bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrocatalytic Oxygen Evolution over Nano Scaled Amorphous NiâFe Particles in Alkaline Electrolyte
Authors: Qiu Yang , Xin Le , Li Wenzhen
Published: February 2020

Electrocatalytic water oxidation plays the key role as efficient and stable platform in some of the promising renewable energy conversion and storage devices, such as water electrolyzers, solar water-splitting cells, and lithium-air batteries. The electrocatalytic oxygen evolution reaction (OER) at the anode often couples with electron or photoelectron CO2 reductionand, H2 evolution reactions at the cathode for the above devices but limits the performance of the entire system because of the sluggish OER kinetics, insufficient reaction sites, or low stability of precious metal catalysts. Series of different transition metallic catalysts were investigated in order to significantly increase the activity of OER catalysts and efficiently improve the performance of energy conversion and storage systems. Ni-Fe system is found to be the most promising bimetallic catalytic system with robust stability, much lower cost, and considerably higher activity than the IrO2, the well-known best OER catalyst. Nano scaled catalysts with high electrochemical surface area (ECSA) not only exhibits a promising feasibility to effectively increase the performance of OER catalysts, but also to be simply utilized in renewable energy conversion and storage devices Herein, we reported 4 nm Ni−Fe nanoparticles (NiyFe1−yOx/C) featuring amorphous structures prepared via a solution-phase nanocapsule method for active and durable OER electrocatalysts in alkaline electrolyte. The Ni−Fe nanoparticle catalyst containing 31% Fe (Ni0.69Fe0.31Ox/C) shows the highest activity, exhibiting a 280 mV overpotential at 10 mA cm−2 (equivalent to 10% efficiency of solar-to-fuel conversion) and a Tafel slope of 30 mV dec−1 in 1.0 M KOH solution. The achieved OER activity outperforms NiOx/C and commercial Ir/ C catalysts and is close to the highest performance of crystalline Ni−Fe thin films reported in the literature. In addition, a Faradaic efficiency of 97% measured on Ni0.69Fe0.31Ox/C suggests that carbon support corrosion and further oxidation of nanoparticle catalysts are negligible during the electrocatalytic OER tests. Ni0.69Fe0.31Ox/C further demonstrates high stability as there is no apparent OER activity loss (based on a chronoamperometry test) or particle aggregation (based on TEM image observation) after a 6 h anodization test. The high efficiency and durability make these supported amorphous Ni−Fe nanoparticles potentially applicable in the (photo)electrochemical cells for water splitting to make H2 fuel or CO2 reduction to produce usable fuels and chemicals.
New Catalysts for the Hydrogen and Oxygen Evolution Reactions
Authors: Gross Zeev , Mahammed Atif
Published: February 2020

We have recently introduced corrole metal complexes (metallocorroles) as catalysts for various reactions, including those that are of prime importance for water splitting into its elements- the hydrogen and oxygen evolution reactions. A careful choice of substituents on the corrole ligand and the kind of metal ion chelated by them allows for lowering of the electrocatalytic overpotential and increasing reactivity.

 An arsenal of electrochemical and spectroscopic methodologies, which in the case of metallocorroles is very rich, was applied for acquiring highly valuable information about the mechanisms of action (see upper part of the Figure for the hydrogen evolution reaction). Preliminary results regarding water oxidation with the aid of immobilized catalysts (see lower part of the Figure) will be presented as well.

 REFERENCES

 “Cobalt Corrole Catalyst for Efficient Hydrogen Evolution Reaction from H2O under Ambient Conditions: Reactivity, Spectroscopy and DFT Calculations”, Inorg. Chem.
2013, 52, 3381-3387.

"The Cobalt Corrole Catalyzed Hydrogen Evolution Reaction: Surprising Electronic Effects and Characterization of Key Reaction Intermediates" Chem. Commun.
2014, 50, 2725-2727.

Figure 1
An All Solution-Processed Lead Halide Perovskite-BiVO4 Tandem Architecture Delivering STH of 2.5%
Authors: Chen Yong-Siou , Manser Joseph S , Kamat Prashant V
Published: February 2020

We report an all solution-processed tandem water splitting device composed of a BiVO4 photoanode and a single-junction lead halide perovskite solar cell (CH3NH3PbI3). In this configuration, the surface of BiVO4 photoanode is in contact with water for water oxidation reaction, and the lead halide perovskite solar cell is situated behind the BiVO4 photoanode to supply additional photovoltage to drive water reduction reaction through a Pt gauze. This architecture allows efficient solar photon management, with BiVO4 photoanode selectively harvesting high energy photons (< 500 nm) and lead halide perovskite solar cell selectively harvesting low energy photons (500 to 800 nm) in a single-pass excitation. By modifying the surface of BiVO4 photoanode with an earth-abundant cobalt phosphate thin film, we showed that this design is capable of delivering solar to hydrogen conversion efficiency (STH) of 2.5 % under AM 1.5G illumination at neutral pH. Our results demonstrate the potential of using low-cost, single-junction lead halide perovskite solar cells to assist n-type metal oxides to carry out bias-free photocatalytic water splitting. The unique photoanode-photovoltaic design offers opportunities to explore other semiconducting materials with extended visible light absorption ability to further improve the STH.
Electronic Properties of III-V Semiconductor Photocathode-Water Interfaces: Predictions from First-Principles Calculations
Authors: Pham Tuan Anh , Wood Brandon C. , Ogitsu Tadashi
Published: February 2020

Photoelectrochemical (PEC) cells based on III-V semiconductor photocathodes offer a promising avenue for hydrogen production from water and sunlight. The efficiency of these devices depends on the electronic structure of the interface between the photocathode and liquid water, including the alignment between the semiconductor band edges and the water redox potential. Accurate theoretical predictions of this quantity remain a challenging task, as conventional electronic structure methods such as density functional theory (DFT) often yield substantial errors [1]. In this talk, we present calculations of the electronic properties of two representative III-V semiconductor electrodes, i.e. GaP and InP, at the interface with water using a combination of first-principles molecular dynamics simulations and many-body perturbation theory (MBPT). We show that the use of MBPT is key to obtain band alignments in agreement with experimental measurements. In addition, we describe the relationship between interfacial structure, electronic properties of semiconductors and their reactivity in aqueous solutions.

1. T. A. Pham, D. Lee, E. Schwegler and G. Galli, J. Am. Chem. Soc. in press (2014).

This work was supported by the U.S. Department of Energy at the Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Metal-TiO2 Composite Nanofibers for Plasmon-Driven Photocatalytic Hydrogen Generation
Authors: Xue Can
Published: February 2020

We present the preparation of electronspun TiO2 nanofibers co-decorated with Au and Pt nanoparticles. By using these composite nanofibers, we demonstrate the direct evidence of plasmon-enhanced hydrogen generation through through dual-beam irradiation. The Au/Pt/TiO2 nanofibers exhibit certain activity for hydrogen generation under a single irradiation at 420 nm that excites the defect/impurity states of TiO2. Significantly, when a secondary irradiation at 550 nm is introduced to simultaneously excite Au SPR, we observed 2.5 times higher activity for hydrogen generation. Further investigations by finely controlling the irradiation wavelengths reveal that the enhancement factor on hydrogen generation is directly correlated with the plasmon absorption band of the Au nanoparticles in the Au/Pt/TiO2 nanofibers. The control experiments with different sacrificial agents suggest that the hot plasmonic electrons of Au are responsible to the enhanced photocatalytic activity that can be magnified when the semiconductor is simultaneously excited. Our observation and the enhancement principle would have impact to future plasmonic nanocomposite design for efficient solar energy conversion.
Photoelectrochemical Reduction of Carbon Dioxide to Methanol at Hybrid System Composed of Titanium(IV) and Copper(I) Oxides
Authors: Szaniawska Ewelina , Bienkowski Krzysztof , Solarska Renata , Rutkowska Iwona Agnieszka , Kulesza Pawel J
Published: February 2020

Due to gradual decline of energy resources, there has been growing interest in new energy systems that include direct transformation of solar energy to chemical energy using oxide semiconductor materials. Furthermore, carbon dioxide (CO2), as the primary greenhouse gas also emitted through human activities, could be converted using sunlight to organic compounds. The approach permits simultaneous generation of alternative fuels and environmental remediation of carbon emissions from the continued use of conventional fuels.

The aim of this work has been to develop hybrid materials by utilizing combination of metal oxide semiconductors thus capable of effective photoelectrochemical reduction of carbon dioxide. The combination  of titanium (IV) oxide (TiO2) and copper (I) oxide (Cu2O) has been explored toward the reduction of carbon (IV) oxide (CO2) before and after sunlight illumination. Application of the hybrid system composed of both above-mentioned oxides resulted in high current densities originating from photoelectrochemical reduction of carbon dioxide mostly to methanol (CH3OH) as demonstrated upon identification of final products.

 In particular, fabrication of the hybrid system (heterojunction photocathode) of  TiO2 and Cu2O (on the conducting glass) has required first the cathodic electrodeposition copper (I) oxide. The latter step has been followed by sputtering n-type titanium (IV) oxide. The spectral responses of the Cu2O/TiO2­ electrode is comparable to that of simple Cu2O, and the photoresponse is enhanced at relatively short wavelengths. It is reasonable to expect that the light absorbed by the inner Cu2O film produces energetic electron (e-) – hole (h+) pairs. The excited electrons are driven through the conduction band to the external TiO2/electrolyte interface. The role of TiO2 is not stabilizing; the oxide is also expected to prevent the recombination of charge carriers (e- - h+ pairs). By using gas chromatography with the flame ionization detector, it was confirmed that methanol predominates as a final product.
Effect of Annealing Temperature on the Photocatalytic Activity of ZnxCd1-Xs Photocatalyts
Authors: Chang Hao , Weng Yu-Ching
Published: February 2020

The ZnxCd1-xS photocatalyst arrays were prepared by a dispensing system and then annealed under Ar atmosphere at temperatures from 100 to 500°C to investigate the change in microstructure and the effect on the photocatalytic activity. Scanning electrochemical microscopy (SECM) with a scanning optical fiber was used to rapidly identify the best composition of ZnxCd1-xS photocatalyst. Among these arrays, the pure CdS at 200oC annealing temperature exhibits the highest photocurrent under both UV-visible and visible illumination. The physic-chemical and optical properties of the potential photocatalyst were investigated by using X-ray diffraction (XRD), X-ray photoelectron spectrometric (XPS), UV-visible absorption spectra, AC impedance and incident photon to converted electron (IPCE). A possible mechanism induced by the annealing temperature to affect the photocatalytic performance of the CdS was studied in detail.
A Novel Photoelectrochemical Secondary Battery Featuring Phthalocyanine Photocathode Toward the Application to Ubiquitous Sensors
Authors: Shimizu Takashi , Kondo Takashi , Ando Akira , Abe Toshiyuki , Nagai Keiji
Published: February 2020

The conventional photovoltaic cell can be one of the most suitable energy sources for driving ubiquitous sensors when it also has the function as a secondary battery in the dark. However, such a system tends to require high cost and is also of difficulty in the viewpoint of miniaturization. Alternatively, a photoelectrochemical cell can offer a simple and promising battery originating in chemical reaction under solar irradiation. In this study, we proposed a novel photoelectrochemical battery (denoted as PEB) with a photoelectrode of metal-free phthalocyanine (denoted as H2Pc, a p-type semiconductor) deposited on ITO. H2Pc has a great potential in terms of an efficient absorption over the visible-light energy range, low cost, harmlessness, and ease of deposition, which can be expected to be an ideal photoelectrode for versatile PEB. When the photoelectrode was irradiated using the visible-light energy of λ＞500 nm, FeIII(CN)6
3– (electron acceptor) was reduced at the H2Pc surface, whereas FeII(CN)6
4– (electron donor) was concurrently oxidized at the counter electrode. This result indicates that H2Pc worked as the photocathode (i.e., H2Pc induced the generation of photocathodic currents for charging the PEB under the visible-light irradiation). The photocurrent density during charging was ca. 30 μA/cm2. Furthermore, when turning off the light, discharge occurred between the counter electrode and the discharge electrode. Such charge-discharge phenomena were confirmed to occur repeatedly. These results showed that the PEB featuring H2Pc photoelectrode can be an attractive electric power source toward ubiquitous sensors. In addition to the details of the aforementioned results, the origin of the present photocurrent will be discussed in terms of the FeIII(CN)6
3– reduction at the H2Pc photoelectrode.

Figure 1
Interfacial Structure of Nafion
Authors: Dura Joseph A. , DeCaluwe Steven C , Kienzle Paul
Published: February 2020

While ion-conducting materials are primarily considered for their use as electrolytes (which depend upon their bulk properties, i.e. conductivity, crossover rejection, and material strength) their interfacial properties are becoming increasingly relevant for optimizing electrochemical devices.  Ionomers are often applied as binders, which coat fuel cell catalyst electrode particles with layers that are several nanometers thick.  Here confinement effects or the interfacial properties of the ionomer may directly influence the efficiency of the electrochemical device.  Furthermore various fillers are increasingly used to modify the properties of ionomers to improve the bulk electrolyte characteristics.  For example silica particles are added to Nafion to increase water retention especially at high temperatures in fuel cells and to reduce V crossover in flow batteries. 

Neutron reflectometry, NR, is capable of determining structure with sub-Angstrom precision in idealized planar interfaces.   Because of isotopic contrast variations it is particularly sensitive to certain elements such as H (and thus water) as well as Li, V, and numerous others.  Herein, NR has been applied to investigate finite-size effects on the lamellar ordering of water domains in Nafion at interfaces with hydrophilic materials.  Moreover, contrast variation was employed to quantify the segregation of the sulfonate groups from the fluorocarbon chains in Nafion.

These results confirm the lamellar structure previously observed on hydrophilic substrates, and demonstrate that for hydrated films they can accurately be described as layers rich in both water and sulfonate groups, alternating with water-poor layers containing an excess of the fluorocarbon backbone. The thickness of these layers increases slightly and the amplitude of the oscillation that defines the water volume fraction exponentially decreases away from the hydrophilic interface.  A partial monolayer of sulfonate groups is determined to be bonded to the SiO2, accompanied by a large excess of water (compared to that expected by the water-to-sulfonate ratio, λ, of the remainder of the film). Ultrathin (6nm) Nafion coatings that were limited in extent enough to truncate this lamellar region showed a depth profile nearly identical to thicker films, indicating that there are no confinement or surface effects altering the structure.  For films dehydrated for 2 hours at 60 °C, the composition oscillations are decreased in amplitude and extent from the interface.  Comparing the SLD profile measured for dried films to modeled composition profiles derived by removing water from the hydrated lamellae suggests incomplete remixing of the polymer groups upon dehydration, indicated either limited polymer mobility or retained equilibrium structures at in the Nafion/SiO2 interface.
Toward a Single-Ion Nanocomposite Electrolyte for Lithium Batteries
Authors: Zhao Hui , Baker Gregory , Liu Gao
Published: February 2020

Lithium ion battery has been widely used nowadays. Occurrence of polarization has been a problem in the currently used electrolyte, especially in high-current application such as hybrid vehicles. In this work we modified silica nanoparticles with polyelectrolytes containing anion groups, lithium cation is the counterion. To get the lithium conductor, the polymer modified nanoparticles were blended with poly(ethylene oxide) oligomer. Movement of the anions were largely restricted by surface anchored polymer backbones, lithium ion became the only ion that is conducting current. Four different polymer structures were explored in this study, aiming at improving conductivity of the material. FTIR and TGA were used to prove successful synthesis of the polymer modified particles. AC impedance was used to measure the conductivity with a room temperature conductivity above 10-5 S/cm. This composite electrolyte has the potential to suppress lithium dendrite growth and enable the use of lithium metal anode in rechargeable batteries.
Study of Morphological Variation on SiO2/Nafion Composite Membrane Under Different Hydration Condition
Authors: Kwon Osung , Son ByungRak , Kim Joogon , Lee Dong Ha
Published: February 2020

Passive air breathing proton exchange membranes fuel cells (AB-PEMFC) have a unique advantage such as remarkably reducing stack weight by minimizing balance of plant (BOP). However, the performance of the AB-PEMFC is worse than general PEMFC because it is difficult to controlling humidification and stack temperature. Thus, the proton exchange membranes (PEMs) which are used to AB-PEMFC have to stably work under various humidification and temperature. A lot of research groups are reported that inorganic fillers (SiO2, TiO2, ZrO2) and Nafion composite membrane show high performance under low relative humidity by increasing water retention on the membrane. In this study, we synthesize SiO2/Nafion composite membrane for compensating the weakness of AB-PEMFC.

The performance of membrane electrode assembly (MEA) with SiO2/Nafion composite membrane is tested under different hydration and temperature conditions. For more detailed characterization, morphological variations of the composite membrane under hydration conditions are studied by using dynamic mode atomic force microscopy (DMAFM). DMAFM can map amplitude and phase distribution on the specimen surface. The phase lag, which is mechanical vibration changing of a cantilever, is resulting of tip-sample interaction, which is induced by microscopic mechanical property of sample. Thus, the DMAFM is best tool for characterizing heterogeneous materials such as composite membrane. The morphological structure variation on the composite membrane by water retention elevation is systematically studied by using phase lag changing under different humidification condition.

References 

C. A. Hayden, and G. R. Goward, Proton Dynamics of Nafion and Nafion/SiO2 Composites by Solid tate NMR and Pulse Field Gradient NMR Macromolecules 40, (2007),  1529-1537

Bella Nicotera, Apostolos Enotiadis, Kristina Angjeli, Luigi Coppola, Giuseppe A. Ranieri, and imitrios Gournis, Effective Improvement of Water-Retention in Nanocomposite embranes Using Novel Organo-Modified Clays as Fillers or High Temperature PEMFCs,  Journal of Physical Chemistry B 115, (2011), 9087–9097

Figure 1
Aptamer-Based Electrochemical Biosensors for Marine Toxins
Authors: Eissa Shimaa , Siaj Mohamed , Zourob Mohammed
Published: February 2020

Marine toxins are naturally occurring chemicals that can contaminate certain seafood. They are usually tasteless, odourless and have no toxic effect on shellfish. However, they exhibit toxicity towards marine mammals, birds, fish and humans. The ethical problems as well as the technical difficulties associated with the currently employed analysis methods for marine toxins are encouraging the research for suitable alternatives to be applied in a regulatory monitoring regime. Here, we report electrochemical biosensing platforms for okadiac acid (OA) as well as brevetoxin-2 (BTX-2) detection using aptamers as specific receptors. Using in vitro selection, high affinity DNA aptamers to OA and BTX-2 were successfully selected for the first time from a large pool of random sequences. The binding of the toxins to aptamer pools/clones was monitored using fluorescence and electrochemical impedance spectroscopy (EIS). Most of the selected aptamers exhibited high binding affinity to their target toxins with a dissociation constants in the nanomolar range. The effects of the incubation time, pH and metal ions concentrations on the aptamers-toxins binding were studied. The highest affinity aptamers were then used to construct label-free impedimetric biosensors for both OA and BTX-2 detection showing good sensitivity. A high degree of cross reactivity of the selected BTX aptamers to the two similar congeners, BTX-2 and BTX-3 was observed, whereas no cross reactivity to other marine toxins was obtained. Moreover, the aptasensors were applied for the detection of OA and BTX-2 in spiked shellfish extracts showing very good recovery percentages. We believe that the continual emergence of novel, high-affinity aptamers will open the way to a variety of biosensing architectures, particularly for small-molecule toxin detection in complex samples.
Label-Free Electrochemical Aptasensor for the Sensitive Detection of Cyanotoxin Anatoxin-a
Authors: Elshafey Reda , Siaj Mohamed , Zourob Mohammed
Published: February 2020

The sensitive detection of neurotoxin anatoxin-a (ATX) is a necessary to effectively manage and control the treatment of water resources. Here we report the selection of high affinity DNA aptamers targeting ATX for developing an impedimetic aptasensor for ATX for which there are no reported biosensors so far. The dissociation constants (Kd) of the aptamers are in the nanomolar range. The sensor was designed by self assembling of disulfide modified aptamer on a gold electrode. The aptasensor fabrication process was characterized using cyclic voltammetry and electrochemical impedance spectroscopy. Upon ATX recognition to the immobilized aptamer, a marked decrease in the electron-transfer resistance was recorded. This is as a result of the aptamer conformation change which is used as sensor signal. The aptasensor showed a limit of detection of 0.5nM and a wide linear range for ATX concentrations between 1nM and 100nM. The Kd that was calculated from the aptasensor signal showed a lower value implying that the anchoring of the aptamer on the Au surface enhanced its affinity to ATX. The ATX aptasensor showed high stability as well as high specificity against common cynaobacterial toxins. Further biosensor designs will be expected using those aptamers for simple ATX detection
(Invited) Graphene and 2d Crystals for Energy Devices
Authors: Pellegrini Vittorio , Bonaccorso Francesco
Published: February 2020

Energy conversion and storage are two of the grand challenges that our society is facing. New materials and processes [1] can improve the performance of existing devices or enable new ones [2] that are also environmentally benign. In this talk we will start by reviewing recent progress on the application of graphene, related two-dimensional crystals, and hybrid systems for energy conversion and storage [3]. The versatility of graphene and related materials can lead to new power management solutions for portable and flexible devices, as well as integration in living environments. In this context we will present our latest results on the development of solar module based on graphene ink deposited by spray coating on large area (~50cm2), a promising starting point for façade applications. We will then focus on our recent development of graphene-based ink battery that displays an estimated energy density of about 200 Whkg-1 and a stable operation for over 80 charge-discharge cycles [4]. These properties are linked to the graphene nanoflake anode displaying crystalline order and high uptake of lithium at the edges. Our approach, compatible with any printing technologies, is cheap and scalable and opens up new opportunities for the development of high-capacity Li-ion batteries.

References

F. Bonaccorso, et al., Production and processing of graphene and 2d crystals.
Materials Today
, 15, (2012), 564-589.

F. Bonaccorso, Z. Sun, Solution processing of graphene, topological insulators and other 2d crystals for ultrafast photonics.
Opt. Mater. Express
4, (2014) 63-78.

F. Bonaccorso, et. al., Graphene, 2d crystal and hybrid structures for energy conversion and storage.
Science
in press (2014).

J. Hassoun, et al. An advanced lithium-ion battery based on a graphene anode and a lithium iron phosphate cathode.
Nano Lett
. 14, 4901-4906 (2014).

 * Work done in collaboration with A. Di Carlo, E. Kymakis, B. Scrosati,
Artificially Tailored Plasmonic Nanostructures for High-Performance Biosensing Devices
Authors: Pradhan Aswini K
Published: February 2020

Rapid advances in nanoscience and nanotechnology have been driven by many novel experimentations, which have revolutionized nanostructure synthesis and fabrication for a variety of applications. Artificial and engineered nanoscopic structures, which interact with the electromagnetic field, extend the antenna concept into the optical wavelength for molecular detection applications. Currently, biosensors based on surface plasmon resonances (SPR) have become one of the most important tools for analyzing biomolecule interactions and detecting chemical and biological substances. They have been increasingly applied to life science and pharmaceutical research as well as some important areas such as medical diagnostics, environmental monitoring, food safety and security. Although there are numerous of development and studies on SPR biosensing systems and devices, it remains an ongoing challenge to design and fabricate the biosensors with high sensitivity, low cost, and the ability to realize lab-on-a-chip devices for point-of-care diagnostics. We will present project the hybrid nanostructures to expand the plasmonic sensing application and deepen the understanding of the mechanism in engineered photonic nanostructures but also aims for realizing a high sensitivity and low cost lab-on-a-chip biosensing device.
A Miniature Sensor Integrating Multiple Detection Technologies for Evaluating Water Pollution
Authors: Poorahong Sujittra , Lefèvre Florent , Perron Marie-Claude , Juneau Philippe , Izquierdo Ricardo
Published: February 2020

A portable system to monitor water quality in both developed and developing countries is highly required. Currently, there is no commercial test available to satisfy this demand, as only accredited laboratories can perform such evaluations. Miniaturization of analytical instrumentation is one of the dominant trends within the chemical and biological sciences. Miniaturization of diagnostic devices not only affords portability and significant cost reductions but also performance gains in terms of speed, analytical efficiency, automation and reproducibility.

To address this issue, a phytoplankton (alga and cyanobacteria) based detection system implemented in a micro-fluidic platform was developed. As change of the environment of algae induced by toxic compound can affect their metabolism, this makes phytoplankton ideal natural biosensors. Their response can be measured in real time by various detection mechanisms i.e., optical, chemical or electrical. The innovation of the system presented in this study, is to integrate both electrochemical and fluorescence detection in a single chamber. The system is shown in Fig.1.

 In general, photosynthesis process of algae is inhibited in presence of toxic compound, in our case, Diuron. Electrochemical detection is based on the measurement of oxygen produced by algae under such conditions. It was carried out using transparent silver nanowires electrode. The size distribution of the Ag nanowires is  ~ 80 nm in length and the transparency of the electrode is 80%. Fluorescence detection is based on the activity of photosystem II in the presence and absence of Diuron. The concentration of Diuron can be detected by electrochemical detection between 50 and 1000 nM. (Fig. 2A) and 0.50 to 1000 nM using fluoresecense detection (Fig. 2B). The two detection systems were integrated into a single chamber in a way which enables for more reliable and sensitive detection of water pollutant.

 Figure 1  Edge view of the opto-electrochemical sensing device: a transparent oxygen sensor is integrated with a fluorescence sensor into the same chamber.

 Figure 2 response curves of electrochemical and fluorescense detections of algae to the herbicide, Diuron

Figure 1
(Invited) Nanobiosensors for Healthcare and Environmental Monitoring
Authors: Aguilar Zoraida Pascual
Published: February 2020

Nanobiosensors applications are among the most promising commercial products developments involving nanotechnology. It was predicted that in 2017[i], the global market for biosensors in medical diagnostics would reach US$16.5 billion. Various entities working on  new product developments focus on health, food, water, pharmaceuticals, industrial,  and environmental monitoring. Nanobiosensors  which are robust, sensitive, inexpensive, and have ultra-low limits of detection are revolutionizing the various areas of sensing with advances beyond conventional science and technology.  The preliminary developments of nanobiosensor platforms that are potentially applicable across all fields of science, engineering, technology, and medicine will be presented.  The unique attributes of nanobiosensors for healthcare and environmental applications that harness the unique properties and attributes of nanomaterials will be discussed.

[i] Global Industry Analysts, Inc., accessed on February 3, 2014. http://www.prweb.com/releases/medical_biosensors/environmental_biosensors/prweb9242715.htm
Electrochemical and Electrocatalytic Properties of Platinum Electrode Modified With Gold-CNT Nanocomposite
Authors: Adekunle Abolanle Saheed , Ayenimo J. G. , Fang X. -Y. , Doherty W. O. , Arotiba A. O. , Mamba B. B. , Ebenso Eno E
Published: February 2020

Dopamine (DA) is an important neurotransmitter in the mammalian central nervous, hormonal and renal system [1]. It can cause Parkinson’s disease (when in low amount) and other similar diseases [2]. Epinephrine, (EP) on the other hand belongs to the group of substances known as catecholamine neurotransmitters which include norepinephrine and dopamine [3]. They are mainly important for message transfer in the mammalian central nervous system (CNS). Changes in concentration of epinephrine in the body can result in many diseases such as Alzheimer’s disease and aging effect. Therefore, various analytical methods to detect these analytes have been developed in the past. Some examples of these methods are the liquid chromatography, mass spectrometry, gas chromatography methods, and capillary electrophoresis mass spectrometry method. These methods require several derivatization procedures which are time consuming and very expensive. It is also known that with a bare electrode the oxidation peaks of DA and AA are at nearly same potential, which results in the overlapped voltammetric responses making their discrimination very difficult. Thus, motivation to this work is to fabricate sensitive, specific and selective sensors that would discriminately detect DA and EP in the presence of other interfering species such as ascorbic and uric acids. An electrochemical method was employed since it provides a simple, cost effective and quick way of analyzing biologically and environmentally important molecules.

In this study, the electron transfer and electrocatalytic properties of gold nanoparticle catalysts supported on MWCNTs/platinum modified electrode were described. The Pt-MWCNT-Au and Pt-MWCNT-AuO and the other modified electrodes were successfully characterised with FESEM, HRTEM, XRD, EDX, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The MWCNT-Au based electrodes demonstrated fastest electron transport and current response towards DA and EP compared to the other electrodes studied, with a relatively high catalytic rate constant, high sensitivity and nano molar (10-9 M) limit of  detection. The electrode can detect DA and EP without interference from ascorbic acid (AA) signal. The electrode demonstrated good potential towards DA detection in real drug sample analysis.

REFERENCES:

1. N.Q. Jia, Z.Y. Wang, G.F. Yang, H.B. Shen and L.Z. Zhu,  Electrochem. Commun., 9, pp 233, 2007

2. Q. Wang, N. Jiang and N. Li, Microchemical Journal, 68, pp 77, 2001

3. P. Hernandez, O. Sanchez, F. Paton and L. Hernandez, Talanta, 46, pp 985, 1998
Amperometric Oxygen Sensor Based on Bimetallic Pd-V/C/Nafion Electrode
Authors: Wu Hui-Lun , Weng Yu-Ching
Published: February 2020

A novel oxygen sensor based on bimetallic Pd-V/C/Nafion electrode was developed. Carbon-supported bimetallic Pd-V nanoparticles were prepared by chemical reduction method at low temperature and sprayed on the Nafion membrane as working electrode. Their morphologies, compositional and structural properties were characterized by transmission electron microscopy (TEM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), thermogravimetric analysis (TGA) and x-ray diffraction (XRD). Chemical reduction conditions including reducing agents and pH values for maximum catalytic efficiency, electrode selectivity, and reproducibility were discussed. Results showed that the optimal operating condition to generate the bimetallic Pd-V/C/Nafion electrode was using sodium borohydride as reducing agent at pH 4. The Pd6V4/C/Nafion electrode with face-centered cubic (fcc) structure exhibited the highest sensitivity of 7.42 µA/ppm·cm2. It has a linear relationship between response current and oxygen concentration in the detection range from 100 to 1000 ppm. The sensor also displayed good selectivity and reproducibility.
Gas Sensing on Oxidized Bronze
Authors: Banerjee Sriya , Myung Yoon , Banerjee Parag
Published: February 2020

We perform oxidation and phase segregation of bronze (an alloy of Cu: Sn = 95: 5) and demonstrate that the heterogeneous oxide formed is suitable for oxygen sensing. Tin oxide (SnO2) is an n-type semiconductor whereas, cupric oxide (CuO) is a p-type semiconductor. Both oxides have shown sensitivity to detecting gas molecules. Therefore, the presence of both n and p-type oxide on the same substrate can lead to a sensory platform with a wide array of gas sensing capabilities.

Thermally oxidized bronze forms a CuO layer on top, underneath which exists a mixed, CuO-SnO2 layer. It is found that Sn segregates to the grain boundaries whereas Cu exists mostly on grain surfaces. This happens due to the differences in the diffusion constants of the Cu and Sn atoms. Further, the oxidation process creates a variety of nanostructures including CuO nanowires and SnO2 plates. Supporting characterization data is provided via SEM, HRTEM, Raman and x-ray diffraction.

The oxidized samples are then prepared as conductometric sensors for testing various gasses. As an example, on the introduction of dry air into a vacuum chamber (maintained at 2 mTorr), the devices showed a 10% resistance change at 400 K and a 6% resistance change at 373 K. This indicates that facile thermal oxidation of low-cost alloy substrates can lead to the formation of effective, ‘on-skin’ sensors.
a New Bifunctional Electrochemical Sensor for Hydrogen Peroxide and Nitrite Based on Bimetallic Porphyrin MOF
Authors: Zhou Bo , Shi Li-Mei
Published: February 2020

Metalloporphyrin molecules are excellent candidates to act as molecular building blocks for the construction of MOFs, because of various functional group substituents in the periphery of the molecule and the huge variety of available derivatives incorporating different centre-coordinated metals.[1] in this work, a new bimetallic porphyrin MOF, [Cu2(Co-TCPP)(H2O)2]·0.5DMF·5H2O (Cu-CoTCPP), consisting of [5,10,15,20-(4-carboxy-phenyl)porphyrin]Co(II) (CoTCPP) struts which were bound by Cu(II)-carboxylate clusters (Cu2(COO)4), was prepared solvothermally and characterized by various techniques, including XRD, IR, elemental analysis, TG, and TEM. Cu-CoTCPP showed novel bifunctional electrocatalytic ability toward both the reduction of H2O2 and the oxidation of NaNO2 which might be due to Cu and Co, respectively. With the assistance of multi-walled carbon nanotubes (MWNTs), Cu-CoTCPP showed greatly improved sensing performance in the determination of H2O2 and NaNO2. Cu-CoTCPP/MWNTs/GCE also showed fast response, and high selectivity, steadiness and reproducibility. Excellent determination performance and high biocompatibility make the metalloporphyrin functionalized MOFs promising in electrochemical biosensing.

Keywords: porphyrin

MOF

, bimetallic, electrochemical sensing

[1] LI, Q. W., ZHANG, W. Y., MILJANIC, O. S., SUE, C. H., ZHAO, Y. L., LIU, L. H., KNOBLER, C. B., STODDART, J. F. & YAGHI, O. M. 2009. Docking in Metal-Organic Frameworks. Science, 325, 855-859.

The authors thank National Natural Science Foundation of China (Grant No. 21175068) for the financial support.
Characterization of the Double Layer By Time Resolved Surface Enhanced FTIR Spectroscopy
Authors: Parr Daniel , Zibart Christina , Egan Bryce , Malik Kasim , Shadley Tyler , Haverhals Luke M.
Published: February 2020

The utilization of ionic liquids (ILs) for future electrochemical applications shows great promise.  Recently ILs have been investigated for many electrochemical systems however, further characterization and development of ILs remains to be done before they are applied to devices such as batteries, capacitors, and fuel cells.  For example, data that yield understanding of the interfacial structure and dynamics of ILs at electrode surfaces are vital since these interactions ultimately allude to electrochemical device efficiency.  We will present time resolved (TRS) FTIR spectroscopy data as a means to characterize IL-based electrolytes.  In particular, we will exhibit two modes of TRS: step scanning and rapid scanning during simultaneous electrochemical perturbation to better understand IL interactions at metal electrode surfaces.
Pit Initiation in Aluminum and Aluminum Alloys
Authors: Pinkowitz Ainsley , Straub Sarah , Duquette David , Hull Robert
Published: February 2020

The growth of pits in passive metals and alloys exposed to chloride solutions is reasonably well understood and has generally been attributed to chemistry changes in occluded cavities in the metal surfaces.  The initiation of pits, however, is still a matter of some conjecture.  In particular the processes associated with the propagation of stable pits, versus pits that initiate but then apparently re-passivate are not particularly well understood.  It is well known that, many passive metals and alloys exhibit well-established relationship between the onset of stable pitting (as measured by an irreversible pitting potential) and chloride concentration [1].  The goal of this program is to study the local breakdown of passive films by onset of pitting in dilute chloride solutions where it is presumed that the pitting processes will be delayed and the specific interactions between chloride and passive films can be examined in more detail.  Pitting potential experiments on A1100 aluminum and A2024 aluminum alloys were performed in aqueous chloride solution, as a function of pH, from 10-6 M to 3 M chloride, using conventional potentiodynamic techniques.  The results obtained for both alloys, in solutions ranging from 10-3 M to 3 M chloride replicate those of McCafferty [1] that showed a specific relationship between pitting potential and chloride concentration.  However, the sensitivity of the pitting potential to chloride concentration shows a well defined inflection at chloride concentration of approximately 10-3M.  Data will be presented comparing the pit distributions and morphologies at low, intermediate and high chloride concentrations.  The results will be discussed in terms of the specific interactions of chloride with passive films, transport of the chloride through the passive films, and the reaction of the chloride with the underlying metal surfaces.

1.  McCafferty, E. (2003). Sequence of steps in the pitting of aluminum by chloride ions. Corrosion Science, 1421-1438.

This project was supported by the National Science Foundation under grant #NSF-DMR 1309509
Lithium Ion Battery Energy Storage System for Grid Applications
Authors: Moss Eugene Newton , Nelson Ruben , Weatherspoon Mark H , Moss Pedro L.
Published: February 2020

Due to the increasing demand for lower energy costs for the supplier and the consumer, using energy storage devices can offer a number of high-value benefits, provided that lower costs can be gained from using this method.  Using rechargeable lithium batteries as a storage device in tandem with the power grid can be viewed as a viable way to reduce costs of generation and distribution by the power company and also as a way to drive down electricity bills for consumers.  Possible grid applications with energy storage devices can  range from frequency regulation and load following, for which short response times are needed, to peak shave and load shift, both of which can lead to improvements in grid reliability, stability, and cost [1]. 

Energy storage systems (ESS) are becoming  widely used as a compliment to the power grid (need a citation to prove this). Large scale ESS are often used due to the advancement of the technology but  smaller scale  technologies such as compressed air, thermal (thermal what?) and batteries, are also being used more. The smaller scale application can be used more often because there is not a need for specific geographical requirements such a remote location [2]. The ESS that will be discussed is one composed of lithium-ion batteries. There are many advantages of using this specific device, including a high energy-to-weight ratio, no memory effect, and a little self-discharge[3]. Common applications include portable equipment, mobile telephones, and plug-in hybrid and electric vehicles.

In this study, an overview of a proposed ESS organization and simulation of the response of both parallel and series lithium-ion battery ESS configurations will be compared to determine the most efficient method of powering a load.  Factors that determine the better response include capacity fade and useful life. From these results, it can be concluded which may be a better design to incorporate into an ESS based on cost.

 Figure 1: Flowchart of Energy Storage System Design

Acknowledgment

This work was supported by the FREEDM ERC program of the National Science Foundation under award number EEC-08212121.

References

B. Dunn, H. Kamath and J. Tarascom.  Electrical Energy Storage for the Grid: A Battery of Choice. American Association for the Advancement of Science. 2011

M. Arifujjaman, A comprehensive power loss, efficiency, reliability and cost calculation of a 1 MW/500 kWh battery based energy storage system for frequency regulation application, Science Direct. 2013

S. Vazquez, S. M. Lukic, E. Galvan, L. Franquelo, J.M. Carrasaco. Energy Storage Systems for Transport and Grid Applications

Figure 1
Laterally Assembled Ga2Te3/In2Te3 Hetero-Nanostructures for Thermoelectric Applications
Authors: Hung Yu-Ting , Chen Taung-Han , Chang Hsiu-Cheng , Chen Chun-Hua
Published: February 2020

Hetero-nanostructuring has been theoretically and experimentally proven as a practical strategy to enhance the thermoelectric figure of merit, ZT (defined as σS2T /κ) via largely creating various nanoscaled heterogeneous interfaces which could not only effectively scatter phonons to have a much lower thermal conductivity, but potentially activate the electron filtering phenomenon for simultaneously improving the Seebeck coefficient and electrical conductivity. In this presentation, a series of laterally- and periodically-assembled Ga2Te3/In and Ga2Te3/In2Te3 hetero- nanocomposite films were successfully fabricated using pulsed laser deposition (PLD) with subsequent various annealing processes. The distinct interfacial structures as well as the corresponding enhanced thermoelectric properties will be discussed.

Keywords: thermoelectric, heterostructure, assembly, nanocomposite, pulsed laser deposition
Core-Shell Structured Supported Size-Selective Catalysts with High Catalytic Activity
Authors: Shang Zeyu , Liang Xinhua
Published: February 2020

Heterogeneous catalysts are widely used due to many advantages including the easiness of separating the catalysts by filtration after reaction. However, heterogeneous catalysts cannot selectively convert specific molecules in the reactant mixture to only desired products. Size-selective catalysis is an important concept of improving the selectivity of heterogeneous catalysts. In previous studies, both supported and unsupported metallic nanoparticles were enshrouded in relative thick porous structures to realize the size-selectivity of heterogeneous catalysts. However, the catalytic activity of the catalysts reduced significantly due to the mass transfer limitation brought by the relatively thick shells. In this study, we deposited an ultra-thin porous oxide shell on supported Pt catalysts using molecular layer deposition (MLD) method. The core-shell catalyst shows pretty high catalytic activity and size-selectivity in hydrogenation reactions of n-hexene over cis-cyclooctene.
Direct Electrodeposition of Crystalline Si Nanowires at Low Temperatures
Authors: Ma Luyao , Lee Sudarat , Maldonado Stephen
Published: February 2020

Crystalline Si nanowires (SiNWs) were synthesized through an electrochemical liquid-liquid-solid (ec-LLS) deposition process from dissolved SiCl4 in propylene carbonate at 90 °C using Ga nanoelectrodes. Scanning electron micrographs showed controlled growth of nanowire structured deposits from an array of Ga nanoelectrodes after the ec-LLS process. Energy dispersive X-ray spectroscopy indicated that the chemical composition of as deposit nanowires was Si with low Ga incorporation. X-ray diffraction and Raman spectroscopy separately indicated that the film of as-deposited SiNWs were crystalline. Electron beam diffraction of a single SiNW was taken within a transmission electron microscope and patterns for a diamond cubic crystal structure was obtained. Scanning electron micrographs of the orientation of nanowires on Si(111) and Si(100) substrates with different crystalline orientations suggested that epitaxial nanowire growth was achieved under these conditions. Cyclic voltammogram of SiCl4 electrolyte on Ga nanoelectrodes and potential response of the chronopotentiometry experiment that produced SiNWs indicated that the SiNW deposition is energetically favorable to other parallel processes in the deposition electrolyte. Temperature dependence study showed that SiNWs could be produced using ec-LLS at as low as 60 °C, at which temperature Si solubility in Ga and Si diffusivity in Ga is sufficient for heterogeneous nucleation to occur at Ga/substrate interface.