bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stability of Novel Anolyte and Catholyte Materials for Organic Nonaqueous Redox Flow Batteries
Authors: Giurini Michael , Dan Adina , Brinks Marcus , Hoekstra Elizabeth , Symstad Kassia , Porath Anthony , Guarr Thomas F. 
Published: July 2021

In recent years, many improvements have been made in renewable energy technologies, allowing them to outcompete fossil fuels in terms of the cost-efficiency of energy production. However, the biggest challenge in the implementation of renewable energies is matching energy production to energy consumption. In an effort to bridge this gap, there has been significant academic and commercial focus on energy storage technologies, with redox flow batteries being of particular interest.
Organic nonaqueous redox flow batteries provide several improvements over traditional flow batteries. These improvements include higher accessible cell voltage, enhanced energy density, wider operating temperature range, and reduced operational costs compared to current flow battery technology. Current redox flow battery chemistries often utilize toxic metals such as vanadium for anolyte and catholyte materials. These metals are expensive, difficult to safely dispose of, and require a highly acidic electrolyte. Organic anolyte and catholyte materials provide a potential solution to these problems but also introduce other challenges, most notably stability of the battery materials in their oxidized and reduced states.
In this study a number of organic redox-active molecules been evaluated for their use as anolyte and catholyte materials capable of highly reversible one electron and two electron oxidations and reductions. Cyclic voltammetry and spectroelectrochemistry were utilized to determine oxidation or reduction potentials as well as the electrochemical stability of those materials in their oxidized or reduced states.
Preparation of Furfural Resin-Based Active Carbon with Acid Treated Pore Surface Electric Double Layer Capacitor
Authors: Hokari Kanade , Shimizu Shota , Okamoto Naoki , Saito Takeyasu , Ide Isamu , Nishikawa Masanobu , Onishi Yoshikazu 
Published: July 2021

Demand for high capacity and high power energy saving devices is recently increasing for environmental conservation and energy saving. Electric double layer capacitor (EDLC) is a capacitor utilizing an electric double layer generated at the interface between an activated carbon electrode and an electrolyte. While high power and high durability are attractive, low energy density remained as a crucial issue. We reported that EDLC capacity increased as the amount of acidic surface functional groups increases. In this study, we employed mixed-acid treatment and KMnO4 treatment to introduce acidic surface functional groups on active carbon and investigated the relationship between physicochemical properties and electrical properties.
Furfural resin-based particles (1 µm in diameter) were carburized in a nitrogen atmosphere for 3 h at a temperature ramping rate of 1°C/min to 400°C. The carbonized particles were mixed with KOH at a KOH : carbonized particles ratio of 4:1; the mixture was then activated at 800°C under flowing nitrogen gas at a temperature ramping rate of 10°C/min. After heat treatment had been performed, the active carbon was impregnated with mixed acid and KMnO4. Specific surface area/pore size distribution was evaluated by N2 adsorption method. Surface functional groups were evaluated by Boehm method. Active carbon, carbon black and polytetrafluoroethylene were mixed at a mass ratio of 8: 1: 1 (=0.08 g:0.01 g:0.01 g), then pellets (14 mm in diameter and 2 mm in thickness) were prepared and dried at 115ºC for 24 hours to obtain activated carbon electrodes. Constant current charge/discharge test (potential width: 0-1.0 V, current density: 20-500 mA/g) and was performed at room temperature by two-electrode cell using KOH aqueous solution (6 M) as an electrolytic solution.
Table 1 shows the pore structure and specific capacity per weight at 20 mA/g of active carbon treated mixed-acid treatment and KMnO4 treatment. Due to acid treatment, the surface structure was destroyed and the specific surface area decreased in the following order: Control (1291 m2/g) > Mixed-acid (883 m2/g) > KMnO4 (793 m2/g) KMnO4 & Mixed-acid (358 m2/g). Although acid treatment result in a smaller specific surface area (883, 793, 358 m2/g) than that of control (1291 m2/g), they had higher specific capacity per weight (160, 219, 149 F/g) than that of no acid treatment (111 F/g). The improvement in wettability or pseudo-capacity due to redox reaction was a possible reason why the high the specific capacity per weight and high rate characteristics were obtained by the acid treatment.

Figure 1
(Invited) A Brief Overview and Future Outlook on the Progress of III-Nitride Semiconductors Research
Authors: Freitas Jaime A. 
Published: July 2021

The increasing need for devices capable of performing under extreme condition of power and temperature, and opto-electronic devices operating in the UV-Vis spectral range has been the principal driving force for research interest in III-Nitrides semiconductors over the last three decades. Progress in bulk growth and film deposition techniques for homo- and hetero-epitaxial growth of III-Nitride semiconductors has led to successful fabrication and commercialization of an increasing number of devices that are revolutionizing both the optoelectronic and electronic device industries.
Many relevant figures of merit related to electronic device performance scale superlinearly with the band gap; hence, ultra-wide band gap (UWBG) materials (Eg > 3.4 eV) have the potential for far superior performance than conventional WBG materials such as GaN and SiC. UWBG materials will be critical enablers of future electronic components and systems, and a fundamental understanding of their synthesis and properties is critical to exploiting their advantages. In particular, cubic boron nitride (c-BN), among the semiconductor materials in the UWBG group (c-BN, AlN, Ga2O3, and diamond), with a band gap of ~6 eV and thermal conductivity of 13 W/mK (second only to diamond, 20 W/mK) offers the best combination of breakdown voltage and specific on-resistance. Another advantage of c-BN over other UWBG semiconductors is that it can be doped with donors and acceptors, enabling the fabrication of bipolar devices.
The development of high quality GaN substrates and device grade films will be reviewed and a brief overview of the intrinsic properties of the WBG and UWBG semiconductors will be presented.
Effect of HfO2 Passivation Layer on Light Extraction Efficiency of AlInN Nanowire Ultraviolet Light-Emitting Diodes
Authors: Patel Moulik , Jain Barsha , Velpula Ravi Teja , Nguyen Hieu Pham Trung 
Published: July 2021

Diverse applications of ultraviolet (UV) light in the field of purification, sterilization, detection, surface disinfection, sensing, and many others have been studied mostly on AlGaN light-emitting-diodes (LEDs). However, the external quantum efficiency (EQE) of AlGaN deep UV LEDs is limited due to strong induced polarization fields, high dislocation density, severe electron leakage, difficulty in p-type doping, low internal quantum efficiency (IQE), IQE droop, and low light extraction efficiency (LEE). Alternatively, AlInN semiconductor has been recently gained tremendous attention for high power UV LEDs [1-3]. Our group has successfully demonstrated the first AlInN core-shell nanowire UV LEDs with a relatively high IQE of ~52%[1]. However, the light extraction study of such nanowire LEDs is unexplored. In this context, we have studied the LEE of a single AlInN nanowire UV LED at 220 nm - 400 nm wavelength regime. Moreover, we report that the LEE of a single AlInN nanowire UV LED could be increased by ~60% using HfO2 passivation compared to conventional nanowire LED at 282 nm.
The schematic structure of AlInN nanowire UV LED is shown in Figure 1(a). The nanowire is composed of 200 nm n-GaN, 100 nm n-AlxIn1-xN quantum barrier (QB)/40 nm i-AlyIn1-yN quantum well (QW)/100 nm p-AlxIn1-xN QB, and 20 nm p-GaN layer. We have estimated the LEE of nanowire LEDs using the finite difference time domain (FDTD) simulation method. Silicon (Si) is used as a substrate, and the n-GaN layer is tapered with a diameter from 70 nm (bottom) to 100 nm (top). The diameter is set to be 100 nm for the rest of the regions. We have placed a single TM-polarized dipole source at the QW center to calculate LEE for a nanowire LED in the simulations. The estimated LEE of 282 nm wavelength single nanowire AlInN UV LED with various HfO2 passivation layers thickness is provided in Figure 1(b). The LEE of such LED without any passivation is ~25.2%, whereas the maximum recorded LEE is ~40.6% with the utilization of 35nm thickness HfO2 passivation layer. This study provides a promising approach for enhancing the light extraction efficiency of nanowire UV LEDs.

Reference

R. T. Velpula, B. Jain, M. R. Philip, et al., Sci. Rep., 10(1) 2547-2556 (2020).

R. T. Velpula, B. Jain, H.Q.T. Bui, et al., Opt. Mater. Express, 10(2), 472-483 (2020).

B. Jain, R. T. Velpula, M. Tumuna, et al., Opt. Express, 28(15), 22908-22918 (2020).

Figure 1
(Invited) Electrical Performance Improvement in 300mm Ge-Based Devices
Authors: Tapily Kandabara , Nakamura Genji , Consiglio Steven , Clark Robert D , Newman Danny , Triyoso Dina H. , Niimi Hiroaki , Wajda Cory S , Leusink Gert J 
Published: July 2021

As device feature size continues to scale, new device architecture and dielectric materials with engineered properties are becoming essential in overcoming the issues in scaled CMOS devices such as short channel effects. Some of the recent innovations device makers are exploring for better electrostatic control and improved performance are the introduction of new device architecture such as gate all around devices (nanowires/nanosheets), and channel engineering such as high mobility channel materials (Ge and III-V). Ge is particularly attractive for use as a channel material for P-type MOSFETs due to its high hole mobility and Si VLSI high volume manufacturing (HVM) compatibility. However, there are couple significant remaining challenges to integrating Ge into 300mm Si VLSI HVM which are a stable gate-stack formation and integration of Ge on Si (1-5). In this talk, advances in Ge gate stack engineering will be discussed. Using Si compatible technologies we have demonstrated scaled EOT by engineering both the interface and high-k formation.
Reference

Swaminathan, Y. Oshima, M. Kelly, P.C. McIntyre, Appl. Phys. Lett.,
95, 032907 (2009).

Zhang, M. Gunji, S. Thombare, P.C. McIntyre, IEEE Electr. Device. L., 34, 736 (2013).

H Lee, T. Nishimura, C. Lu, S. Kabuyanagi, A. Toriumi, IEDM, 32.5.1 (2014).

S. Goley, M. K. Hudait, Materials, 2301 (2014).

Xie, S. Deng, M. Shaekers, D. Lin, M. Caymax, A. Delabie, X-P Qu, Y-L. Jiang, D. Dedytsche, C. Detavernier, Semicond. Sci. Technol. 074012 (2012)
Optical and Structural Properties of Ga and in Co-Doped ZnO Nanocrystals Films
Authors: El Filali Brahim , Torchynska Tetyana , Garcia Jorge Luis Ramirez , Lozada Erick Velazquez , Shcherbyna Lyudmyla 
Published: July 2021

The impact of double donor doping on the crystal structure, emission and electrical resistivity has been studied in the ZnO:Ga:In films. The films were deposited by ultrasonic spray pyrolysis on a previously cleaned silicon substrate. To the study of double donor doping, two groups of samples were prepared. In the first group the In content was 1at% and the Ga contents were varied in the range 0.5-3.0at.%. In the second group the In content was 2at% and the Ga content were changed in the range 0.5-2.5at%. To stimulate the film crystallization, all samples were annealed at 400oC for 2 hours in nitrogen flow 5l/min. The high quality nanocrystal (NC) films with the wurtzite-type crystal structure, bright near band edge (NBE) emission and the small intensity of defect related PL bands have been aobtained. The variation non monotonically of the ZnO crystal lattice parameters, as well as the PL intensities of NBE emission bands has been detected. The reasons for the parameter variation non monotonically and the optimal concentrations for the Ga/In double donor doping of ZnO NC films have been analyzed and discussed.
Corresponding author E mail: braelf@hotmail.com
Pr-Based Nanofiber Cathode for Intermediate Temperature SOFCs
Authors: Gumeci Cenk , Parrondo Javier , Abdul Jabbar Mohammed Hussain , Thompson Dave , Dale Nilesh 
Published: July 2021

In this work, praseodymium based double perovskite (PrBa0.5Sr0.5Co1.5Fe0.5O5+𝛿) - PBSCF nanofibers cathodes were fabricated by electrospinning technique for intermediate-temperature solid oxide fuel cells (IT-SOFCs).The optimized three-dimensional nanofiber network cathode provides high porosity coupled with the higher interfacial contact area, leading to a faster oxygen reduction reaction (ORR) kinetics.
EIS analysis of the nanofiber structured cathode resulted in a polarization resistance of ~0.025 Ω cm2 at 750 °C. Resulted low resistance is smaller than the commercial LSCF cathode showing polarization resistance of ~0.041 Ω cm2 at 750 °C. The peak power densities of the PBSCF fibers are ~2539, 1580 and 993 mW/ cm2 at 750, 700, and 650 °C, respectively when compared to LSCF cathode performance of ~ 1974, 1304 and 769 mW/ cm2 at same temperature. Such promising performance of fiber cathode IT-SOFCs in this study was achieved via careful selection of the catalyst structure and composition, electrode structure for efficient ORR, and perhaps through process optimizations. The results obtained in this study illustrates that one-dimensional nanostructures obtained by adopting nanofibers can be an appropriate cathode material choice for intermediate-temperature SOFCs suitable for automotive applications.
(Invited) Metal-Supported Solid Oxide Fuel Cells and Electrolyzers for Low-Cost, Robust, Rapid-Start Systems
Authors: Tucker Mike C , Shen Fengyu , Hu Boxun , Welander Martha M , Skafte Theis Løye , Lau Grace Y. 
Published: July 2021

This talk will provide an overview of performance, durability, and applications of metal-supported solid oxide fuel cell and electrolysis cell technology developed at Lawrence Berkeley National Laboratory (LBNL). The unique LBNL symmetric cell architecture design, with thin zirconia ceramic backbones and electrolyte sandwiched between porous metal supports, offers a number of advantages over conventional all-ceramic cells, including low-cost structural materials (e.g. stainless steel), mechanical ruggedness, excellent tolerance to redox cycling, and extremely fast start-up capability.
MS-SOFC performance with a variety of fuels will be presented, including hydrogen, ethanol, natural gas, and simulated reformates. The impact of the presence of carbon and internal reforming catalysts on the durability of the cells will be examined. In particular, oxidation of the stainless steel supports in the presence of carbon is analyzed. Scale-up from button cells to 50cm2 will be presented.
The case for use of MS-SOECs for dynamic electrolysis operation will be made. Detailed analysis of degradation modes over 1000h of operation with 50/50 steam/H2 informed efforts to improve durability through the use of coatings and catalyst processing techniques.
In addition to our long-standing development of zirconia-based metal-supported cells, recent efforts on metal-supported proton-conducting cells are ongoing. Co-sintering of 400-series stainless steel and BZCY-type proton conductors presents a number of challenges, including: Ba evaporation in reducing atmosphere, over-densification of steel at the high temperatures (>1400°C) required for BZCY processing, mismatch of metal and ceramic sintering behavior, and migration of Cr and Si from the steel support into the BZCY layers. Feasibility of new approaches to overcome these challenges will be discussed.
Interplay of Activity and Stability within Hydrous Cobalt-Iridium Oxide Oxygen Evolution Electrocatalysts
Authors: Rhodes Christopher P. , Ying Yuanfang , Godinez Salomon Jose Fernando 
Published: July 2021

To further the development of proton-exchange membrane electrolyzers, oxygen evolution reaction (OER) electrocatalysts with high activity, extended durability, and lower costs are needed. We have explored iridium-nickel and iridium-cobalt two-dimensional nanoframes where the interaction of iridium with other metal alters the surface electronic structure and influences the activity and stabiity.1,2 In contrast to comparable structures with nickel, hydrous cobalt-iridium oxide two-dimensional nanoframes exhibit higher oxygen evolution activity and similar stability compared to commercial IrO2; however, the bimetallic catalyst undergoes different degradation processes compared to the monometallic catalyst. Bimetallic cobalt-iridium (Co-Ir) two-dimensional nanoframes are composed of interconnected Co-Ir alloy domains within an unsupported, carbon-free, porous nanostructure that allows three-dimensional molecular access to the catalytically active surface sites. After electrochemical conditioning within oxygen evolution potentials, the predominately bimetallic alloy surface is transformed to oxide/hydroxide surface. From rotating disk electrode measurements, hydrous Co-Ir oxide nanoframes provide 17 times higher OER mass activity and 16 times higher specific activity compared to those of commercial IrO2. The higher OER activities of hydrous CoIr nanoframes are attributed the interaction of Ir with Co within the surface and subsurface region that modifies the surface atomic and electronic structure. After accelerated durability testing, IrO2 has a lower specific activity and resulted in partial dissolution of Ir. In contrast, durability testing of hydrous Co-Ir oxide nanoframes resulted in an increase in specific activity, an increase in the relative contribution of surface iridium hydroxide groups, and a higher Ir dissolution rate. Understanding the differences between degradation processes invovled in bimetallic and monometallic catalysts furthers our ability to design high activity and stability acidic OER electrocatalysts.

References

Godínez-Salomón, F.; Albiter, L.; Mendoza-Cruz, R.; Rhodes, C.P. Bimetallic Two-dimensional Nanoframes: High Activity Acidic Bifunctional Oxygen Reduction and Evolution Electrocatalysts”, ACS Applied Energy Materials, 2020, 3, 2404-2421.
http://dx.doi.org/10.1021/acsaem.9b02051

Godínez-Salomón, F.; Albiter, L.; Alia, S.M.; Pivovar, B.S.; Camacho-Forero, L.E.; Balbuena, P.B.; Mendoza-Cruz, R.; Arellano-Jimenez, M.J.; Rhodes, C.P. Self-Supported Hydrous Iridium-Nickel Oxide Two-dimensional Nanoframes for High Activity Oxygen Evolution Electrocatalysts, ACS Catalysis
2018, 8, 10498-10520. DOI: 10.1021/acscatal.8b02171
Bipolar Membrane Electrode Assemblies for Water Electrolysis – Goals and Challenges
Authors: Mayerhöfer Britta , Ehelebe Konrad , Speck Florian Dominik , Bierling Markus , McLaughlin David , Böhm Thomas , Hegelheimer Manuel , Cherevko Serhiy , Peach Retha , Thiele Simon 
Published: July 2021

Hydrogen production from water electrolysis is considered a promising large-scale solution for energy storage of intermittent, renewable sources. Besides mature alkaline electrolysis employing caustic KOH solutions as a liquid electrolyte, modern technologies focus on the use of ion exchange membranes as a solid electrolyte. While the widespread application of state of the art proton exchange membrane (PEM) water electrolyzers is impaired by the requirement of costly and rare iridium-based catalyst for the oxygen evolution reaction (OER), anion exchange membranes (AEM) are recently reaching higher technological readiness levels.
Besides the progress in AEM water electrolysis, also the combination of a PEM for the cathode and an AEM for the anode, referred to as bipolar membrane water electrolysis is gaining more scientific interest. As depicted below, the bipolar interface (preferably decorated with a water dissociation (WD) catalyst [1]) enhances the water dissociation rate into protons and hydroxide, which feed the respective electrode reactions.
We have established various modular AEM- and PEM-based building blocks, which allow us to thoroughly investigate zero-gap bipolar membrane electrode assemblies for water electrolysis in various configurations. [2] As the AEM is expected to contribute the most to ohmic losses, we have employed additive manufacturing techniques to decrease the AEM layer thickness stepwise. Moreover, we have evaluated performance determining parameters such as the WD interlayer, operating conditions and water management in the membrane electrode assembly. All these studies allow us a critical assessment of the potential and the drawbacks of this novel MEA system for water electrolysis.

Acknowledgements

This work was performed in collaboration with the National Research Council of Canada in the Materials for Clean Fuels Challenge Program.

References

[1] S. Z. Oener, M. Foster, S. W. Boettcher, Science (2020).
[2] B. Mayerhöfer, D. McLaughlin, T. Böhm, M. Hegelheimer, D. Seeberger and S. Thiele, ACS Appl. Energy Mater. (2020).

Figure 1
Single Stage Reactors for Electrifying Bio-Methanation
Authors: Jayathilake Buddhinie Srimali , Pang Simon H. , Chandrasekaran Swetha , Freyman Megan C. , Deutzmann Jörg S. , Kracke Frauke , Spormann Alfred , Baker Sarah 
Published: July 2021

As a combined solution for minimizing CO2 emissions and meeting global energy demands, upgrading CO2 to produce renewable natural gas is an emerging technology to utilize and store renewable energy. When this process is performed by efficient and product selective biocatalysts, conventional and energy intense thermal methanation technologies can be replaced by bio-methanation technology. The bio-methanogenesis process is typically performed with hydrogen produced externally in electrolyzers, but is severely limited by poor mass transport and solubility issues of molecular hydrogen. A system where both electrolysis and microbial conversion are combined in a single reactor helps overcome these problems. However, despite the outstanding opportunities of in-situ electro-bio-methanogenesis, there are challenges of electrified bioreactors that must be overcome, including microbial tolerance and enhancing the kinetics of in-situ hydrogen evolution. Thus, developments to achieve the balance between both biochemical and electrochemical requirements will allow these reactors to achieve optimum performance. The developments include maintaining physiological pH, effective separation of anode and cathode, improving charge transfer kinetics and reducing internal resistance.
We have used our advanced manufacturing capabilities to design and fabricate components for developing electro-bioreactors from 0.1 W scale in sluggish H-cells to MW scale stacks of flow cell CO2 electrolyzers. This allows us to achieve the balance between both biochemical and electrochemical requirements mentioned above. In this study, we show how utilization of high surface area porous 3D electrodes can support maintaining biocompatible conditions near the vicinity of hydrogen evolving electrode at effective rates of electrolysis, while improving both efficiency and productivity of microbial methanogenesis. We have conducted studies to understand the effect of electrode geometry and surface area on energy efficiency and microbial health. Finally, we demonstrate the ability to produce pipeline-quality methane (>97% CH4) from CO2 for an extended period.