bluuebunny/crossref_metadata_2025_split huggingface dataset:
Atomic Layer Deposition Nanoelectrode Array As a Platform for Ion Transport Studies
Authors: Zenyuk Iryna V. , Sabarirajan Dinesh C 
Published: February 2020

Ionic conductivity in electrochemical application is a function of the number of charge carriers and their mobility. In the electrodes containing ionomer both numbers are high, whereas in deionized water, the ion concentration is ~7 orders of magnitude lower than that in a polymer electrolyte, such as Nafion. In ionomer-free electrodes for fuel cell applications, such as Pt-black or extended-surface Pt electrodes, water assists in ion conduction and expected ionic conductivity should be close to that of deionized (DI) water. However, ionic conductivity of ionomer-free electrodes was measured to be 2-3 orders of magnitude higher than DI water (1, 2). These findings suggest that local confinement and electric double layers (EDLs) affect ion concentration or/and ion mobility, especially in porous high surface area electrodes. Over the years several experimental and modeling studies propose two ion transport mechanisms: 1) Ions transport through surface adsorption and subsequent neutral species surface diffusion and 2) water-mediated ion conduction due to EDLs (3). To understand these mechanisms, model electrodes with controlled geometry and active area have to be designed.
In this study, Atomic Layer Deposition (ALD) was used to fabricate model thin-film electrodes to study ion-transport mechanisms under varied levels of relative humidity. The ALD gas-phase fabrication process provides a uniform and conformal Pt layer with precise thickness on a high aspect-ratio substrates. Here, we fabricate Pt electrodes with a novel thermal ALD process. The activity of the deposited electrodes is characterized with RDE tests and within actual fuel cell hardware. Ionic conductivity studies are conducted in a membrane electrode assembly (MEA) fuel cell set-up under various relative humidities and operating potentials to elucidate the range of proton transport mechanisms. Furthermore, various interlayers were added to the MEA to switch on and off the ion transport processes to separate Had surface diffusion from charged proton surface migration mechanisms.
Figure 1. SEM images of the Pt nanoelectrode array a) after 500 cycles showing a thickness of 8 µm b) honeycomb structured in-plane view after 500 cycles c) cross sectional side view of 5 µm after 300 cycles d) In-plane view of the nanoelectrode array after 300 cycles e) In-plane view of the nanoelectrode array fabricated using 100 nm pore sized AAO and 200 cycles.
References

K. C. Hess, W. K. Epting and S. Litster, Analytical Chemistry, 83, 9492 (2011).

P. K. Sinha, W. Gu, A. Kongkanand and E. Thompson, Journal of Electrochemical Society, 158, B831 (2011).

I. V. Zenyuk and S. Litster, Electrochimica Acta, 146, 194 (2014).

Figure 1
Anodic TiO2 Nanotube Layers: Excellent Platform for Secondary Materials
Authors: Zazpe Raul , Sopha Hanna , Krbal Milos , Prikryl Jan , Macak Jan M. 
Published: February 2020

The self-organized TiO2 nanotube layers have attracted considerable scientific and technological interest over the past 10 years, which are motivated for their possible range of applications including photo-catalysis, solar cells, hydrogen generation and biomedical uses [1]. The synthesis of 1D TiO2 nanotube structure is carried out by a conventional electrochemical anodization of Ti sheet. The main drawback of TiO2 is its applicability in the UV light (wavelengths < 390 nm). In order to enhance the efficiency, TiO2 has been doped by N [2] or C [3] to shift its absorption into the visible light.
Except of doping, one of the major issues to extend the functional range of nanotubes is to coat homogenously tube interiors by a secondary material. It has been shown that additional ultrathin surface coating of TiO2 by secondary materials such as Al2O3 [4], ZnO [5] or MgO [6] annihilates electron traps at the TiO2 surface and thus increases the concentration of the photogenerated charge carriers. The presentation will focus in detail on the coating of the nanotube arrays by various secondary materials using ALD. The deposited materials influence strongly photo-electrochemical properties of nanotube layers. Experimental details and some very recent photocatalytic [7, 8], sensing [9] and solar cell [10] results will be presented and discussed.
References:

J. M. Macak et al., Curr.
Opin. Solid State Mater.
Sci. 1-2 (2007) 3.

C. Burda et al., Nano Lett. 3 (2003) 1049.

S. Sakthivel et al., Angew. Chem., Int. Ed. 42 (2003) 4908.

R. Zazpe et al., Langmuir 41 (2016) 32.

A. Ghobadi et al., Sci. Rep. 6 (2016) 30587.

H. Park, et al., J. Electroceram. 23 (2009) 146.

H. Sopha et al., Appl. Mater. Today, 9 (2017) 104.

S. Ng et al.,
Adv. Mater. Inferf., in press

S. Ng et al. Adv. Eng. Mater., in press, DOI: 10.1002/adem.201700589.

M. Krbal et al., Nanoscale 9 (2017) 7755
A Portable System for Plant Volatile Detection
Authors: Fang Yi , Ramasamy Ramaraja P. 
Published: February 2020

Volatile organic compounds (VOCs) have been proven to be important biomarkers for predicting pathogen/pest-induced diseases in plants1. Methyl salicylate (MeSA) has been identified as one such important biomarker for biotic stress in plants2-4. Advanced detection of MeSA could help in early identification of plant diseases and has a profound significance for precision agriculture industry to maintain effective use for disease precautions. Previous research has demonstrated the development of biosensor consisting salicylate hydroxylase (SH) / tyrosinase (TYR) for salicylate detection. However, the method requires high temperature hydrolysis and pH neutralization steps before detection, rendering it more complex for device miniaturization5. In this project, we aim to eliminate these additional steps by developing a tri-enzyme detection platform consisting of esterase (ES), SH and TYR for direct MeSA detection without additional hydrolysis or pH neutralization steps. Two different immobilization strategies were used and compared using a lab-on-chip model and the sensitivity and specificity were determined to be 3.1 ± 0.2 µA·cm-2·µM-1 and 0.8 ± 0.2 µM respectively. An open source computer hardware and software Arduino was used for fabricating the computer-controlled automatic collection device for VOC collection. The prototype of a portable device for MeSA detection device was designed and fabricated, and the measurement was carried with the enzymatic biosensor strip.

Reference

(1) Laothawornkitkul, J., et al., Discrimination of plant volatile signatures by an electronic nose: a potential technology for plant pest and disease monitoring. Environmental Science & Technology, 2008. 42(22): p. 8433-8439.
(2) Buttery, R., et al., Characterization of some volatile constituents of bell peppers. Journal of Agricultural and Food Chemistry, 1969. 17(6): p. 1322-1327.
(3) Seskar, M., V. Shulaev, and I. Raskin, Endogenous methyl salicylate in pathogen-inoculated tobacco plants. Plant Physiology, 1998. 116(1): p. 387-392.
(4) Zhu, J. and K.-C. Park, Methyl salicylate, a soybean aphid-induced plant volatile attractive to the predator Coccinella septempunctata. Journal of chemical ecology, 2005. 31(8): p. 1733-1746.
(5) Fang, Y., et al., Detection of methyl salicylate using bi-enzyme electrochemical sensor consisting salicylate hydroxylase and tyrosinase. Biosensors and Bioelectronics, 2016. 85: p. 603-610.
Impact of Bio-Recognition Element Density and Other Factors Impacting Impedance Sensor Performance
Authors: Brothers Michael , Nicolini Ariana , Chavez Jorge , Martin Jen , Grigsby Curt , Drummy Lawrence , Naik Rajesh , Kim Steve 
Published: February 2020

Human performance monitoring ultimately requires integrating real-time data from both traditional physiological traits, such as body temperature, heart rate, and blood velocity and neurological biochemical molecular biomarkers to predict performance. While real-time monitoring of such physiological parameters are readily available using commercial off the shelf sensors, precise monitoring of biochemical biomarkers in real-time is still a challenging area.
Electrochemical impedance based sensors (EIS Sensors) have promise to provide detection of a wide array of molecular biomarkers of interest. The possibility to “plug and play”, the ability to integrate into a miniaturized format, and the potential to make reagentless sensors cause these sensors to be of high interest for performance monitoring. However, the self-assembled monolayer (SAM) containing the biorecognition element and issues that impact drift and noise are seldom investigated thoroughly.
The work presented here takes an in-depth look at packing density in the SAM and the effect on signal, as well as factors that may cause sensor drift. Through studying SAM density and drift, we are able to optimize signal and minimize noise, especially in highly sensitive sensors, even enabling detection of cortisol, a cognitive level biomarker of interest. Using both a proof-of-concept lysozyme aptamer, as well as a cortisol aptamer, we were able to observe the impact of packing density on sensor performance, and the consistency of these aptamers enabled through optimization of self-assembled monolayer (SAM) formation. With the results from the lysozyme SAM optimization, we followed a similar methodology to optimize the SAM for detection of cortisol. In order to broaden out the scope of this work, we used these finely tuned SAMs and performed a direct comparison of optimal and suboptimal SAMs on gated Field-Effect Transistor (FET) sensors as well.
We conclude that not only does SAM density result in an order of magnitude change in output signal, but that understanding and compensating for drift factors enable for reliable, consistent, reproducible sensors for implementation in a broad array of applications.
Conductive Shape Memory Gels for Sensing Application
Authors: Ahmed Kumkum , Shiblee MD Nahin Islam , Khosla Ajit , Furukawa Hidemitsu 
Published: February 2020

Shape memory gels (SMGs) are one of the interesting and unique classes of soft and wet materials having wide application in actuator, sensor, optical and biomedical field. Thermal responsive SMGs have the ability to return from a temporary deformed state to its original shape under the influence of heat thus having the limitation of quick and proper control. On the other hand, conductive hydrogels have high potential in the field of medical treatment (drug release), electrochemistry (bioactive electrode coating), sensors and actuators. Our group has developed DMAAm-co-SA SMG with high mechanical strength, very good transparency and biocompatibility having potential application in different sectors [1]. Thus, we are motivated to combine the physical and mechanical properties of the SMGs with the electrical activity of an electroactive component in order to create unique prospects for the next generation materials. However, conductivity is not part of the inherent characteristics of the hydrogels, it can be provided by other materials or particles that are incorporated within the network of the hydrogels (e.g., conductive particles, conjugated polymers, etc.). Fully swollen hydrogels with conducting particles, such as graphite, carbon nanotubes or metallic particles incorporated in their structure typically show conductivity but conductivity is inversely affected by the swelling ratio, and the hydrogels exhibit brittle mechanical behavior [2]. In this work conductivity of the SMGs was achieved by chemically polymerizing EDOT (with PSS as the molecular dopant) within the tough SMGs fully swollen network. Here we could achieve conductive SMG with high swelling ratio and good mechanical toughness and studied their electric signal as a function of applied pressure or strain for application in sensor devices like pressure sensor or strain sensor.

References

[1] Amano, Y; Hidema, R; Gong, J; Furukawa, H. Chem Lett.,41, 1029-1031 (2012)
[2] Morita, S; Kawai, T; Yoshino, K. J. Appl. Phys., 69 (8), 4445−4447 (1991).
A Review of Electrochemical and Non-Electrochemical Approaches to Determining Oxide Concentration in Molten Fluoride Salts
Authors: Goh Bonita , Carotti Francesco , Scarlat Raluca Olga 
Published: February 2020

The design of reactor core and heat transfer systems for molten salt reactors (MSRs) and fluoride-salt cooled high temperatures reactors (FHR) necessitates a precise understanding of the parameters affecting thermophysical and chemical properties of the molten salt medium. Oxides constitute a significant component of the impurities in alkali metal halide melts commonly implemented in MSRs. They are present initially in the raw materials due to the manufacturing process. If present in high enough concentrations, oxides can affect molten salt chemistry and thermodynamics, potentially affecting its thermophysical properties and corrosivity to structural materials. The dissolved oxide content in the melt can vary during reactor operation due to transmutation or migration to/from the environment. Therefore, it is important to develop capabilities to quantify the oxide concentration at reactor conditions. The benefit is threefold: firstly, measuring oxide concentration precisely and accurately will allow us to correlate oxide concentration with variation in thermophysical and chemical properties; secondly, knowing these correlations can facilitate the formulation of more incisive experiments to more accurately determine the activity of oxide in molten fluorides ; thirdly, such an oxide measurement system can be deployed online in a reactor as a sensor to add to the suite of reactor diagnostic instrumentation. These goals in concert will help us gain a better understanding of the basic science of a molten salt solvent environment.
In context of the ongoing effort to design an oxide sensor for molten salt systems, a review of the literature of electrochemical and non-electrochemical approaches to determining oxide concentration in molten fluoride salts was conducted and an evaluation of their merits is presented here. This evaluation served as the basis on which we selected square wave voltammetry as the most promising technique with which to develop an oxide sensor.
Fabrication of 3D Nanocarbon Structure for Potential Sensor Applications
Authors: Senegor Richard , Baron Zack , Luo Dayou , Shaffer Julia , Michelmore Andrew , Yang Cary Y 
Published: February 2020

An all-carbon 3D nanocarbon structure has been designed and fabricated using carbon nanotubes (CNT) grown on multi-layer graphene (MLG). This work was motivated by the need of current integrated circuit (IC) technology to eventually replace copper (Cu) and tungsten (W) as interconnect materials. Such a structure can also potentially be part of a chemical or biological sensing system.
Our experimental process consists of using a plasma-enhanced chemical vapor deposition (PECVD) process to grow CNT arrays directly on an MLG-covered silicon substrate after sputtering a thin nickel, iron, or cobalt (Co) catalyst film. The fabricated devices are evaluated and characterized through a combination of scanning electron microscopy and electrical measurements using a nanoprober.
The PECVD process results in highly aligned but non-conductive CNT/Graphene structures due to damages in the graphene film during CNT growth. To mitigate this challenge, we successfully identified the source for graphene damage as the plasma in the CNT growth process and, as a result, replaced PECVD with a thermal CVD growth process.
The resulting CNT/Graphene devices fabricated using Co as catalyst are conductive, with an estimated CNT-graphene contact resistance of 1.4 kΩ. Thus, we have taken the first step in demonstrating electrical conduction through an all-carbon, 3D nanostructure fabricated by growing CNTs directly on graphene.
Further experimentation is currently underway to verify and improve upon our process, including in situ nanoprobing to fully characterize the electrical properties of these devices. In addition, we use a combination of transmission electron microscopy and electron energy loss spectroscopy to verify a homogenous interface between the CNT and MLG by demonstrating the continuation of C-C sp2 bonding. Independently, we are investigating the compatibility of our current process with other CNT growth catalysts. To achieve effective sensing, additional improvements are needed, such as vertical CNT alignment, high CNT areal density, and small average CNT diameter.
Lanthanum Nickelate Cathode Materials for Intermediate Temperature-Solid Oxide Fuel Cells
Authors: Lee John In , Park Ka-Young , Park Jun-Young 
Published: February 2020

Solid oxide fuel cells (SOFCs) have been considered as the next-generation energy conversion electrochemical devices that can transform chemical energy of fuel to electrical energy. In particular, various advantages of SOFCs, such as high energy conversion efficiency, negligible pollutant emission, and the multi-fuel capability, make them indispensable for the renewable society [1].
The rate determining step of energy conversion in state-of-art SOFCs at intermediate temperature (IT) is the sluggish kinetics of oxygen reduction reaction (ORR) in the cathode, and thus the cathode material significantly affects performances of IT-SOFCs. Up to now, cobalt-based perovskite oxides have received great attentions for the cathode material because of the low overpotential for ORR. [2]. However, cobalt-based materials have significantly high thermal expansion coefficient (TEC) values ( ), compared to those of typical electrolytes (yttria-stabilized zirconia and rare-earth-doped ceria, ). This big discrepancy gives rise to mechanical stress to the cell, which affects the long-term stability of cells [3]. Furthermore, cobalt-based materials are expensive and have a low stability under reducing atmospheres. In contrast, the TEC of lanthanum nickelates (Lan+1NinO3n+1) is , which is nearly analogous to the TEC of electrolyte materials [4]. In addition, lanthanum nickelates have high electrical conductivity with the great stability at IT. In this work, the performance and durability of lanthanum nickelates are investigated in the anode-supported cell design and analyzed by using various tools such as TEM, XPS, and DFT calculations [5].
References
[1] K.T. Lee, E.D. Wachsman, Science 334 (2011) 935.
[2] W. Zhou, Z. Shao, J. Power Sources 192 (2009) 231
[3] S. Pang, X. Xi, J. Power Sources 326 (2016) 176.
[4] R.K. Sharma, E. Djurado, J. Power Sources 325 (2016) 337.
[5] T.H Lee, J.-Y. Park. J. Power Sources 331 (2016) 495

Keywords: Solid oxide fuel cells; Lanthanum nickelate; Thermal Expansion Coefficient; Conductivity, Stability
Annealing Effects on the Electrical and Optical Properties of CaCu3Ti4O12 Thin Films
Authors: Skaria Giji , Sundaram Kalpathy B 
Published: February 2020

There is an increased interest in very high dielectric constant (high-k) material studies due to their potential applications in energy storage elements. In this aspect, the perovskite materials seem to achieve very high-k values [1]. In this study, the focus has been to deposit thin films of CaCu3Ti4O12. These films are deposited by RF magnetron sputtering process using CaCu3Ti4O12 target. The films are deposited in an argon ambient and subsequently annealed in oxygen to investigate the electrical and optical properties. The studies include resistivity, dielectric constant and the band gap of the annealed films. Metal–insulator–metal (MIM) structures have been fabricated using aluminum film as the electrodes to study the electrical properties. The transmission and reflection properties are performed using the UV-Visible spectrophotometer to extract the bandgap of these annealed films.
REFERENCE:
[1] M.A. Subramanian, Dong Li, N. Duan, B.A. Reisner, A.W. Sleight, High Dielectric Constant in ACu3 Ti4 O12 and ACu3 Ti3 FeO12 Phases
High Performance Low Temperature Solid Oxide Fuel Cells with Alkali Metal Carbonate Additives in Co-Doped Ceria Electrolyte
Authors: Khan Ieeba , Basu Suddhasatwa 
Published: February 2020

Doped ceria-carbonates composites are a new class of electrolytes for low temperature solid oxide fuel cells, these show very high ionic conductivity due to fast interfacial transport [1-2]. As reported by Chockalingum and Basu [3], 25 wt% (LiNa)2CO3-GDC electrolyte exibited an ionic conductivity of 0.17 S cm−1 at 550 °C and lowest activation energy of 0.127 eV in the temperature range 550–800 °C. To further improve the ionic conductivity, a series of calcium gadolinium/neodymium/samarium co-doped cerium oxide, M0.2CaxCe0.8-xO2 (x = 0.01 to x = 0.1) (M= Gd, Nd, Sm) have been synthesised by solgel method. The electrolytes have been physically and electrochemically characterized with respect to their thermal behaviour, phase, microstructure, elemental analysis and electrochemical performance using thermogravimetric analysis, X-ray diffraction (XRD), scanning electron microscopy, Transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy and electrochemical impedance spectroscopy respectively. The particle size of as synthesized electrolyte powders is ~ 20 nm as observed from the TEM. XRD results of the prepared electrolytes show that the powders are phase pure. The gadolinium calcium co-doped ceria lithium sodium carbonate (25% (LiNa)2CO3-Gd0.2Ca0.05Ce0.75O2) composite electrolytes exhibit high ionic conductivity (0.3 Scm-1 at 650°C), as it combines both the advantages of co-doping and the composite effect. Co-doped composite electrolytes show higher conductivity and stability due to the presence of calcium than the previously investigated composite electrolytes of (LiNa)2CO3-GDC [4, 5].

References

[1] L. Fan, C. Wang, M. Chen, B. Zhu, J. of Power Sources, 234, 154 (2013).
[2] R. Raza, H. Qin, L. Fan, K. Takerda, M. Mizuhata, B. Zhu, J. of Power Sources, 201, 121 (2012).
[3] R. Chockalingam and S. Basu, J. Hydrogen Energ., 36,14977 (2011).
[4] I. Khan, M.I. Asghar, P.D. Lund, S. Basu, J. Hydrogen Energ., Volume 42, 20904 (2017).
[5] I. Khan, P.K. Tiwari, S. Basu, S. Ionics (2017), doi.org/10.1007/s11581-017-2184-9.

Figure 1