bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Novel in-Situ Operando X-Ray Absorption Spectroscopy Techniques for the Characterization of the Electrochemical Growth of Metal Oxides
Authors: Di Benedetto Francesco , Berretti Enrico , Giaccherini Andrea , Giurlani Walter , Innocenti Massimo , Lavacchi Alessandro , Montegrossi Giordano 
Published: February 2020

In-situ Operando X-ray Absorption Spectroscopy (XAS) has been widely adopted to understand materials modification under working conditions. Under appropriate conditions, In-situ operando XAS provides surface information, being a tool of primary importance to study electrochemical growth.
In the present talk we will describe the application of a recently developed XAS technique to the electrochemical growth of metal oxides. This technique, known as FEXRAV (Fixed Energy X-ray Absorption Voltammetry), is an experimental method that couples cyclic voltammetry (CV) with the acquisition of the XAS signal at a fixed energy diagnostic of a chemical and/or structural modification of the material. This approach is extraordinary powerful and we propose it as a new tool to understand the formation of oxide thin films on metals relevant to electrochemical energy conversion and storage.
This contribution reviews the fundamental principles, the electrochemical cell design, and the synchrotron beamline set-up that enable the collection of FEXRAV data. As a case study, we report the investigation of the formation of palladium oxides on palladium nanoparticles in alkaline media, a subject of extreme importance for alkaline fuel cells. With our investigation we have discovered that palladium oxidation occurs at potential larger than 0.65 V (RHE) and that the passivation layer blocks out the capability of palladium to oxidize alcohols. Remarkably, these conditions happen in real systems and are responsible of the loss of efficiency of direct alcohol fuel cells. We have also found that the presence of promoting metal oxide in contact with Pd accelerate the oxidation and, ultimately are detrimental for the stability of the devices.
Finally, the description of a novel experimental set-up with enanched surface sensitivity based on grazing incidence FEXRAV experiments will be given, together with preliminary results on the in-situ electro-oxidation of palladium thin films thae have been obtained at the LISA BM08 beamline of the European Synchrotron Radiation Facility.
Electrodeposition of Iron Group Metals from Ethylene Glycol Solution: From Thin Films to Nanowires
Authors: Panzeri Gabriele , Accogli Alessandra , Gibertini Eugenio , Magagnin Luca 
Published: February 2020

Iron group metals (Fe, Ni, Co) electrodeposition has been studied extensively from aqueous solutions, especially because of the great practical interest of such elements and their alloys. However, there are cases where non-aqueous solvents show advantages over the traditional baths and for some systems they may represents the only solution to carry out successfully electrodeposition [1, 2]. Nowadays, particular attention is paid to deep eutectic solvents (DESs) because of their easy preparation method and working conditions [2]. In this work we tried to simplify further this kind of solutions by studying the electrodeposition of Fe, Ni and Co from ethylene glycol solvent without the employment of quaternary ammonium salt; it has to be noted that only a few studies on this system are reported in literature [3, 4, 5]. Fundamental electrochemical characterization was firstly carried out highlighting analogies and differences among the three systems considered. Microstructural, morphological and magnetic characterization were performed on metallic deposits obtained by means of potentiostatic electrodeposition. In addition, commercially available aluminium membranes ware employed for the synthesis of nanowires with enhanced magnetic properties with respect to the film. Finally, considerations on the results obtained are given with respect to deposits properties typically obtained from aqueous solutions.

References

[1] Welton T. Room-temperature ionic liquids. Solvents for synthesis and catalysis. Chemical reviews. 1999 Aug 11;99(8):2071-84.
[2] Abbott AP, Boothby D, Capper G, Davies DL, Rasheed RK. Deep eutectic solvents formed between choline chloride and carboxylic acids: versatile alternatives to ionic liquids. Journal of the American Chemical Society. 2004 Jul 28;126(29):9142-7.
[3] Vorobyova TN, Vrublevskaya ON. Electrochemical deposition of gold–tin alloy from ethylene glycol electrolyte. Surface and Coatings Technology. 2010 Jan 15;204(8):1314-8.
[4] Nguyen HP, Wu M, Su J, Vullers RJ, Vereecken PM, Fransaer J. Electrodeposition of bismuth telluride thermoelectric films from a nonaqueous electrolyte using ethylene glycol. Electrochimica Acta. 2012 Apr 30;68:9-17.
[5] Neuróhr K, Pogány L, Tóth BG, Révész Á, Bakonyi I, Péter L. Electrodeposition of Ni from various non-aqueous media: the case of alcoholic solutions. Journal of The Electrochemical Society. 2015 Jan 1;162(7):D256-64.
(Invited) Conductive Polymer/Metal Composite for Filling of TSV
Authors: Kawakita Jin , Chikyow Toyohiro 
Published: February 2020

Fast formation of through-silicon via (TSV) is an essential issue to fabricate the 3D-IC with respect to production efficiency. Currently, TSV is formed by opening a hole in silicon wafer, followed by stacking of an insulation layer and a diffusion barrier on the wall inside the hole and by filling of a conductive material such as metal copper by electroplating often after preparing a seed layer. Since it takes more than one hour to complete all these steps, the efficiency of formation process of TSV should be improved.
The purpose of this research was to shorten the time of the filling step less than 10 minutes. In order to realize that, solution chemistry was used in this research. Photo chemical reaction enabled conducting polymer/metal composites to be synthesized and took advantage of fast deposition of the composite ten times larger than electroplating metal in terms of growth rate. The composite obtained showed conductivity two orders of magnitude higher than commercial conducting polymer. Furthermore, reaction solution was penetrated deeply into narrow hole in silicon wafer because of its high wettability to silicon and silicon oxide.
Filling of polypyrrole/silver as conducting polymer/metal composite was carried out in two ways; 1) injection of reaction solution to silicon holes followed by UV irradiation for photo chemical reaction to form the composite and 2) injection of dispersion solution containing the composite prepared by photo chemical reaction. Filling of the composite was confirmed with laser microscopy and cross sectioning, and time of filling was within 10 minutes. The electrical characteristics such as an I-V curve were obtained with a measurement device in which the electric signal was applied between any two electrodes formed by filling of holes silicon wafer. In addition, the structure at the interface between the composite and silicon wafer was revealed and new diffusion barrier was found to attain both silver anti-diffusion and interfacial adhesion.
These results summarized that the solution chemistry of conducive polymer/metal composite could decrease the time and step for filling to narrow vertical hole of silicon wafer, indicating fast formation of TSV.
Kinematically Driven Triboelectric Nanogenerator As a Practical Power Source
Authors: Bhatia Divij , Choi Dukhyun 
Published: February 2020

Triboelectric nanogenerators (TENG) can convert various forms of wasted mechanical energy in our environment into useful electrical energy that can power wireless sensor nodes constituting an internet of things (IoT) application. The TENG usually generates at high voltage and low current. This is a problem when trying to power portable devices which commonly require low voltage and high current. Our goal in this work was to address this common problem and demonstrate how any TENG can be used as a practical power source. For this purpose we designed a kinematic system that can reliably drive a transformer based power circuit. Our TENG system utilizes mundane rotation energy to power a IoT sensor node. A windup spring based mechanism was used to store the input rotation energy. Then using a custom gear-train and four-nose cam, the TENG was driven at a high frequency. A power converter constituting a transformer and charge pump circuit was used to reliably power a temperature and humidity sensor node that periodically transmitted data wirelessly via bluetooth to any smart device like a laptop or mobile phone. Such a system is applicable in self-powered environment monitoring as well as in industrial control systems where maintaining specific temperature and humidity is critical.
(Invited) Band Gap Engineering and Heterostructures of Low Dimensional Semiconductors
Authors: Yang Tiefeng , Zhang Xuehong , Pan Anlian 
Published: February 2020

Band gaps are one of the most important parameters of semiconductor materials for their optoelectronic applications since they determine the spectral features of absorptions and emission processes [1,2]. Due to the limited band gaps of natural semiconductors, alloying and heterostructured semiconductors with different band gaps have long been the standard methods of achieving semiconductor structures with new band gaps and functions [3,4]. In this talk, I will report our recent progress on the band gap engineering of 1D semiconductor nanowires and 2D atomically thin layered materials through controlled vapor growth. Using some examples, I will show how to realize composition graded and interface sharped low dimensional semiconductor heterostructures through composition controlled band gap modulation. The achieved band gap engineered nanostructures can give continuously tuned or white light emission, and can be used to realize multi-color nanolasers, wavelength splitter, asymmetric waveguiding and high-performance photodetectors etc [5-7].
References
[1] Hong Zhou, Shuangping Yuan, Anlian Pan et al., Vapor Growth and Tunable Lasing of Band Gap Engineered Cesium Lead Halide Perovskite Micro/Nanorods with Triangular Cross Section. ACS Nano, 2017, 11 (2), pp 1189-1195.
[2] Honglai Li, Xueping Wu, Anlian Pan et al., Composition-Modulated Two-Dimensional Semiconductor Lateral Heterostructures via Layer-Selected Atomic Substitution, ACS Nano, 2017, 11, 961-967.
[3] Xidong Duan, Anlian Pan, Xiangfeng Duan et al., Synthesis of WS2xSe2–2x Alloy Nanosheets with Composition-Tunable Electronic Properties, Nano Lett. 2016, 16 (1), pp 264-269.
[4] Xidong Duan, Anlian Pan, Xiangfeng Duan et al.. Two-dimensional transition metal dichalcogenides as atomically thin semiconductors: opportunities and challenges, Chem. Soc. Rev., 2015, 44, 8859-8876.
[5] Honglai Li, Anlian Pan, Xiangfeng Duan et al., Lateral growth of composition graded atomic layer MoS2(1-x)Se2x nanosheets, J. Am. Chem. Soc., 2015, 137, 5284-5287.
[6] Xidong Duan, Anlian Pan, Xiangfeng Duan et al., Lateral epitaxial growth of two-dimensional layered semiconductor heterojunctions, Nature Nanotechnology, 2014, 9,1024-1030.
[7] Pengfei Guo, Xiujuang Zhuang, Anlian Pan et al., Semiconductor Alloy Nanoribbon Lateral Heterostructures for High-performance Photodetectors, Adv. Mater., 2014, 26, 2844-2849.
Controlling the Polymer/Gas Interfacial Property of the Ionic Polymer Phase of a PEM Fuel Cell Catalyst Layer during Membrane Electrode Assembly Fabrication
Authors: Dowd Regis Paul , Nguyen Trung Van 
Published: February 2020

Water management in a PEM fuel cell is vital during high current density operation. Water production in the cathode catalyst layer can negatively impact performance by lowering mass transport of oxygen into the cathode. Various advances have been developed to overcome water management issues related to PEMFCs. A few of these discoveries include the development of the interdigitated flow field [1], integration of hydrophobic PTFE nanoparticles into the catalyst layer [2, 3], and gas diffusion layer fabrication from various types of non-wetting materials [4, 5]. Each of these advances led to improved mass transport performance during high current density operations.
In this presentation, a novel heat treatment process for controlling the ionic polymer phase surface properties in the fuel cell catalyst layer is incorporated into the fabrication process of the membrane electrode assembly (MEA). XPS is used to characterize the catalyst layer ionomer-gas interface in order to verify specific heat treatment conditions lead to a hydrophobic or hydrophilic ionomer surface. The MEA fabrication procedure is modified to ensure the catalyst layer is subjected to suitable heat treatment exposure conditions in order to create a hydrophobic ionomer-gas interface inside the cathode catalyst layer. Fuel cell performance results will be presented using the new MEAs under different operating temperatures, flow field types, and air humidification conditions.

Acknowledgement

The work presented was partially funded by the National Science Foundation under Grant No. EFRI-1038234 and CBET-1518755.

References

T.V. Nguyen, J. Electrochem. Soc., 143, L103 (1996).

R. Friedmann and T.V. Nguyen, J. Electrochem. Soc., 157, B260 (2010).

M. Uchida, Y. Aoyama, N. Eda and A. Ohta, J. Electrochem. Soc., 142, 4143 (1995).

J. Benziger, J. Nehlsen, D. Blackwell, T. Brennan and J. Itescu, J. Membrane Science, 261, 98 (2005).

T.V. Nguyen, A. Ahosseini, X. Wang, V. Yarlagadda, A. Kwong, A.Z. Weber, P. Deevanhxay, S. Tsushima and S. Hirai, J. Electrochem. Soc., 162, F1451 (2015).
Oxygen Electrocatalysis on Transition Metal Spinel Oxides
Authors: Xu ZhiChuan, Jason 
Published: February 2020

Exploring efficient and low cost oxygen electrocatalysts for ORR and OER is critical for developing renewable energy technologies like fuel cells, metal-air batteries, and water electrolyzers. This presentation will presents a systematic study on oxygen electrocatalysis (ORR and OER) of transition metal spinel oxides.[1] Starting with a model system of Mn-Co spinel, the presentation will introduce the correlation of oxygen catalytic activities of these oxides and their intrinsic chemical properties. The catalytic activity was measured by rotating disk technique and the intrinsic chemical properties were probed by synchrotron X-ray absorption techniques. It was found that molecular orbital theory is able to well-explain their activities.[2,3] The attention was further extended from cubic Mn-Co spinels to tetragonal Mn-Co spinels and it was found that the molecular theory is again dominant in determining the catalytic activies. This mechanistic principle is further applied to explain the ORR/OER activities of other spinels containing other transition metals (Fe, Ni, Zn, Li, and etc.).
References
[1] Wei C, Feng Z, Scherer G, Barber J, Shao-Horn Y, Xu Z, Adv. Mater. 2017, DOI: 10.1002/adma.201606800.
[2] Suntivich J, Gasteiger, HA, Yabuuchi, N, Nakanishi H, Goodenough, JB, Shao-Horn, Y. Nat. Chem. 3 (2011) 546.
[3] Suntivich J, May KJ, Gasteiger HA, Goodenough JB, Shao-Horn Y, Science 334 (2011) 1383.
[4] Wei C, Feng Z, Baisariyev M, Yu L, Zeng L, Wu T, Zhao H, Huang Y, Bedzyk M, Sritharan T, Xu Z, Chemistry of Materials, 2016, 28, 4129–4133.
Understanding the Trilemma in Electric Vehicle Batteries: Energy Density, Fast Charging, and Cycle Life
Authors: Yang Xiao-Guang , Wang Chao-Yang 
Published: February 2020

Range anxiety is one of the most significant barriers to mainstream adoption of electric vehicles (EVs). An effective solution to range anxiety is increasing energy density of EV batteries combined with fast charging. Energy density of EV batteries has advanced significantly over the past few years, from 150 Wh/kg in 2012 to ~220 Wh/kg of state-of-the-art cells, and is targeting >300 Wh/kg by 2020. A practical approach to higher energy density of Li-ion cells is to increase areal loading of electrode active materials. Two critical challenges, however, arise. One is that cycle life of Li-ion cells drops significantly with increasing loading amount. The other is that the ability of fast charging is drastically limited with increasing electrode loading. Gallagher et al. (1) tested a sets of graphite/NMC622 cells with different areal loadings, and found that cells with higher areal loadings have much poorer cycle life. Furthermore, though the cells were cycled at room temperature with only 1C charge rate, a significant amount of lithium deposit was observed in cells with higher anode loading, indicating serious lithium plating in these high energy cells. These results differ greatly from those in the literature based on high power cells. Aging of high power cells is typically believed to be dominated by growth of solid-electrolyte interphase (SEI), and lithium plating is expected to occur only at harsh charge conditions (e.g. low temperature, high charge rate). To date, research on aging behavior of high energy Li-ion cells is still rather limited (2).
In this talk, we will give a comprehensive discussion on the aging characteristics of high energy Li-ion batteries for next generation EVs, with special focus on fast charging conditions @2-3C rate. An aging model will be introduced which incorporates both SEI growth and lithium plating. As such, cell aging associated with SEI growth and with lithium plating can be distinguished. The model is applied to predict the cycle life of Li-ion cells at various operating conditions. Specially, we will focus on the effects of a) areal loading density, b) operating temperature, and c) charge rate on the cycle life of Li-ion cells.

References:

1. K. G. Gallagher, S. E. Trask, C. Bauer, T. Woehrle, S. F. Lux, M. Tschech, P. Lamp, B. J. Polzin, S. Ha, B. Long, Q. Wu, W. Lu, D. W. Dees and A. N. Jansen, J. Electrochem. Soc., 163, A138 (2016).
2. Y. Leng, S. Ge, D. Marple, X.G. Yang, C. Bauer, P. Lamp and C.Y. Wang, J. Electrochem. Soc., 164, A1037 (2017).
(Invited) Investigation of Thermal Quenching Process for 5d-4f and 3d-3d Luminescence
Authors: Ueda Jumpei , Tanabe Setsuhisa 
Published: February 2020

White light LEDs (light-emitting diodes) are rapidly replacing incandescent lamps and (compact) fluorescent tubes in all lighting markets (consumer, automotive, and professional). The most widely used type of white LEDs (w-LEDs) is a phosphor-converted w-LED (PC-LED), which is composed of an InGaN-based blue LED and visible light emitting inorganic phosphors, such as oxides and nitrides doped with Ce3+, Eu2+ , Mn4+ as an active center. These phosphors are required to have excellent thermal quenching behavior because the LED chip reaches temperatures up to ∼200 °C in recent high-power w-LED. In these phosphors, two processes of thermal quenching are considered generally. One is the thermally activated cross over from the excited state to the next lower state. The other is the thermal ionization from the excited state to the bottom of the conduction band (CB). In this study, we investigated the thermal quenching mechanism for the 5d-4f and 3d-3d luminescence in w-LED phosphors doped with Ce3+ or Mn4+.
Ce3+-doped Y3Al5O12 garnet (yttrium aluminum garnet,YAG) is the most prominent phosphor in w-LEDs. The excellent thermal quenching behavior of the Ce3+ luminescence in YAG:Ce3+ is well established, but the mechanism for thermal quenching remains unclear. To elucidate the mechanism of thermal quenching of YAG:Ce3+, thermoluminescence excitation (TLE) spectra were recorded at room temperature and 300 °C. At room temperature, the lowest 5d1 band at 450 nm does not contribute to the charging process for TL while at 300 °C, a temperature corresponding to the onset of thermal quenching of the Ce3+ luminescence, the excitation in 5d1 band gives rise to a TL signal. This result indicates that thermal ionization is responsible for thermal quenching of the Ce3+luminescence.
We also investigated the thermal quenching process for calcium aluminum magnetoplumbite, CaAl12O19, doped with Mn4+ (CAO:Mn4+), which is narrow red luminescence phosphor. We tried to understand the quenching mechanism of Mn4+ compared with the luminescence quenching properties of Mn2+. From the temperature dependence of Mn4+: 2E-4A2 red luminescence and Mn2+:4T1-
6A1 green luminescence intensities in CaAl12O19, the quenching temperatures of Mn4+ and Mn2+ are 330K and 800K, respectively. There is a big difference between the quenching temperatures of Mn4+ and Mn2+ in spite of the same host material and the similar luminescence transtion energy. The Mn4+:2E-4A2 red luminescence is quenched by the thermally activated crossover through the 4T2 excited state whose potential curve possesses a large configurational offset in a configurational coordinate diagram. Mn2+ green luminescence is also quenched by the thermally activated crossover, but the activation energy for non-radiative process is much larger than that for Mn4+ because there are no other excited states related with the quenching process.
CO2 reduction on Cu2O(110) Surface: A Combined Theoretical and Experimental Study
Authors: Li Liang , Zhang Rui , Wu Yimin , Liu Yuzi , McNulty Ian , Vinson John , Shirley Eric , Guest Jeffrey R , Chan Maria K. Y. 
Published: February 2020

The rational design of novel catalysts for CO2 reduction has attracted considerable attention, owing to the increasing global fuel demand and greenhouse gas emission. Cu2O has been suggested to be thermodynamically capable of photocatalytically reducing CO2 to methanol.1 However, due to the inertness of CO2 molecules, it is relatively hard for CO2 to draw electrons from the catalyst and become reactive. Earlier studies have shown that the CO2 conversion rate is quite limited on stoichiometric, defect-free oxide surfaces due to the low catalytic activity; on the other hand, defected surfaces generally have higher activity and may provide better catalytic performance.2

In this work, we performed density functional theory (DFT) calculations to investigate the catalytic activity of Cu2O(110) surface, with a primary focus on the surface affinity of CO2 molecules. The preferred CO2 adsorption sites and configurations on both pristine and defected Cu2O(110) surfaces are determined, and the surface stoichiometry that favors CO2 adsorption is thus identified. Scanning tunneling microscopy (STM) images and X-ray Absorption Near-Edge Structures (XANES) of various adsorption configurations are also simulated within the first-principles framework. The results from this study demonstrate the importance of rational surface engineering of catalysts for effective CO2 conversion, and provide important insight into experiment design.
(1) Bendavid, L. I.; Carter, E. a. First-Principles Predictions of the Structure, Stability, and Photocatalytic Potential of Cu2O Surfaces. J. Phys. Chem. B
2013, 117 (49), 15750–15760.
(2) Liu, L.; Zhao, H.; Andino, J. M.; Li, Y. Photocatalytic CO2 Reduction with H2O on TiO2Nanocrystals: Comparison of Anatase, Rutile, and Brookite Polymorphs and Exploration of Surface Chemistry. ACS Catal.
2012, 2 (8), 1817–1828.