bluuebunny/crossref_metadata_2025 huggingface dataset:
Surfactant Ionic Liquids for Supercapacitors
Authors: Xu Ningjin , Klein Jeffrey Michael , Huang Phoebe , Gurkan Burcu
Published: February 2020

Supercapacitors are electrochemical energy storage devices that find use in many electronic devices as well as increased application in large high-power requirement devices. The primary advantages of using a supercapacitor are the fast charge/ discharge rates and the long cycling lifetime. Traditionally supercapacitors have utilized organic or aqueous electrolytes both of which introduce significant drawbacks. For example, organic electrolytes are flammable which creates safety considerations that need to be addressed while aqueous electrolytes are limited to the electrochemical stability of water (1.23 V). Ionic Liquids (ILs) are a growing class of electrolyte that offer increased thermal and electrochemical stability over standard electrolytes. Additionally, ILs are non-flammable and are non-volatile, eliminating the possibility of flammable devices. Despite the advantages of IL electrolytes, they are highly viscous and do not easily access the pores of the electrode material in supercapacitors. Most commonly, high surface area carbon is used as supercapacitor electrodes but is only effective if the pores are filled with electrolyte. It is expected that successful wetting of the electrode surface will make IL electrolytes competitive with the current state of the art. Here, new surfactant ILs are synthesized and assessed as the electrolyte in supercapacitors containing porous carbon electrodes.

The physical properties of ILs can be tailored by modification of the anion and cation structures. Here, a mixture of surfactant ILs was used as the electrolyte which is shown to offer enhanced capacitance over the parent ILs. Each surfactant IL was synthesized in house and characterized through NMR, TGA, as well as viscosity and conductivity measurements. Capacitance, calculated from the integration of cyclic voltammograms, is shown to depend on the concentration of each IL and temperature, which is attributed to the changes in viscosity and conductivity of the mixture. Improved capacitance in supercapacitors with porous carbon electrodes can be related to lower surface tension and increased wettability of the porous electrodes the surfactant IL additive. In addition we demonstrate a significant thermal operating window of the proposed electrolyte.
(Keynote) Pyrochemical Process in Molten Salts for Spent Nuclear Fuel Reprocessing and Radioactive Waste Treatments
Authors: Fujita Reiko
Published: February 2020

The pyrochemical process in molten salts for spent nuclear fuel reprocessing and radioactive waste treatment has been developed since 1988. The pyrochemical process for metallic fuel reprocessing has been started using electrorefining. The electrowinning for spent oxide fuel in molten salts has been developed since 1994. The radioactive waste treatment such as metallic waste contaminated by uranium and chemical trap materials in uranium enrich plant, zirconium recycle for spent zircaloy waste from Light Water Reactors was based on the spent nuclear fuel reprocessing. A treatment process for fuel debris in Fukushima Daiichi Nuclear Power Plant recently has been developing. This paper reviews pyrochemical process for spent nuclear fuel reprocessing and radioactive waste treatment.
Photoelectrochemical and Impedance Spectroscopy Investigation of Water Oxidation Reaction over Coordination Polymers Decorated TiO2 Nanotubes Arrays Electrodes
Authors: Rosas-Barrera Kevin Leandro , Pedraza Julio Andrés , Reguera Edilso , Acevedo-Peña Prospero
Published: February 2020

Loading a cocatalyst onto a photoelectrodes is a wide spread strategy to enhance the efficiency of the photoelectrochemical water splitting process [(Yang, Wang, Han, & Li, 2012)]; however, its performance is strongly dependent of the method employed to form the heterojunction between cocatalyst and photoelectrode, as well as the alignment of their energetic levels to separate successfully the photogenerated charge carriers. In this study, we report water splitting photoanodes constituted from TiO2 nanotubes arrays decorated with coordination polymers as cocatalyst. Highly ordered TiO2 nanotubes were synthesized by the electrochemical anodization process of titanium (Ti) foil in a 0.2 M NH4F, ethylene glycol/10% H2O electrolyte under constant anodization time and applied potential. Coordination polymers were deposited onto TiO2 nanotubes by using the low cost successive layer adsorption and reaction (SILAR) method. Cocatalyst was successfully deposited on TiO2 nanotubes with tunable loading amounts by controlling the deposition cycles of SILAR. The structural characterization, morphology, elemental composition and light absorption capability of the samples were characterized by XRD, RAMAN, FT-IR, FE-SEM, EDX and UV–Vis methods respectively. Furthermore, the semiconducting properties of the modified TiO2 nanotubes were also estimated from Mott-Schottky plots. It was found that under illumination, the cocatalyst can efficiently collect photogenerated holes from the TiO2 nanotubes electrodes promoting charge separation and lowering the onset potential which yields an increased water oxidation efficiency.

Yang, J., Wang, D., Han, H., & Li, C. (2012). Roles of Cocatalysts in Photocatalysis and Photoelectrocatalysis. Accounts of Chemical Research, 46(8), 1900–1909. https://doi.org/10.1021/ar300227e
Plasmon-Directed Photocatalytic Deposition of Platinum Onto Gold Nanorods Via Hot Electrons
Authors: Forcherio Gregory T. , Boltersdorf Jonathan , McClure Joshua P. , Leff Asher C , Baker David R , Lundgren Cynthia A.
Published: February 2020

Targeted, reductive photodeposition of catalytic metals via plasmonic hot electrons excited on an electrode is a promising, economical approach to manufacturing plasmon-sensitized photoelectrodes for catalysis applications. This work examines liquid-phase, anisotropic photodeposition of Pt(0) co-catalysts from chloroplatinic acid, Pt(IV), onto suspended Au nanorods under localized surface plasmon (LSP) excitation. Photochemical Pt(0) nucleation is initiated by plasmonic hot electrons, which migrate to the Au surface according to the plasmon polarity. In situ, time-resolved absorbance monitoring of the photochemical reaction elucidated Au nanorod surface functionalization with Pt(IV), Pt(0) growth kinetics under Au LSP excitation, and the evolving light-matter interactions. Energy dispersive spectroscopy (EDS) mappings show preferential Pt(0) deposition on the Au nanorod ends, consistent with the laser-induced LSP dipoles. Discrete dipole approximation (DDA) of Maxwell’s equations corroborated measured optical responses and allows a priori design of hot electron energetics. Electronic valence band structure of the Pt-functionalized Au nanorod was measured by x-ray photoelectron spectroscopy (XPS) and calculated by density functional theory (DFT) to enumerate the energy distribution of carriers accessible for surface chemistry. Together, these techniques and analyses accelerate development of plasmon-sensitized photoelectrodes for solar fuel generation.

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Stable Hydrogen Generation from Copper/Titanium Oxide Heterogeneous Photocatalyst: A Confined Material Preparation Approach
Authors: Zhang Xiao LI
Published: February 2020

Possessing exceptional properties, such as suitable band edges for redox reactions, environmental friendliness, low cost, availability, as well as long-term stability against photo- and chemical-corrosion, further modification of titanium oxide with heterogeneous structure has drawn considerable attention in today’s development of high efficiency photocatalysts toward efficient hydrogen generation. In contrast to precious noble metals, e.g. Pt and Au, earth abundant copper based materials have proven to be capable alternatives. Relevant researches mainly focused on the preparation of copper oxides modified titanium oxide with only very limited attention on metallic copper. The most widely used conventional preparation approach, wet-impregnation, has shown difficulties in achieving a fine dispersion for a high population of small particles. In the present work, we demonstrate a new synthesis strategy, layered-titanate mediated preparation for high efficiency copper-modified titanium oxide photocatalysts that exhibit a hydrogen generation efficiency excess that of copper-modified P25 titanium oxide prepared through wet-impregnation for over 40%.
N-Doped TiO2/CdS Nanohybrid System for Photocatalytic Degradation of 4-Chlorophenol
Authors: Kierulf-Vieira Walace Peterle Soares , Aragon Alexander Gennadivich , Lecki Tomasz , Widera Justyna , Skompska Magdalena
Published: February 2020

Titanium dioxide (TiO2) is a semiconductor widely used for photocatalytic applications. Its most notable limitation is a wide optical bandgap (Eg~3.2 eV) that restrains its functionality to UV-irradiation (1). One way to solve this issue involves doping of TiO2 with nitrogen and/or coupling with a narrow bandgap semiconductor, such as cadmium sulfide (CdS; Eg~2.42 eV). However, during the process of photocatalysis, CdS undergoes photocorrosion contaminating the water source (2). Common means of fixing this issue involve the use of hole scavengers, such as S2- ions. In this work, we present a new alternative involving the use of a thin layer of poly(1,8-diaminocarbazole) (PDACz) as a protective agent against CdS photocorrosion. The hybrid system was fabricated by depositing N-TiO2 on a fluorine doped tin oxide plate via sol-gel, CdS nanoparticles were deposited via SILAR method, and a thin PDACz film was deposited on the surface of the CdS nanoparticles. The prepared hybrid was characterized by x-ray photoelectron spectroscopy (XPS) and energy dispersive x-ray spectroscopy. It was found that the cadmium/titanium ratio in the hybrid was 0.135 to 1. The N-TiO2/CdS/PDACz hybrid system had a bandgap of 2.26 eV, as found via UV-vis spectroscopy. In studying the photodegradation of 4-chlorophenol, the reaction rate constant was 72% higher when applying the hybrid as catalyst compared to bare TiO2. These findings indicate that the N-TiO2/CdS/PDACz hybrid system may be a suitable option for future practical applications.

Chen, S. S. Mao, Chem. Rev., 107 (2) (2007) 2891-2959

Yamada, A. Y. Nosaka, Y. Nosaka, Journal of Electroanalytical Chemistry, 585 (1) (2005) 105-112
Modified Bismuth Vanadate Photoelectrodes for TEMPO-Mediated Oxidation of 5-(Hydroxymethyl)Furfural
Authors: Chadderdon David J , Wu Ivy , Panthani Matthew G , Li Wenzhen
Published: February 2020

Integrating photoelectrochemical biomass upgrading and hydrogen production is a promising route for sustainable energy conversion and chemical production. In this presentation, we report bismuth vanadate (BVO) photoanodes modified with cobalt phosphate (CoPi) to facilitate TEMPO-mediated oxidation of 5-(hydroxymethyl)furfural (HMF). Tuning CoPi electrodeposition time enabled the preference for TEMPO oxidation or oxygen evolution reaction (OER) to be tailored. Photoanodes optimized for TEMPO oxidation decreased the required potential by 500 mV and increased charge injection efficiency by seven-fold compared to BVO, while also suppressing undesired OER. Using transient photocurrent measurements, we revealed that the back-reduction of oxidized TEMPO was detrimental to BVO photocurrents. We propose that the role of CoPi for enhancing TEMPO oxidation photocurrents was to suppress the back-reduction, rather than to directly accelerate TEMPO oxidation. TEMPO-mediated oxidation of HMF with BVO/CoPi achieved 88% yield to 2,5-furandicarboxylic acid (FDCA), an important biobased polymer precursor, under mild conditions. In contrast, <1% FDCA was generated with BVO under identical conditions. These findings will promote the development of more efficient photoelectrochemical devices for biomass upgrading and renewable energy conversion in the future.
(Invited) Interaction of Anions with Partially Oxidized Carbon Nanotubes and the Influence on the Performance of Polypyrrole-Carbon Nanotube Composite Electrodes
Authors: Wei Chaohui , Akinwolemiwa Bamidele , Yu Linpo , Hu Di , Xia Lan , Chen George Zheng
Published: February 2020

Partial oxidation of carbon nanotubes (CNTs) in mixed HNO3 and H2SO4 is commonly used for the preparation of polymer-CNT composites. This procedure, however, emits toxic NOx fumes, making it difficult for commercial scale-up. Herein we report an environment-friendly new method which utilizes mixed H2O2 and H2SO4 to partially oxidize CNTs to produce composite electrodes with polypyrrole (PPy). With the aid of Raman, Fourier Transform Infrared, and X-ray photoelectron spectroscopic techniques, the physiochemical properties of the CNTs prepared from H2O2 aided oxidation were compared with those CNTs treated in HNO3 aided oxidation. Furthermore, through cyclic voltammetry, electrochemical impedance spectroscopy, and electrochemical quartz-crystal microbalance, the interaction of the doping anions (Cl-, SO4
2-, etc.) with partially oxidized CNTs were studied and used to explain the performance of different PPy-CNT composites. Results showed that the capacitance of the composite with CNTs treated by H2O2 aided oxidation (ca. 156.0 F/g) was comparable to that with CNTs treated by HNO3 aided oxidation (ca. 163.0 F/g). Furthermore, the need for critically appraising the charge storage mechanism on the carbons used in making the PPy-CNT composites is emphasized, and general observations that various oxygen containing functional groups could contribute in different ways to the observed charge storage mechanism of both the oxidized CNTs and their corresponding polymer composites were also explained. It can thus be predicted that the H2O2 aided partial oxidation of CNTs is suitable for producing high performance polymer composite electrodes, and the new process is promising for commercial scale-up with low environmental impact.

REFERENCES

Zhou X, Peng C, Chen GZ. 20 V stack of aqueous supercapacitors with carbon (−), titanium bipolar plates and CNT‐polypyrrole composite (+). AIChE journal. 2012;58(3):974-83.

Chen GZ, Shaffer MS, Coleby D, Dixon G, Zhou W, Fray DJ, et al. Carbon nanotube and polypyrrole composites: coating and doping. Advanced Materials. 2000;12(7):522-6.

Peng C, Zhang S, Jewell D, Chen GZ. Carbon nanotube and conducting polymer composites for supercapacitors. Progress in Natural Science. 2008;18(7):777-88.

Frackowiak E, Khomenko V, Jurewicz K, Lota K, Béguin F. Supercapacitors based on conducting polymers/nanotubes composites. Journal of Power Sources. 2006;153(2):413-8.

Khomenko V, Frackowiak E, Beguin F. Determination of the specific capacitance of conducting polymer/nanotubes composite electrodes using different cell configurations. Electrochimica Acta. 2005;50(12):2499-506.

ACKNOWLEDGEMENT: This work received funding from the International Doctoral Innovation Centre, Ningbo Education Bureau, Ningbo Science and Technology Bureau, and the University of Nottingham, and Ningbo Municipal Government (3315 Plan and 2014A35001-1).

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(Keynote) 3-D Customized and Electrically Conducting Polymer Based Skin Mapping for the Clinical Treatment of Skin
Authors: Lisak Grzegorz , Fu Xiaoxu , Ramírez-Pérez Ana C. , Zeng Wenqiu
Published: February 2020

The conducting polymers are chemically versatile functional materials that are used widely in energy, biomedical and sensors applications [1-3]. Interestingly, conducting polymers were also explored for the use in imaging as for the recovery of the fingerprints from the metallic surfaces [4, 5].

In this work we further exploration on the use of the conducting polymer, namely PEDOT:PSS, for the purpose of customized skin mapping was performed. An ex-situ and an in-situ 3-D and electrically conducting mapping of the skin topography via electropolymerization of conducting polymer on previously sampled skin stamp or directly on an alive human subject skin (Figure 1) were performed here for the intention to be further used in biomedical applications, e.g. wound and scar healing.

The developed off-body and on-body skin patterns were evaluated for their 3-D nature/topography using AFM, for their morphology using SEM and for their conductivity using electrochemical methods. We have shown that the direct electropolymerization of skin features on alive human skin was possible and may be applied if purely non-toxic set of compounds is used to produce 3-D and electrically conducting skin patterns. For that, the electrochemistry of skin pattern polymerization was performed in custom layered electrochemical cell which opens new possibilities and designs of conducting electrochemical experiments and application of the new electrochemical cell

Figure 1. Scheme of on-body, direct electropolymerization on alive human skin featuring high-resolution camera picture of developed 3-D and electrically conducting skin pattern.

References:

Bobacka, Electroanalysis, 2006, 18, 7-18.

K. Wagner, L.L. Crowe, P. Wagner, S. Gambhir, A.C. Partridge, J.C. Earles, T.M. Clarke, K.C. Gordon, and D.L. Officer, Macromolecules, 2010, 43, 3817–3827.

Mawad, E. Stewart, D.L. Officer, T. Romeo, P. Wagner, K. Wagner and G.G. Wallace, Adv. Funct. Matt. 2012, 22, 2692-2699.

M. Sapstead, K.S. Ryder, C. Fullarton, M. Skoda, R.M. Dalgliesh, E.B. Watkins, C. Reebee, R. Baker, A. Glidle and A.R Hillman, Faraday Discuss., 2013,164, 391-410.

M. Sapstead, N. Corden and A.R. Hillman, Electrochim. Acta, 2015, 162, 119-128.

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Charge Propagation in Redox-Conducting Materials: Diagnosis of Mechanisms and Dynamics with Microelectrochemical Devices
Authors: Kulesza Pawel J. , Rutkowska Iwona Agnieszka
Published: February 2020

Historically, electrochemistry in the absence of a bulk liquid phase has focused on the problems of energy storage and production. Recently, it has become possible to apply conventional electrochemical methods to characterize solid-state type redox electrolytes with respect to analytical characterization of materials, measurement of electron transfer rates, and determination of analytes using amperometric sensing. The characterization of materials by solid-state voltammetry primarily has focused on mixed-valence, ionically conducting compounds and on diverse organic ionomers hosting identifiable molecular (redox) sites.

We are going to address practical issues related to the principles and analytical aspects of electrochemical studies (typically done at room temperature) of solid, rigid or semi-rigid (nonfluid) systems in the absence of a liquid solution phase. Representative examples include redox and conducting organic polymers, melts and solid solutions of redox centers in solid ionic conductors, mixed-valence polynuclear inorganic materials, transition metal salts, oxides, and zeolites. The emphasis is on the elements of dynamics for the efficient delivery of charge and on reactivity of the ‘redox conducting’ materials. The effective (apparent) diffusional mechanism is critical to the success of most analytical measurements in solid-state.

The potential materials for solid-state electrochemical measurements are expected to contain three-dimensionally distributed highly concentrated redox centers between which fast electron self-exchange (hopping) is feasible. These redox centers are fixed and, although they may have short range mobility about an equilibrium position, they classically are macroscopically immobile. The applicable materials also must host mobile counter-ions that are capable of providing charge balance during electron transfers, thereby serving the same purpose as the supporting electrolytes in conventional electrochemistry. The population of these ions must be sufficient to support diffusive mass transport of electrons and to minimize ohmic effects.

We will describe typical electrochemical cells and experimental tactics to overcome the relatively slow dynamics of transport in solid (non-fluid) systems. Application of microdimensional electrodes leads to an improvement in the quality of solid-state electrochemical data and provides new diagnostic and analytical possibilities. Basic concepts of mechanistic studies, which are relevant to the development of novel analytical methods, together with trends towards possible future applications will also be addressed.
(Invited) Electrochemistry of Solid-State Inorganic Polymer Electrolyte
Authors: Zhan Dong-Ping
Published: February 2020

Electrochemistry explores the charge transfer reaction across the interfaces, such as solid/liquid interface, liquid/liquid interface and also solid/solid interface. Most reported charge transfer behaviours across the “solid/solid” interface are involved liquid electrolyte. For example, in the lithium-ion batteries, the redox of cobalt-based active material is coupled by the heterogeneous intercalation/deintercalation of Li+ ions, which is existed in the electrolyte solution. In another words, the electron transfer occurs at the solid/solid interface while the ion transfer occurs at the solid/electrolyte solution.

We employ SECM to construct the solid-solid interface and to study the electron transfer phenomena therein. That means there is no liquid electrolyte environment. When the electron transfer occurs at the solid/solid interface, the counterion transfer will occur in the crystal due to the crystalline defects. For example, we cultured the NaCl microcrystals, which are doped with iron oxides, between the pair electrodes on a microchip. The multi-step electron transfer processes of iron from Fe(0) to Fe(VI) through Fe(II) and Fe(III) were observed.

The solid-state electrolyte solution just like an inorganic polymer. The electron transfer is wired through hopping between the neighboring redox lattice sites, coupling with the counterion transfer in the crystalline defects. The electrochemical behavior in the solid-state inorganic “polymer” electrolyte will be discussed in this presentation.
Polyviologens As Electron Transport Material in Photosystem I-Based Photovoltaic Cells
Authors: Dervishogullari Dilek , Jennings G. Kane , Cliffel David E.
Published: February 2020

Photosynthesis, the conversion of solar energy into chemical energy, fuels our increasing energy consumption through the use of fossil fuels derived from ancient organic matter. However, the associated greenhouse gas emissions have resulted in several problems such as climate change and environmental pollution. As a result of the increasing demand for alternative energy sources, decades of research have been dedicated to mimicking photosynthesis in artificial bio-hybrid devices. Photosynthesis is powered by two key proteins, Photosystem II (PSII) and Photosystem I (PSI), that act in series as biological pseudo-photodiodes. Both proteins can be extracted from a wide variety of plant materials and have the potential to be implemented on a global scale for low-cost solar energy conversion.

Photosystem I (PSI), in particular, is ideal for use in solar cells due to its innate ability to photoexcite electrons with a quantum efficiency approaching unity. In vivo, these electrons are then mediated to the water-soluble redox protein called ferrodoxin; in artificial biohybrid devices, these electron acceptor proteins must be replaced with electrodes and electrochemical mediators. In this work, novel PSI-based solar cells were prepared by using polyviologens as the electron-transport layer between the PSI protein and the indium tin oxide (ITO) anode. Redox polymer-modified electrodes are increasingly used as electron-transfer catalysts in electrochemical applications. Polyviologens are a unique class of organic polycationic polymers, which can rapidly accept excited state electrons from a primary donor such as PSI and subsequently donate them to a secondary acceptor. Our device is a unique example of the direct use of extracted PSI protein to create photoactive biohybrid electrodes and represents one of few reported methods for incorporating PSI into a solid-state device, eliminating the problems associated with wet photoelectrochemical cells, such as corrosion and leaks.
Effects of Surface Passivation on Photoluminescence Properties and Biomedical Imaging of Graphene Quantum Dots
Authors: Zhang Wenxian , Dong Jian , Wang Kaiqi , Zhao Yanli , Dong Lifeng
Published: February 2020

Owing to fluorescence properties and small size, graphene quantum dots (GQDs) have been investigated for biomedical imaging and drug delivery. Although GQDs demonstrate some desirable properties, poor stability and low biocompatility have limited their applications in various aspects. Therefore, in this study, we synthesized surface-passivated GQDs and studied their properties. GQDs were prepared using thermal exfoliation of graphite oxide, followed nitric acid refluxing. Then GQDs were passivated with polyethylene glycol (PEG) using hydrothermal at 120 ℃ for 72 h. Both GQDs and PEG-GQDs were characterized by transmission electron microscopy (TEM),UV-Vis absorption and photoluminescence spectroscopy. Compared with GQDs, PEG-GQDs exhibit higher fluorescence intensity and fluorescent quantum yield, which indicates that PEG-GQDs are more desirable for biomedical imaging. Also, PEG-GQDs demonstrate less cytotoxicity than GQDs in terms of cell survival rate in MTT assay. Our findings demonstrate that both fluorescence characteristics and biocompatibility of GQDs can be improved by PEG surface passivation.
Design of a Mercury(II) Selective Electrode through a Multi-Objetive Optimization Model
Authors: Juarez-Gomez Jorge , Ramírez-Silva María Teresa , Mora-Gutierrez Roman Anselmo , Ponsich Antonin , Rincón-García Eric Alfredo
Published: February 2020

The mercury (Hg) is an element that is naturally present in air, water and soils, however it is one of the most toxic metals, so that severe damage to in the health of living organisms are cause by the exhibition of they whit at small amounts of Hg. The importance its timely detection in the environment is to avoid or lessen the damage to public health. One of the various devices for detecting pollutants are the so-called ion-selective electrodes, which offer advantages over traditional instrumental methods, such as: low prices, short response times, simple construction, among others.

In the present work, the design and development of efficient electrodes for the determination of mercury(II) in aqueous medium is addressed. We should be mentioned that the design and construction of electrodes is not an easy task, since the potential of the electrode is a function of several variables such as temperature, analyte concentration, ionophore concentration, etc., as well as the interactions between them. Therefore, it is necessary to build a broad experimental design to achieve the limit of detection (LOD) and the slope closest to the prediction for the Nernst equation. However, generally into experimental purposes a set of simplified and carried out in the behaviors of the variables are involved with in order to minimize experimental work. As a result of the experimental work, information be able serve as base into developing of new electrodes is generated. Here, three multiobjective optimization models are proposed, in which the concentration of mercury ions, the concentration of ionophore, the concentration of plasticizer and the ion exchanger concentration in the membrane as well as their possible interactions are involved as variables. It should be mentioned that the objectives implied in the models are to minimize the LOD and minimize the difference between the slope and the experimental one.

The results obtained by the models were tested in the laboratory to determine and characterize their behavior, later the model data were compared with the experimental results.
(Invited) Fluid Spectroscopy with Piezoelectric Ultrasound MEMS Transducers
Authors: Pratap Rudra , Dangi Ajay , Roy Kaustav , Gupta Harshvardhan
Published: February 2020

Piezoelectric micromachined ultrasound transducers (PMUTs) are making rapid strides in terms of application development in varied areas such as proximity sensing, gesture recognition, medical imaging, photoacoustics, etc. Our ability to fabricate these devices more reliably and integrate them in suitable form factors is paving the way for new and promising applications. PMUTs are now expanding in terms of their fabrication technology as well, with the introduction of new active materials such as AlN and ZnO. In particular, AlN based PMUTs hold great promise because of their CMOS compatibility. We have been exploring PMUT fabrication using three different materials — PZT, AlN and ZnO — and integrating them in fluidic environments for developing fluid spectroscopy.

Probing fluids in very small volumes for detecting changes in their properties such as density, viscosity, and homogeneity can pave the way for online and in-situ monitoring of various fluids in applications as wide ranging as petrochemical industries to medical emergency care. In most health monitoring applications, whether for machines or humans, the emphasis is on early detection of onset of undesirable conditions. For fluids, minute but persistent changes in their density and viscosity can be used as signatures for such onsets. PMUTs hold promise for such detection because of the ease with which they can scan for these changes. We have carried out experiments with PMUTs in different fluids to find spectral shifts with change in their density and viscosity. In this paper, we show how these shifts are quantitatively related to density variation. We report a density sensitivity of 145 Hz/(kg/m3) with a 500 kHz PMUT. We also show some initial results with an array of PMUTs of different frequencies — a new technique we are developing for fluid spectroscopy. PMUTs spanning a range of frequencies and embedded in microfluidic channels are intended for probing fluid inhomogeneity due to particulate suspensions or variations in discrete constituents such as cells in biofluids. Our PMUTs in these studies employ the same material stack for the individual PMUT-cell structures with thin film PZT as the active material, and the frequency variation is achieved simply from geometric scaling. This approach provides great flexibility in terms of building frequency-pixelation of desired resolution. The study of the relationship between frequency-pixelation and the resolution of inhomogeneity in fluids does not exist and is currently underway in our research group.
Textile Based Thermoelectric Temperature Sensor for Wearable Device
Authors: Jung Minhyun , Kim Kyungkwan , Bae Jihyun , Jeon Sanghun
Published: February 2020

Recent technological advances in wearable electronics with high performance, flexibility, stretchability, and ultra-thinness are emerging. But they still have challenges in terms of processibility, reliability, and power consumption. In this report, we present a highly stretchable textile-based thermoelectric temperature sensor fabricated using commercially available thermoelectric inks. With various combinations of poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS), carbon-nanotube(CNT), silver nanoparticle(AgNP) inks, we confirmed high performances of temperature-sensing capability. The optimized thermoelectric temperature sensor generates a Seebeck voltage of 1.1 mV for a temperature difference of 100˚C through a thermocouple consist of PEDOT:PSS and AgNPs inks. This textile based temperature sensor shows a high durability up to 200 cycles under 20% stretched condition. In addition, we obtained the dependence of temperature sensing characteristics with stretching directions of knitted structure textile substrate. We believe that this stretchable thermoelectric fabric to be the innovative elements in wearable device such as healthcare system, humanoid robotics, and human-machine interactive technique.
(Invited) 3D Printing of Gels for Soft-matter 3D Innovation
Authors: Furukawa Hidemitsu , Tamate Hideaki , Takamatsu Kyuichiro , Sasasaki Hiroyuki , Kodama Mai , Yoshida Kazunari , Saito Azusa , Khosla Ajit , Makino Masato , Kawakami Masaru
Published: February 2020

3D printing technology has been becoming more common and diverse for various researches and developments. Here we focus on 3D printing of soft-matter, especially introducing the latest progress of our 3D gel printing. We are developing various 3D gel printers, including bath-tub type, dispenser type and brick-building type. These printers can 3d-print finger tips for robotics, medical models for surgery, and fun foods for playing and nursing. The minimum and maximum dimensions of 3D printed objects depend on both the type and the materials used in printing. We will discuss what we need to study for leading Soft-matter 3D Innovation.
Oxidation Kinetic of Nickel Base Superalloy C 263 for Seamless Wrought Rings
Authors: Almeraya Facundo , Tiburcio Citlalli Gaona , Zambrano Patricia , Cabral José Angel , Estupiñan-Lopez Francisco , Samaniego Gamez Oliver P. , Taboada Solis Jorge , Lira Manuel Alejandro
Published: February 2020

In the present investigation was conducted to study the oxidaction kinetics of nickel-base superalloy, Haynes C 263, used in the manufacture of rings for aircraft engines. For carrying out this study, we first conducted microstructural characterization of the pieces using the techniques of Optical Microscopy, Scanning Electronic Microscopy and X-Ray Diffraction, subsequently using the technique Thermogravimetric Analysis, the kinetic oxidation was performed the metal in a temperature range of 600 to 900 ° C and using different atmospheres (N2, O2 and SO2 + O2). The results of the micrographs show the formation of a protective oxide film on the surface of the material in different oxidizing agents. XRD, it was possible to determine the composition of the film and it was observed that as the reaction temperature diffraction patterns of the phases are defined, the reaction rate also increases also increases. Finally it was found that the kinetics of high temperature oxidation of the superalloy C 263, follow the parabolic law of corrosion rate.
Effect of Bisphenol a on the Transfer of TEA+ across the Water|1,2-Dicloroethane Interface
Authors: Martínez-Hernández Eric , Amador-Hernández Judith , Colunga Urbina Edith M , de la Garza Rodríguez Iliana M , Velazquez-Manzanares Miguel
Published: February 2020

Bisphenol A (BPA) is a synthetic monomer used in the production of polycarbonate plastics, epoxy resins, among others; therefore, it is usually founded in food and beverage containers, dental sealants, etc. In 2003, more than 6 billion pounds of this compound were produced around the world, while the EPA estimates that at least 1 million pounds arrive in the environment each year. On the other hand, endocrine alterations in human beings have been associated with BPA due to its estrogenic capacity; the high hydrophobicity of the compound aids to go through biological membranes. For this reason, it is important to study the interfacial behavior of BPA in a dynamic model system as the interface between two immiscible electrolyte solutions (ITIES). The aim of this work was to study the inhibitory effect of bisphenol A on the transfer of the cation tetraethylammonium (TEA+) a cross the interface water|1,2-dichloroethane (1,2-DCE). The electrochemical experiments were carried out in a 4-electrode cell (two references and two counterelectrodes) and the interface was polarized by cyclic voltammetry (CV) and square wave voltammetry (SWV). According to the results, the BPA acts as an inhibitor of the transfer of the TEA+ at the water|1,2-DCE interface. Due to the high hydrophobicity of the BPA, this compound reaches the interface on the side of the organic phase and is accumulated. The discussion is focus on the diffusion coefficient values of the TEA+ (DTEA+) across the interface, since the DTEA+ decreases as a function of the BPA concentration. This study assisted to understand the way in which this compound is accumulated in living systems.
Verification of Immersed Boundary Method and Numerical Simulation of Newtonian Fluid in Microchannels By Openfoam
Authors: Chen Lin Di , Ye Jian , Xu Li , Kang Xin , Zhou Yi , Li Jie
Published: February 2020

Research on Microfluidics and Nanofluidics has advanced rapidly over the past two decades, which is a cutting-edge subject and has great application potential in biochemistry, human health, new energy, advanced materials, and so forth. The IBM (immersed boundary method) allows for a precise representation of fixed and moving solid obstacles embedded in the physical domain, using uniform or stretched Cartesian meshes. We recall that the IBM formulation chosen in this work is the discrete forcing approach. The motion of particles suspended in fluid in straight and curved microchannels was simulated by immersed boundary method, and several laws of particle in flow, including the distribution and velocity variation characteristics were obtained. In addition, various 2D and 3D well-documented test cases were carried out to validate IBM solver, based on simulated results of different ratios of Re to viscosity. In summary, the mathematical model of microfluid, in the movement of straight and curved microchannels, is established and further explored in theoretically and experimentally, leading a foundation for the optimal design of microfluidic control.
Cu2-x­se Nanorods with Tunable Surface Plasmon Resonance for NIR Photocatalysis
Authors: Kuo Ming-Yu , Hsu Yung-Jung
Published: February 2020

Heavily doped semiconductors such as Cu2-xSe have demonstrated significant surface plasmon resonance (SPR) primarily in the NIR region.[1,2] For solar fuel generation, the effective use of NIR spectrum has been limited although it accounts for over 50% of the solar radiation. In this work, we demonstrated the tunable NIR SPR absorption for Cu2-xSe nanorods with various aspect ratios. The samples were prepared by directly inserting Cu+ ions into Se nanorods during the ion exchange process.[3] With the distinctive NIR SPR absorption, the Cu2-xSe nanorods exhibited remarkable photocatalytic activity toward hydrogen production. This demonstration suggests a possibility to further extend the utilization of solar spectrum toward near IR region, an important merit for advanced photocatalytic and photoelectrochemical applications.

References

[1] A. Comin, L. Manna, Chem. Soc. Rev., 2014, 43, 3957-3975.

[2] J. Kim, A. Agrawal, F. Krieg, A. Bergerud, D. J. Milliron, Nano Lett., 2016, 16, 3879-3884.

[3] M.-Y. Chen, Y.-J. Hsu, Nanoscale, 2013, 5, 363-368.
1D/2D Materials, Flexible Substrates and Surfaces
Authors: Yang Eui-Hyeok , Kang Kyungnam , Godin Kyle , Wang Xiaotian , Xu Jian , Fu Shichen , Zhang Runzhi , Palumbo Anthony , Chen Siwei , Hader Greg , Cupo Christian , Yan Kang , Wang Minjie
Published: February 2020

There has been a growing interest in two dimensional (2D) crystals beyond graphene, exhibiting novel properties and potential applications in next generation electronic and photonic devices. Graphene has superior properties, including high carrier mobility, ultrahigh surface area and excellent thermal conductivity. Whereas the lack of a band gap is a critical limitation for the use of graphene in electronic devices, monolayer semiconducting transition metal dichalcogenides (TMDs) have shown highly promising prospects in electronics and optoelectronics. Therefore, non-graphene 2D atomic layers, such as hexagonal boron nitride (hBN) and TMDs, have been integrated into research scale devices, thereby probing mechanical, chemical, electrical and optoelectrical functions. This abstract reports on our investigation of chemical vapour deposition (CVD)-growth, achieving localized, patterned, single crystalline or polycrystalline monolayers of TMDs, including MoS2, WS2, WSe2 and MoSe2, as well as their heterostructures. Particular focus is on enabling the fabrication of epitaxially grown TMDs on other van der Waals materials towards synthesizing TMDs with an ultralow-defect density. Furthermore the growth of TMD homobilayers with well-ordered stacking angles is demonstrated using the control of edge structures of the underlying TMD layer. Other nanomaterials, including vertically aligned carbon nanotubes for stretchable supercapacitors, are also investigated toward combining 2D materials with flexible substrates. Smart polymer functional surfaces using dodecylbenzenesulfonate-doped polypyrrole (PPy(DBS)) are also investigated to demonstrate in situ control of droplet pinning on the polymer surface, enabling the control of droplet adhesion from strongly pinned to extremely slippery (and vice versa). The pinning of organic droplets on the surfaces is dramatically controlled in situ, presenting great potential for manipulation and control of liquid droplets for various applications including oil separation, water treatment and anti-bacterial surfaces. We believe that our work represents a major advance in materials science and engineering, especially pertaining to those topics that involve functional and tunable surfaces.
Hydrogen Generation Reaction Catalyzed By Platinum Nanoparticle Multi-Walled Carbon Nanotube Composites
Authors: Abdel-Fattah Tarek M , Huff Clay , Long Julia Madeline
Published: February 2020

The increasing dependence of the modern world on fossil fuels has resulted in major economic and environmental crisis. The strain of these events has prompted a deeper investigation into the study of carbon-free fuels. [1] Hydrogen gas is known for its renewable nature when produced by the hydrolysis reaction of water and sodium borohydride. The reaction produces no harmful emissions and results in only environmentally-benign byproducts. [1,2] Platinum nanoparticles were synthesized using beta-cyclodextrin and were adhered onto multi-walled carbon nanotubes (MWCNTs) via an incipient wetness impregnation method. [3-5] The resulting composite was characterized using Transmission Electron Microscopy (TEM). TEM confirmed the presence of uniformly shaped 3 nm platinum nanoparticles decorated onto the sidewalls of ~30 nm MWCNTs. Catalytic activity of the composite in a hydrogen evolution reaction was measured. [3-5] The composite best catalyzed the reaction at 303K and a pH of 7 generating hydrogen at a rate of 21.2 mLmin-1gcat
-1. Overall, the composite performed well as a catalyst of the hydrolysis of sodium borohydride with the activation energy being calculated to be 46.17 kJmol-1.

References

Retnamma, R.; Novais, A.Q.; Rangel, C.M. Kinetics of hydrolysis of sodium borohydride

for hydrogen production in fuel cell applications: a review. Int J Hydrogen Energy 2011,

36, 9772-9790.

Chinnappan, A.; Kang, H.C.; Kim, H. Preparation of PVDF nanofiber composites for

hydrogen generation from sodium borohydride. Energy 2011, 36, 755-759.

Huff, C.; Dushatinski, T.; Barzanjii, A.; Abdel-Fattah, N.; Barzanjii, K.; Abdel-Fattah,

T.M. Pretreatment of gold nanoparticle multi-walled carbon nanotube composites for

catalytic activity toward hydrogen generation reaction. ECS J Solid State Sci Technol

2017, 6, M69-M71.

Huff, C.; Dushatinski, T.; Abdel-Fattah, T. M. Gold nanoparticle/multi-walled carbon

nanotube composite as novel catalyst for hydrogen evolution reactions. Int J Hydrogen

Energy 2017, 42, 18985-18990.

Huff, C.; Long, J.; Aboulatta, A.; Heyman, A.; T. Abdel-Fattah, Silver Nanoparticle/Multi-Walled Carbon Nanotube Composite as Catalyst for Hydrogen

Production. ECS J Solid State Sci Technol. 2017, 6, M115-118.
3D Assembly of Gold Nanoparticles As a Novel Catalyst for Hydrogen Generation Reaction from a Hydrogen Feedstock Material
Authors: Abdel-Fattah Tarek M , Osborne Justin , Horten Mitchell
Published: February 2020

With the limited supply of fossil fuels becoming more of a concern, there has been an increased focus in finding alternative sources of energy. One source of clean energy is hydrogen gas. Studies have been done examining the generation of hydrogen gas from water, which is an energy intensive process. There has been less effort in generating hydrogen gas from a solid feedstock, such as sodium borohydride. In the presence of water, sodium borohydride releases hydrogen gas slowly. In order to be used as an efficient source of energy, this reaction needs to be catalyzed so the reaction happens at a sufficient rate. One area of catalysis is the noble metals such as gold at the nanoscale. Using metal nanoparticles is a cost-effective way to use these metals as a catalyst, because much less of the bulk precursor is needed [1,2]. Without a support, the nanoparticles will not be as effective, so a 3D assembly of gold nanoparticles were synthesized and tested to determine its effectiveness as a catalyst [3]. The data show an increase in the efficiency of the generation of hydrogen gas with the addition of gold catalyst when compared to the un-catalyzed reaction. The reaction catalyzed by the gold assembly has a rate constant of 15.8 L mol-1 hr-1, compared to the un-catalyzed reaction which produced hydrogen at rate of 6.42 L mol-1 hr-1, and was determined to be a second order reaction. This catalyzed process produced 92% more moles of hydrogen gas than the un-catalyzed reaction in the same time period.

References

Abdel-Fattah T. M.; Wixtrom A. Catalytic Reduction of 4-Nitrophenol Using Nanoparticles on Carbon 2014,
ECS J Solid State 3(4) M18-M20.

Huff C, Dushatinski T, Abdel-Fattah TM. Gold nanoparticle/multi-walled carbon nanotube composite as novel catalyst for hydrogen evolution Int. J. Hydrogen Energy, 2017, DOI: https://doi.org/10.1016/j.ijhydene.2017.05.226

Wen, Dan; Liu, Wei; Gold Aerogels: Three-Dimensional Assembly of Nanoparticles and Their Use as Electrocatalytic Interfaces. 2016, ACS Nano, 10(2), pp 2559 – 2567
Engineering Artificial SEI for Improving Performance of Anode Free Batteries
Authors: Assegie Addisu Alemayehu , Cheng Ju-Hsiang , Huang Chen-Jui , Kuo Li-Ming , Su Wei-Nien , Hwang Bing-Joe
Published: February 2020

Practical implementation of a lithium battery or an anode-free battery with promising high capacity is hampered by dendrite formation and low coulombic efficiency [1,2]. Most notably, these challenges stem from non-uniform lithium platting and unstable SEI layer formation. Here, we revealed a homogeneous lithium deposition and effective dendrite suppression with engineering artificial SEI layer. Surface coating reinforces a thin and robust artificial SEI layer film formation via hosting lithium and regulating the inevitable reaction of lithium with electrolyte. The cell with engineered SEI layer showed stable cycling of lithium with an average coulombic efficiency of ~100% over 200 cycles and low voltage hysteresis (~30 mV) at current density of 0.5 mA cm-2. Moreover, we have proved the anode-free battery experimentally by integrating it with various cathodes into a full cell configuration. The new cell demonstrated stable cycling with excellent average coulombic efficiency. These impressive enhanced cycle life and capacity retention results from the synergy of electrode modification, high electrode-electrolyte interface compatibility, and stable artificial SEI formation. Our result opens up a new route to realize the anode-free batteries by engineering artificial SEI layer to achieve safe interfacial chemistry and controlled dendrite formation.

Reference
s
:

[1] A.M. Tripathi, W.N. Su and B.J. Hwang, Chem. Soc. Rev., 47, 736–851 (2018).

[2] J.H. Cheng, A.A. Assegie, C.J. Huang, M.H. Lin, A.M. Tripathi, C.C. Wang, M.T. Tang, Y.F. Song, W.N. Su, and B.J. Hwang, J. Phys. Chem. C, 121, 7761–7766 (2017).