci Technol 2017, 6, M69-M71.

Kochkar, H., Aouine, Ghorbel, A.,Berhault, G. Shape-Controlled Synthesis of Silver and Palladium Nanoparticles Using β-Cyclodextrin. Journal of Physical Chemistry 2011, 115, 11364-11373.