bluuebunny/crossref_metadata_2025_split huggingface dataset:
Exploring Catalytic Traits of so4
2--Functionalized Iron Oxides Exploited to Decompose Aqueous Recalcitrant Pollutants
Authors: Kim Jongsik , Choe Yun Jeong , Kim Sang Hoon 
Published: February 2020

Iron oxides are considered as ubiquitous yet valuable carriers of surface Fe2+ activators to excite H2O2, which results in the production of •OH used to decompose refractory contaminants present in H2O. To exploit catalytic nature provided by surface Fe2+ species, Fe2+ species can experience their modification by S to form S-doped iron oxide, Fe3S4, and Fe7S8, etc.1,2 For instance, we have synthesized Fe2O3 and have functionalized its surface using S species.2 The resulting S-doped Fe2O3 has manifested itself as an intriguing catalytic solid for H2O2 activation. This was because of its several benefits including 1) the incorporation of large amount of surface Fe2+ species used to cleave H2O2 via heterogeneous catalysis, 2) meso-porosity allowing for improved accessibility of H2O2 into surface Fe2+ species, and 3) chemical rigidity leading to minimized loss of Fe2+ species during H2O2 scission reactions.2 Nonetheless, surface of S-doped Fe2O3 isn't disclosed in two particular aspects of 1) H2O2 scission mechanism on S-modified Fe2+ species and 2) their catalytic functions. To answer these questions, we strategized the functionalization of Fe2O3 (pristine) surface with SO4
2- species at 300-600 °C to generate S300-S600 and investigated their surface properties using chemi-sorption/spectroscopy techniques. We then performed reaction runs under regulated environments, while using phenol as a model compound of recalcitrant compounds. Apparently, phenol degradation was directed by the characters of SO4
2- functionalities dispersed on Fe2O3 surface, whose features were markedly varied upon the change in the temperatures utilized to modify Fe2O3 surface with SO4
2- functionalities. 500 °C was required to degrade phenol in the most efficient manner among all SO4
2- functionalization temperatures studied, as showcased below. (XPHENOL and kAPP
denote conversion of phenol and reaction rate constant, respectively.) In this presentation, we will address the answers to pivotal questions detailed above. In addition, we will also highlight our efforts for clarifying catalytic roles of surface SO4
2- functionalities via a series of kinetic assessment.

References

[1] J. Kim and co-workers, Appl. Catal. B 233 (2018) 272.
[2] S. H. Kim and co-workers, Appl. Catal. B 184 (2016) 132.

Figure 1
Nanoarray Device for Detection of Gas Phase I2
Authors: Klavetter Kyle Christopher , Coleman Jonathan Joseph , Perez Carlos R. , Siegal Michael P. 
Published: February 2020

We report on a nanoelectrode array sensor for the detection of I2 (iodine gas) at levels as low as near 0,02 ppm within tens of seconds of exposure. The sensor is constructed on a free-standing anodic aluminum oxide wafer with nanopores of 120 nm diameter and 50 um length. On each wafer surface, continuous metal films of tens of nm thickness are deposited: on one surface, a gold film is deposited such that it covers the nanopores, and, on the opposite surface, a platinum film is deposited such that the nanopores remain open and their volumes in contact with the environment. The gold film serves as the working electrode and the platinum film serves as the auxiliary and pseudo-reference electrode. The nanopores are filled with a pH 9 buffer aqueous solution to create an array of electrochemical cells in parallel, and ionic conductivity is maintained for environments with relative humidity levels greater than about 30%. The detection mechanism is the electrochemical oxidation of anionic species of I2 that form from the dissolution and subsequent hydrolysis of gas phase I2 in the pH 9 buffer electrolyte: the gas phase I2 dissolves in the buffer in proportion to Henry's Law constant and then the dissolved I2 is hydrolyzed to several species, including the anionic species iodide and tri-iodide. The detection of I2 is achieved by measuring oxidizing current during the cyclic voltammetry technique bounded between -0,2 and 0,5 V vs the Pt pseudoreference electrode. The hydrolysis mechanism of I2 in the pH 9 buffer enables the buffer to function as a concentrator for the anionic species of I2. When the sensor is exposed to a gas stream containing I2, practically continuous accumulation of the electrochemically detectable anionic species of I2 is possible, with a saturation point where the pH 9 buffer contains > 100 ppm iodide anion. For context, the sensor can detect iodide anions in pH 9 buffer at levels as low as 0,01 ppm.
Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
Carbon Dioxide Sensing Characteristics of LaFe0.8Co0.2O3 – ZnO Thin Films: The Role of Homo and Heterojunctions
Authors: Bhowmick Tynee , Nag Sudip , Majumder Subhasish Basu 
Published: February 2020

Carbon dioxide is a colourless and odourless gas and detection of carbon dioxide is critical to maintaining the quality of breathable air in the atmosphere. The current concentration of carbon dioxide in the atmosphere is 400 ppm and this concentration has increased manifold in the past 50 years or so leading to global warming and other climate phenomena.
Exposure to 2000 – 5000 ppm of carbon dioxide causes poor concentration, increased heart rate and nausea and when the concentration is > 5000 ppm, oxygen deficiency may occur. This creates an urgent need to develop sensors suitable to carbon dioxide detection. Semiconducting metal oxides such as SnO2 (n-type), CuO (p-type), ZnO (n-type) WO3 (n-type) etc. have long been considered for detecting reducing gases such as carbon monoxide, hydrogen and methane. However, such metal oxides perform poorly when it comes to carbon dioxide detection. Thus, we have proposed the formation of p-n junctions with n-type metal oxide (ZnO) and p-type perovskite (LaFe0.8Co0.2O3) that has been shown previously to aid carbon dioxide sensing. LaFe0.8Co0.2O3 (LFCO) – ZnO composite thin films have been synthesized using wet chemical synthesis in which the mol % of LFCO has been varied. The role of both homo and heterojunctions in carbon dioxide sensing can be elucidated from this configuration. This configuration is cross-sensitive to carbon monoxide and mathematical analyses has been performed to differentiate it from carbon dioxide. LFCO – ZnO thin films with a single p-n junction has also been synthesized and it has been found that this configuration is much more selective to carbon dioxide than the previous one. In addition to this, the role of LFCO – ZnO multi-layered thin films has also been explored with respect to carbon dioxide sensing.
Sandwiched Platinum Thin Film TCD for 3-Omega Technique for Detection of Ammonia Gas
Authors: Lotfi Ardalan , Navaei Milad , Hesketh Peter J 
Published: February 2020

Over the past few decades, sensor technology has been revolutionized by exploring the disciplines of nanotechnology and nanofabrication process. As a result, environmental sensors including gas sensors have been miniaturized and become more advanced in the terms of sensitivity and accuracy. Todays, gas sensors can cover a broader range of volatile compounds with a limit of detection (LOD) as low as single ppm. Despite these advances, ammonia sensing is still challenging because of its corrosive nature. The chemical-based gas sensors for ammonia are not reliable due to several factors such as slow recovery time, sensor base-line drifting, vulnerability to degradation and false alarm [1]. On the other hand, physical-based ammonia sensing approaches have the advantage of fast response time and long-term durability [2].
The Thermal Conductivity Detector (TCD) limit of detection has been improved to 30 ppm by making use of the 3-omega measurement technique, however the sensor requires a robust geometrical design, and careful material selection to withstand the higher temperature during operation [3,4]. To enhance LOD further, a new design including design elements which eliminates the shortcomings in the current cantilever design. The temperature difference in the deposition process for Al203 and platinum layer causes the sensor to bend away from the silicon wafer surface, and be vulnerable to fluid velocity. Hence a supporting platinum layer has been added underneath of Al2O3 layer so that thermal stresses introduced during fabrication, and generated in operation are compensated. The new design of micro wire TCD also includes optimized shape to bear the high thermal stresses caused by continuous current needed for the 3-omega measurement technique, and a higher stability of the temperature coefficient of resistance with platinum film to improve reproducibility of response.
[1] Azad, A. M., Akbar, S. A., Mhaisalkar, S. G., Birkefeld, L. D., & Goto, K. S. (1992). Solid‐state gas sensors: A review. Journal of the Electrochemical Society, 139(12), 3690-3704.
[2] Mahdavifar, A., Navaei, M., Hesketh, P. J., Dimandja, J. D., Stetter, J. R., & McMurray, G. (2015). Implementation of a polysilicon micro electro-thermal detector in gas chromatography system with applications in portable environmental monitoring. ECS Journal of Solid State Science and Technology, 4(10), S3062-S3066.
[3]Lotfi, Ardalan, Milad Navaei, and Peter J. Hesketh. "A Platinum Cantilever-Based TCD for 3-Omega Sensing of Gas Mixtures." ECS Transactions 86.16 (2018): 79-86.
[4] Lotfi, A., Mahdavifar, A., Struk, D., Stetter, J. R., Navaei, M., & Hesketh, P. (2017). Ultimate Sensitivity of Physical Sensor for Ammonia Gas Detection Exploiting Full Differential 3-Omega Technique. ECS Transactions, 80(10), 1571-1578

Figure 1
(Invited) Interfacial Charge-Transfer Excitation at an Anatase-Rutile Junction: A Hypothesis
Authors: Ohtani Bunsho , Shen Yang , Nitta Akio , Takashima Mai 
Published: February 2020

Titania, the most widely used metal oxide for photocatalytic applications, is categorized into semiconductor based on its electronic energy structure, and therefore its band structure, which must impact on the physicochemical properties of titania, is very important. We have developed a novel method for identification and characterization of metal-oxide powders with energy-resolved distribution of electron traps (ERDT) measured by reversed double-beam photoacoustic spectroscopy (RDB-PAS) [1,2]. In this study, ERDT patterns of anatase and rutile titania powders as well as their mixtures were measured and analyzed to elucidate the actual position of valence-band of two kinds of crystallites.

Figure 1 shows ERDT patterns of ST-21 (anatase), ST-G1 (rutile) and their thoroughly brayed 50/50 mixture as well as simulated patterns by summing up to ST-21 and ST-G1 patterns with and without lower-side energy shift (ΔE = 0.19 eV) of the former. The degree of coincidence in the ERDT-pattern shape of observed and simulated mixtures, ζ, was calculated by changing ΔE to obtain the maximum ζ, 0.70, at ΔE =0.19 eV. If valence-band (VB) electrons are excited to ETs during RDB-PAS process independently in two titania samples, the mixture may give an ERDT pattern as simple summation. The results suggest that interfacial electron excitation from VB of ST-G1, which is slightly higher than that of ST-21, to ETs in ST-21. As has been already claimed that energy of ETs measured as energy from VBT in the ERDT patterns might be overestimated and electrons in a high-DOS part of VB (h-DOS(VB)), not VBT of the least DOS, are excited to ETs [1,2]. The above mentioned consideration may suggest that h-DOS(VB) of rutile is ca. 0.19 eV higher than that of anatase.
Thus, RDB-PAS analysis of ERDT patterns of mixtures of different titania samples is a novel method to clarify the relative band position of semiconducting metal oxides such as titania.
[1] A. Nitta, M. Takase, M. Takashima, N. Murakami, B. Ohtani, Chem. Commun., 52, 12096–12099 (2016).
[2] A. Nitta, M. Takashima, N. Murakami, M. Takase, B. Ohtani, Electrochim. Acta, 264, 83–90 (2018).

Figure 1
(Invited) Multifunctional Nanoplatforms for Biomedical Applications
Authors: Ma Dongling 
Published: February 2020

Near-infrared (NIR) absorbing and emitting nanomaterials attract significant attention in bioimaging, which shows great potential for disease detection due to its high sensitivity at the subcellular level and low cost of related imaging facilities. However, currently available optical probes are mainly based on visible-emitting materials. The tissue-induced optical extinction and autofluorescence in the visible range result in limited penetration depth and ambiguous photoluminescence signal, which restricts their in vivo use. To address this issue, photoluminescent probes, with both absorption and emission wavelengths operating in the biological windows in the NIR range, in which tissues are optically transparent, are highly desired. Their integration with superparamagnetic nanomaterials to make a multifunctional platform further opens a wide range of promising applications, including bimodal imaging (photoluminescence and magnetic resonance imaging), synergistic hyperthermia (magnetothermal and photothermal), magnetic confinement of trace amounts of biospecies for ultra high-sensitivity biodetection, etc. In this talk, I will present our most recent work on the synthesis of NIR-emitting water soluble, stable core/shell/shell quantum dots (QDs) and multifunctional (NIR photoluminescent and superparamagnetic) nanoparticles and their use in biomedicine. For instance, in one case, multifunctional particles contain single superparamagnetic nanoparticles as cores and NIR-luminescent nanomaterials as shells. In another case, the multifunctional nanoplatform is compose of multiple superparamagnetic nanoparticles and NIR quantum dots in single particles. These different types of multifunctional particles are designed for different biomedical applications.
References: [1] ACS Nano 2018, accepted; [2] Adv. Funct. Mater. 2018, 1706235 (Inside Back Cover).
(Invited) Understanding Downstream Risk from Lithium-Ion Battery Thermal Runaway & Designing for Safety
Authors: Spray Ryan , Barry Michael , Vickery James 
Published: February 2020

As battery technologies continue to advance, batteries are being placed in an increasing number of consumer products and being used for energy storage applications from microelectronics to the grid scale. Because of the high energy density in a battery, the sudden, unintended release of stored energy can have significant negative consequences. Consumer products are often in close proximity—and are even sometimes attached—to people, and large energy storage systems may be supporting critical infrastructure. Manufacturing variation (both within one supplier’s processes and between different suppliers producing “identical” batteries / cells) can lead to variations in the conditions under which the onset of thermal runaway occurs as well as the differences in the resultant evolved gases.
In this study, we subject lithium-ion cells produced by different commercial manufacturers to the same abuse conditions via external heating in both adiabatic (accelerating rate calorimetry or ARC) and non-adiabatic conditions. We examine the behavior of the cells during these abuse conditions, and analyze the volume and composition of the gases evolved due to thermal runaway in order to investigate potential differences in severity and/or mitigation strategies. Additionally, the potential effects of inert atmosphere on the failure severity will be evaluated. The general implications of this work as it relates to assessing hazards and designing for safety will be discussed.
Safety Assessment of Solid State Batteries
Authors: Masias Alvaro , Tawfik Samar , Sakamoto Jeff 
Published: February 2020

The ubiquitous growth of personal electronics and increasing introduction of electrified vehicles have been enabled by continuous improvements in batteries. The state of the art technology, lithium ion, has evolved steadily since its introduction in 1991 with specific energy rising from 100 to 250+ Wh/Kg while costs have declined. However it is likely that more dramatic advancements in energy and cost (while maintaining high levels of safety) are necessary to enable the widespread adoption of electrified vehicles.
One of the leading candidates for next generation battery technology is the solid state (SS) battery in which the liquid electrolyte and thin film separator are replaced by an ionically conducting solid. By replacing the flammable electrolyte with a non-flammable ceramic, glass or polymer, it is generally assumed that safety may be enhanced. However, the addition of highly reactive lithium metal and potentially brittle separator materials can introduce new safety hazards. In this context a broad safety assessment of lithium metal solid state batteries is performed against existing international battery safety test standards and regulations.
Varying Thermal Runaway Mechanism Caused By Fast Charging for High Energy Pouch Batteries
Authors: Li Yalun , Feng Xuning , Ren Dongsheng , Ouyang Minggao , Lu Languang 
Published: February 2020

Increasing charging rate is usually considered as safety issue inducements for lithium-ion batteries, especially for high energy batteries with thick electrodes. However, the interaction mechanism between charging rate and safety behavior still needs to be further explored.
In this work, thermal runaway process of commercial NMC532/graphite pouch cells are compared after undergoing increasing charging rates, and decreasing trends of self-heating temperature, onset temperature and maximum temperature are observed, which poses potential danger for battery applications after fast charging. Through the ARC test of corresponding card cells and DSC test of active materials, it was found that the full cell’s characteristic temperature of thermal runaway evolution and active energy of the self- heating process under high charging rate are similar to the reaction between anode and electrolyte, while those under low charging rate are similar to the reaction between cathode and anode. Moreover, the thermal runaway behavior at middle charging rate is influenced by both reactions simultaneously. Under condition where reaction between anode and electrolyte is the dominant factor of thermal runaway process, the lithium plating which discovered on the graphite surface, is found to trigger the strongly exothermic reaction around 110℃ and heat the cell to thermal runaway. It was concluded that the thermal runaway mechanism changes from cathode and anode reactions to anode and electrolyte reactions after batteries are fast charged.
This work will help researchers understand more about the principle of thermal runaway process under different charging rates, and develop more reasonable charging profiles for high energy batteries avoiding deteriorated battery’s safety performance.

Figure 1
Chemically-Engineered Host Materials Enabling Safe Sodium Metal Anodes
Authors: Wang Chuanlong , Wang Huan , Luo Jianmin , Li Weiyang 
Published: February 2020

As an anode material, sodium (Na) metal is the most promising alternative for lithium for the next‐generation energy storage systems. Nevertheless, its practical implementation is impeded by the huge volume change and severe Na metal dendrite growth during electrochemical stripping/plating. Herein, the employment of chemically-engineered porous copper (Cu) and titanium carbide (Ti3C2) MXene as stable host for metallic Na anode is presented. By treating the commercial Cu foam through a facile and cost‐effective method, a composite matrix consists of cylindrical core–shell skeleton is achieved, facilitating uniform impregnation and confinement of Na within the matrix pores promoted by the chemical interaction between Na and the matrix. While by treating Ti3C2 via a facile cetyltrimethylammonium bromide prepillaring followed by subsequent Tin cation (Sn2+) pillaring, a Sn2+ pillared Ti3C2 MXene matrix is obtained, guiding the Na nucleation/growth within the matrix interlayer space and contributing to uniform Na deposition facilitated by the chemical interaction between Na and Sn-based nanocomplexes encapsulated within the MXene layers. The unique characteristic of the chemically-engineered host materials can well accommodate hostless Na+, suppressing the volume change and mossy/dendritic Na growth during cycling. A stable Na cycling behavior is demonstrated in carbonate electrolyte without any additives at a high capacity up to 3 mAh/cm2 with a current density up to 2 mA/cm2. While in ether electrolyte, a stable Na performance at a high capacity up to 5 mAh/cm2 along with a high current density up to 10 mA/cm2 is achieved. Furthermore, electrochemical measurements of a full cell made of the Na composite matrix anodes clearly reveal the superior performance over that using bare Na metal. We believe that our approach provides facile approaches to the fabrication of stable Na metal anodes for high‐energy Na‐based batteries, and could be a viable strategy for other metallic anode systems.[1,2]

Reference：
[1] C.Wang, H. Wang, E. Matios, X. Hu, W. Li, Adv. Funct. Mater, 2018, 28, 1802282.
[2] J. Luo, †
C. Wang, † H. Wang, X. Hu, E. Matios, X. Lu, W. Zhang, X. Tao, W. Li, Adv. Funct. Mater, 2018, 1805946.

Figure 1
(Invited) Correlations in Photon Emission from Neutral and Charged Exciton States in Functionalized Carbon Nanotubes
Authors: Högele Alexander 
Published: February 2020

Covalently functionalized carbon nanotubes support localized excitons with a discrete photoluminescence spectrum and single photon emission statistics [1,2]. The spectrum of hexyl-modified nanotubes features two distinct photoluminescence bands attributed to neutral and charged configurations of exciton-localizing sp3-defects [3]. Here we report correlations in photon emission events by the respective states of neutral and charged defect-trapped excitons, and explain the observations in the framework of different exciton manifolds that compete for the photogenerated population.
[1] X. Ma, N. F. Hartmann, J. K. S. Baldwin, S. K. Doorn, and H. Htoon, Nat. Nanotechnol.10, 671 (2015).
[2] X. He, N. F. Hartmann, X. Ma, Y. Kim, R. Ihly, J. L. Blackburn, W. Gao, J. Kono, Y. Yomogida, A. Hirano, T. Tanaka, H. Kataura, H. Htoon, and S. K. Doorn, Nat. Photon. 11, 577 (2017).
[3] H. Kwon, M. Kim, M. Nutz, N. F. Hartmann, V. Perrin, B. Meany, M. S. Hofmann, C. W. Clark, S. K. Doorn, A. Högele, and Y. Wang, submitted.