bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) A Real Time Platform for Observing Surface Processes at Activated Battery Cathodes:Resolving CO2 and O2 Evolution
Authors: Mishra Abhiroop , Rodríguez-López Joaquín 
Published: December 2020

Understanding the impact of surface catalysis on the interfacial evolution of battery electrodes during energy storage is key to developing reliable, efficient, and safe high-energy density technologies. The formation of interphases is essential for the operation at anodes, where the solid-electrolyte interphase (SEI) kinetically stabilizes the electrode; recently, the formation of interfacial structures at high-energy density cathodes has also garnered great interest due to the kinetic and Coulombic limitations it places on the performance of various promising materials. [1] Elucidating how electrode surface structure, composition, and potential-dependent behavior impact the degradation reactions of the electrolyte and solvent is a fundamental pursuit with significant practical implications, as it may be key to engineering safe devices and to improve the efficiency of growing and aging stable interfaces at an industrial scale. Thus, understanding how surface reactions prompt the evolution of interfaces is a pressing challenge. While X-ray and mass-spectrometric methods [2,3] have been used to characterize these chemistries, probing the surface chemistry of these electrodes with higher versatility, in situ and with high spatiotemporal and chemical resolution represents a formidable analytical challenge.
Here, we present an analytical methodology based on the use of scanning electrochemical microscopy in various modes for quantitatively detecting the formation, in real time and with high spatial resolution, of gaseous by-products such as O2 and CO2 from the catalytic decomposition of the electrolyte/solvent at battery electrodes. Using the generation/collection mode we developed an analytical platform capable of resolving these two species in order to quantify material degradation processes as a function of state of charge, and by using the feedback mode we can simultaneously monitor their impact on the interfacial kinetics of the electrode. By insightfully using ultramicroelectrode methods, and principles of CO2 electroreduction, we evaluated the nonaqueous reaction mechanisms involved in the detection to provide quantitative guidance on the relationship between the detected signal and the quantification of the processes undergoing at the battery electrode. We tested the response of our probes on a model NMC cathode, confirming O2 and CO2 evolution processes under conditions reported to exhibit bulk decomposition and surface passivation, respectively. This work creates a foundation not only for the high spatiotemporal evolution of interfacial processes at battery electrodes, but also for the understanding of CO2-related mechanisms in nonaqueous solvents.
[1] Li, W. et al. Nature Comm.
2017, 8, 14589
[2] Li, Q. et al. ACS Appl. Mater. Interfaces
2020, 12, 2, 2319–2326
[3] McCloskey, B.D. et al. J. Phys. Chem. Lett.
2012, 3, 997-1001
First-Principles Analysis of Coverage, Ensemble, and Solvation Effects on Selectivity Trends in NO Electroreduction on Pt3sn Alloys
Authors: Deshpande Siddharth , Greeley Jeffrey 
Published: December 2020

Nitrogen cycle electrochemistry is an upcoming area of interest in the chemical and environmental engineering communities, with applications ranging from removal of nitrates from wastewater streams to the development of fundamental understanding of NO electrochemistry. In spite of a significant amount of fundamental research for this chemistry on single crystal surfaces, however, the mechanistic details of the reactions are not fully known.
In this work, we begin by describing a detailed analysis of the reaction mechanism of NO electroreduction on PtSn alloys. These alloys are of interest because they have been experimentally shown to be selective to products such as hydroxylamine (NH2OH) in acidic solutions, which is a more valuable product compared to NH3, the only product formed on pure platinum surfaces. In spite of this interest, however, little is known about the structural and electronic features of the PtSn that cause this selectivity change.
To elucidate these features, we make use of periodic Density Function Theory calculations combined with theoretical electrochemistry analyses. We first present our analysis for low coverages of NO present on the Pt3Sn(111) surface and derive preliminary conclusions about the reaction mechanism. Subsequently, we introduce an in-house graph theory based tool to efficiently estimate higher coverage structures of adsorbed NO on the Pt3Sn(111) surface, and we extend the kinetic analysis to the limit of higher NO coverages, resembling the state of a real catalyst under continuous reaction conditions. Further, we compare the mechanistic insights for NO electrochemical reduction on Pt-Sn alloys with that on Pt(111) and Pt(100) surfaces, to understand the role of ‘Sn’ in promoting the selectivity to NH2OH. We close by suggesting design strategies to tune the selectivity of NO electroreduction to desired products, including N2 and hydroxylamine, on other transition metals and alloys.
Ni-BTC Derived Porous Ni/C/Graphene Composite for Highly Sensitive Non-enzymatic Electrochemical Glucose Detection
Authors: Li Guofu , Chen Di , Chen Yingjie , Dong Lifeng 
Published: December 2020

Electrochemical detection of glucose, including enzymatic and non-enzymatic detections, has gained widespread attention due to its rapid response, unparalleled sensitivity, and common applications in both biomedical and healthcare fields. Compared with enzymatic glucose detection, non-enzymatic detection has lower cost, better stability and simpler immobilization operation. However, due to relatively inert nature of glucose and prone-to-contaminant characteristic of solid electrodes, non-enzymatic glucose detection suffers from weak sensitivity and reproducibility. To address these problems, various transition metal-based materials and graphene-based materials have been explored to improve electrochemical responses to glucose.
Herein, a highly sensitive non-enzymatic glucose detection electrocatalyst was synthesized by in-situ growing porous NiO nanoparticles derived from Ni-BTC (1,3,5-Benzenetricarboxylic acid) on graphene (NiO/G). By virtue of highly porous Ni-BTC as a precursor, the composite exhibited homogeneous metal distribution, massive exposure of active sites, and spatially ordered structure. The NiO/G demonstrated superior steadiness, electron transfer rate, excellent electrocatalytic activity towards glucose oxidation, and high sensitivity (1030 μA mM−1 cm−2) in alkaline media. Thus, the NiO/G can be utilized as electrocatalysts for applications in non-enzymatic glucose detection, and the preparation strategy can be used to synthesize other nano-composites with low cost, such as CuO/G and Co/G, for non-enzyme glucose sensors.
Insight into Lithium Ion Transport Properties of Artificial Solid Electrolyte Interfaces By Molecular Dynamics Simulations
Authors: Verweyen Elisabeth , Bedrov Dmitry , Winter Martin , Brunklaus Gunther 
Published: December 2020

Among the most promising technologies for the next generation of electrochemical energy storage devices are lithium metal anode based batteries. In practical application, however, issues such as parasitic reactions of lithium metal with liquid electrolytes or the transient inhomogeneous lithium deposition on the metal anode occur for these storage systems.
To enable the use of lithium metal electrodes with liquid electrolytes, an artificial solid electrolyte interface (SEI) can be introduced, which should be affordable but also enhancing the electrochemical performance as well as calendar and cycle life of the cells. The ongoing search for feasible materials suggested the copolymer poly(3,4-ethylenedioxythiophene)-co-polyethylene glycol (PEDOT-co-PEG) as a promising candidate. The PEG homopolymer is ion-conductive whereas PEDOT is electron-conductive and offers good electrochemical stability [1]. The copolymer PEDOT-co-PEG exhibits sufficiently high ionic conductivity and may stabilize lithium electrode interfaces, thereby reducing lithium dendrite growth [1].
This work includes an analysis of the lithium ion transport properties of PEDOT-co-PEG by extensive molecular dynamics (MD) simulations, exploiting the Atomistic Polarizable Potential for Liquids, Electrolytes and Polymer (APPLE&P) method. Multiple constitutions of the copolymer as well as blend polymers of both PEDOT and PEG were studied in the presence of lithium bis(trifluoromethane)sulfonamide (LiTFSI) in different concentrations, at simulated temperatures between 300 and 500 K. Notably, the impact of selected parameters not only on the resulting polymer morphology, but also on the dissociation of the lithium salt, the mean square displacement of lithium ions, the corresponding lithium coordination, as well as the lithium transport mechanism is detailed. This work affords deeper insight and comprehensive understanding of molecular processes that govern the lithium conduction, thereby paving ways for tailored design of future materials, including the development of electrode coatings and electrolyte formulations, based on which superior electrochemical performance and lifetime for lithium metal based batteries could be achieved.

References:
[1] I.S. Kang, Y.-S. Lee, D.-W. Kim, J. Electrochem. Soc. 161 (2014) 53-57.
High Dielectric, Robust Organic-Inorganic Composite Protective Layer for Lithium Metal Anode
Authors: Jang Eun Kwang , Im Jinsol , Cho Kuk Young 
Published: December 2020

The development of lithium metal anodes for next-generation batteries is still a challenge. Li dendrite growth, one of the challenges, not only induces severe safety issues but also leads to capacity fading by continuously consuming the electrolyte. In this study, we demonstrate the design and fabrication of a composite protective layer to overcome these challenges. Composite protective layers exhibit high ionic conductivity and mechanical strength. This layer not only suppresses dendrite growth but also prevents salt degradation.
The composite protective layer, which exhibits synergistic soft-rigid characteristics, is placed on the Li metal anode and facilitates superior interfacial stability during long-term cycles. LiMn2O4/ coated lithium full cells using the composite protective layer enhanced capacity retention compared to the cells using bare lithium anode. The proposed strategy opens new avenues to fabricate a sustainable composite protective layer that affords superior performance in lithium metal batteries.
Preperation of Br-Doped Li4Ti5O12 Anode and Its Electrochemical Performance in Li-Ion Battery
Authors: Piao JunJi , Kim Seokhun , Lee Seulgi , Islam Saiful , Kim Jaekook 
Published: December 2020

In this work, we studied about Br-doped Li4Ti5O12-xBrx (“x”= 0, 0.1, 0.3, 0.5 and 0.7) anode materials, which were synthesized by a conventional solid-state reaction using precursors of Li2CO3, TiO2 and LiBr, and we found that their electrochemical properties were related to the doping behavior
Most of the Br ions are situated on the surfaces/interfaces of agglomerated particles rather than in the bulk lattice after quantitative instrumental analysis.
This lead to the formation of Narrow conduction paths of electron and Li-ion on their surfaces/interfaces.
The presence of these narrow surface electrical conduits increased the rate-capability of the LTOBr samples during charging/discharging process.
Highly Br-doped sample (LTOBr0.7) showed a slight reduction in capacity. The LTOBr0.5 sample, by the mean time, showed the highest capacity of 125 mAh/g at 1C compared to 115 mAh/g for pure LTO.
This was explained with the formation of fine precipitations (Br-containing second phase) on the surfaces of the LTO particles due to high Br addition.
The formation of fine precipitations (Br-containing second phase) on the surfaces of the LTO particles due to high Br addition could be the explanation of this.
Analysis of Irreversible Charge-Discharge Reaction in LiFePO4/Li4Ti5O12 Full-Cell Using Two-Phase Reaction Active Material
Authors: Omote Yuki , Katayama Misaki , Orikasa Yuki 
Published: December 2020

In laboratory charge-discharge tests of lithium-ion battery electrodes is often used half-cell with a lithium metal anode, which can supply enough lithium ions. On the other hand, practical lithium-ion batteries do not contain lithium metal and use full-cell configuration with almost similar capacities between cathode and anode. Limited number of lithium ions supplied by the cathode contributes as carrier ions, which determines the actual charge-discharge capacity. Since the degradation behavior observed in full-cell is different from in half-cell [1, 2], it is important to understand the problems that occur during charge-discharge in full-cell to maximize battery performance. In this study, we investigated the irreversibility in full-cell with lithium iron phosphate (LiFePO4) cathode and lithium titanate (Li4Ti5O12) anode as an unnatural case, where both active materials show two-phase reaction in almost all composition. The potential changes of cathode and anode were tracked using the three-electrode full-cell with a lithium metal reference electrode. In addition to the electrochemical measurements, the charge-discharge state was analyzed from the X-ray absorption spectroscopy (XAS), which provides the valence change information.
Half-cell charge-discharge tests of LiFePO4 and Li4Ti5O12 at 0.1C result in reversible charge-discharge profile. However, the distinct irreversible capacity is observed in the LiFePO4 / Li4Ti5O12 full-cell configuration. The initial charge and discharge capacity are 162 nd 126 mAh g-1, respectively and this irreversibility is continuously observed in the subsequent cycle. The three-electrode test indicates that the potential of Li4Ti5O12 anode sharply increases despite in the middle of the discharge. Fe K-edge XAS shows similar edge energy for the half-charged and half-discharged LiFePO4 cathode. However, Ti K-edge XAS of half-charged Li4Ti5O12 anode shows the different edge energy from that of the half-discharged. The full-discharged LiFePO4 cathode does not reach the lithiated state even after discharging, which agrees with the results from the three-electrode test. At the end of the charge, little edge-energy shift in the Li4Ti5O12 anode is observed, indicating that the insertion reaction of lithium ions does not progress. Therefore, the irreversible capacity is caused by a side reaction at the Li4Ti5O12 anode in end of the charge.
[1] Bjorklund, D. Brandell, M. Hahlin, K. Edstrom, R. Younesi, J. Electrochem. Soc
., 164 (2017) A3054-A3059.
[2] H. Kim, N.P.W. Pieczonka, Z.C. Li, Y. Wu, S. Harris, B.R. Powell, Electrochim. Acta. , 90 (2013) 556-562.
Coordination Complex Templated Battery Materials
Authors: Shuaib Umaira , Powell Annie K. 
Published: December 2020

Transition-metal oxides (TMOs) have plenty of applications across many different fields of science; solar cells, gas sensors and the electronics industry are some of the areas where the progression from research to application has been extremely rapid. Manganese oxides (MnOs) are a common and commercially available active material used in the electrodes of energy storage devices such as batteries, because they have a higher theoretical capacity (c.a. 756 mAh g-1) compared to the conventional anode material graphite (372 mAh g-1). As shown in the ‘cycling stability’ graph, nearly 600 mAh g-1 of discharge capacity can be obtained during the first 40 cycles, followed by a gradual drop in capacity to 420 mAh g-1 before increasing again after the 82nd cycle and surpassing the initial 600 mAh g-1 after the 135th cycle.
While suggesting a reaction has taken place during long-term cycling (e.g. phase conversion), the isosbestic points in the insitu XAS studies aren’t necessarily correlated to CTAM behaviour. Alternate reactions in the electrode causing changes in the mechanism during the discharge profile are present. The radial distance between 1 and 2 Å is much lower than expected for the Mn-O bond. In the graph portraying the potential against time, we can see at 0.4 V the capacity is held at a stable potential between 10 h to 28 h.
Here we explored the unique electrochemical behaviour of these simple and sustainable oxides templated from metal-organic frameworks (MOFs) as a competitor for graphite and current oxide-anodes.

Figure 1
Crystallization and Wear Behavior of SiO2-Al2O3-ZrO2-Ba(Sr, Ca)O Glass-Ceramics Added with Cr2O3 By Different Methods
Authors: Feng Min , Chen Minghui , Wang Fuhui 
Published: December 2020

The merits of glass-ceramics are mainly derived from the refractory crystallites, but controlling crystallization of glass is a complicated process. Although substantial work was conducted on crystallization and its effect on mechanical and thermal properties of glass-ceramics, few were available on the effect of crystallization on friction. In the current work, Cr2O3 was incorporated into a, BaO-rich, SiO2-Al2O3-ZrO2-Ba(Sr, Ca)O based glass system through two methods: (1) melted into the glass; (2) added as foreign ceramic crystallites. After heat treated at high temperature, it transformed to glass-ceramics. Then crystallization and its influence on friction of the glass-ceramics were carefully studied.
The results showed that, on annealing at 1173 K, SiO2 and acicular BaSi2O5 crystallites were precipitated out from the silicate glass-ceramics which thereafter possessed high friction coefficient and wear rate. Adding Cr2O3 retarded the precipitation of BaSi2O5 and decreased wear resistance. But this retardation effect varied with the way that Cr2O3 was added. When Cr2O3 was added by ball milling, precipitation of BaSi2O5 was only partly retarded, and wear rate was decreased marginally. However, adding Cr2O3 during the smelting process, the precipitation of BaSi2O5 was almost fully prohibited, and BaCrO4 and/or BaCr2O4 substituting BaSi2O5 precipitated out. The nanoscale barium chromates promoted the formation at worn surfaces of a lubricating glaze layer that decreased largely the wear rate and friction coefficient.

Figure 1
Membrane Scaffolds Silver Nanoparticles As a New Platform of Antiviral Personal Protective Equipment for COVID-19
Authors: Kalil Haitham , Maher Shaimaa , El-falouji Abdullah I. , Samir Omar , Gad Emad , Youssef Mohamed F. 
Published: December 2020

The coronavirus disease 2019 (COVID-19) emerged as a worldwide challenge to researchers and scientists. All research communities are working relentlessly in their labs hoping to find cure for the current COVID-19 pandemic. Developing a new vaccine for COVID-19 is not down on the road, it is a long process that needs numerous clinical trials. Moving the battle out of the body requires personal protective equipment (PPE), particularly masks and gloves. Together, they will limit spread of the virus, whether by reinforcing the PPE and developing synergistic antiviral coatings or finding a cure and vaccine to COVID-19.
Virus infection is one of the major global health challenges. In the meantime, several antiviral agents have been under testing to assess their efficacy as potential therapies for COVID-19. The viral resistance and the side effects associated with antiviral agents are adding more challenges, which resulted in lagging of their effectiveness as antiviral treatment. This opens the door for the development of safe and potent alternative antiviral drugs. In the current study, silver nanoparticles loaded fiber mat have emerged as a new antiviral platform in terms of their capability to deactivate a wide array of viruses. Silver nanoparticles have been studied exhaustively for their antimicrobial activity against wide-ranging of bacteria. Besides they have also shown promising activity versus several types of viruses including hepatitis B, human immunodeficiency virus (HIV), herpes simplex, monkey pox, and respiratory syncytial virus. Silver nanoparticles provide an alternative route as a new antiviral therapy. Interestingly, silver metals have the power to attack multiple targets in the virus, which results in diminishing its possibility to develop resistance as compared to imitative antivirals.
Considering the ongoing challenge, our lab has been preparing silver nanoparticles loaded on filter papers, cellulose membrane, polymer dressings, and cotton fabrics. These new generation of fiber mats will be fully characterized and tested against several viruses. Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), Transmission Electron Microscopy (TEM), and Dynamic Light Scattering (DLS) will be used to determine the morphology of our fibers and measure the particle size of the embedded nanoparticles.
Secondary Effects in Electrical Behavior of Body-Diode Integrated AlGaN/GaN HEMTS
Authors: Mahaboob Isra , Yakimov Michael , Rocco Emma , Hogan Kasey , Meyers Vincent , Shahedipour-Sandvik F. Shadi 
Published: December 2020

We have recently demonstrated dual-gate control in AlGaN/GaN high electron mobility transistors (HEMTs) with the integration of body-diode based back-gate [1]. To integrate body-diode, conventional AlGaN/GaN HEMT structure is grown on a p-GaN layer and a back-gate terminal is connected to the underlying p-GaN layer. This design allows the back-gate voltage to control the depletion width of the body-diode, which in turn modulates the two-dimensional electron gas (2DEG) density at the AlGaN/GaN interface. A positive/negative shift in the threshold voltage is obtained by increasing/decreasing the depletion width of the body-diode with the application of back-gate voltage. With dual gate control, we have successfully demonstrated shift in the threshold voltage of a normally-ON HEMT towards normally-OFF mode along with improved breakdown voltage. Here we present, observations of secondary effects in the integrated body-diode AlGaN/GaN HEMT device structure. Secondary effects are investigated under both biased and floating back-gate conditions [2]. Our results show that, at higher drain voltages, bias at the drain terminal plays a crucial role in biasing the body-diode under dynamic operation. Secondary effects such as kink-effect in the saturation channel current and light emission under the source terminal are observed under dynamic operation. We will further discuss the effect of parasitic bipolar junction transistor (BJT) formation on the device performance in this integrated device configuration.

References

[1] I. Mahaboob, M. Yakimov, K. Hogan, E. Rocco, S. Tozier, and F. Shahedipour-Sandvik, “Dynamic Control of AlGaN/GaN HEMT Characteristics by Implementation of a p-GaN Body-Diode-Based Back-Gate,” IEEE J. Electron Devices Soc., vol. 7, no. 1, pp. 581–588, 2019.
[2] I. Mahaboob, M. Yakimov, E. Rocco, K. Hogan, and F. Shahedipour-Sandvik, “Drain Voltage Induced Secondary Effects in AlGaN/GaN HEMTs with Integrated Body-Diode,” unpublished, submitted to IEEE-TEDS.