bluuebunny/crossref_metadata_2025 huggingface dataset:
CoP As an Acid-Stable Electrocatalysts for the Hydrogen-Evolution Reaction: Synchrotron-Based Operando Oxidation-State Determinations
Authors: Saadi Fadl Hussein , Carim Azhar I , Drisdell Walter , Yano Junko , Lewis Nathan S. , Soriaga Manuel P.
Published: February 2020

Electrochemical water splitting is an important component of several developing clean-energy technologies that aim to be sustainable, renewable, and carbon-neutral. In order to carry out this process efficiently, catalysts for the cathodic half reaction (hydrogen evolution, HER) and anodic half reaction (oxygen evolution, OER) are essential. Currently, earth-abundant, low-cost materials are being vigorously sought for these purposes. Here we report a facile electrochemical method for the synthesis of a cobalt phosphide film that displays both excellent HER activity and stability during operation in acidic media. 

CoP films were synthesized electrochemically via cathodic deposition from oxidized precursors in aqueous solution at room temperature. The as-deposited films required an overpotential of only 85 mV to drive a current density of 10 mA cm−2 in 0.5M H2SO4. Over 24 h of galvanostatic electrolysis at 10 mA cm-2  resulted in an overpotential increased of less than 20 mV.

X-ray photoelectron spectroscopic examination of the film surface after electrocatalysis revealed that the phosphorus existed in both reduced (phosphide) and oxidized states (orthophosphate). In order to determine the surface character during electrocatalysis operando X-ray absorption and Raman spectroscopic analysis were performed. Such analysis directly confirmed that the catalyst existed solely in the reduced state (phosphide) during catalysis.
Developing Cost Competitive Nanostructured Systems for Solar Fuel and Chemical Production
Authors: Mubeen Syed , Cheng Wei , Rassoolkhani Alan , Lee Joun , Stickney John Lewellen
Published: February 2020

The conversion of solar photons directly to valuable chemicals and fuels efficiently and cost-effectively, has been, and continues to be a major societal goal. Because, any system that captures sunlight and converts it into significant quantities of electrochemical potential will require large areas, to make the system cost-effective requires that products with the highest value be produced and the feedstock be as inexpensive as possible. This talk will introduce our research efforts to develop novel light absorbing materials and stable photoelectrochemical devices utilizing several potential concepts including: (i) semiconductor and/or Schottky junction based nanostructures employing earth abundant elements (e.g. SnS photocathodes; BiVO4/WO3 photoanodes); (ii) low-cost electrochemically manufactured multi-junction cell (e.g. CdTe based multijunction cells) and (iii) oxide encapsulated stable photoelectrochemical nanoreactors. The structures created are designed to produce high value oxidation (Cl2 and Br2) and reduction (H2) products sustainably for at least 3 hours in acidic medium. The selection of these materials is due to their appropriate bandgap, and suitable placement of their conduction and valence bands. While, the proper bandgap allows for absorption of a significant part of the visible spectrum, their appropriate band edge positions make a wide range of electrochemical reactions possible.
Tuning the Exposed Facets of Photocatalysts to Improve the Performance
Authors: Zhang Junying
Published: February 2020

Exposed crystal facets of the photocatalysts are one of the most important factors to determine the photocatalytic activities. We investigated several photocatatlysts, revealing the relationship between the morphology, especially the exposed facets, and the photocatalytic activities.

Cu2O microcrystals demonstrate better performance in producing hydrogen by degrading formaldehyde solution under visible light in comparison with other materials. Cu2O microcrystals exposing {110} facets show higher activity than Cu2O exposing {111} facets because of a larger density of surface copper atoms.

BiOCl microsized square nanosheets exposing {001}facets, with a large lateral size of 3−5 µm and the side length/thickness ratio of about 100, present good photocatalytic activity toward decoloring Rhodamine B solution under the ultraviolet-visible light irradiation.

{020} is the active facet of orthorhombic WO3•0.33H2O. The orthorhombic WO3•0.33H2O exposing most {020} facets shows much higher activity than other samples in decoloring Rhodamine B solution under visible light.

LaTi2O7, with the layered perovskites structure, prefers to grow into nanosheets exposing the {010} facets. By exposing small {012} facets with high surface energy, the photocatalytic hydrogen releasing rate has been substantially increased.

References

Min Li, Junying Zhang, Hong Gao, Feng Li, Sten-Eric Lindquist, Nianqiang Wu, Rongming Wang, ACS Applied Materials & Interface, 2016, 8, 6662−6668

Yesheng Li, Zilong Tang, Junying Zhang, Zhongtai Zhang, CrystEngComm, 2015, 17, 9102-9110

Hong Gao,Junying Zhang, Rongming Wang, Mei Wang, Applied Catalysis B: Environmental, 2015, 172, 1-6
Solid-State Characterization of Wide-Bandgap Cuga(S,Se)2 for PEC Water Splitting
Authors: DeAngelis Alexander D , Horsley Kimberly , Gaillard Nicolas
Published: February 2020

The development of a semiconductor of bandgap 1.7 – 2.1 eV that is both highly efficient and stable is necessary for an economically viable water splitting device to produce clean and renewable H2. Copper chalcopyrites are excellent candidates for this purpose, as they output current densities close to their theoretical maximum, tend to be relatively durable compared to other material systems used for PEC applications, and can theoretically be engineered to have a bandgap from 1.0 to 3.0 eV. This material class covers a wide range of elements, many of which have yet to be explored.

In this work, we have focused on the CuGa(S,Se)2 (CGSSe) alloy, which has been theoretically shown to have a bandgap within the ideal energy range. By our process, we have been able to successfully synthesize CGSSe films with a bandgap ranging from 1.7 to 2.4 eV. Preliminary PEC measurements under AM1.5 illumination on these materials exhibit current densities exceeding 10 mA/cm2 (equivalent to STH efficiencies in the 10-12% range) along with an anodic shifting of the photocurrent-onset voltage by approximately 0.3 V, relative to that of CuGaSe2. However, the PEC devices suffer from a highly negative photocurrent onset of about -0.3 V vs Ag/AgCl, most likely due to the generally poor energy band alignment of copper chalcopyrites with water splitting redox potentials. To circumvent this energetics problem, we have taken the so-called buried junction approach, creating an internal electric field to anodically shift the onset voltage. Thus, PV devices were studied as an archetype of our ultimate stand-alone device. Solid-state PV devices made with our champion CGSSe materials so far yield approximately a short-circuit photocurrent density of 5 mA/cm2, an open circuit voltage of 650 mV, and a fill factor of 55 %. Further discussion of how the different facets of the synthesis process can be changed to improve device performance will be presented.
Site-Selective Binary Alloy Nanoparticles Deposition on TiO2 Nanorod for Acetic Acid Oxidative Decomposition Under UV-Vis Irradiation
Authors: Tanabe Toyokazu , Miyazawa Wataru , Gunji Takao , Hashimoto Masanari , Kaneko Shingo , Ohsaka Takeo , Matsumoto Futoshi
Published: February 2020

Alloy nanoparticles (NPs) loaded TiO2 photocatalysts have attracted considerable attention in recent years as a promoter of highly active photocatalysts under ultraviolet (UV) irradiation [1]. Many synthetic techniques have been utilized in preparation of binary alloy NPs loaded TiO2. However, control of deposition site for alloy NPs on TiO2 is one of a challenging theme in TiO2 study. Herein, we present that site-selective Pt-Pb NPs deposition on rutile TiO2 nanorod by successive reduction of metal ions, photo-reduction of Pt4+ and followed by microwave assisted polyol reduction of Pb2+ (2-step method). The Pt-Pb NPs were site-selectively deposited on the reduction site on (110) surface of the rutile TiO2 nanorod. The photocatalytic activity of rutile TiO2 was significantly enhanced after Pt-Pb NPs loading for oxidative decomposition of AcOH in aqueous phase as shown in following figure. The AcOH was completely oxide to CO2 and the CO2 evolution of the site-selectively Pt-Pb NPs deposited TiO2 was nearly six times higher than that of a bare rutile TiO2 and three times higher than randomly Pt-Pb NPs deposited TiO2. The well mating of the reduction reaction site on photocatalyst, TiO2, and deposition site for co-catalyst, Pt-Pb NPs, induces efficient electron injection from photocatalyst TiO2 to co-catalyst Pt-Pb NPs, promoting oxygen reduction reaction, reduction process of AcOH oxidative decomposition. The accelerated electron consumption in reduction process leads to smooth oxidative decomposition of AcOH at oxidation site. These findings suggest that the site-selective deposition of alloy NPs is a predominant way to bring out catalytic performance of co-catalyst alloy NPs on TiO2.

[1] T. Gunji, A. J. Jeevagan, M. Hashimoto, T. Nozawa, T. Tanabe, S. Kaneko, M. Miyauchi, F. Matsumoto, Appl. Catal B 181 (2016) 475-480.

Figure 1
Understanding Magnesiation Mechanism and Cation Dynamics in Transition Metal Oxides for Magnesium-Ion Batteries
Authors: Key Baris , Vaughey John T. , Wang Hao , Sa Niya , Incorvati Jared T , Bayliss Ryan D , Cabana Jordi , Poeppelmeier Kenneth , Burrell Anthony K.
Published: February 2020

Elucidation of positive chemical and electrochemical magnesiation and favorable cation dynamics has been an ongoing challenge in rechargeable multivalent-ion battery materials. The lack of experimental methodologies to study favorable cation dynamics and positive intercalation in multivalent-ion batteries limits both theoretical approaches to confirm materials of interest and experimental materials screening processes. Despite major methodological challenges working with multivalent-ion nuclei (M= 25Mg, 67Zn, 43Ca etc.) with solid state NMR spectroscopy (one of the few methods that can directly probe cation dynamics in solids), an experimental approach to study favorable and non-favorable ion dynamics in bulk MgMn2O4 has been developed. Although the findings that will be reporting are orders of magnitude slower than Li-ion battery cathode analogs the results are in some agreement with theoretical predictions (for ex. ~200-300 meV difference predicted between Li+ and Mg+2 in Mn-spinels) and experimentally show, for the first time, favorable and controllable structure-activity relationships in high voltage multivalent-ion battery materials. Furthermore, distinct differences in magnesiation mechanisms are observed with spectroscopic methods for alpha-V2O5 and xerogel-V2O5, former involving only protonic activity and the latter via a magnesium/solvent co-intercalation1,2. This mechanism will be compared with the traditional intercalation mechanism observed for MoO2.8F0.2.
3

References:

1. Niya Sa et al. “Is alpha-V2O5 a Cathode Material for Magnesium Insertion Batteries”, submitted, Journal of Power Sources, 2016

2. Niya Sa, Tiffany L Kinnibrugh, Hao Wang, Gopalakrishnan Sai Gautam, Karena W Chapman, John T. Vaughey, Baris Key, Timothy T. Fister, John W Freeland, Danielle L. Proffit, Peter J. Chupas, Gerbrand Ceder, Javier G. Bareno, Ira D. Bloom, and Anthony K Burrell “Structural Evolution of Reversible Mg Insertion into a Bilayer Structure of V2O5·nH2O Xerogel Material” Chemistry of Materials, Just Accepted, 2016

3. Jared T Incorvati, Liwen F Wan, Baris Key, Dehua Zhou, Chen Liao, Lindsay Fuoco, Michael Holland, Hao Wang, David Prendergast, Kenneth R Poeppelmeier, John T Vaughey “Reversible Magnesium Intercalation into a Layered Oxyfluoride Cathode” Chemistry of Materials 2016, 28 (1), 17–20
Catecholamine Functionalized Reduced Graphene Oxide-Sulfur Composite As a Cathode Material for Lithium-Sulfur Batteries
Authors: Abdul Ahad Syed , Kim Joo-Hyung , Kim Do Kyung
Published: February 2020

Among various next generation rechargeable batteries, Lithium-Sulfur batteries have emerged as a potential candidate to replace Li-ion batteries because the former has high theoretical energy density of 2500 Wh/Kg, which is almost 7 times higher than that of the currently used Li-ion batteries. To address the low conductivity of sulfur and polysulfide dissolution in the sulfur cathode during discharge cycling, we propose the use of functionalized reduced graphene oxide-sulfur composite as a better candidate compared to graphene oxide-sulfur composite (GO/S) which has relatively lower conductivity. The reduced graphene oxide structure with simultaneous introduction of catecholamine functional groups will have the advantage of higher electrical conductivity along with a better ability to adsorb polysulfides through chemical interaction. Catecholamine functionalized reduced graphene oxide (c-rGO) was prepared starting from GO as a raw material, followed by sulfur infiltration (c-rGO/S) at 155°C with an intended sulfur content of 74-75%. To emphasize the importance of introducing catecholamine functional groups in rGO/S composite for polysulfide adsorption by chemical interaction, thermally reduced graphene oxide- sulfur composite (t-rGO/s) with no functional groups and bare GO/S composite was tested too. The use of c-rGO/S composite maintains the capacity to as high as 700 mAh/g after 100 cycles at 0.5C whereas the high electrical resistivity of oxidized graphene-sulfur composite lower the capacity to as low as 300 mAh/g after 100 cycles at 0.5C. Even with the higher electrical conductivity, the t-rGO/S composite delivered a discharge capacity of only 400 mAh/g at 0.5C after 100 cycles amid the absence of any polysulfide adsorbing functional groups like the one present in c-rGO/S composite. Moreover, the evidence of effective polysulfide adsorption by chemical interaction in c-rGO/S in comparison to GO/S has be shown by in-situ UV-Vis spectroscopy results.

Keywords: Catecholamine, Graphene-oxide, Polysulfide adsorption, In-situ UV-Vis spectroscopy
Computational Modelling Studies on Stability of Li-S-Se System
Authors: Ngoepe Phuti Esrom , Masedi Cliffton , Sithole Happy
Published: February 2020

Recent rechargeable batteries are mainly based on conventional lithium intercalation chemistry, using lithium transition metal oxides as cathode material with typical capacities of 120-160 mA.h/g [1]. The low energy density and/ or high cost of these cathode materials have limited their large scale production and application in Li ion batteries. Exploration of new cathode materials is consequently necessary to realise more efficient energy storage systems. Lithium sulphur cells have a promise of providing 2-5 times the energy density of Li-ion cells, however, they suffer poor cycling performance [2]. Improvements that are effected by using Li/SeSxsystem in different electrolytes have been reported [3].

In the current study we employ computational modelling methods to explore stability, structural and electronic properties of discharge products formed in the Li/SeSx battery, which has potential to offer higher theoretical specific energy and remedies the challenges that Li-S battery encounters. First principle methods were used to calculate thermodynamic properties of Li2S and Li2Se, which agreed with available experimental results. A cluster expansion technique [4] generated new stable phases of Li/SSex system and Monte Carlo simulations determined concentration and temperature ranges in which the systems mix. Interatomic Born Meyer potential models for Li2S and Li2Se were derived and validated and used to explore high temperature structural and transport properties of mixed systems.

[1] M.S. Whittingham, Chem. Rev. (2004), 104, 4271

[2] B. Zhang, X. Qin, G.R. Li and X.P. Gao, Energy Environ. Sci., (2010) 3,1531

[3] Y. Cui, A. Abouimrane, J. Lu, T. Bolin, Y. Ren, W. Weng, C. sun, V.A. Maroni, S.M. Heald and K. Amine, J. Am. Chem. Soc. (2013), 135, 8047.

[4] D. Lerch, O Wieckhorst, G.L.W. Hart, R.W. Forcade and S. Muller, Model. Simul. Mater. Sci. Eng. (2009), 17, 055003.
Synthesis and Characterization of Mg-Doped Na0.6Ni0.3-XMgxTi0.7O2 as Anode Material for Sodium Ion Battery
Authors: Wang Ji Eun , Kim Joo-Hyung , Choi Han-gil , Kwon Hyung-shin , Kim Sung-hwan , Kim Do Kyung
Published: February 2020

Recently, sodium-ion batteries (SIB) have gained great amount of attention as a next generation rechargeable battery. The lithium-ion batteries (LIB) have been successfully commercialized and widely applied in electronic devices, vehicles, etc. due to its high energy density. Compared to LIB, SIB system is more desirable in view point of cost because the sodium source is more abundant and widely distribution. Similar to LIB, many studies about SIB cathode reported electrode materials with layered structure where Na ion can intercalate and deintercalate during electrochemical reaction. The electrodes with layered structure can also be utilized as anode. Although the theoretical capacity of layered material is generally lower than that of other materials which undergo conversion or alloying reaction, the electrode material with layered structure shows smaller volume change and better structure stability. Among many anode materials, NaxNix/2Ti1-x/2O2 has been reported to have layered structure with low operating voltage (~0.7V vs Na/Na+) and has shown promising performance. In this study, Mg and Ni was co-doped into NaTiO2 in order to study effect of Mg doping on anode performance. The Na0.6Ni0.3-xMgxTi0.7O2 was synthesized by simple solid-state synthesis method while varying Mg amount from x=0.0 to x=0.1. The structure change depending on the amount of Mg dopant was analyzed by high-resolution X-ray diffraction, scanning electron microscopy and electrochemical test were conducted to evaluate its performance.
Octahedron like Antimony Oxide: An Efficient Anode for Rechargeable Sodium Ion Batteries
Authors: Kalubarme Ramchandra S , Park Chan-Jin , Gosavi Suresh W
Published: February 2020

Rechargeable electrochemistry’s, Li-ion batteries (LIBs) have been greatly considered as one of the most important energy storage devices for portable electronic devices and stationary energy storage, due to their advantages of high energy density, excellent cycling stability and environmental friendliness. However, the low abundance and uneven distribution of lithium resources show the potential difficulties of the long-term and large-scale applications of lithium-ion batteries in terms of their availability and cost. Considering the availability of sodium, the sixth richest element on earth, and similar chemistries of sodium- ionand Li-ion, sodium-ion batteries (SIBs) could successfully substitute LIBs in applications such as smart grids and large-scale energy storage.

The major obstacle in realizing NIBs was the absence of suitable negative electrodes. Because, graphite, a commercially well-known anode material for LIBs, cannot be utilized as an insertion host for Na ions due to their large ionic size. Moreover, only few noticeable studies on negative electrode materials, e.g., lead and hard carbon have been found in the past. Metal oxides are considered to be important electrode materials, as they follow a conversion reaction mechanism. However, metal oxides suffer from several problems when used as anode materials which limit their use, such as swelling and shrinking of active material particles upon the insertion and extraction of Li+ or Na+ions, which can induce poor contact between the active materials and the electron conducting agents, leading to low electric and ionic conductivity.

In this study, we report the electrochemical activity of spherical antimony oxide nanostructures for Na-ion batteries, prepared with the simple hydrothermal oxidation of antimony chloride in alkaline condition. The effect of hydrothermal process parameter, like reaction temperature and time on the microstructure, morphology, and electrochemical performance of of the final product was investigated. The single phase Sb2O3 was resulted for the hydrothermal reaction at 140 oC. The field-emission scanning electron microscopy (FE-SEM) image shown in Fig. 1, reveals the octahedron like morphology for antimony oxide. In cell tests, the anodes of Sb2O3 exhibit stable cycling performance and attain capacity of about 675 mAh g-1 on the first charge. The antimony oxide when tested at high current of 5C delivered 282 mAh g-1. Moreover, an excellent cycling stability is also demonstrated maintaining 82 % of the capacity over 200 cycle when tested at 0.2 C. The outstanding life cycle and high-rate capability are the result of the synergistic effect involving the conversion and alloying reactions mechanism, which accelerate the kinetics of the reactions by stabilizing the structure of anode material.

Figure 1 SEM image of antimony oxide prepared by hydrothermal method

Figure 1
Bi2O3-Added Li1.4Al0.4Ti1.6(PO4)3 with Enhanced Li-Ion Conductivity As a Solid Electrolyte for All-Solid-State Battery
Authors: Lee Jong-Won , Jung Kyu-Nam
Published: February 2020

Lithium-ion battery (LIB) has been one of the most attractive energy sources for mobile devices, energy storage systems and electric vehicles, however, the safety issue is one of the remaining challenges for commercial LIBs. All-solid-state lithium battery with a solid electrolyte has been regarded as alternative technology for LIBs that use organic liquid electrolyte because of likely higher energy density and superior safety. Various solid electrolytes such as polymer, sulfides and oxides have been extensively studied to eliminate the flammable components in LIBs and to achieve the high lithium-ion conductivity required for the practical use [1,2].

Among the oxide-based solid electrolytes, NASICON-type Li1+xAlxTi2-x(PO4)3 (LATP) has received much attention due to its fast lithium conduction in the bulk at room temperature up to 1 mS cm-1 as well as its superior mechanical strength and chemical stability. However, the high grain boundary resistance of LATP gives a high total resistivity for the inorganic solid electrolyte, which hinders its application and use in all-solid state batteries. While the sintering process is one of the effective ways to minimize the grain boundary resistance of LATP by densification of oxide ceramics, the sintering temperature should be reduced with maintaining high density and lithium-ion conductivity. Bismuth oxide (Bi2O3) is a well-known sintering aid, which can promote densification and lower sintering temperature.

In this work, we present the Bi2O3-added Li1.4Al0.4Ti1.6(PO4)3 as a solid electrolyte for all-solid-state battery. The high purity LATP nano-powders were synthesized by Pechini method and the Bi2O3-added LATP solid electrolytes with high density were fabricated via sintering process at various temperatures of 800 oC - 950 oC. Based on the analyses of structural and electrochemical properties for Bi2O3-added LATP electrolytes, the effects of Bi2O3 addition on the microstructure and the behavior of lithium ion conduction in LATP solid electrolyte were examined. The LATP with Bi2O3 sintered at 850 oC shows the enhanced lithium-ion conductivity (ca. 0.9 mS/cm) compared with that (ca. 0.4 mS/cm) of pristine LATP, which implies that added-Bi2O3 effectively promotes the densification of LATP and reduces the grain boundary resistance. The cycle performances and rate capabilities for the Li half-cells constructed with Bi2O3-added LATP were also compared with those of the cell with pristine LATP.

Reference

[1] P. Knauth, Solid State Ionics, 180 (2009) 911.

[2] J. C. Bachman et al., Chem. Rev, 116 (2016) 140.
Performance and Interface Properties of Vapor-Phase Deposited Electrode and Electrolyte Materials for Conformal Solid State Batteries
Authors: Pearse Alexander J , Gregorczyk Keith , Schmitt Tom , Liu Chanyuan , Kozen Alexander C , Gerasopoulous Konstantinos , Talin A. Alec , El Gabaly Farid , Rubloff Gary W
Published: February 2020

All-solid-state batteries exhibit distinct advantages over existing liquid-electrolyte lithium-ion cells, including greater chemical and thermal stability, a wider voltage window, and a reduced need for packaging. Thin film solid state batteries, generally made via physical vapor deposition (PVD), are also capable of supporting high power densities due to their short diffusion pathways for transported species and high quality interfaces, but they are generally limited to planar substrates and can only store on the order of 0.1 mAhr/cm2 as a result. One route to dramatically increasing the energy density would be to develop conformal deposition processes for the electrodes and electrolyte, allowing for the deposition of solid state batteries on arbitrary 3D structures, including high aspect-ratio trenches for use in microelectronics, or conductive fabrics for use in energy-storing textiles.

Multiple groups have explored atomic layer deposition (ALD) as a precisely controllable, highly conformal, and relatively low-temperature (≤ 250C) technique for synthesizing thin film battery components. Anodes and cathodes made using ALD have so far been tested almost exclusively in half cells due to the lack of an adequate ALD-grown solid electrolyte, as well as challenges relating to patterning and contacting multiple layers of conformally-deposited materials. Our group previously demonstrated1 atomic layer deposition of the solid electrolyte LiPON, which is the material used currently in PVD-based batteries and exhibits a conductivity of better than 10-6 S/cm. In this presentation, we will discuss the fabrication and testing of true solid state batteries made with ALD-deposited materials. We will present data from operating planar solid-state cells utilizing a mix of ALD and PVD deposited materials, as well as thin film stacks fabricated on both planar and 3D flexible substrates. Electrochemical characterization, secondary ion mass spectroscopy (SIMS), and x-ray photoelectron spectroscopy (XPS) are utilized to understand the processes occurring within the cells. In particular, we highlight in-situ XPS data demonstrating that undesirable interface reactions during the ALD of battery components present an additional challenge over existing PVD processes, illustrated by the deposition of LiPON on LiCoO2.

1 A.C. Kozen, A.J. Pearse, C. Lin, M. Noked, and G.W. Rubloff, Chem. Mater. 27, 150730080053001 (2015).
(Invited) Electrolyte Developments for Rechargeable K-O2 Batteries
Authors: Wu Yiying
Published: February 2020

Oxygen is a crucial component in emerging technologies in energy conversion and storage. For example, Li–O2 battery is regarded as one of the most promising energy storage systems for future applications. However, its energy efficiency is greatly undermined by the large overpotentials of the discharge (formation of Li2O2) and charge (oxidation of Li2O2) reactions. The parasitic reactions of electrolyte and carbon electrode induced by the high charging potential cause the decay of capacity and limit the battery life. Here, I will present our systematic investigation of a K–O2 battery that uses K+ ions to capture superoxide (O2
-) to form the thermodynamically stable KO2 product. This allows for the battery to operate through the facile one-electron redox process of O2/ O2
-. Without the use of catalysts, the battery shows a low discharge/charge potential gap of less than 50 mV at a modest current density. In this talk, I will emphasize our investigation of the side reactions between K metal and electrolytes and our development in electrolytes that suppress the side reactions. As the consequence, significant improvement in cycle life has been achieved, moving the technology closer to practical applications.
Mercury Chemical Sensors Based on Chalcogenide Glasses
Authors: Paraskiva Alla , Milochova Mariana , Khaoulani Sohayb , Bychkov Eugene
Published: February 2020

Mercury is one of the highly toxic heavy metal cations and its concentration is continuously increasing in the environment due to extensive industrial applications. Mercury species and Hg(II) ions have a serious impact on human health and may cause kidney intoxication, neurological damage, paralysis, chromosome breakage, and birth defects. Consequently, it is important to control mercury levels in natural and potable water. The highest concentration of mercury allowed in drinking water is 1 ppb.

Chalcogenide glasses are promising membrane materials for chemical sensors. We will report R&D work on mercury sensors capable of continuous in situ monitoring of Hg(II) ions in natural and waste waters with a low detection limit of 2 ppb. Figure 1 shows typical sensor response in natural water at neutral pH 7.3 with mercury additions to determine low detection limit of the developed sensors.

Sensor sensitivity, selectivity and stability will be discussed and applications to the analysis of natural and waste waters will be described. In addition, a special attention will be paid to sensor sensitivity mechanism since the sensor response is neither Nernstian nor linear.

Figure 1
The Bathtub Method for Detecting Small Quantities of Specific Pathogens
Authors: Horikawa Shin , Du Songtao , Liu Yuzhe , Chen I-Hsuan , Chai Yating , Wikle Howard Clyde , Chin Bryan A
Published: February 2020

Current techniques used to concentrate pathogens, such as centrifugation and size-exclusion filtration, are non-specific for pathogens of interest and inefficient to deal with large volumes of liquids and liquid foods. In addition, the isolated pathogens need to be analyzed subsequently with expensive, laborious, sample-based lab methods (e.g., culturing and PCR) that do not enable rapid identification of the pathogens. This paper presents a revolutionary method for the capture and rapid detection of small amounts of specific bacteria from entire liquid streams. The method combines a volumetric biomolecular filter and an automated biosensor measurement system. The volumetric biomolecular filter is a three-dimensional, multi-layered net with each layer made up of hundreds of phage-coated magnetoelastic (ME) biosensors with a pre-determined resonant frequency. These biosensors are arrayed with a desired spacing and held flexibly (i.e., cantilever-like configuration) on an electro-magnetized silicon steel comb structure. The phage that is coated on the biosensors are responsible for capturing a specific pathogen. In this way, only the pathogen of interest can be captured on the filter whereas the other matters (non-specific pathogens, debris, etc.) are allowed to pass. In addition, the biosensors can bend over for large, heavy debris, eliminating a common issue of clogging found in the current filtration techniques. Once the entire liquid is flowed over, the biosensors on the filter are transferred into etched cavities on a silicon wafer by shutting off the electromagnetic field. These etched cavities are indexed such that a surface-scanning detector can be used to wirelessly measure the biosensors sequentially in an automated manner. The resonant frequency changes of the biosensors due to the attachment of the pathogen can be measured in 250 milliseconds per sensor. The presented method enables the evaluation of large volumes of liquids for the presence of small numbers of pathogens. The capture efficiency of pathogens was found to be dependent on the filter design.
(Invited) Integrated Selection of Aptamers Against Biomolecules in Microfluidic Devices
Authors: Lin Qiao
Published: February 2020

We describe a microfluidic approach to integrated and rapid selection of aptamers against biomolecular targets. Aptamers are oligonucleotides that recognize biological targets via specific affinity binding. Compared to other affinity molecules such as antibodies, aptamers can be synthetically developed for a broad range of targets and are attractive to biomedical applications both in vitro and in vivo. We have been employing microfluidic technology to realize physical and functional integration of aptamer selection, which is a complex iterative process involving affinity selection and amplification of target-binding oligonucleotides from a randomized library. Using electrokinetic or hydrodynamic manipulation of oligonucleotides, we have made early demonstration of microfluidic devices capable of efficiently and rapidly isolating aptamers against biomolecular targets, such as proteins and small molecules, within drastically reduced times (~10 hours) compared to conventional methods (several days). This integration and speedup of the aptamer selection process can potentially enable new applications of aptamers to basic biological sciences and clinical diagnostics and therapeutics.
Enyzyme-Immobilized Electrode Prepared Using Cellulose Nanofiber
Authors: Yasuzawa Mikito , Mima Daisuke , Fuchiwaki Yusuke , Harada Toshihiko
Published: February 2020

Various procedures have been proposed for the preparation of enzyme-immobilized electrode, such as covalent attachment, cross-linking, hydrogel entrapment, polymer film entrapment, and the combination of two or more methods.Cellulose is a linear polysaccharide of glucose, which have significant high strength and stability due to strong intra- and inter-molecular hydrogen bonds within and among individual chains. Cellulose nanofiber (CNF) dispersion solution can be obtained by stripping down water insoluble cellulose fibers using procedures such as wet jet milling. In this study, CNF was applied for the immobilization of enzyme by entrapping it within CNF matrix. Glucose oxidase (GOx) was employed as the enzyme, and GOx-CNF immobilized electrodes were fabricated by simple repetitious drops of cellulose solution containing GOx on the surface of an electrode. The obtained electrode provided a glucose sensor with significantly high response speed and good linear relationship between glucose concentration and response current. Introduction of CNF films on GOx-CNF film successfully reduced the release of GOx from enzyme-immobilized electrode and glucose sensor with good long term stability was obtained.
Exosomes Detection by a Label-free Localized Surface Plasmonic Resonance Method
Authors: Duraichelvan R. , Srinivas B. , Badilescu S. , Ouellette R. , Ghosh A. , Packirisamy Muthukumaran
Published: February 2020

Exosomes contain disease biomarkers for cancer and other pathological conditions. They are groups of nano-scale extracellular communication organelles which dynamically transport cargoes of molecules and genetic materials between cells. Exosomes circulating in our body-fluids provide a snap-shot in real-time for virtually all aspects of our physiology. Isolation detection and quantification methods of exosomes from various bio-fluids are challenging for clinical applications, like liquid biopsy. Here, we present a simple label-free technique to capture and detect exosomes integrating an exosome-capturing synthetic polypeptide (called Vn96) into microfluidic device. We use our in-house developed nanocomposite plasmonic sensing platform, prepared by in-situ synthesis of Ag-PDMS (silver- polydimethylsiloxane), using silver nitrate as the silver nanoparticle precursor by the in-situ reduction of silver ions. The Ag-PDMS nanocomposites are subsequently high-temperature annealed to improve the uniformity of morphology to accomplish improved sensing properties. We grafted the Vn96 peptide on the Ag-PDMS nanoparticle using functionalization chemistry to covalently attach streptavidin followed by affinity-grafting of biotinylated Vn96 peptide on streptavidin. The biotinylated Vn96 peptide has a polyethylene glycol linker between the peptide and biotin moieties providing flexibility to Vn96 to access and capture exosomes from contacting bio-fluids. We measured localized surface plasmon resonance (LSPR) bands of Ag for all the chip development steps mentioned above and after exosome-capture. The Ag plasmon band shifts to longer wavelengths (redshift) as the refractive index of the surrounding medium is increased at each step of the protocol till exosome-capture-step. The extent of the red shift of the Ag LSPR band is proportional to the concentration of exosome in the fluid till saturation of Vn96 on the Ag-PDMS nanocomposite. Hence, the concentration of exosomes in a bio-fluid can be measured by using calibration curves without pre- or post- labelling exosomes. This exosome-capture chip can efficiently quantitate exosomes present in a fluid and will be used for subsequent molecular analysis (protein and nucleic acid) to facilitate liquid biopsy.
(Invited) Microheater-Based Gas Sensing Platform for Low-Power Environmental Monitoring
Authors: Maboudian Roya , Carraro Carlo
Published: February 2020

Accurate detection of toxic and flammable gases is critical to public health and the environment, and to the safe operation of many industrial processes. This presentation will discuss our efforts in low-power gas sensing for health, environmental and process monitoring. The core technology is a suspended polycrystalline silicon microheater functionalized with a number of nanotechnology-based sensing materials, targeting various analytes. Our microheater platform will be described and the latest results in sensitive, selective, and stable detection of several target gas molecules (including H2, propane, CO and NO2) will be presented. The talk will end with plans for future directions.
Development of Instrument for Simultaneous Measurement of Rotating and Sliding Friction of Hydrogels
Authors: Wada Masato , Yamada Naoya , Khosla Ajit , Makino Masato , Kawakami Masaru , Furukawa Hidemitsu
Published: February 2020

Gels have superior features such as high water content, materials permeability, extremely low friction, and biocompatibility, which are not found in the hard and dry materials, because these features are due to their soft and wet features. Now artificial gels have become similar to natural gels of the human body: the articular cartilage of our knee has both several MPa of mechanical strength and about 0.01 of surface frictional coefficient. Above all, we paid attention to high functionality of shape memory gel (SMG). The frictional behavior of SMG was studied. SMG has some characteristics such as shape-memory characteristics; low friction characteristics wear resistance than the conventional gels. SMG has a shape-memory characteristic by temperature responsiveness namely the temperature change. SMG is expected practical use of to medical materials and machine materials. As for the reason, a shape-memory function does not need chemical fixation, and what I can fix mechanically is given. The machine fixation enables the solvent nonuse in the burden decrease of the patient by the medical care, machine assembling and the design and the reduction of the part mark, the miniaturization of the apparatus. In this study, Implication water rate of different SMG of the composition is measured, and power by changing implication water rate reports the characteristic, and we performed the friction behavior of SMG for the purpose of the use to the underwater apparatus. We made the gel that was low friction with high strength for the practical use of SMG and evaluated it in a Young's modulus, water content ratio, a coefficient of friction quantitatively. The dynamic frictional behavior was observed with Young's modulus and compared with frictional measurement data. This result shows that surface action peculiar to soft and wet materials except the friction behavior based on a contact theory works. This friction behavior means adaptation range expansion of the gel. We developed a new device to inspect the conformity of the range. As for it, a vertical direction and rotatory direction can measure seal materials made with gel materials. As for appearing, the low friction evaluation that gel seal materials were able to be superior to in comparison with the commercial seal materials was provided as a result of in this study. New utility value of the high-performance gel is found by elucidating friction behavior of gel changing a concept of the conventional friction and believes it when it is with the clue to practical use.
Hydrogel Coating on Soft Polymeric Substrates for Microfabricated Devices
Authors: Ahmed Kumkum , Yamada Naoya , Wada Masato , Kameyama Toshiki , Kawakami Masaru , Khosla Ajit , Furukawa Hidemitsu
Published: February 2020

In microfabricated MEMS actuator, sensor and biomedical devices, soft polymeric materials like silicone and nylon are widely used for their light weight, low cost, high corrosion resistance, high electrical resistance, high flexibility and high dimensional stability. Along with their numerous beneficial functions these materials have some shortcomings during real application for their hydrophobic high frictional surface and stiction. There are several methods of hydrophilic and anti-stiction coating on surface of different substrates for MEMS microfluidic devices. In this work we focused on a very unique type hydrogel coating on silicone and nylon by highly hydrophilic hydrogels containing N, N, Dimethylacrylamide (DMAAm), Benzophenon (BzPh) and N,N'-Methylenebisacrylamide (MBAA) as a hydrophilic monomers, photo initiator and crosslinker respectively. This gel is highly hydrophilic (~90 % water) in nature and as a result shows very low friction coefficient value in wet condition. Prior to coating the substrates were modified by plasma treatment and silane coupling agent followed by binding of hydrogel on the surface by photopolymerization. The coating was done by several conventional methods (dipping, solvent casting, spin coating) as well as digital fabrication method of 3D printing by gel 3D printer. Frictional, hydrophilic and morphological properties of the coated surface have been investigated by friction measuring machine, contact angle measurement and atomic force microscopy (AFM) respectively. The comparison between coated and uncoated surface has been made to understand the coating phenomenon clearly. The advantage of this process is, it will make the hydrophobic surface to hydrophilic one and possess less friction. In dry state the substrates show similar behavior as silicone or nylon but in contact with water or other fluid materials it gets slippery and greasy. This study can make significant influence in medical field for development of micro devices for blood analysis, drug delivery, bio-implant and bio-MEMS technologies.
Development of Film-Based Electrochemical Integrated Microfluidic Chip for Identification of Food-Borne Pathogens
Authors: Shin Sujeong , Lee Tae Jae , Lim Sun Young , Lee Moon Keun , Bae Nam Ho , Jeong Soon Woo , Han So Young , Yang Min Ho , Lee Kyoung G , Yun Seok Oh , Lee Seok Jae
Published: February 2020

Food safety is a global issue directly related with human life and foodborne diseases take a major crisis on health. In this reason, a reliable and cost-effective device is required as a solution to the prevention and recognition of problems concerned with health and safety. Conventional and standard bacterial detection methods such as culture and colony counting methods, immunology-based methods and polymerase chain reaction based methods, may take up to several hours or even a few days to yield an answer. Obviously this is inadequate, and recently many researchers are focusing towards the progress of rapid methods. Here, a fully integrated electrochemical microfluidic chip was developed for identification of food-poisoning bacteria, consisting of three compartments such as film-based gene amplification, three-dimensional micro mixer for homogeneous mixing, the detection electrodes for obtaining electrochemical signal. Just after loading genomic DNA into a developed microfluidic chip, which is extracted from cells such as Esterichia coli. O157:H7, Salmonella enteritidis, Staphylococcus aureus, Clostridium perfringens and Listeria monocytogenes, gene is amplified during PCR procedure in film-based reaction chamber followed by mixing amplified PCR product with electroactive reagent. And then electrochemical signal was produced on electrode surface. If there is no corresponding target pathogen, no electrochemical signal was produced. Furthermore, we can detect one or multiple pathogens at the same time by reason that 5 kinds of foodborne pathogens are amplified in parallel and identify the target pathogens simultaneously. With just one-step including sample injection, identification of different varieties of food-borne pathogens was successfully performed in a microfluidic chip within an hour. Owing to its simplicity and rapidity, the developed microfluidic device holds great promise for identification of several species in facility-limited environment or POCT applications.
High Performance Piezoelectric Nanogenerators Using Vanadium-Doped Ferroelectric ZnO Nanosheets and Polymer Composite
Authors: Nah Junghyo , Shin Sung-Ho , Kwon Yang Hyeog , Lee Min Hyung
Published: February 2020

We report high performance flexible piezoelectric nanogenerators (PENGs) by employing vanadium (V)-doped ZnO nanosheets (NSs) and the polydimethylsiloxane (PDMS) composite structure. The V-doped ZnO NSs were synthesized to overcome the inherently low piezoelectric properties of intrinsic ZnO. Ferroelectric phase transition induced in the V-doped ZnO NSs contributed to signifi- cantly improve the performance of the PENGs after the poling process. Consequently, the PENGs exhibited high output voltage and current up to ∼32 V and ∼6.2 μA, respectively, under the applied strain, which are sufficient to directly turn on a number of light emitting diodes (LEDs). The composite approach for PENG fabrication is scalable, robust, and reproducible during periodic bending/releasing over extended cycles. The approach introduced here extends the performance limits of ZnO-based PENGs and demonstrates their potential as energy harvesting devices.
The Effect of Metal Oxide Supports on the Activity of Pt-Ru Towards Methanol Electrooxidation
Authors: Tavakoli Bahareh Alsadat , Fuentes Roderick Eliel , Tan Shuai , Williams Christopher , Weidner John W.
Published: February 2020

Several inexpensive but non-conductive materials (TiO2, CeO2, Al2O3 and SiO2) were chosen as supports for Pt-Ru electrocatalysts used for methanol oxidation. Although the metal oxide supports were found to have low conductivity, they have high surface area and could promote activity towards the desired reaction for heterogeneous catalysis. In order to increase the conductivity and make these electrodes (metal particles + support) suitable for electrochemistry; the metal nanoparticles were deposited onto the supports at loadings of 60 wt% metal. We aimed to determine if these non-conducting oxides could be used as supports for Pt-Ru to oxidize methanol electrochemically, and if the type of oxide affected activity. Using cyclic voltammetry experiments for methanol electrooxidation, it was demonstrated that for some of metal oxide supports, the activity of Pt-Ru towards methanol oxidation was excellent, even surpassing the activity of the same electrocatalysts supported on carbon. The results confirmed that the same loading of Pt-Ru electrocatalysts supported on these different metal oxides can have different activities for methanol electrooxidation. Pt-Ru/SiO2 and Pt-Ru/anatase TiO2 have showed the highest activity and Pt-Ru/anatase TiO2 could be a good candidate also as its activity was the highest after the current was normalized by  both the active site of the catalyst and by the mass of platinum metal deposited in the electrode.