bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanistic Insight into the Relationship between Electrolyte Additives, Solid Electrolyte Interphase Formation, and Lithium Morphology in Lithium Metal Batteries
Authors: Kasse Robert , Geise Natalie R , Ko Jesse S. , Weker Johanna Nelson , Steinrück Hans-Georg , Toney Michael F
Published: December 2020

Directing the morphology of lithium metal deposits during electrodeposition is crucial to the development of safe, high energy density batteries with robust cycle life. Towards this end, mechanistic insight is imperative to understand the relationship between electrolytes, additives, cycling conditions, and the resulting lithium morphologies. In this work we used a standard carbonate-based electrolyte while systematically adding water (0-250 ppm, corresponding to ~0-500 ppm HF) in Li||Cu cells to study the links between electrolyte composition, initial solid electrolyte interphase (SEI) formation, and morphology of electroplated lithium metal. Under conditions in which the electrolyte contains several hundred ppm added HF and applied constant currents on the order of 0.5 mA/cm2, this system yields electrodeposited lithium metal with a highly monodispersed columnar morphology, whereas HF-free electrolytes result in lithium metal with a mossy morphology. We used electrochemical characterization to investigate the HF reduction process, X-ray photoelectron spectroscopy to characterize SEI chemistry, wide angle X-ray scattering to probe the nanostructure of the initial SEI and crystallographic texture of electrodeposited lithium metal, scanning electron microscopy to observe the resulting lithium metal morphology, and operando small angle X-ray scattering to understand cyclability of columnar lithium. Our systematic experimental approach enables insights to be drawn concerning the underlying mechanisms of columnar lithium formation. This morphology arises from an SEI layer comprising crystalline LiF deposits, formed through selective reduction of HF, embedded in an amorphous matrix of solvent reduction products. This interphase structure contains fast lithium ion diffusion pathways which lead to a high nucleation density and uniform growth of lithium metal deposits. The mechanism proposed herein will help to inform future electrolyte additive design and rational cycling protocols for lithium metal batteries.

Figure 1
Hierarchical Porous Structure of Niobium Prepared By an Electrochemical Method
Authors: Joe Gi hwan , Shin Heon-Cheol
Published: December 2020

Fabrication of meso-/macro-porous electrode materials is known to be one of the effective ways to improve the performance of functional electrochemical devices since the porous structure would provide large surface area and allow rapid transport of atoms and ions. Recently, niobium (Nb) or Nb-based porous material has drawn much attention because of its highly versatile chemical and physical properties. There are various ways to form the porous Nb structure, such as hydrothermal, sol-gel, anodic oxidation and electrochemical etching methods. Among them, an electrochemical etching method is noteworthy because it is cost-effective, and the porous structure of the surface is easily tunable by adjusting etching conditions. Nevertheless, the general use of a noxious chemical (e.g. HF) for Nb porous structure formation needs to be avoided and then the creation of highly-porous Nb structure using F--free, more environmentally-benign chemical is still a challenge.

In this work, the novel hierarchical Nb porous structure is created by an electrochemical method by using F--free etching solution. In particular, it is confirmed that the pulse etching is far more effective to form a hierarchical or self-similar fractal porous structure of Nb than conventional continuous etching, most likely due to the repetitive and incessant supply of aggressive anion. It is further proved experimentally that the initial concentration of aggressive anion is one of the essential factors in forming well-defined, high-order hierarchical Nb porous structure. Under the optimal etching condition, the porous Nb structure with more than 3 hierarchical order can be successfully created by single etching process.

On the basis of the experimental observation of pore shape, the formula for the surface area of porous Nb is derived as a function of the hierarchical order of pore. From the comparison of the theoretically calculated surface area with the experimentally estimated one, the actual pore shape along with the hierarchical order of pores can be reasonably analyzed. In this presentation, the governing factors to construct a hierarchical Nb porous structure are suggested. Moreover, the utility of the formula between surface area and hierarchical pore order is discussed in terms of the non-uniformity of porous structure and hypotheses used to derive it.
Welcome Remarks - A04: Electrolytes, Interfaces, and Interphases
Authors: Xu Kang
Published: December 2020

Welcome to A04: Electrolytes, Interfaces, and Interphases! Take a moment to listen to welcome remarks from the lead organizer, Kang Xu.
Ionic Percolation Networks in Composite Electrodes for All-Solid-State Batteries
Authors: Abraham Corey , Leong Victor Gin He , Bach Tran , Barati Yousef , Lee Sang-joon John , Oh Dahyun
Published: December 2020

Solid-state composite electrolytes made of polymers and ceramics can balance the need for high ionic-conductivity and mechanical flexibility in constructing all-solid-state lithium batteries. Although the interface of solid composite electrolytes and Li-metal anodes have been well studied, the ionic conduction through the interface with porous electrodes has not received the same level of attention. In this study, we fabricated ion-conductors used as both flowable gel-like ionic fillers and stiff ion-conducting separators to address interfacial ionic conduction challenges with porous electrodes. A composite electrolyte made of Li6.4La3Zr1.4Ta0.6O12 (LLZTO) and a poly(ethylene oxide) (PEO)-lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) matrix was chosen as a model system to study interfacial ionic conduction properties. This solid composite electrolyte exhibits a room temperature ionic conductivity of 1.2×10-4 S cm-1. The bulk moduli of these ionic conductors were adjusted by varying polymer molecular weight, filler content, and salt concentration. In order to minimize the impact of porosity induced interfacial impedance on the overall cell performance, an ionic percolation network within the electrode pores was created using flowable ionic filler. We built symmetric cells that are made of cathodes or ionically percolated cathodes to determine the impact of having ionic fillers on the interfacial impedance of porous electrodes. In conclusion, ionic conductors filled solid-state battery cells with zero porosity promise a reduction in the interfacial impedance of the composite electrode.
(Invited) Recent Progress on Solid State Batteries - Challenges and Opportunities
Authors: Meng Shirley Shirley
Published: December 2020

All-solid-state batteries (ASSBs) have attracted enormous attention over recent years because they have many advantages over their liquid counterparts such as the enhanced safety and improved energy density by enabling the use of metallic anodes. However, the performance of ASSBs is still yet to meet the requirements for commercialization. Many challenges have remained in order to improve the interfacial properties, increase the cycling life and energy density. Herein, we demonstrate the progression to build practical ASSBs by using sulfide-based superionic conductors as electrolytes since they have high ionic conductivities, facile synthesis procedures, and favorable mechanical properties that allow intimate contact with cathode and anode materials. We show that each step is critical to achieving high-performance ASSBs, from synthesis optimization, interfacial engineering to scalable fabrication. We will also demonstrate the similar success in room temperature sodium solid state batteries and showcase their promising future for grid-scale energy storage.
Enhancement of Electrochemical Performance of All-Solid-State Lithium‐Ion Thin-Film Batteries By Interface Modification with Al2O3 Interlayer
Authors: Kim Jong Heon , Xiao Cheng-Fan , Kim Hyun-Suk
Published: December 2020

Introduction

All-solid-state lithium-ion thin-film battery is one of the promising candidates for next-generation battery systems. However, the low Li-ion conductivity of solid electrolytes and the considerable electrolyte/electrode interface resistance greatly hamper the commercialization of all-solid-state thin-film Li-ion batteries. In this study, we fabricate the all-solid-state lithium-ion thin-film battery using V2O5 electrode and LiPON solid electrolyte. And we introduce Al2O3 interlayer between the Li metal and LiPON solid electrolyte to decrease the interfacial resistance.

Experimental

The Cathode (V2O5), the solid electrolyte (LiPON) and the interlayer (Al2O3) were prepared on Ti/Pt-coated Si substrates by RF sputtering system. In addition, The Li anode and the Cu current collector were deposited by thermal evaporation. The thicknesses of the V2O5 and LiPON thin films were approximately 100 and 500 nm, respectively. To evaluate the electrochemical properties, 2032-type coin cells were assembled in an argon-filled glove box. Charge/Discharge tests were carried out at various C rates from 0.5 to 100 C with cutoff voltages of 2 and 4 V. Electrochemical impedance spectroscopy was conducted in the frequency range of 100 KHz – 1 Hz with a sinus amplitude voltage of 10 mV.

Results and Discussion

The XRD results of the V2O5 and LiPON thin film shows the amorphous structure. The Charge/Discharge profiles shows typical curves of amorphous V2O5 electrode. The rate capability results show that the insertion of Al2O3 interlayer between the Li metal and the LiPON solid electrolyte sample enhanced the rate performance. Also, The TEM cross-section image results demonstrate that Al2O3 interlayer improves the adhesion to Li metal on LiPON solid electrolyte. These results indicate that as the adhesion between Li metal and LiPON solid electrolyte is improved, electrochemical performance is improved in all-solid-state lithium-ion thin-film batteries.

Conclusions

We successfully fabricated the all-solid-state lithium-ion thin-film battery using the amorphous V2O5 electrode and LiPON solid electrolyte. In addition, through the insertion of Al2O3, the interface between LiPON and Li became uniform and the electrochemical properties were improved. In other words, the interfacial control between solid electrolyte and Li metal is a key factor for the improvement of the electrochemical properties of all-solid-state lithium-ion thin-film batteries.
Eco-Friendly All Water-Based Solution Process for Robust Ag Nano-Mesh Transparent Electrodes
Authors: sung Min Lee , In Hyeok Oh , hong Sik Eom , In Hyeok Oh
Published: December 2020

Transparent conducting electrodes have attracted substantial attentions as an essential component of various optoelectronic devices. Recently, the grid-structured metal mesh electrodes are considered as highly efficient transparent electrodes that possess high optical transmittance while maintaining sufficient electrical conductivity and are suitable for flexible conductors with isotropic electrical conductivity. Here, we report a simple and effective approach for the fabrication of highly transparent Ag nano-mesh prepared by all water-based solution process. The Ag mesh electrodes were formed by combination of colloidal gold nanoparticles deposition and silver enhancement. The optical and electrical properties of the Ag mesh can be finely tuned by varying condition of gold nanoparticle deposition and silver enhancement. The smallest feature size of the obtained metal mesh patterns is about 700 nm with a thickness of 30-60 nm. The transparent electrodes with the Ag nano-mesh structure exhibit not only excellent electrical conductivity with a sheet resistance of 70 Ω/sq at a transmittance of 96.2% but also strong adhesion strength to substrate which is confirmed by peeling off test. Our all water-based solution processed metal mesh electrodes is applied to transparent heater which is able to heat up to 250 °C at 7 V. Through this study, Not only fabrication of high performance metal mesh but also low cost fabrication without any hazardous wastes is succeeded.

This research was funded and conducted under [the Competency Development Program for Industry Specialists] of the Korean Ministry of Trade, Industry and Energy(MOTIE), operated by korea Insstitute for Advancement of Technology (KIAT). (No. P0012453, Next-generation Display Expert Training project for Innovation Process and Equipment, Materials Engineers)
High-Mobility, Low-Temperature, CMOS Back-End Compatible III-V Crystalline Material Growth
Authors: Sarkar Debarghya , Tao Jun , Kapadia Rehan
Published: December 2020

In this work, we present a low temperature templated liquid phase (LT-TLP) growth process, that enables us to directly grow high optoelectronic quality single crystalline compound semiconductors on amorphous dielectrics at temperatures below 400 0C. Importantly, we show that when compared to other non-epitaxial growth techniques, this approach results in materials which exhibit 1-2 orders of magnitude improved mobility. This is attributed to the ability to grow single crystalline materials in desired geometries, removing the polycrystalline interfaces which dramatically degrade mobility of most crystalline materials. We demonstrate both InP and InAs, and interestingly observe a peak in quality when InP is grown at 300 oC, a temperature which is low enough to enable back-end-of-line growth on fully fabricated Si CMOS circuits. Using this low-temperature grown InP, we then develop a transistor fabrication process entirely carried out at 300 oC or below and demonstrate an indium phosphide nanoribbon field effect transistor with excellent on/off ratios, indicating low defect density in the material. Additionally, we demonstrate high electron mobility single crystal InAs mesas monolithically integrated on amorphous dielectric substrates at a growth temperature of 300°C. Critically, a room temperature mobility of ~5800 cm2/V-s was measured, the highest mobility reported for any thin-film semiconductor material system directly grown on a non-epitaxial substrate. Detailed modeling of the scattering mechanisms in the grown material indicates that the mobility is limited by surface roughness scattering, not the intrinsic material quality. We project that reducing the RMS surface roughness of the InAs from 1.8 nm to 1 nm would produce materials with room temperature mobilities of >10,000 cm2/V-s, and RMS roughness of 0.5 nm would result in mobility ~20,000 cm2/V-s, essentially identical to epitaxially grown materials. These results pave the way for growth of high-mobility materials directly onto the back-end of silicon CMOS wafers as well as other non-epitaxial substrates such as glass, and polymers for flexible electronics.

Figure 1
Empirical Mode Decomposition Applied to Proton Exchange Membrane Electrolyzer for Non-Intrusive Diagnosis
Authors: Aubras Farid , Damour Cedric , Benne Michel , Bessafi Miloud , Lin-Kwong-Chon Christophe , Grondin-Perez Brigitte , Deseure Jonathan , Kadjo Jean Jacques Amangoua
Published: December 2020

The water electrolysis based on Polymeric Electrolyte Membrane technology (E-PEM) is an interesting solution for efficient carbon-free hydrogen production. By the end of the 21st century, the contribution of hydrogen will continue to achieve significant rate in the energy mix. As there have been advances of efficient end-use technologies, hydrogen could even become the main energy carrier [1]. Regarding diagnosis purposes, Empirical Model Decomposition (EMD) method has proven to be a versatile and efficient tool to analyze non-stationary signals and extract features from them [2].

As a starting point of its decomposition, oscillations are considered, at a local level, as the sum of a specified number of high and low frequency contributions called Intrinsic Mode Functions (IMFs). IMFs represent the natural oscillatory mode embedded in the signal and work as the basis functions, which makes EMD a self-adaptive method. fig.1 shows the decomposition of the E-PEM current into a finite set of intrinsic mode functions.

This study presents a non-intrusive tool designed to fulfill on-line diagnosis requirements. Indeed, the proposed method does not require any excitation signal or stabilization period as Electrochemical Impedance Spectroscopy-based approaches [3]. Therefore, the electrolyzer remains continuously available, even while the diagnosis is being performed. Besides, it only requires measurement of current and has a low computational costs, which are significant economic and technical advantages. Here, EMD has been used to study the anode flow rate dynamics. Several experiments have been conducted and experimental results have demonstrated the effectiveness of the proposed diagnosis tool and its advantages compared to other methods.

Acknowledgements

This project has received funding from the Reunion Island Region and the European Commission – ERDF

References

Barbir, “PEM electrolysis for production of hydrogen from renewable energy sources,” Solar Energy, vol. 78, no. 5, pp. 661–669, May 2005, doi: 10.1016/j.solener.2004.09.003.

Damour, M. Benne, B. Grondin-Perez, M. Bessafi, D. Hissel, and J.-P. Chabriat, “Polymer electrolyte membrane fuel cell fault diagnosis based on empirical mode decomposition,” Journal of Power Sources, vol. 299, pp. 596–603, Dec. 2015, doi: 10.1016/j.jpowsour.2015.09.041.

C. Garcia-Navarro, M. Schulze, and K. A. Friedrich, “Measuring and modeling mass transport losses in proton exchange membrane water electrolyzers using electrochemical impedance spectroscopy,” Journal of Power Sources, vol. 431, pp. 189–204, Aug. 2019, doi: 10.1016/j.jpowsour.2019.05.027.

Figure 1: Intrinsic mode functions decomposition for operating conditions of 1.6 V and 0.5 ml.min-1

Figure 1
Thermal History Induced Surface Restructuring of La0.6Sr0.4CoO3-δ thin-Film Solid Oxide Electrodes and Its Significance for the Catalytic Activity and Stability
Authors: Celikbilek Ozden , Cavallaro Andrea , Kerherve Gwilherm , Fearn Sarah , Chaix-Pluchery Odette , Aguadero Ainara , Kilner John , Skinner Stephen
Published: December 2020

Thin-films deposited by Pulsed Laser Deposition (PLD) have enabled the fabrication of cathodes for solid oxide cells (SOC) to possess various microstructures, crystalline states and surface chemistry. These films are often subjected to various processing and thermal treatments which influence the chemical activity and stability of the films. Here, we investigate how the catalytic activity and stability is affected by the thermally induced surface restructuring in complex transition metal oxides, in particular, La0.6Sr0.4CoO3-δ (LSC) thin films grown by PLD.(1) To this end, the influence of substrate temperature during PLD as well as post-annealing treatments on the film microstructure and surface chemistry were studied. In comparison to high-temperature grown films, the post-annealed low-temperature grown films showed 2-fold lower degradation rate in the long-term electrochemical tests at 500 °C. The differences in the electrochemical stability were found to be related to the initial microstructure and morphology of the films (Fig 1). The post-annealed low-temperature grown film showed localised Sr-segregation into protruding particles, leaving the remaining surface with catalytically active stoichiometry. On the other hand, the high-temperature grown films showed a fully covered surface with Sr-rich particles, which continued to thicken with time. Here we emphasise the importance of processing and thermal history in the elemental surface distribution, especially for the stability of LSC64 electrodes and propose that it should be considered as among the main pillars in the design of the active surface.

Fig. 1 Top-view (a,d,g) and cross-section view (b,e,h) SEM micrographs and corresponding AFM images (c,f,i) showing the topography of LSC64 films deposited by the PLD: (a−c) LT-grown film, (d−f) postannealed LT-grown film, and (g−i) HT-grown film. (https://pubs.acs.org/doi/10.1021/acsami.0c08308) Reprinted with the permission of the American Chemical Society. Further permissions related to the material excerpted should be directed to the ACS.

(1) Celikbilek, O.; Cavallaro, A.; Kerherve, G.; Fearn, S.; Chaix-Pluchery, O.; Aguadero, A.; Kilner, J. A.; Skinner, S. J.. ACS Appl. Mater. Interfaces 2020, 12, 34388−34401.

Figure 1
Modeling Single and Two-Phase Transport in Thin Porous Layers Using a Composite Continuum-Pore Network Formulation
Authors: Garcia-Salaberri Pablo , Zenyuk Iryna V. , Gostick Jeff T. , Weber Adam Z.
Published: December 2020

In this work, a composite continuum-pore network formulation is presented to model single and two-phase transport thin porous layers, such as gas diffusion layers in polymer electrolyte fuel cells (PEFCs) and active electrodes in redox flow batteries (RFBs). The formulation can be integrated into CFD codes, thus combining the ease of implementation of continuum-based modeling and the computational power of pore-network modeling. The composite model includes a control volume (CV) mesh at the layer scale, which embeds a cubic pore network [1,2]. The pore-network model is used to determine analytically local anisotropic effective transport properties (local effective diffusivity and permeability), which are mapped onto the CV mesh to simulate transport in the porous transport layer [3,4]. Good agreement is found between the predicted global effective transport properties (global effective diffusivity and permeability) under dry and wet conditions and previous experimental data reported in the literature for Toray TGP-H series carbon paper. Water saturation distributions are also compared with results obtained using X-ray computed tomography [4].

[1] P.A. García-Salaberri, I.V. Zenyuk, J.T. Gostick, A.Z. Weber, Modeling Gas Diffusion Layer in Polymer Electrolyte Fuel Cells Using a Continuum-Based Pore-Network Formulation, ECS Trans. 97 (2020) 615.

[2] P.A. García-Salaberri, Modeling diffusion and convection in thin porous transport layers using a composite continuum-network model: Application to gas diffusion layers in polymer electrolyte fuel cells, Int J. Heat Mass Transf. (2020), submitted.

[3] P.A. García-Salaberri, J.T. Gostick, G. Hwang, A.Z. Weber, M. Vera, Effective diffusivity in partially-saturated carbon-fiber gas diffusion layers: Effect of local saturation and application to macroscopic continuum models, J. Power Sources 296 (2015) 440–453.

[4] P.A. García-Salaberri, G. Hwang, M. Vera, A.Z. Weber, J.T. Gostick, Effective diffusivity in partially-saturated carbon-fiber gas diffusion layers: Effect of through-plane saturation distribution, Int. J. Heat Mass Transf. 86 (2015) 319–333.
Modeling of High-Temperature Multiphase Solid/Molten Carbonate Membranes for CO2 Capture
Authors: Jin Xinfang , Li Xin , Huang Kevin
Published: December 2020

High-temperature solid/molten-carbonate composite represent an emerging class of CO2 transport membranes to capture CO2 from flue gas with advantages in flux density and selectivity over conventional solvent/sorbent- and polymer-based counterparts. While significant technical progress in these membranes has been made in the past years, a deeper fundamental understanding of CO2 transport mechanisms is still limited. Aimed to bridge this gap, we here report a theoretical study on flux performances of four types of solid/molten-carbonate CO2 transport membranes by analytical and numerical modeling. We first demonstrate the general analytical solutions for CO2 flux of dual-phase solid/MC membranes by solving the partial differential equations (PDEs) along with the boundary conditions. These analytical solutions are then compared with those derived directly from Wagner theory. We also develop numerical CO2 flux solutions and compare them with the existing or our derived analytical solutions to point out the issues with using analytical methods to solve CO2 flux in complex multiphase systems. Finally, we apply our numerical models to simulate CO2 flux in more complex multiphase solid/MC membranes.

From the results, we found that analytical and numerical results are virtually identical for solids with single charge carrier. However, for mixed conducting solids, numerical method is preferred since analytical method cannot solve the nonlinear local concentrations of charge carriers. Application of numerical method to a new three-phase membrane containing a mixed conducting solid, a pure electron conducting solid and molten-carbonate reveals a 75% increase in CO2 flux compared to the two-phase (mixed conducting solid and molten-carbonate) counterpart. The models presented here are expected to provide better fundamental insights and guidance for designing next-generation high-performance CO2 transport membranes.

Figure 1
Bioelectrochemistry of Neuronal Protein Tauoral
Authors: Martic Sanela
Published: December 2020

Tau is a neuronal protein and one of the biomarkers of neurodegenerative diseases, such as Alzheimer’s disease. Tau protein undergoes post-translational modifications, aggregation, and is a viable drug target. In addition, this protein is a vital biomarker in biological fluids towards early detection of neurodegenerative diseases. We reported on using electrochemical impedance spectroscopy and cyclic voltammetry for detection of protein-protein interactions (1), protein-ligand interactions (2), enzymatic catalysis and enzyme inhibition (3) while focusing on tau protein and its biochemistry. For example, tau-tau, tau-ferritin, tau-transferring protein interactions were monitored, and protein kinase-catalyzed phosphorylation of tau protein was detected. The phosphorylation inhibitors, such as antibodies, were screened for their efficacies. New research directions in neuroelectrochemistry of tau protein alongside other neuronal biomarkers, such as Amyloid beta and alpha synuclein, will also be described.

References

A) Carlin, N., Martic-Milne, S. (2018). Anti-tau antibodies based electrochemical sensor for detection of tau protein. J. Electrochem. Soc.165: G3018-G3025. B) Jahshan, A., Esteves, J.O.V., Martic-Milne, S. (2016). Evaluation of ferritin and transferrin binding to tau protein. J. Inorg. Biochem. 162: 127-134. C) Esteves, J.O.V., Trzeciakiewicz, H., Loeffler, D.A., Martic, S. (2015). Effects of tau domain-specific antibodies and intravenous immunoglobulin on tau aggregation and aggregate degradation. Biochemistry. 54: 15-18.

Trzeciakiewicz, H., Esteves, J.O.V., Carlin, N., Martic, S. (2015). Electrochemistry of heparin binding to tau protein on Au surfaces. Electrochim. Acta. 162: 24-30,

Esteves, J.O.V., Martic-Milne, S. (2016). Electrochemical detection of anti-tau antibodies binding to tau protein and inhibition of GSK-3-β-catalyzed phosphorylation. Anal. Biochem. 496: 55-62
Harnessing Photoelectrochemistry for Resource Recovery from Wastewater Nitrates
Authors: Barrera Luisa , Bala Chandran Rohini
Published: December 2020

Nitrates are present in industrial effluent streams from fertilizer production, iron/steel production, coal mining, and municipal wastewater streams. Typically, nitrates are eliminated from wastewater through biological nitrification-denitrification treatment processes, but these are energy and carbon intensive, are not applicable for all waste streams and have not prioritized nitrogen recovery. We propose a photoelectrochemical device is proposed to transform wastewater nitrates to ammonia, nitrous oxide, and dinitrogen, coupled with water oxidation. Numerical models are developed to quantify process efficiencies and nitrogen-removal as a function of light absorber band gaps, electrocatalytic kinetic parameters, competing oxygen reduction and hydrogen evolution reactions, and the reacting nitrate species concentrations. A device-scale model was also developed to capture the coupled effects of light absorption, species transport and reaction kinetics. With a single light-absorber and state-of-the-art catalysts, optimal solar-to-chemical efficiencies of 7% and 11% and nitrogen-removal rates of 251.3 and 451.6 gN m-2 day-1 are predicted for the formation of ammonia and nitrous oxide respectively. Theoretically predicted peak nitrogen removal rates and specific energy intensities are competitive with reported estimates for bioelectrochemical and Sharon-Anammox processes that recover ammonia from waste streams. This result, together with the added benefit of harnessing sunlight to effect the nitrate transformation to value-added products, indicates promise in the proposed photoelectrochemical pathway for wastewater nitrogen removal coupled with resource recovery.

Figure 1
Pit Formation Mechanism of Monolayer MoS2 By Thermal Oxidation
Authors: Park Sangwook , Siahrostami Samira , Park Joonsuk , Mostaghimi Amir Hassan Bagherzadeh , Kim Taeho Roy , Vallez Lauren , Gill Thomas Mark , Park Woosung , Goodson Kenneth E , Sinclair Robert , Zheng Xiaolin
Published: December 2020

Generating pits and thereby active edge sites of molybdenum disulfide (MoS2) monolayers is desirable for many electrochemical catalytic reactions including hydrogen evolution reaction (HER). Thermal oxidation is one of the potentially scalable and facile methods to effectively create the pits on MoS2 monolayers. Therefore understanding the thermal oxidation mechanism is very important to precisely control the generation of active edge sites of MoS2-based electrocatalysts. To date, pits are assumed to be favorably formed on MoS2 at undercoordinated sites such as sulfur (S) vacancies at high temperatures. However, the thermal oxidation studies have not considered the existence of adventitious carbon (C) that exists almost everywhere and interact with oxygen at elevated temperatures. Herein, we investigated the influence of adventitious C on the thermal oxidation of MoS2 monolayers. We employed in situ environmental transmission electron microscopy (ETEM) to demonstrate the pit formation mechanism with the presence of adventitious C at the oxidation temperature of 300 °C. The in situ ETEM results show that the adventitious C is agglomerated at high temperatures. Then, the interfaces between monolayer MoS2 and C nanoparticle provide preferred sites for thermal oxidation of MoS2 and thus pit formation while the individual S vacancies exist intact. Density functional theory (DFT) calculations show the interfaces between MoS2 and C nanoparticle make the sequential adsorption of oxygen atoms thermodynamically favorable, unlike only S vacancy sites. We also tested the electrochemical performance of MoS2 with pits for HER and it reduced the overpotential by ~ 130 mV. These results demonstrate the combination between ETEM experiment and DFT calculation can be effectively used to study the chemical reaction mechanism between 2-dimensional materials such as MoS2 and gaseous species. Furthermore, we provide the potential to control the active edge site of MoS2-based electrocatalyst by understanding the fundamental pit formation mechanism by thermal oxidation.
Development of Novel FRET Substrate for the Evaluation of β-Secretase (BACE1) and Its Application
Authors: Lui Zhi Ling , Iida Yasuhiro
Published: December 2020

A neuropathological diagnosis of Alzheimer's disease (AD) relies on the detection of amyloid plaques, clumps of beta-amyloid made up of insoluble fibrils. Sequential cleavage by β-secretase (BACE) and γ-secretase produces the amyloid-β peptide fragment, which then aggregates into the clumps of amyloid plaques. As the β-secretase activity is specifically high in AD patient, the enzyme is regarded as the primary target of anti-AD reagent. All the conventional β-secretase inhibitors are substrate analogs, which means those inhibitors are competitive and reversible inhibitors. Therefore, a non-competitive enzyme inhibitor of β-secretase might be a perfect inhibitor for AD. To search for non-competitive enzyme inhibitor of β-secretase, we developed new method to evaluate non-competitive enzyme inhibitors easily by using flow injection analysis (FIA) in combination with immobilized enzyme. In general, FRET substrates linked by recognition sequence of β-secretase are used to evaluate the β-secretase activity. In this study, we constructed a novel FRET substrate which is made up of ECFP as the donor, and EYFP as the acceptor. These proteins are then linked with β-secretase recognition sequence with 8 amino acids. ECFP transfers its excitation energy to EYFP, causing EYFP to emit its characteristic fluorescence. By observing the wavelength using spectrophotometer, we can judge if the material or herbs have the ability to be the inhibitor of β-secretase. Therefore, both the FRET substrates and β-secretase we constructed can be produce with a large amount by using E. coli. And because the protein of FRET substrates and BACE1 can be obtained easily with the E. coli we constructed, therefore we will be able to search for the inhibitors of β-secretase by the FIA screening method with low cost.
Ultrafine Ni-Based Nanomaterials on Hierarchically Porous Carbon from Biomass: An Efficient Bifunctional Electrocatalyst for Water Splitting
Authors: Hoang Van Chinh , Gomes Vincent G.
Published: December 2020

A highly efficiency bifunctional electrocatalyst, consisting of Ni/NiO nanoparticles decorated on biomass-derived hierarchically porous carbon (BHPC) was fabricated via one-step pyrolysis. Cauliflower leaf waste was used as a natural biomass carbon/nitrogen source for our cost-neutral BHPC. The catalytic activities of Ni/NiO/BHPC towards oxygen evolution reaction (OER) and hydrogen evolution reduction (HER) were investigated with variable pyrolysis temperatures ranging from 400 to 600 oC, which triggered changes in the crystallography and composition ratio between Ni and NiO in the resultant composite. For the optimal temperature of 500 oC, the resulting hybrid had 20.8 at.% Ni0, exhibiting modest Tafel slopes of 70 and 121 mV dec-1, while requiring 346 and 180 mV overpotentials to reach 10 mA cm-2 for OER and HER in 0.1 M KOH solution, respectively. When used for total water electrolyser, the Ni/NiO/BHPC electrodes achieved a current density of 10 mA cm-2 at 1.688 V only, and demonstrated superior cycling stability and rate capability over 20 h between 10 and 30 mA cm-2. The catalytic activity of the NiOx/BHPC-500||NiOx/BHPC-500 electrolyser is comparable to that of the recently reported cells assembled with Ni-based electrocatalysts. The excellent catalytic properties of the designed electrocatalyst are ascribed to the synergistic effect of Ni/NiO heterostructure and hierarchically porous carbon framework, which generates large electrochemical active surface area, numerous catalytic active sites and fast electron transport. This work provides strategies for the sustainable design of bifunctional electrocatalysts for efficient total water splitting.

Keywords: hierarchically porous carbon, Ni/NiO heterostructure, biomass, water splitting
Electrochemical Synthesis of Struvite from Wastewater: Implications of Chloride Ion and Initial pH
Authors: Sultana Ruhi , Greenlee Lauren Fay
Published: December 2020

Electrochemical precipitation of magnesium ammonium phosphate (MAP) compounds, specifically as struvite (NH4MgPO4.6H2O) from wastewater is gaining importance as one of the techno-economically feasible pathways of sustainable development [1]. However, systematic exploration of the optimal range of anode potential for maximizing phosphate recovery under varied parametric conditions of pH and ion concentrations, other than NH4
+ and PO4
3- has not been attempted so far. Additionally, ion dissolution from sacrificial magnesium anode over stipulated potential range between pitting and secondary passivation needs to be investigated for maximum struvite production with minimal consumption of magnesium. In this study, we have characterized the role of initial pH (4 and 8) and chloride ion concentration (1 M) on phosphate recovery and magnesium dissolution by conducting batch electrochemical experiments with three different anode potentials covering the entire range of feasible potential window. Linear Sweep Voltammetry (LSV) was performed at two different initial pHs to identify the aforementioned potential range. Subsequently, batch experiments at different anode potentials were conducted in an electrochemical cell consisting of pure magnesium sheet as sacrificial anode and stainless steel cathode. 77 mM solution of dihydrogen ammonium phosphate (NH4H2PO4) and 1M sodium chloride was used as electrolyte. Lower value of Pitting potential in presence of chloride ions with respect to that with baseline NH4H2PO4 solution was indicative of the favorable effect of chloride in rupturing the passive layer of magnesium hydroxide that normally forms on anode surface and hinders magnesium dissolution. Higher magnesium dissolution rate and phosphate recovery were recorded above and over respective pitting potentials for both pHs. Moreover, monotonic increasing profiles of precipitate masses with increasing anode potential unambiguously indicates higher dissolution of magnesium with as alternatively reflected in terms of elevated charge transfer as per Faraday’s law. In both cases of different initial pHs, final pH was recorded in alkaline range. Nevertheless, ammonia loss was observed to increase with anode potentials and increasing pH. Precipitates, formed at the surface of anode and in bulk solution, on characterization revealed the presence of several MAP and other magnesium phosphate precipitates including Struvite (MgNH4PO4.6H2O), Dittmarite (MgNH4PO4.H2O), Magnesium phosphate tribasic (Mg3(PO4)2) and Newberyite (MgHPO4.3H2O). Magnesium hydroxide was detected at higher pH. Simulation of saturation indices and product distribution using Visual Minteq 3.1 predicted optimal recovery of Struvite (MgNH4PO4.6H2O) in the pH range 8-10.

Reference:

[1] Cid, C. A.; Jasper, J. T.; Hoffmann, M. R., Phosphate Recovery from Human Waste via the Formation of Hydroxyapatite during Electrochemical Wastewater Treatment. ACS Sustainable Chem. Eng. 2018, 6 (3), 3135-3142.
Development and Engineering of Nanostructured Ternary Catalyst for PEM Fuel Cells: The Role of Electrode Composition in Oxygen Reduction Kinetics
Authors: Sahin Nihat , Akaydin Beril , Ozenler Sibel , Kadirgan Figen
Published: December 2020

Low-temperature proton exchange membrane fuel cells (PEMFCs), offering significantly higher efficiency compared to conventional heat engines play a crucial role in responding to the growing energy demand, especially for transportation applications. The fundamental understanding of bulk electrocatalysis both in acidic and alkaline media at nanostructured electrodes that possess compositional and structural heterogeneity has a profound effect on electrode kinetics and reaction mechanisms. Because the electrocatalytic activity depends mainly upon the nanoscale size, composition as well as surface properties of the prepared catalyst, development and engineering of advanced electrocatalysts is needed for giving a lead towards unprecedented improvements in electrode performance so in fuel cell systems1. It has hypothesized2 and reported3 that alloying Pt with different metal components (herein Sn and Ni) brings about modifying the electrotonic states such as the d-band centers as well as geometric factors, which has attracted a great deal of attention in electrocatalysis. Moreover, the superior catalytic synergy of nanostructured binary4 and ternary5 electrocatalysts towards oxygen reduction activity was previously reported. To this end, highly active, robust and low-cost carbon-supported ternary nanoparticles (Pt2Sn1Ni1/C) were synthesized using a modified microwave-assisted polyol method6 in diethylene glycol (DEG) without additional protective agents. The morphostructural properties of the catalyst were determined via various advanced-characterization techniques. Cyclic voltammetry (CV) and rotating (ring) disk electrode (RRDE) measurements reveal that the alloying of Pt with Sn-Ni significantly boosts the catalytic activity towards oxygen reduction reaction (ORR) in O2-saturated 0.1M HClO4 electrolyte. The kinetic parameters were assessed through Koutecky-Levich approach. The influence of the alloying structure on the kinetic parameters such as exchange current density, limiting current density, Tafel slopes, reaction rate, and the number of exchanged electrons is extensively discussed.

References:

M. Shao, Q. Chang, J. P. Dodelet, R. Chenitz, Chem. Rev., (2016), 116, 3594.

J. K. Norskov, J. Rossmeisl, A. Logadottir, L. Lindqvist, J.R. Kitchin, T. Bligaard, H. Jonsson, J. Phys. Chem. B, (2004), 108, 17886.

T. Toda, H. Igarashi, H. Uchida, M. Watanabe, J. Electrochem. Soc., (1999), 146, (10), 3750.

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S. Beyhan, N. E. Sahin, S. Pronier, J. M. Leger, F. Kadirgan, Electrochimica Acta, (2015), 151, 565.

N. Sahin, T. Napporn, L. Dubau, F. Kadirgan, J. M. Leger, K. B. Kokoh, Applied Catal. B: Environ., (2017), 203, 72.
Solid Polymer Electrolytes in Lithium Batteries: Challenges and Opportunities for High Specific Energy
Authors: Stolz Lukas , Homann Gerrit , Winter Martin , Kasnatscheew Johannes
Published: December 2020

Besides enhanced safety aspects, solid polymer electrolytes (SPEs) offer the opportunity to increase the specific energy of secondary batteries by enabling lithium metal as negative electrode in all-solid-state lithium batteries (ASSLB). Therefore, the SPE needs to provide sufficient mechanical strength to prevent short circuits caused by lithium dendrite penetration especially favoured at high current densities.[1] In order to obtain the maximum specific energy of ASSLBs, lithium metal negative electrodes are combined with high voltage positive electrodes, e.g. LiNi0.6Mn0.2Co0.2O2 (NMC622).[2]

In the frame of this work, a novel SPE is applied to NMC622 based ASSLB cells and studied regarding energy limits on battery cell and pack level. In a first step, the active mass loading is systematically increased revealing the specific energy limit on battery cell level. Additionally, the chosen system is applied to a bipolar (serial) stacking aiming towards further energy improvements on battery pack level.[3] In sum, this work reveals remaining challenges but still points towards opportunities enabling the aimed energy increase of ASSLBs.

[1] G. Homann, L. Stolz, J. Nair, I. C. Laskovic, M. Winter and J. Kasnatscheew, Sci Rep, 10, 4390 (2020).

[2] J. Kasnatscheew, M. Evertz, R. Kloepsch, B. Streipert, R. Wagner, I. Cekic Laskovic and M. Winter, Energy Technology, 5, 1670-1679 (2017).

[3] G. Homann, P. Meister, L. Stolz, J. P. Brinkmann, J. Kulisch, T. Adermann, M. Winter and J. Kasnatscheew, ACS Appl. Energy Mater., 3, 4, 3162–3168 (2020).

Figure 1
Methods of Redox Control and Measurement in Molten NaCl-CaCl2-UCl3
Authors: Newton Matthew Laughlin , Hamilton David Ethan , Simpson Michael Forrest
Published: December 2020

The U.S. Department of Energy is currently supporting the design and planned construction of the Versatile Test Reactor (VTR) capable of performing experiments in a fast neutron field. This will allow for study of the effect of fast neutron irradiation on nuclear fuels, materials, and functional components. The molten salt irradiation experiment will utilize the VTR to study the chemical changes and speciation in molten chloride and/or fluoride salts.

In preparation for future experiments involving irradiation of candidate molten salt fuels, the redox potential measurement and control methods in molten NaCl-CaCl2-UCl3 at 500oC were studied. The goal was to identify a metal/metal chloride redox buffer that can be used to control the redox potential, thereby helping to mitigate the corrosion risks posed by irradiation of the uranium salt fuel. An ideal candidate would both adequately reduce the redox potential and possess a low neutron interaction cross section.

The first metal/metal chloride redox buffer investigated was Zr/ZrCl4. ZrCl4 has a standard state reduction potential of -2.02 V vs. Cl-/Cl2 at 500° C. The standard state reduction potentials for UCl3 and CrCl2 are -2.41 and -1.55 V, respectively. Zr metal should, thus, oxidize to ZrCl4 and control the redox potential at a level that simultaneously prevents Cr corrosion while leaving UCl3 unreduced from the salt.

In order to test Zr metal for redox control, a 6.2-mm diameter Zr rod (99%) was submerged in molten NaCl-CaCl2-UCl3 salt at 600°C. The open circuit potential (OCP) of the salt was measured at a tungsten working electrode vs a Ag/AgCl reference electrode encased in a mullite tube. NiCl2 was added to the salt to simulate the effect of fission on redox potential. After submerging the Zr rod, the measured open circuit potential between the W WE and the RE dropped by -0.63 V over a period of 100 minutes.

There is concern as to whether the rate of reaction of insoluble Zr metal with the salt can keep up with the rate of potential change due to the irradiation of the salt. Other redox buffer candidates being considered include uranium, calcium, and sodium. The latter two choices are attractive because of their predicted solubility in the molten salt, supporting homogenous redox control reactions. The problem with the latter three choices is that amounts contacted with the salt will need to be precisely controlled to avoid reduction of UCl3. OCP measurements will also be reported for molten NaCl-CaCl2-UCl3 using U, Na, and Ca as the redox buffer. Conclusions will be drawn regarding the most effective metal to use in the future VTR experiments in order to control the redox potential of the irradiated salt.
Selective Permeation of Neodymium Through an Alloy Diaphragm in Molten Chloride Systems
Authors: Oishi Tetsuo , Yaguchi Miki , Katasho Yumi , Nohira Toshiyuki
Published: December 2020

The authors have been investigating a new RE (RE=Dy and Nd) recycling process from Nd-Fe-B permanent magnets, which is characterized by the use of RE-IG (IG=Fe, Ni, Co) alloy diaphragms for separation of REs in molten salts (Fig. 1) [1, 2]. In this process, the RE-IG alloy diaphragm performs as a bipolar electrode and RE ions permeate via three steps: (1) reduction of RE ions to form alloy on the anolyte side of the diaphragm, (2) diffusion of RE atoms in the diaphragm, and (3) oxidation of RE atoms to dissolve into the catholyte as RE ions on the other side of the diaphragm. Because the reaction and diffusion rates depend on the kinds of RE elements and the electrolytic conditions, selective permeation of Dy and/or Nd is possible under an appropriate condition. Using this selective permeation phenomenon through the alloy diaphragms, Dy and Nd can be separately recovered from Nd-Fe-B permanent magnets only by molten salt electrolysis, as shown in Fig. 1.

Recently, the authors reported selective Dy permeation through a RE-Ni alloy diaphragm in molten LiCl-KCl eutectic melts containing NdCl3 and DyCl3 at 450 ℃ [3]. Whereas, in the present study, selective permeation of Nd was examined using a similar experimental setup at the different electrolytic conditions. The obtained molar ratio of permeated Nd/Dy was around 6. Interestingly, EDX analysis revealed that the molar ratio of Nd/Dy in the alloy diaphragm was less than 0.05, which was two orders of magnitude lower than that of the permeated amount. These results suggested that the diffusion rate of Nd atoms in the alloy diaphragm was extremely high compared to that of Dy.

Acknowledgement

This work was partly supported by the New Energy and Industrial Technology Development Organization (NEDO) of Japan.

Reference

[1] T. Oishi, H. Konishi, T. Nohira, M. Tanaka and T Usui, Kagaku Kogaku Ronbunshu, 36, 299–303 (2010).

[2] T. Oishi, Molten Salts (Yoyuen Oyobi Koon Kagaku), 63, 78–83 (2020).

[3] T. Oishi, M. Yaguchi, Y. Katasho and T. Nohira, Rare metal technology 2020, 151–156 (2020).

Figure 1