bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Self-Doped TiO2 Nanotube Array for Photoelectrochemical Water Treatment: Effects of Cathodization Condition
Authors: Kim Hyeonjeong , Cho Kangwoo
Published: December 2020

Electrochemical self-doping of TiO2 by cathodization in mild conditions has been evinced to enhance the photoelectrochemical (PEC) activities for water treatment and molecular hydrogen generation. In this study, the effects of doping conditions such as annealing, current density, electrolyte (pH, buffering intensity), and duration were systematically interrogated with respect to the physico-chemical properties and water treatment efficacy of the TiO2 nanotube array (TNA). The incident-photon-to-electron conversion efficiency (IPCE) and the rates of model organic compounds degradation were comparatively evaluated. The self-doping of crystalline (anatase) TNA reduced the band gap to 2.4 eV (blue TNA), while the same sequence for amorphous TNA even further narrowed the gap to 1.4 eV (black TNA). The level of passed charge during the cathodization showed marginal influence. Depth profiles of X-ray photoelectron spectroscopy indicated that the dopants (Ti3+) were exclusively located on surface for the blue TNA, whereas they penetrated into the bulk tube structure for the black TNA which was accompanied with quasi-permanent lattice distortion as confirmed by X-ray diffraction patterns. Therefore, the electrical conductivity in terms of donor density was found to be greater for the black TNA. The buffering intensity of the cathodization electrolyte switch the relative level of proton intercalation in comparison with oxygen vacancy formation, which was demonstrated by time-of-flight and dynamic secondary ion mass spectrometry analysis. Even though the black TNA showed superior double layer capacitance and dark electrochemical oxidation, the blue TNA marked greater IPCE and PEC water treatment efficiency. The findingss of this study would broaden the usage of TiO2 nanomaterials by tuning the physico-chemical characteristics depending on variable water treatment purposes (mineralization of organic compounds versus disinfection).
Sulfonated Phthalocyanine Redox Flow Cell for High-Performance Electrochemical Water Desalination
Authors: Pan Yanbo , Yao Libo , Wu Dezhen , Bentalib Abdulaziz , Li Jialu , Peng Zhenmeng
Published: December 2020

A reliable clean water supply is now one important and challenging issue for the human society. With the facts that only 0.4% of the water on earth is readily drinkable and 98% of the water is saltwater, water desalination for clean water production has become a key strategic solution to satisfy the increasing global water demand. Over the years, different saltwater desalination technologies were researched and developed, including reverse osmosis membrane desalination (RO), electrodialysis (ED), capacitive desalination (CDI) and multi-effect distillation (MED). However, some inherent technical issues, like high operation cost, large capital cost and/or low desalination capacity, associate with these existing technologies that lead to a high clean water production cost and limit their applications. Thus, there is a need of new water desalination technology that can purify saltwater with low cost and high efficiency.

In this work we report a new water-soluble nickel phthalocyanine tetrasulfonic acid tetrasodium salt (NiPcTATS)-based redox flow desalination battery (RFDB) for safe, effective and efficient water-salt separation. The fabricated RFDB cell exhibited a high desalination rate at 3.4 gNaCl/(molNiPcTATS∙hr) even with a low 0.5 V cell voltage and required as low as 11.5 kJ/mol salt in energy consumption. The cell showed excellent reversibility and durability for long-term operation, benefiting from the fast-redox kinetics and chemical stability of the redox couple. With no consumption of the redox couple and energy recovery during the salination process, this new method provides a continuous desalination capability with unlimited salt removal capacity. We also demonstrated the use of simple solar panel for effectively driving the RFDB cell, proving it a promising and practical technology for clean water production in remote places like islands and ships.
The Gate Cut Process Window Discussion
Authors: Ji Shi-liang , Han Qiu-Hua , Zhang Hai-Yang
Published: December 2020

The technology of FinFET has led to the continuity of device scaling and enabled the prolongation of Moore’s Law towards the 7 nm and beyond nodes. The gate cut last has been widely adopted since it can provide better SiP/SiGe growth environment, hence yielding the better electrical performance. However, This approach requires a higher level of defect control.

As we all know, the first task of gate cut is to completely cut off the gate, so that the metal gate that do not need to be connected can realize electrical separation. If good electrical insulation can not be achieved, there will induce a large leakage, so that the working voltage is increased. However, due to the miniaturization of the size, the distance between the end of the metal gate and the effective Fin is very short, which requires that the gate cutting can not only achieve electrical isolation through the size increase. The filling and patterning of the various materials of the metal gate must be considered. On the other hand, defect control is also critical for many special structures, such as gate ends formed by SaDP and gate cutting with special relationship to Fin.

This paper focuses on defect issues related to gate cutting in FinFET. It mainly includes: the first, some common defects related to gate cutting itself, such as the absence of cutting pattern caused by etch bias in dense and iso areas, the mutation of gate cutting pattern caused by stress introduction, and the gate bridge caused by tapered bottom profile, etc. The second, defect issues caused by gate cutting size affecting other manufacturing processes, such as residue generated by HKMG pattering, dummy poly gate residue, capping layer residue, single diffusion break induce metal gate bridge, etc. The third, defect issue of a structure that has a special relationship to the gate cut pattern, gate line end bridge, etc. In this article, we will discuss these typical defect issues in detail to gain a better understanding of the gate cut process. By understanding these defects, we can better control the metal gate cut process and maximize the process window.
A Cell-Based Electrochemical Biosensor to Detect Environmental Pollutants
Authors: Furst Ariel L
Published: December 2020

Endocrine disruptors, dangerous contaminants found in many household and industrial products, are pervasive in the environment. These compounds have been implicated in many health problems, including cancer, infertility, and diabetes because they target hormone receptors in our bodies. However, the chemical dissimilarity of these compounds makes their detection a challenge. We have developed a novel portable detection platform to detect a subset of these compounds that target human estrogen receptors. Our platform is based on bacteria engineered to surface express a native estrogen receptor, enabling recognition of many dissimilar compounds. The large size of the cell affords inherent signal amplification with electrochemical impedance spectroscopy upon binding to a modified electrode. We have detected sub-ppb levels of the native hormone estradiol and ppm levels of the pollutant bisphenol A (BPA) from complex solutions. As our system reports the total activity of a sample rather than the concentration of specific components, we can measure the activity of unknown compounds, including chemicals released from a BPA-free plastic baby bottle. Importantly, this approach is broadly applicable to the detection of chemically diverse compounds that bind to a single receptor.
1-Amino 2-Naphthol Modified Solvent Filled Carbon Nanotubes for Enhanced Electrochemical Sensing of Bioanalytes
Authors: Gurusamy Tamilselvi , Ramanujam Kothandaraman
Published: December 2020

My research interest is mainly on developing cost-effective electrochemical sensors for bioanalytes sensing. For example, bioanlytes such as ascorbic acid, dopamine, and uric acid present together in human body poses challenge for selective sensing of one over other. As these molecules play a vital role in controlling the body’s metabolism, it is paramount to develop a sensor tool with high sensitivity towards these bioanlytes for diagnosing diseases, including AIDS, Parkinsonism, etc. Development of fast and reliable methods for sensing these biomolecules is of considerable importance in offering rapid diagnosis.1–3 In the present experimental work, it is shown for the first time that liquid-filled multi-walled carbon nanotubes (MWCNT) exhibit remarkably enhanced characteristics for sensor applications, the detection threshold being lowered by as much as an order of magnitude, while detection sensitivity is doubled for a number of molecules including ascorbic acid, dopamine, and uric acid. 1H NMR relaxometry at a moderately low field, i.e., 14.6 MHz (0.34 T), confirms that the improved sensor characteristics are correlated with the filling of MWCNTs with solvents such as acetonitrile, dimethyl sulfoxide, etc. The molecular motions are slowed down when solvent molecules fill MWCNTs, thus increasing motional correlation times, and hence, longitudinal relaxation rate increases under extreme narrowing conditions. The filling of MWCNTs appears to relate to solvent-CNT interactions that are in line with the principle of hard and soft acids and bases, and also correlates with solvent dipole moments.4 We have further enhanced the detection limit and selectivity towards ascorbic acid by modifying the MWCNTs surface with amino naphthol.

References

K. Iriyama, M. Yoshiura, T. Iwamoto, and Y. Ozaki, Anal. Biochem., 141, 238–243 (1984).

L. Jothi, S. Neogi, S. kumar Jaganathan, and G. Nageswaran, Biosens. Bioelectron., 105, 236–242 (2018).

M. Jahan, Z. Liu, and K. P. Loh, Adv. Funct. Mater., 23, 5363–5372 (2013).

T. Gurusamy, A. Banerjee, N. Chandrakumar, and K. Ramanujam, J. Electrochem. Soc., 166, B1186–B1195 (2019).
Electrochemical Properties of AuNP-Tind Nanostructures As Glucose Sensing Materials and Thorough Interference Study
Authors: Grochowska Katarzyna , Olejnik Adrian , Karczewski Jakub , Siuzdak Katarzyna
Published: December 2020

Non-enzymatic glucose sensors are prominent alternatives to the commercially available glucometers. Their main advantages over enzyme–based devices are higher stability to changes of the environment such as pH and temperature and lack of complicated immobilization procedure [1]. However non-enzymatic glucose sensitive materials are typically less selective, so there is a strong requirement for the development of proper coatings or membranes in order to minimize the negative influence of interferences. Therefore we present Au-Ti heterostructure covered with various coatings (e.g. Nafion, poly(sulfobetaine methacrylate)) and novel approach for analysis of interfering species influence onto electrode performance in neutral solution.

Fabrication procedure of material consists of the following steps: preparing structured titanium template (TiND) by anodization and etching of nanotubes, gold sputtering and subsequent dewetting. After those steps electrode morphology is investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM) [2] revealing the presence of gold nanoparticles (AuNPs) in every dimple of Ti foil. Lastly, as formed material is covered by protective coating. Electrochemical properties and catalytic activity towards glucose oxidation are determined by standard techniques - cyclic voltammetry (CV) and impedance spectroscopy (EIS). Examining interference phenomena of various compounds (such as ascorbic acid (AA), acetaminophen (AAp), urea and glycine) is realized by both CV and EIS techniques in certain configuration. Moreover influence of those species on the catalytic activity of the material is established. Obtained results confirm the possibility of using prepared electrodes in sensors applied for noninvasive glucose detection in human body fluids.

Acknowledgements

This work has been financed by National Center for Research and Development under the LIDER program (LIDER/2/0003/L-8/16/NCBR/2017).

References

[1] Hwang, Dae-Woong, et al. "Recent advances in electrochemical non-enzymatic glucose sensors–a review." Analytica chimica acta 1033 (2018): 1-34.

[2] Olejnik, Adrian, et al. "A Flexible Nafion Coated Enzyme‐free Glucose Sensor Based on Au‐dimpled Ti Structures." Electroanalysis 32.2 (2020): 323-332.

Figure 1
Block-Copolymer Derived Nanoporous Thin Films for the Development of a L-BMAA Aptamer-Based Impedimetric Biosensor
Authors: Santiago-Maldonado Xaimara , Nicolau Eduardo
Published: December 2020

Produced by diverse cyanobacteria, b-N-methylamino-l-alanine (L-BMAA) is a non-protein neurotoxic cyanotoxin that has been linked to an elevated incidence of neurodegenerative diseases such Parkinson’s and Alzheimer’s disease and Multiple Lateral Sclerosis. The continuing rising of water temperatures and eutrophication of the water bodies propitiate the increment and size of harmful algal blooms, subsequently increasing the production of L-BMAA and other cyanotoxins. This toxin is known to bioaccumulate in plants, animals and humans. Currently, the detection of L-BMAA in water is limited by its hydrophilicity, absence of ultraviolet and fluorescent properties, and the isomers that cause false positives. Given the threat that this cyanotoxin could represent to the long-term human health, it is imperative to develop new analytical techniques for its detection in water. Therefore, this project proposes the development of an impedimetric aptamer-based biosensor, using block-copolymer (BCP’s) derived nanoporous thin films as the electrode, for the detection of L-BMAA. Our hypothesis is that the development of such aptasensor will lead to the advancement of an innovative device for a sensitive, portable, economic and flexible way to achieve the detection of the cyanotoxin in water. To achieve this, we used BCP polystyrene-poly(methylmethacrylate) (PS-b-PMMA), known to form cylinder-like structures, to create recessed nanodisk-array electrodes (RNEs). These cylindrical nanostructures provide primary mass transport pathways for ionic and redox active species which changes upon analyte binding, making them ideal to use in biosensing applications. The nanoporous electrodes were prepared by spin-coating a PS-b-PMMA solution in toluene over gold-coated silicon wafers, followed by thermal annealing and UV etching. Different annealing times, temperatures and UV exposure has been used in order to produce the alignment of the cylindrical polymer microdomains in a vertical fashion over the surface of the electrode. The prepared films were characterized using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), to confirm the formation of RNE’s. Under specific sets of conditions, CV data shows sigmoidal curves at high scan rates characteristic of RNE’s, suggesting the formation of this type of nanopores with a sufficiently large distance among them to attain radial diffusion. Atomic force microscopy (AFM) images of the samples evidence the formation of vertical nanopores but mixed with horizontal alignments. Furthermore, grazing incident small angle x-ray scattering (GISAXS)11 suggests that the polymer was well-dispersed among the surface although the expected scattering profile for RNEs is missing. Future work includes the optimization of the electrode preparation methods and the selection of a L-BMAA specific aptamer through graphene oxide-assisted selection evolution of ligands by exponential enrichment (GO-SELEX).
Development of a Thin Film Sensor for Electrochemical Analysis of Molten Fluoride Salts
Authors: Consiglio Anthony , Scarlat Raluca Olga
Published: December 2020

Due to their favorable heat transfer and neutronic characteristics, as well as chemical stability at high temperatures, molten fluoride salts have been proposed as a coolant in fluoride salt-cooled high-temperature reactors (FHR), a fuel solvent in molten salt reactors (MSR), and as a tritium breeding blanket in fusion reactors. A fundamental understanding of the chemistry of molten salts is extremely important for advances in these fields. Electrochemical techniques encompass a suite of tools that can be used to probe corrosion mechanisms as well as study the chemical composition and various chemical and physicochemical properties. The tools available to investigate the chemistry of molten salts are limited, however, due to the challenges in instrument design associated with high-temperature operation, material compatibility and chemical stability of all sensor construction materials. Here we report the fabrication and characterization of a thin film sensor for electrochemical analysis of molten fluoride salts. Photolithographic patterning and etching, as well as other standard deposition techniques are used to deposit electrode and supporting materials onto a planar substrate. A typical three-electrode configuration, comprising a working, counter, and quasi-reference electrode, is employed, and incorporation of a fourth auxiliary electrode permits the use of the dynamic reference electrode procedure to provide a common reference potential. Optimized device design and material selection ensure stability of the probe under the demanding chemical and thermal conditions of molten salt systems. By minimizing the required quantity of analyte salt and providing a standardized electrode architecture, this fully integrated device enables high-throughput, reproducible experimentation.
(Keynote) Design of Ultra-High-Sensitive Gas Sensors By Combination of Metal Oxides Semiconductor and MEMS
Authors: Shimanoe Kengo , Suematsu Koichi , Watanabe Ken
Published: December 2020

Ultra-High-Sensitive (UHS) gas detection in ppt level has been proposed by using pulse-heating of MEMS-device based on SnO2. My group reported three important factors, receptor function, transducer function and utility factor, for gas sensor material designs and their integration in 2003 (1) and 2006 (2), respectively. In 2014, based on the integration of the above factors, the gas sensor using Pd-loaded SnO2 clusters prepared by hydrothermal treatment could successfully detect toluene in ppb level (3). To enhance the sensor response more, we investigated the combination of utility factor and pulse-heating of MEMS. The MEMS-type gas sensors are repeatedly heated and allowed to cool by the application of voltage to the micro-heater; the toluene gas penetrates into the interior of the sensing layer (Pd-loaded SnO2 clusters) during its unheated state. In 2018, we reported that such sensor responded to toluene in 0.1 ppb (4). To enhance the sensor response, we paid attention to oxygen adsorption species and the amounts. In the case of Pd-loaded SnO2, oxygen adsorbed as mainly O2- on the surface, but the amounts become smaller with decreasing in temperature. To overcome such oxygen adsorption state, we investigated the preheating and waiting-time before pulse-heating for measurement. Finally, the gas response was found to increase as shown in Fig. 1. It is found that the sensor response depends on the waiting-time between pre-heating and measure-heating. In addition, to apply the UHS gas sensor using MEMS-type for aliphatic compounds such as alcohol, we have investigated a composite material that consists of the perovskite-type oxide (Ba0.9La0.1FeO3-σ) and SnO2 nanoparticles. The obtained results indicated that perovskite type oxide added SnO2 nanoparticles exhibits higher sensor response to C2H5OH than that of pure SnO2. Furthermore, the introducing of the pre-heating before measurement was effective for the sensor response as same as the case of toluene detection. Such sensor operation for composite material enabled the detection of ethanol in ppb level. It seems that the perovskite-type oxide plays a role of oxygen supplier to avoid the situation of oxygen absent or that the perovskite-type oxide works as a partial oxidation catalyst. In the presentation, I will show the design of UHS gas sensor in details.

References

(1) N. Yamazoe, G. Sakai, K. Shimanoe, Catalysis Surveys from Asia, 7(1), 63-75 (2003).

(2) K. Shimanoe, N. Yamazoe, Proc. The 4th AIST International Workshop on Chemical Sensors, pp. 43-51 (2006).

(3) K. Suematsu, Y. Shin, Z. Hua, K. Yoshida, M. Yuasa, T. Kida, K. Shimanoe, ACS Appl. Mater., 6, 5319−5326 (2014).

(4) K. Suematsu, W. Harano, T. Oyama, Y. Shin, K. Watanabe, K. Shimanoe, Anal. Chem., 90(19), 11219-11223 (2018).

Figure 1
Ultra-Stable and Highly Sensitive Co Exsolution Material for Gas Sensing Applications
Authors: Sharma Bharat , Myung Jae-Ha
Published: December 2020

Gas sensors can operate with high performance depending on various ways as stability of sensing material to perform in harsh conditions such as high operating temperature, selectivity, and long-term stability. Conventional metal oxide semiconductors can operate at high temperature with display rapid detection and recovery, an outstanding response at the ppm concentration level. In contradiction, at a high temperature generally leads to a reduction in gas response due to the electron depletion layer (EDL) disappears at the grain boundaries. Thus, investigations on searching appropriate sensing materials for high-temperature sensing application requires more momentous effort. The in-situ metal exsolution have engrossed superior thought as an auspicious tactic to formulate in-situ growth of metal nanoparticles for gas sensing technology due to their high thermal and chemical stabilities that prevent the aging effect. Here we investigated the gas sensing properties of Co exsolved nanoparticle during a wide range of growth by controlling reduction temperature. In metal exsolution, demonstrated in Fig. 1a, a catalytically active metal is implanted into crystal lattice of backbone in oxidizing environments, creating solid solution, and is unconfined (exsolved) on the surface of the nanostructure as metal nanoparticles on exposure to a reduction atmosphere. Form our results, we found that Co ex-solution exhibit high gas response of Ra/Rg 135.1 at operating temperature of 350 °C with high selectivity to acetone gas as presented in Fig. 1b. Our findings suggest that the metal exsolved nanoparticles have potential for achieving high gas response, high selectivity and long-term stability for high temperature sensing applications

Fig. 1 (a) Schematic for in-situ metal exsolution, (b) Evolution of La0.43Ca0.37Co0.06Ti0.94O3-d based sensor, gas response at different operating temperatures

Figure 1
Integrated Micro Total Analysis Systems for Personalized Drug Screening
Authors: Wanzenboeck Heinz
Published: December 2020

We will present a novel sensor concept with 3-dimensional electrodes, that can measure the bioelectronic processes of stem-cell derived human cells.
Optical Characteristics of the Nano-Apertures on the Pyramid
Authors: Choi Seong Soo , Lee Yong Min , Bae Byung Seong , Kim Hyun Tae , Choi Soo Bong
Published: December 2020

Recently there have been tremendous interests for developing the single molecule analysis device. We have previously reported the fabrication of the nanopores and nano-slit pores on the various nanostructures such as the Au-coated pyramid and the flat membrane for optical detection detection device. In this report, we address the fabrication of the various nano-aperture optical platform, and optical characterization of the fabricated devices. For aperture opening less than 50 nm, the strong spp-mediated intraband transmission peak at 500 nm is presented, while for the aperture size greater than 200 nm, the surface plasmonic coupling peaks among the nano-apertures are observed. As an example, we present the optical intensities measured from the various size of the nanopores on pyramid as in figure. The fabricated spp-mediated optical intensites from the optical platform device can be utilized for the next generation optical detection device.

Figure 1
Detecting Alzheimer’s Disease Biomarkers in-Vivo with Near-Infrared Optical Nanosensors
Authors: Antman-Passig Merav , Heller Daniel A. , Frost Georgia , Wong Wan Fang , Agustinus Albert , Chen Ziyu , Mancinelli Chiara , Kamel Maikel
Published: December 2020

Alzheimer’s disease (AD) and other dementias are the 5th leading cause of death globally and pose an increasing global health challenge as the proportions of elderly population increase demographically. Although research aimed at providing treatments has been rigorously ongoing for the past few decades, no curative therapy has been established. Consequently, a focus on the identification of early, presymptomatic stages of the disease offer avenues for optimal timing of preventative treatments. Amyloid beta (Aß) accumulation and self-assembly is a central event in disease pathogenesis, and its use as a biomarker is established for disease prognosis and monitoring. Frontline diagnostic tools for detecting Aß, such as neuroimaging tools (Amyloid PET) and cerebral spinal fluid (CSF) analyses, are vital in classifying AD, yet detecting the early stages of dementia remains an ongoing challenge. High costs, limited availability, adverse effects, risk of complications, and exposure to radioactive isotopes limit the use of current Aß imaging tools to high risk individuals with measurements with limited measurements at short intervals. Therefore, there is a vital need to establish detection technologies that can specifically differentiate Aß burden from early stages and enhance identification of individuals that may progress to develop AD. We have developed a carbon nanotube (CNT) optical sensor that can monitor Aß biomarkers in live samples over time. We have designed and characterized a new class of bio-functionalized, intrinsically photoluminescent CNT sensor that can detect Aß via shifting of their intrinsic near-infrared emission wavelength. Our results show CNT sensors differentiate between AD models in-vitro and in in-vivo.
(Invited) A Protein Corona-Based Design Strategy for Carbon Nanotube Sensors
Authors: Pinals Rebecca , Ledesma Francis , Chio Linda , Landry Markita P
Published: December 2020

Unpredictable protein adsorption on nanoparticles remains a considerable challenge towards effectively applying nanotechnologies in biological environments.1 However, if well understood and controlled, proteins adsorbed on nanoparticles can be exploited to develop protein-based nanosensors.

Herein, we employ our knowledge of spontaneous “protein corona” formation on single-walled carbon nanotubes (SWCNTs) in biofluids towards rational nanosensor design based on protein-SWCNT complexation.2 SWCNTs are implemented as the sensor platform due to their desirable optical and physical characteristics, including photostable fluorescence in the near-infrared tissue transparency window3 and high aspect ratio that confers delivery capabilities.4 We functionalize carbon nanotubes with proteins that, in turn, bind to their natural ligand partners. The adsorbed protein thus acts as the recognition moiety that interacts with the environment and detects the analyte of interest, tethered to the SWCNT that serves as the signal transducer. This nanosensor platform combines the sensitive and selective binding capabilities of proteins for their ligand partners with the near-infrared fluorescence readout of SWCNTs that is modulated upon protein-ligand binding. In this manner, we demonstrate that although formation of the nanoparticle protein corona can impede the intended nanobiotechnology application, it also presents an opportunity to create improved protein-nanoparticle architectures by manipulating selective protein adsorption on the nanoparticle surface.

References

Pinals, R. L. et al. Protein Corona Composition and Dynamics on Carbon Nanotubes in Blood Plasma and Cerebrospinal Fluid. bioRxiv 2020.01.13.905356 (2020) doi:10.1101/2020.01.13.905356.

Pinals, R. L., Yang, D., Lui, A., Cao, W. & Landry, M. P. Corona Exchange Dynamics on Carbon Nanotubes by Multiplexed Fluorescence Monitoring. J. Am. Chem. Soc.
142, 1254–1264 (2020).

Boghossian, A. A. et al. Near-Infrared Fluorescent Sensors based on Single-Walled Carbon Nanotubes for Life Sciences Applications. ChemSusChem
4, 848–863 (2011).

Demirer, G. S. et al. High aspect ratio nanomaterials enable delivery of functional genetic material without DNA integration in mature plants. Nat. Nanotechnol.
14, 456–464 (2019).
A Green Route for Preparation of Nickel-Vanadate-Nanoparticles as Negative Electrode for Rechargeable Lithium-Ion Batteries
Authors: Zulkifli Z. , Sambandam Balaji , Islam Saiful , Kim Seokhun , Kim Jaekook
Published: December 2020

A low-cost for large-scale production, it is still a big challenge for high capacity and good cycling ability of anode materials. Herein, we approve a facile green route to synthesize nickel-vanadate (Na3V2O8) nanoparticles (NPs) using an inexpensive universal solvent, water. An intermediate precipitate of Ni-V-ZIF (Zeolitic Imidazolate Framework) was obtained, which transformed into phase pure Ni3V2O8 NPs by slow annealing process in air, without affecting the original morphology. As an anode material for Li-ion batteries (LIBs), the Ni3V2O8 NPs with uniform spherical shapes can provide an extraordinary retained capacity of 1024 mA h g-1 after 525 cycles, at the current densities of 2 and 0.5 A g-1, which were alternated for every 100 cycles. Additionally, the electrode showed stable specific capacities of 940 and 305 mA h g-1 at 1 and 5 A g-1, respectively after 400 and 1000 cycles. Thus, the fine Ni3V2O8 NPs-based anode can withstand high current densities, indicating that this facile green route revealed an economically applicable and efficient preparation for the large-scale production of nanostructured-electrode materials for high energy density rechargeable batteries.
Development of Flame Retarding Separator for Lithium Ion Battery By Crosslinkable Binder Coating
Authors: Roh Youngjoon , Jeon Hyunkyu , Jin Dahee , Ryou Myung-Hyun , Lee Yong Min
Published: December 2020

Conventional polyolefin separators undergo thermal shrinkage under abnormal conditions such as overcharging and overheating, and this may induce catastrophic thermal runaway in LIBs, resulting in gas venting, fire, rupture, or explosion. Ceramic-coated separators (CCSs) have been widely used because inorganic materials with high heat resistance protect the polyolefin surface to prevent thermal shrinkage of the separator. However, without the use of highly adhesive and thermally stable polymeric binders, the ceramic coating layer is incapable of functioning properly to maintain the thermal stability of the CCSs when exposed to heat.

As one method for securing the thermal stability of the separator, we propose crosslinking of the binder in the ceramic coating layer. This study presents a thermally stable crosslinkable silsesquioxane-based ceramic-coated separator (x-CCS) with flame-retarding capabilities for the fabrication of safe Li-ion batteries. The binder used for crosslinking is ePOSS (inorganic polyhedral oligomeric silsesquioxane with epoxy functional end groups) with high thermal stability, which can form crosslinks with each other through UV irradiation. The x-CCS was fabricated by applying a 3 μm thick composite layer of Al2O3/ePOSS/PVdF-HFP to both sides of a conventional polyethylene separator. This remarkably improved the thermal stability of the separator at 140°C, with the original form of the separator maintained even after an ignition test. Because ePOSS, which has high thermal stability, is crosslinked like a net in the coating layer and maintains its shape after combustion. Although the permeability of the CCS was slightly decreased by the applied coating, the resultant improved wettability towards liquid electrolyte thereby enhancing the ionic conductivity, cycle performance, and rate capability when used in a Li-ion battery.
All-MXene 3D Aerosol-Jet Printed Microsupercapacitors
Authors: Spurling Dahnan , Kremer Matthias Peter , Coelho João , Zhang Chuanfang (John) , Nerl Hannah , McEvoy Niall , Nicolosi Valeria
Published: December 2020

The Internet of Things (IoT) promises users a wider gamut of features and enhanced ease-of-use for devices in both professional and domestic settings. For such devices to have a future however, they will require compact energy storage, especially considering the widespread abandonment of cables in electronic devices for both power and data transfer. One possible answer to this requirement are micro-supercapacitors (MSCs), specifically those based on the MXene Ti3C2Tx, which has been well established as a material for supercapacitors owing to its high capacitance, cycling stability and conductivity.1 Specifically, the creation of Ti3C2Tx supercapacitors via printing techniques such that energy storage can be directly incorporated into the structure of electronics is very appealing and an area of much recent study.2,3 A plurality of these printing techniques have produced planar supercapacitors consisting of a dense MXene film which, while highly conductive, has a limited surface area for intercalation and ion transport.4 These planar devices also have intrinsically inferior space efficiency in real-world electronics. To address this issue, very recent studies have demonstrated 3D printing of nanomaterial-based supercapacitors, however these have been achieved using composites5 or post-processing steps such as freeze-drying.6 In this work, we show that aerosol-jet printing (AJP) of aqueous Ti3C2Tx inks can be used to directly fabricate high aspect ratio 3D structures up to 1 mm in height and with feature sizes as small as 20 µm. These can be realised without the aid of any supporting structures and in a wide range of geometries such as walls, pillars and pyramids. No post-processing is necessary, as only aqueous dispersions are used, without the need for additives, binders or additional drying steps. When such 3D features are integrated into symmetric interdigitated MSCs with gel electrolyte, the 3D structured electrodes exhibit 29% higher areal capacitance than comparable, mass-equivalent planar electrodes, up to 33 mF/cm2 at 10 mV/s.

Figure 1 shows the comparison between 2D (top row) and 3D (bottom row) Ti3C2Tx MSCs of equivalent mass. Cyclic voltammograms show a 29% increase in areal capacitance for the 3D device, 33 mF/cm2 at 10 mV/s. The difference in geometry between the two devices is evident in the low and high magnification SEM images, of particular note are the uniform 3D Ti3C2Tx pillars with height and diameter of approximately 300 µm and 20 µm, respectively.

References:

[1] B. Anasori et al., Nat. Rev. Mater., 2017, 2, 2

[2] C. J. Zhang et al., Adv. Funct. Mater., 2018, 28, 9

[3] C. J. Zhang el al., Nat. Commun., 2019, 10, 1

[4] Y. Xia et al., Nature, 2018, 557, 7705

[5] Z. Wang et al., ACS Appl. Mater. Interfaces, 2018, 10, 10437–10444

[6] W. Yang et al., Adv. Mater., 2019, 1902725, 1

Figure 1
A Robust Computational Framework for High-Throughput Density Functional Theory Calculations for Electrochemical Applications
Authors: Spotte-Smith Evan Walter Clark , Blau Samuel M , Wood Brandon , Dwaraknath Shyam , Persson Kristin A.
Published: December 2020

High-throughput density functional theory (DFT) calculations are now commonly employed to screen materials for diverse applications and to populate databases of molecular properties. More recently, high-throughput DFT has been used to generate computational reaction networks for the analysis of reactive pathways. The automation of DFT calculations related to electrochemical systems has thus far been limited. Geometry optimization and SCF convergence are inherently more difficult when considering charged and open-shell molecules, coordinated metal ions, and solvated species, all of which are critically important for studies involving liquid-phase electrochemical environments such as those found in batteries. In addition, the chemical complexity of such species necessitates advanced levels of theory. We present a framework to automate the calculation of fully-optimized molecular geometries and molecular thermodynamic properties (enthalpy, entropy, and free energy) for molecules representing all the above challenges, including radical, charged, metal-coordinated, and solvated species. Our framework leverages the pymatgen,[1] fireworks,[2] custodian, and atomate[3] libraries to prepare, execute, and process electronic structure calculations using the Q-Chem DFT code.[4] Through benchmarking studies, we have identified appropriate methods for use in electrochemical environments, including an accurate density functional, basis set, and implicit solvent model. We have also implemented algorithms to correct common issues such as SCF convergence failures, geometric optimization to a non-minimal stationary point on the potential energy surface (a saddle point), and many more. In general, even when using an appropriate level of theory, 25% of calculations fail in some way without additional error correction. Our framework, using our suggested parameters and a suite of on-the-fly error handlers, converges to a minimum energy structure and calculates the molecular thermodynamic properties successfully in over 97% of cases. Individual calculations using our framework can be combined to perform complex workflows in a fully automated fashion. To date, we have applied this framework to over 25,000 unique molecules relevant to the formation of solid-electrolyte interphases in Li-ion and Mg-ion batteries.

[1] S. P. Ong et al., Computational Materials Science, 68, 314–319 (2013).

[2] A. Jain et al., Concurrency and Computation: Practice and Experience, 27(17), 5037-5059 (2015).

[3] K. Mathew et al., Computational Materials Science, 139, 140-152 (2017).

[4] Y. Shao et al., Molecular Physics, 113(2), 184-215 (2015).

Figure 1
Factors Affecting on Electrochemical Properties of O3-Type NaFeO2 for Sodium Ion Batteries
Authors: Kobayashi Tokio , Yabuuchi Naoaki
Published: December 2020

LiCoO2 is generally used as a positive electrode material for lithium ion batteries. However, the abundance of cobalt in the Earth’s crust is limited to be less than 100 ppm, and therefore cobalt is expensive element. Iron-based electrode materials would be attractive as positive electrode materials for battery applications because iron is the most abundant transition metal ion. However, as a counterpart of LiCoO2, layered LiFeO2 is electrochemically inactive.[1] In contrast, layered NaFeO2 is electrochemically active, but cyclability is not enough associated with the irreversible structural change upon charge.[2, 3] In this study, we examine different factors affecting the electrode properties of NaFeO2 and discuss possibility as the positive electrode material for sodium ion batteries.

O3-type NaFeO2 was prepared by solid-state reaction from stoichiometric amount of Na2O2 and Fe2O3 as described by Takeda et al.[4] These starting materials were mixed using a mortar and pestle in an argon-filled globe box, and then pressed into a pellet. The pellet was heated at 650 oC for 12 h in O2. After the sample was prepared, the sample was mixed with acetylene black (NaFeO2: acetylene black = 90: 10 wt%) by using the planetary ball mill.

Figure 1 shows the XRD patterns and SEM images of O3-type NaFeO2 before and after mixing with acetylene black (denoted as as-prepared and carbon-composite NaFeO2, respectively). The as-prepared sample crystallizes into an O3-type layered structure as previously reported, and, from the XRD patterns, no change in the structure is found after milling with carbon. However, the particle size of the sample is clearly reduced by milling with carbon. Charge/discharge curves of O3-type NaFeO2 before and after milling with carbon are compared in Fig 2. A voltage profile of the as-prepared sample with a well-defined voltage plateau at 3.3 V is similar to that of the previous reports, and capacity degradation on electrochemical cycles is clearly observed. In contrast, carbon-composited NaFeO2 delivers a reversible capacity of over 100 mA h g-1 with much improved capacity retention.

From these results, we will discuss factors affecting electrode reversibility of O3-type NaFeO2 and possibility of rechargeable batteries made from only abundant elements.

References

[1] K. Ado et al., J. Electrochem. Soc.,
144, L177 (1997).

[2] S. Okada et al., ESC Meeting Abstract,
602, 201 (2006).

[3] N. Yabuuchi et al.,
Electrochemistry,
80, 716 (2012).

[4] Y. Takeda et al., Mater. Res. Bull.,
15, 1167 (1980).

Figure 1
Graphene Mobility Dependence on the Resistivity of Si Wafer
Authors: Ravichandran Arul , Cheng Lanxia , Lucero Antonio Tomas , Lee Jaebeom , Young Chadwin D , Venugopal Archana , Polley Arup , Colombo Luigi , Kim Jiyoung
Published: December 2020

Graphene field effect transistors (GFETs) are typically benchmarked based on their field effect mobility. Constant mobility model proposed by Kim1
et.al is extensively used to derive this mobility parameter by directly fitting the transfer curves of graphene devices. Various methodologies were suggested to supplant and improve this existing mobility model. Among them Zhang2
et.al suggested the need for using measured gate oxide capacitance in order to extract mobility for top-gated GFETs. One of the commonly overlooked features, in the case of back gated GEFTs is the dopant concentration or the resistivity of Si substrate used. Herein, we explore the dependence of graphene carrier mobility on the induced carrier concentration and depletion capacitance of underlying Si substrate. Si with resistivities 0.01-0.02 Ω-cm and 0.001-0.005 Ω-cm were used to grow 10 nm thermal SiO2. GFETs were fabricated using CVD graphene on top of this thermal oxide substrate and the corresponding transfer curves are co-related with the capacitance density measured from corresponding MOSCAP structure. Detailed carrier mobility extraction and results are presented.

(1) Kim, S.; Nah, J.; Jo, I.; Shahrjerdi, D.; Colombo, L.; Yao, Z.; Tutuc, E.; Banerjee, S. K. Realization of a High Mobility Dual-Gated Graphene Field-Effect Transistor with Al2O3 Dielectric. Appl. Phys. Lett.
2009, 94 (6). https://doi.org/10.1063/1.3077021.

(2) Zhang, Z.; Xu, H.; Zhong, H.; Peng, L. M. Direct Extraction of Carrier Mobility in Graphene Field-Effect Transistor Using Current-Voltage and Capacitance-Voltage Measurements. Appl. Phys. Lett.
2012, 101 (21). https://doi.org/10.1063/1.4768690.
Reversible Redox Behavior of Quinone-Based Molecule with Activated Carbon Slurry Electrode
Authors: Suzuki Keisuke , Takimoto Daisuke , Hideshima Sho , Sugimoto Wataru
Published: December 2020

The energy density of carbon-based electrochemical capacitors can been improved by grafting electroactive quinone-based molecules.1 The improvement in energy density of the quinone-grafted carbon electrode is attributed to both the redox capacitance of the electroactive molecules and the electrical double layer capacitance of activated carbon. The redox reaction of the quinone-grafted carbon electrodes at high scan rate typically shows quasi-reversible behavior, suggesting rather sluggish charge transfer. In this study, to understand the redox behavior of electroactive molecules in various environments, we investigated the electrochemical properties of activated carbon slurry electrode with electroactive molecules dissolved in the electrolyte (Scheme 1). The behavior of the electroactive molecules was investigated in terms of the pore size, the surface functional group, and specific surface area of activated carbon.

The electrochemical measurements were conducted using a three-electrode cell. A glassy carbon electrode (6 mm in diameter) was used as the working electrode. 4,5-dihydroxy-1,3-benzenedisulfonic acid (BQDS) was used as the electroactive molecule. Activated carbon (AC, average pore diameter = 0.8 nm) was dispersed in n mM BQDS + 0.5 M H2SO4 electrolyte (n = 1, 3, 10, 100 mM).

Cyclic voltammograms show that the ΔE of BQDS dissolved in H2SO4 (1 mM BQDS + H2SO4 | GC) was 345.5 mV at a scan rate of 20 mV s-
1 (Fig. 1a). By adding activated carbon into the electrolyte (1 mM BQDS + AC-dispersed H2SO4 | GC), the peak to peak potential difference ΔE of AC dispersed 1 mM BQDS + 0.5 M H2SO4 | GC was only 3.4 mV at a scan rate of 20 mV s-
1, which is a signature of a fast surface redox reaction (Fig. 1b). The reversibility of the redox reaction was clearly observed when the BQDS concentration was 1-10 mM, while a quasi-reversible reaction was observed when the BQDS concentration was 100 mM (Fig. 1c). The results suggest that the fast surface redox behavior of BQDS is observed only when the BQDS concentration in the electrolyte is low, i.e. below 100 mM BQDS.

AC with various pore sizes was also studied. Fast surface redox behavior was obtained when AC rich with the micropores (pore size < 1 nm) were used even without grafting treatment. The result suggests that the BQDS is trapped in micropores via interaction in confined pores and is responsible for the fast redox reaction.2
,
3

G. Pognon, T. Brousse and D. Bélanger, Carbon , 49, 1340 (2011).

Y. Hanzawa, T. Suzuki and K. Kaneko, Langmuir, 10, 2857 (1994).

K. Kaneko, R. F. Cracknell and D. Nicholson, Langmuir,
10, 4606 (1994).

Figure 1
Multi-Functional Edible Oil-Impregnated Nanoporous Oxide Films of Stainless Steel
Authors: Lee Junghoon , Kang Minjoo , Moon Hyoung-Seok
Published: December 2020

Water-repellent surface provides various functionalities, such as anti-/de-icing, anti-corrosion and anti-biofouling, thus the surface can be used from industrial fields to our daily life. Especially, oil-impregnated porous surfaces have been realized on wide range of commercial materials, due to their exceptional repellency to liquids. However, the oil-impregnated surfaces have used perfluorinated oil and fluorocarbons, which cause issued in human body and environment. Therefore, alternative technology with safe materials to human body and environments is required for the functionalizing of metallic materials. In this study, we employed edible oil as a lubricant being impregnated in porous surface structure on stainless steel, which is one of the most valuable metallic materials used in various application fields. Moreover, a stearic acid treatment for hydrophobizing of nanoporous oxide of stainless steel is used as alternative of fluorocarbon coatings for better affinity between porous surface and lubricant. Due to the edible oil-impregnation and stearic acid treatment, the exceptional repellency to water was realized on the nanoporous oxide of stainless steel. Therefore, the surface shows significantly enhanced anti-/de-icing and anti-corrosion property with self-healing and cleaning capability
Growth and Film Properties of Plasma-Enhanced and Thermal Atomic-Layer-Deposited Magnesium Oxide Films Using Bis(ethylcyclopentadienyl)Magnesium Precursor
Authors: Kang Wangu , Choi Byung Joon , Han Jeong Hwan
Published: December 2020

As the device scaling of dynamic random access memory continues, the demand for the development of new dielectric film with high permittivity and low leakage current that may replace the currently used ZrO2/Al2O3-based dielectric film has increased drastically. In this aspect, MgO thin film has been spotlighted due to its high band gap (7-8 eV) and moderate dielectric constant (9-10).

In this study, we investigated the growth behavior and film properties of the MgO ALD film using Mg(EtCp)2 precursor and the different reactants of H2O and O2 plasma. MgO thin films were deposited at the temperature range of 200-400°C, and the self-limited surface reaction was observed to secure optimal growth conditions. Glancing angle X-ray diffraction and X-ray photoelectron spectroscopy were used to examine crystalline structure and chemical properties, respectively. To evaluate the electrical characteristics of the MgO films, the Pt/MgO/TiN capacitor was fabricated with different MgO thicknesses at various deposition temperatures. The electrical characteristics such as dielectric constant and leakage current density of the MgO film were examined depending on the reactants, and the leakage current conduction mechanism of the MgO thin films was elucidated.

Figure 1