bluuebunny/crossref_metadata_2025_split huggingface dataset:
Understanding the Electrochemical Induction of Urea to Ammonia on Nickel Based Catalyst in Alkaline Medium
Authors: Lu Fei , Botte Gerardine G 
Published: February 2020

Background

Ammonia is an important chemical used in many fields such as the fertilizer industry and food industry. One popular application of ammonia is to control nitrogen oxide (NOx) emissions and ammonia has been proved to be an effective reductant to remove NOx, this technology is known as selective catalytic reduction (SCR) and is commercially available. Conventionally, urea can be thermally hydrolyzed or converted into to ammonia on demand as shown in eqn. (1).
The electrochemical dissociation of urea has been investigated at the Center for Electrochemical Engineering Research (CEER) for the purpose of producing hydrogen using Ni catalyst, two parallel reactions are found as shown in eqn. (2) and (3).It is proposed that urea to ammonia conversion will be induced with the electrochemically generated NiOOH in alkaline medium. Therefore higher yield of ammonia in eU2A is expected comparing to thermal hydrolysis or urea (THU) under the same conditions. This work will demonstrate that eU2A enables higher reaction rate of ammonia production and experiments will be conducted to understand how the urea to ammonia reaction could be induced through an electrochemical approach.

Methodology

An electrochemical induced urea to ammonia (eU2A) reactor was developed at CEER for the production of ammonia from urea. In the reactor, both the cathode and anode are Ni-based materials and during the experiment, different voltages will be applied to the electrodes at various temperatures. If no potential is applied to these electrodes, the reactor will work at thermal hydrolysis of urea (THU) mode. The alkaline supporting medium used in this investigation is hydroxide (KOH). The produced ammonia in the experiments will be determined using an ion selective electrode (ISE) and the residual urea concentration in the reactors will be monitored by spectrophotometric methods such as UV-vis spectroscopy [6]. Preliminary data has already shown that eU2A mode enables higher generation rate of ammonia compare to THU mode at 70 °C with the feed of diesel exhaust fluid (DEF) in the presence of 7 M KOH. Raman Spectroscopy will be used to monitor the surface change of Ni electrodes and how urea to ammonia reaction occurs heterogeneously. In addition, liquid FTIR will be utilized to identify and quantify the intermediates and products to further understand eU2A process in the reactor.

Figure 1
Agarose Based Biopolymer Gel Electrolyte for Electrochemical Applications
Authors: Singh Rahul 
Published: February 2020

A novel electrochemically stable biopolymer gel electrolyte has been reported. To develop biopolymer electrolyte, the solution is comprised of potassium iodide and ionic liquid 1-ethyl-3-methylimidazolium dicyanamide with varying solvents such as distilled water (H2O), Dimethyl sulfoxide (DMSO), Dimethylformamide (DMF) have been added to the Agarose matrix at room temperature and further used in the application of dye sensitized solar cell (DSSC), extra iodine was added in the matrix. Details of the fabrication, characterization and application of the biopolymer gel electrolyte films based on Agarose is given in the paper. Structural, electrical and electrochemical studies have been done on samples which demonstrate promising characteristics of the biopolymer gel electrolyte. The possible conformational/structural changes in the biopolymer due to the formation of a complex nature, entrapment of iodine solution, crystallinity and amorphous nature have been investigated by Fourier transform infrared (FTIR), Polarized optical microscopy (POM) and X-ray diffraction (XRD). Complex impedance spectroscopy showed the manifold enhancement in ionic conductivity by salt doping. The conductivity maxima were obtained near 60:40 compositions at room temperature. The temperature dependence of electrical conductivity of biopolymer–ionic liquid blends and gel polymer electrolyte follows the Arrhenius behavior. The dielectric studies and ion transport number measurement confirms the ionic conduction in the gel polymer electrolyte. DSSC was fabricated using maximum conductivity and comparative measured values of the FF, Voc, Jsc and efficiency at 100mW/cm were tabulated.

Figure 1
Fabrication of Copper / Single-Walled Carbon Nanotube Composite Plating Films By Electrodeposition
Authors: Kirihata Kyohei , Arai Susumu , Uejima Mitsugu , Hirota Mitsuhito 
Published: February 2020

Introduction

Copper has many excellent properties such as high electrical conductivity and good thermal conductivity and ductility, resulting in the wide use of copper plating in the electronics industry. Single-walled carbon nanotubes (SWCNTs) also exhibit attractive characteristics such as stable electrical resistance in the presence of high currents and good thermal conductivity and field emission properties, resulting in their application in a wide range of fields. Cu/SWCNT composites would therefore be expected to have excellent electrical and thermal conductivity properties.Our laboratory previously reported the fabrication of electroless Cu/SWCNT composite plating films, 1)but the fabrication of Cu/SWCNT composite plating films by electrodeposition has not been reported.Here we describe an attempt to fabricate Cu/SWCNT composite plating films with homogeneously distributed SWCNTs using electrodeposition.

Experimental

The Cu/SWCNT composite plating bath comprised 0.1 M CuSO4･5H2O, 0.2 M EDTA･2Na, SWCNTs (Super-growth SWCNTs, Zeon Co.) and dispersants. EDTA･Na was used as a copper chelating agent. A magnetic stirrer, an ultrasonic homogenizer and a mechanical atomizer (Star Burst Labo, SUGINO MACHINE Co.) were used to fragment the SWCNT bundles. The dispersibility of the SWCNTs was evaluated using a particle size distribution analyzer. Electrodeposition was conducted under galvanostatic conditions. A pure copper plate and a phosphorus-containing copper plate were used as cathode and anode, respectively. The morphologies of the composite films were observed by field emission scanning electron microscopy (FE-SEM) and the phase structures of the films were analyzed by X-ray diffraction. The thermal and electrical conductivities of the composite films were also evaluated. In addition, the SWCNTs were quantitatively analyzed.

Results and Discussion

The results demonstrated that fragmentation of the SWCNTs was improved significantly by using a mechanical atomizer. The content of SWCNTs in the films increased with increasing SWCNT concentration in the plating bath. Fig. 1 shows a surface SEM image of a prepared Cu/SWCNT composite plating film and indicates that the SWCNTs are incorporated relatively uniformly into the Cu film. The diameter of the SWCNTs is ca. 15 nm or less, indicating that the bundles of SWCNTs are highly fragmented.

References

1) T. Osaki, S. Arai, Abstract of ADMETAPlus 2013 Asian Session (2013) 86

Figure 1
The Effect of the Angle of Incident of the Light upon the Optical Reflactance on Silicon Nanowires Grown By Electroless Etching
Authors: Velez Victor H. , Mertens Robert George , Sundaram Kalpathy B 
Published: February 2020

Silicon nanowires (SiNW’s) arrays prepared by electroless etching method can significantly suppress light reflection across the visible spectrum [1]. The decrease in reflectivity is evidently due to optical absorption in the silicon. The nanowires scatter the incident light by reflection, refraction, and diffraction processes, and the light will interact with several nanowires until it is either absorbed by a nanowire or the substrate, or is reflected by the sample [2]. However, the Fresnel reflection predicts a large reflectance at a large angle of incidence (AOI) [3]. For effects of comparison, the reflectance versus wavelength data using visible light on SiNW’s grown by eletroless etching in three different concentrations of Hydrofluoric Acid (HF) and Silver nitrate (AgNO3) for different etching times at room temperature have been provided at different AOI values. In general, SiNW’s exhibit low reflectance over a wide range of AOI. SiNW’s etched with high concentration of AgNO3 produce low reflectance. These results are beneficial to the design and fabrication of nanowire-based optoelectronic devices.
In this experiment a Cary 100 UV-Visible Spectrometer was used for reflectance analysis and silicon (Si) wafers were dipped for 15, 30, 45 and 60 minutes at room in an electroless solution prepared in a petri dish containing silver nitrate (AgNO3) and hydrofluoric acid (HF) [4].
Analytical Study of the Band GAP and Optical Characteristics of Copper Sulphide Thin Film: Experiment and Computation
Authors: Ugwu Emmanuel Ifeanyi , Okwo John , Onah Daniel Ugadu , Ekpe John Elom 
Published: February 2020

In this work, the analytical study of optical properties and band gap of copper sulphide thin film were carried out comparatively using two different but related depositional techniques done at room temperature. The techniques were (a) successive ionic layer adsorption and reaction and (b) chemical bath deposition. The film was characterized with emphasis on the optical properties within the spectral range of ultraviolet -infrared region of electromagnetic spectrum, Absorption coefficient depicts a maximal value of the band gap ranging from 1.45eV to 3.33 eV. Theoretically, scalar wave equation was used to analyze the behavior of wave propagated through the copper sulphide thin film for which computation of the optical properties such spectral transmittance, reflectance were computed. The band gap of the thin film was also computed for which all the computation was carried out within the same spectral range. In the analysis, it was observed that there was no significant deviation between the band gap obtained from the two different depositional techniques and the computed band gap
Keywords;Analytical study, copper Sulphide, optical properties, band gap, Scalar wave, deposition, computation, wave propagation.
Fabrication of Large Scale Silver Nanowire Network By Ion Beam Irradiation
Authors: Honey Shehla , Thema F.T. , Ahmad Ishaq , Naseem Shahzad , Malik Maaza 
Published: February 2020

A random two-dimensional nano-network of silver nanowires (Ag-NWs) was fabricated by MeV Hydrogen (H+) ion beam irradiation. Ag-NWs were irradiated under H+ ion beam at different fluences at room temperature. Ag-NWs network was fabricated by H+ ion beam induced coalescence of Ag-NWs at the crossing and the parallel positions. H+ ion beam induced coalescence was confirmed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Moreover, structure of Ag NWs remains stable under H+ ion beam. Threshold dose for the stability of Ag NWs structure under H+ ion beam irradiation was 5x1015 protons/cm2 at room temperature, confirmed by TEM, and XRD. Morphology also remains stable under H+ ion beam irradiation. No slicing, cutting of Ag-NWs were observed under MeV H+ ion beam irradiation. This observation is useful for using Ag-NWs based devices in upper space where protons are abandon in MeV to GeV energy ranges. The results exhibit that the formation of Ag-NWs network proceeds through three steps: ion beam induced local heating, formation of simple junctions, and the formation of large scale network. This high quality network will also be useful as a transparent electrode for optoelectronics devices.
High Resolution 3-Dimensional Chemical and Morphological Imaging of Single Li
x
FePO4 Particles
Authors: Yu Young-Sang , Shapiro David , Farmand Maryam , Kim Chunjoong , Liu Yijin , Cabana Jordi 
Published: February 2020

Understanding chemical and morphological transitions within single nanoparticles of electrochemically active materials is crucial to overcome the performance limitations and degradation of batteries. Techniques that afford high chemical resolution at the nanoscale are ideally suited for this goal. Soft X-ray ptychographic microscopy combined with X-ray absorption spectroscopy (XAS) is a powerful suite which affords chemical and structural information on large volumes of material at spatial resolutions better than 5 nm.1 However, to date, this technique has been intrinsically limited to 2 dimensional observations in transmission mode, which causes complications during interpretation, especially in the case of overlapped particles, because the projection images represent an average over the X-ray penetration path within the crystals.
In this study, soft X-ray tomography combined with ptychography, developed at beamline 5.3.2.1 at the Advanced Light Source (Berkeley, CA) is applied to assess the chemical and morphological consequences of electrochemical delithiation of aggregated nano-sized lithium iron phosphate (LiFePO4) plates (Figure 1). Our work provides quantitative analysis of oxidation states in 3 dimensions at the 10 nm scale. After segmentation, statistical analysis of the chemical phase for any given individual particle was achieved, and information was extracted of the particle interior. The ability to visualize the nanoscale chemical state distribution over functional volumes will revolutionize the study of energy storage materials and enable the design of optimized morphologies for the next generation of devices.

Figure 1. 3 dimensional chemical volume rendering of Li
x
FePO4 crystals. Chemical phase information were extracted from 3 dimensional volumes collected at 708.25 eV and 710.25 eV. The red and blue areas indicate the highest content of LiFePO4 and FePO4, respectively.
1. D. A. Shapiro, Y.-S. Yu, T. Tyliszczak, J. Cabana, R. Celestre, W. Chao, K. Kaznatcheev, A. L. D. Kilcoyne, F. Maia, S. Marchesini, Y. S. Meng, T. Warwick, L. L. Yang, H. A. Padmore, Nat Photon
8, 765 (2014).

Figure 1
Development of Equivalent Circuits for Litihum-Air Battery Impedance Using Mixed and Isolated Diffusion Models
Authors: Nelson Ruben , Weatherspoon Mark H 
Published: February 2020

Typically, equivalent circuit models of electrochemical impedance spectroscopy (EIS) measurements include components that describe kinetic and diffusion behavior. Often, they may be depicted as a series combination of a charge-transfer resistance and a diffusion impedance element to represent a mixed diffusion process. Alternatively, diffusion-independent schematics also model impedance of electrochemical systems. Because equivalent circuit modeling is an inexact description of the electrochemical impedance, either schematic may or may not indicate a good fit of the measured spectra, depending on the parameters of the circuit components. The figure below shows the significance of a mixed diffusion circuit model versus a diffusion-independent circuit model fitting the impedance of a twice cycled lithium-air battery. An appropriate circuit model must not only fit the EIS measurement, but also consider the design of the physical system to account for possible side reactions that introduce ambiguity to the model. To overcome the impact of model uncertainty, however, alternative analysis techniques can help to verify the model of choice, such as the graphical analysis [1].
A graphical analysis of the complex impedance add additional support for a proposed physical model and its circuit parameters. With this method, the imaginary part of the impedance versus frequency, on the logarithmic scale, are plotted to determine the frequency ranges where the impedance is linear. The linear portions of these plots indicate separate electrochemical processes and distributed time constants, or constant phase element (CPE) behavior, with the slope of the line being the value of the CPE coefficient, α. This is helpful in determining the most accurate fit model with reasonable results. Since the focus is on the placement of the diffusion component in the circuit model, more emphasis will be on the low frequency range, where the diffusion impedance dominates.
In this study, the impedance of a lithium-air battery is measured after various cycles, and Nyquist plot and the impedance versus frequency plot are presented. Fitted equivalent circuit models of mixed diffusion and isolated diffusion are fitted to the Nyquist plots and are compared to the results of the graphical analysis technique.
Acknowledgment
This work was supported by the FREEDM ERC program of the National Science Foundation under award number EEC-08212121.
Reference
[1] M. E. Orazem, N. Pebere, B. Tribollet, J. Electrochem. Soc., 153, B129 (2006).

Figure 1
Interpretation of Complex Capacitance Using Equivalent Circuit Involving Constant Phase Element
Authors: Hoshi Yoshinao , Tabei Kozue , Shitanda Isao , Itagaki Masayuki 
Published: February 2020

An electrochemical impedance spectroscopy (EIS) is powerful tool to evaluate the electrochemical parameters of inside the energy conversion devices. The electric-double layer capacitance C
dl can be estimated by the curve fitting of the impedance spectrum generally. It is important to obtain the C
dl of the electrode because it is related to the surface area and structure of electrode/electrolyte interface. The performance of energy conversion devices can be investigated by the capacitance plots calculated from the impedance.
(1-5) Our group
(6) previously reported the calculations of the electrochemical impedance and complex capacitance corresponding to typical equivalent circuits involving a transmission line model (TLM) in order to determine the precise value of the C
dl of electrochemical capacitor. In the present work, theory of complex capacitance were summarized by calculations using equivalent circuits. The complex capacitance calculated by equivalent circuit involving the constant phase element (CPE) was also discussed theoretically.
References:
1. P. L. Taberna, P. Simon and J. F. Fauvarque, J. Electrochem. Soc., 150, A292 (2003).
2. J. H. Jang and S. M. Oh, J. Electrochem. Soc., 151, A571 (2004).
3. J. H. Jang, S. Yoon, B. H. Ka, Y. H. Jung and S. M. Oh, J. Electrochem. Soc., 152, A1418 (2005).
4. S. Yoon, J. H. Jang, B. H. Ka and S. M. Oh, Electrochim. Acta, 50, 2255 (2005).
5. C. Portet, P. L. Taberna, P. Simon and E. Flahaut, J. Electrochem. Soc., 153, A649 (2006).
6. M. Itagaki, S. Suzuki, I. Shitanda and K. Watanabe, Electrochemistry, 75, 649 (2007).
Electrochemical Charge Transfer Reaction Kinetics at Silicon Electrode Surfaces
Authors: Swamy Tushar , Chiang Yet-Ming 
Published: February 2020

The volumetric lithiation capacity of silicon as an anode material is roughly ten times that of conventional graphite, while their densities are comparable. As a consequence, for a given particle size and C-rate, the current density required to cycle a silicon electrode at a given C-rate is about ten times greater than that of graphite. Such high current densities may cause the charge transfer kinetics at the silicon electrode surface to become rate limiting during use, depending on the magnitude of the corresponding Butler-Volmer exchange current density.
Further motivated by the lack of consensus in the literature [1-4], we developed a novel approach to measure the exchange current density, using single crystal electronically conductive silicon wafers with well-defined crystallographic (100) orientation and active areas, and a cycling scheme to avoid stress-induced surface cracking and fragmentation upon lithiation. Electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy were used as characterization tools. It was demonstrated that the silicon electrode surface remains crack free during the first lithiation half cycle, with fracture being induced only during the following delithiation half cycle, which is in agreement with the observations made by Chon et al. [5]. Consequently, it was possible to grow the solid electrolyte interface (SEI) layer as is characteristic of silicon powder electrodes, while still using the geometric area as the electrochemically active surface area to evaluate the surface kinetic parameters from EIS experiments.
The exchange current density at the silicon electrode surface was found to be 0.1 ± 0.01 mA/cm2 for electrolyte consisting of 1 M LiPF6 in EC/DMC (1/1)w + FEC (10%)w + VC (2%)w. Figure 1 shows the corresponding kinetic overpotential as a function of particle diameter and C-rate for silicon and graphite. Clearly, the overpotential is much greater in the silicon case. The impact of these results on cell performance is discussed. The measured exchange current density values may be used as input for porous electrode models, and to devise electrode microstructures and cycling regimes for improved fracture tolerance and overall performance.

Acknowledgments

This work was supported as part of the NorthEast Center for Chemical Energy Storage (NECCES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-SC0012583.

References

[1] L. Baggetto et al., J. Power Sources, 189, 402–410 (2009)
[2] L. Baggetto, R. A. H. Niessen, and P. H. L. Notten, Electrochim. Acta, 54, 5937–5941 (2009)
[3] V. A. Sethuraman, V. Srinivasan, and J. Newman, J. Electrochem. Soc., 160, A394–A403 (2013)
[4] R. Chandrasekaran, A. Magasinski, G. Yushin, and T. F. Fuller, J. Electrochem. Soc., 157, A1139 (2010)
[5] M. J. Chon, V. A. Sethuraman, a. McCormick, V. Srinivasan, and P. R. Guduru, Phys. Rev. Lett., 107, 045503 (2011)

Figure 1
(Invited) Insight into Bulk and Interfacial Structure of Electrolytes and SEI Components from Molecular Modeling
Authors: Borodin Oleg , Olguin Marco , Henderson Wesley A 
Published: February 2020

Obtaining fundamental understanding and ultimately controlling bulk and interfacial properties of battery electrolytes is important for increasing battery power and energy density. Molecular dynamics simulations using many-body polarizable APPLE&P force field and ab initio Born Oppenheimer Molecular Dynamics (BOMD) simulations were used to examine the relationship between the structure of lithium solvates and ion transport in a wide range of electrolytes with potential applications in lithium battery. The solvate structures are systematically examined for electrolytes doped with LiFSI, LiTFSI, LiTriflate, LiPF6 and other salts in multiple solvents. Structural properties of SEI compounds will be also discussed. Previously reported1 interfacial properties for the dilithium ethylene dicarbonate (Li2EDC) – electrolyte interface will be contrasted with the interfacial properties for the Li2EDC – LiF interface. Transport mechanism including grain-boudary diffusion in the Li2EDC – LiF composite will be discussed.
References
1. O. Borodin, in Electrolytes for Lithium and Lithium-Ion Batteries, T. R. Jow, K. Xu, O. Borodin and M. Ue Editors, p. 371, Springer New York (2014).