bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of Perfluorinated Sulfonic Acid Proton Exchange Membranes with Heteropolyacid Functionalized Fluoroelastomer
Authors: Hoffman Jessica , Herring Andrew M , Motz Andrew R , Kuo Mei-Chen , Pandey Tara P 
Published: February 2020

Perfluorinated sulfonic acid (PFSA) membranes have long been the standard for proton exchange membranes (PEMs), despite many efforts to improve upon their chemistry. The saturated conductivity of these PFSAs is impressive, but a need still exists for a membrane with similar proton conductivity at low relative humidities.1 The motivation of this study was to optimize the loading of heteropolyacid (HPA) covalently bonded to the fluoroelastomer in order to increase low humidity conductivity while maintaining chemical and mechanical stability. HPAs are known to be strong Brønsted acids as well as strong oxidants and have high thermal stability in the solid state.2 These qualities should serve to effect enhanced proton conductivity and chemical durability at high temperature ranges (80 - 120 ºC) and lower humidity ranges (less than saturated conditions). Specifically, a Keggin-type silica tungstic HPA was used for its comparative stability to hydrolysis in aqueous solutions.3

In order to classify membrane behavior as a function of weight percent polyHPA (reference figure 1), membranes were synthesized in 0 wt%, 25 wt%, 50 wt%, 75 wt%, and 100 wt% polyHPA and the balance PFSA. Electrochemical impedance spectroscopy (EIS) was used to characterize conductivity of the membranes at 80 ºC with a relative humidity sweep (50 - 90 %RH). Additionally, small-angle x-ray scattering (SAXS) was performed at 80 °C with a relative humidity sweep from 0 - 95 %RH, and FTIR was performed at 80 °C at 0 %RH and 100 %RH. These conditions were chosen specifically for the typical operating region for PEMFC applications. In this blend study, the addition of polyHPA was found to categorically decrease performance (conductivity) of standard 3M© 825EW PFSA membrane. Though improvement of the PFSA membrane was not achieved, this research will provide valuable information regarding the morphology of blended membranes, particularly in membranes exhibiting two-phase behavior; furthermore, results will provide some insight into choosing other viable additives for improved conductivity of PEMFCs.
Figure 1. Chemical structure of polyHPA, 60 wt% HPA (K8SiW11O39)
References

Ramani, V., H.R. Kunz, and J.M. Fenton. "Investigation Of Nafion®/HPA Composite Membranes For High Temperature/Low Relative Humidity PEMFC Operation". Doi.org. N.p., 2017. Web. 24 Apr. 2017.

Kozhevnikov, I.V., and K.I. Matveev. "Homogeneous Catalysts Based On Heteropoly Acids (Review)". Applied Catalysis 5.2 (1983): 135-150. Web.

Tsigdinos, G.A., and G.H. Moh. "Aspects Of Molybdenum And Related Chemistry". Materials Chemistry 4.1 (1979): 111-112. Web.

Figure 1
Fabrication and Electrochemical Properties of Hydrogenated TiO2 Nanotube Arrays
Authors: Zhang Qi , Du Kang , Liu Guohua , Yang Changping , Wang Kaiying 
Published: February 2020

Nowadays, the requirement for energy and environment are a great challenge for our research society. Energy application and storage become the main issues. As a new energy-storage device with high power density, long cycle life and good application prospect, supercapacitors have attracted growing interest in recent years. The electrode materials for supercapacitors play an important role in the field of electrochemical capacitors. [1-5]
In this paper, we report two easy and novel approaches to improve the conductivity of titanium dioxide nanotubes as electrochemical supercapacitor electrodes: first, increase the thickness of the TiO2 nanotube arrays (TNTAs), second, the synthesis of hydrogenated TiO2 NTAs. We fabricated TiO2 for 6 h,12 h and 16 h by anodization respectively(the thicknesses of each TNTAs are 4, 9, 40 micrometer when anodization time increases), and then hydrogenated each of them by electrochemical doping for 5s at the same condition. The H- TiO2 NTAs show great improvement of capacitance. For the 4 um H-TiO2, the hydrogenation improved the capacitance up to 7.83 mFcm-2 from CV calculation at a scan rate of 100mvs-1, which is 11 times higher than the capacitance obtained from TiO2 by air-annealed at the same condition. The largest capacitance we obtained is 25.14 mFcm-2 at a scan rate of 100 mvs-1 for 40 um H-TiO2.Hydrogenation produces reactive oxygen vacancies within the lattice by changing to which increase the host material by acting as a donor. The increase of the thickness provides longer tubular channel path and more active surface sites for ion diffusion and charge transfer. This work provide an suitable route for increasing the electrochemical capacitance of supercapacitors.
Reference

M. Salari, S.H. Aboutalebi, K. Konstantinov and H.K. Liu, Phys. Chem. Chem. Phys. 13, 5038–41 (2011).

J. Wang, J. L. Polleux, J. Lim, B. J. Dunn, Phys. Chem., 111, 14925−14931 (2007).

Z.K. Zheng, B.B. Huang, X.Y. Qin, X.Y. Zhang, Y. Dai and M.H. Whangbo, J. Mater. Chem. 21: 9079–87 (2011)

X. Chen and S.S. Mao, Chem. Rev. 107, 2891–959(2007)

X.H. Lu, G.M. Wang, T. Zhai, M.H. Yu, J.Y. Gan, Y.X. Tong and Y. Li Nano Lett., 12:1690–6 (2012)

Figure 1
Innovative Temperature Management of SOFC Stacks
Authors: Bossel Ulf 
Published: February 2020

Solid Oxide Fuel Cells required a sensitive temperature control for the following reasons:

- Rapid heating of SOFC stacks to operating temperature
- Precise maintenance of the stack temperature
- Variation of the stack temperature with changing power demand.

An innovative system for the management of SOFC stack temperatures has been developed and will be presented at the conference. This system comprised four key elements.

- Some or all bipolar plates are equipped with electric heaters. Heat is supplied where heat is needed – directly to the ceramic SOFC elements;
- The stack temperature is precisely monitored by a thermocouple placed in the geometric center of the stack;
- Electric power is supplied to the heaters only when heating is needed (start-up or increased power demand);
- A temperature controller is used to supply power (AC or DC) from external sources to the heaters as needed to obtain or maintain desired SOFC stack temperatures.

This innovative SOFC stack temperature management system will be described in detail. Experimental results show that the innovative solution (patents pending) offers significant advantages compared to conventional methods of indirect stack heating combined with remote temperature measurements in the stack environment. With this innovative temperature management of SOFC stacks operational temperatures above 600°C are reached in a few minutes after cold start.
(Invited) Aggregation-Induced Emission in Lamellar Solids of Colloidal Perovskite Quantum Wells
Authors: Jagielski Jakub , Kumar Sudhir , Shih Chih-Jen 
Published: February 2020

The outstanding excitonic properties, including photoluminescence quantum yield (η
PL), of individual, quantum-confined semiconductor nanoparticles are often significantly quenched upon aggregation, representing the main obstacle towards scalable photonic devices. Here we report aggregation-induced emission (AIE) phenomena in the lamellar solids containing layer-controlled colloidal quantum wells (CQWs) of hybrid organic-inorganic lead bromide perovskites, resulting in anomalously high solid-state of up to 94%. Upon forming the QW solids, we observe an inverse correlation between exciton lifetime and , clearly distinct from that in typical quantum dot solid systems. Our multiscale theoretical analysis reveals that in a lamellar solid, the collective motion of the surface organic cations are more restricted to orient along the [100] direction, thereby inducing a more direct bandgap that facilitates radiative recombination. Using the QW solids, we demonstrate ultra-pure green emission by completely downconverting a blue GaN light emitting diode (LED) at room temperature, with a luminous efficacy higher than 90 lm/W at 5,000 cd/m2, which has never been reached in any nanomaterial assemblies by far [1].
[1] Jagielski et al., Science Advances, accepted manuscript (2017)
Design of Bodipy-Based Triplet Photosensitizers and Applications in Triplet-Triplet Annihilation Upconversions
Authors: Zhao Jianzhang 
Published: February 2020

Triplet photosensitizers (PSs) are the compounds showing strong absorption of visible light, efficient intersystem crossing (ISC) thus high triplet state yield and good photostability.1 Triplet PSs are widely used in photocatalysis, photodynamic therapy (PDT), and recently the triplet-triplet annihilation upconversion (TTA UC).2 However, the conventional triplet photosensitizers are limited to the porphyrin complexes and Ru(II), Pt(II) complexes, and some halogenated xanthane dyes, such as Eosin Y. It is still a major challenge to design a new triplet photosensitizer which show predictable ISC, especially for those contain no heavy atoms because the intersystem crossing (ISC) of metal-free organic chromophores is usually unpredictable.
TTA UC has attracted much attention, due to the strong absorption of the photoexcitation energy, high upconversion quantum yields, and low photoexcitation threshold (excitation light power density can be as low as 5 mW cm-2. Solar light is sufficient). However, most of the conventional triplet photosensitizers are Pt(II)/Pd(II) porphyrin complexes.1 These complexes are difficult to prepare and to purify, and the molecular structures are unable to be modified feasibly. We proposed a few new approaches to prepare triplet PSs, such as to use Bodipy as the chromophore in heavy atom-containing compounds, or with C60 as the electron spin converter heavy atom-free organic photosensitizers.3

Scheme 1. A strategy to prepare heavy-atom-free organic triplet photosensitizer.

Reference

(a) Singh-Rachford, T. N.; Castellano, F. N. Coord. Chem. Rev. 2010, 254, 2560−2573. Zhao, J.; Wu, W.; Sun, J.; Guo, S.; Chem. Soc. Rev.
2013, 42, 5323; (b) Kamkaew, A.; Lim, S. H.; Lee, H. B.; Kiew, L. V.; Chung, L. Y.; Burgess, K. Chem. Soc. Rev.
2013, 42, 77.

(a) Zhao, J.; Ji, S.; Guo, H. RSC Adv., 2011, 1, 937. (b) Zhao, J.; Ji, S.; Wu, W.; et al., RSC Adv., 2012, 2, 1712.

(a) Zhang, C.; Zhao, J.; Wu, S.; et al, J. Am. Chem. Soc.
2013, 135, 10566; (b) Wu, W.; Zhao, J., et al., J. Org.
Chem.
2012, 77, 5305−5312; (c) Wu, W.; Zhao, J., et al., J. Org.
Chem., 2011, 76, 7056–7064; (d) Guo, S.; Zhao, J., et al., Chem. Sci., 2015, 6, 3724–3737. (e) Chen, Y., Zhao, J., et al., RSC Adv., 2012, 2, 3942–3953.

Figure 1
Distribution of Corrosion Potentials across Galvanically Coupled Interfaces Exposed in Drinking Water
Authors: Fabbricino Massimiliano , Korshin Gregory V 
Published: February 2020

Control of lead release from lead-containing materials galvanically coupled with copper or bronze represent a challenge for corrosion engineers and water treatment practitioners. Currently available data show that in some situations galvanically coupled lead remains passivated and releases little metal while in other cases, for instance those associated with changes of ambient water chemistry, previously passive coupled lead becomes active with resultant episodes of elevated lead release.
While this problem has been thoroughly investigated on a phenomenological level, current understanding of the electrochemistry of galvanic stimulation of lead corrosion and release in drinking water remains insufficient. The goal of this study was to quantify changes of the open circuit corrosion potential (Ecorr(x)) across lead/copper interfaces as a function of the distance from the galvanic juncture and concentrations of background salts such sodium chloride, carbonate and others. The theory developed by Song et al. 2010 provides a detailed mathematical description of the distribution of Ecorr across galvanic interfaces but this theory has been developed and rested for systems that are notably different from those typical for drinking water. Measurements of trans-galvanic interface Ecorr profiles performed in this study showed that Ecorr(x) profiles conformed to predictions made based on the existing theory and the effective length of the longitudinal penetration of ionic currents increased as a square root of solution conductivity. The effective length of the coupled ionic currents was notably different for copper and lead. The data demonstrate that short- and long-term changes of properties of ambient water can cause Ecorr(x) to undergo considerable changes. This can potentially induce shifts of the galvanically affected zone in which accelerated lead release takes place. Further studies are needed to examine actual effects of such Ecorr(x) shifts on spatially localized lead release from galvanically coupled lead-containing materials.
Song, G. L. (2010). Potential and current distributions of one-dimensional galvanic corrosion systems. Corrosion Science, 52(2), 455-480
Anodic Oxidation of Bismuth Towards Various Nanostructures
Authors: Sopha Hanna , Macak Jan M. 
Published: February 2020

The synthesis of highly-ordered nanostructures of valve metal oxides has recently attracted huge scientific and technological interest motivated by their possible use in many applications. The two most established members of this group of materials are nanoporous Al2O3 and TiO2 nanotubes [1,2]. While Al2O3 membranes have been since than widely used as template material of choice for a range of materials [3-5] due to the flexibility of the pore diameter/length and the relative ease of the Al2O3 dissolution, TiO2 nanotubes received high attention because of their applications in e.g. photocatalysis, water splitting, solar cells and biomedical uses [6].
Bismuth oxide is another interesting material and its nanostructures show an enhanced photoelectrochemical performance [7,8]. However, the formation of bismuth nanostructures, such as bismuth oxide nanopores [7, 8] or bismuth phosphate nanorods [9], by anodization is not well explored by now.
Similar to the formation of nanoporous Al2O3, nanostructured Bi2O3 can be produced in acidic, F--free electrolytes [10]. In this presentation, we will demonstrate the anodization of bismuth in various electrolytes towards morphologically very interesting Bi2O3 nanostructures with many potential applications.
References

H. Masuda, K. Fukuda, Science, 268 (1995) 1466.

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

K. Nielsch, F. Müller, A.-P. Li, U. Gösele, Adv. Mater. 12 (2000) 582.

H. Asoh et al., J. Electrochem. Soc. 148 (2001) B152.

J. Kolar, J. M. Macak, K. Terabe, T. Wagner, J. Mater. Chem. C, 2 (2014) 349.

K. Lee, A. Mazare, P. Schmuki, Chem. Rev. 114 (2014) 9385.

X. Lv, J. Zhao, X. Wang, X. Xu, L. Bai, B. Wang, J. Solid. Stat Electrochem. 17 (2013) 1215.

K.C. Chitrada, K. S. Raja, R. Gakhar, D. Chidambaram, J. Electrochem. Soc. 162 (2015) H380.

M. Yang, N. K. Shrestha, R. Hahn, P. Schmuki, Electrochem. Solid-State Lett. 13 (2010) C5.

H. Sopha, V. Podzemna, L. Hromadko, J. M. Macak, Electrochem. Commun. 84 (2017) 6-9.
(Invited) Additives in Cu Plating for Microelectronics Applications
Authors: Radisic Aleksandar , Ross Frances M , Haesevoets Karel P , Struyf Herbert , Vereecken Philippe M. 
Published: February 2020

Electrodeposition is a prevailing method in fabrication of Cu interconnects in microelectronics due to its ability to fill complex structures having a wide range of critical dimensions. A typical acidified Cu electrolyte contains a number of additives, organic and inorganic species in ppm amounts, with a specific role in the plating process. The additives in Cu plating have been extensively studied in the past couple of decades, and grouped according to their role in filling/creating features for microelectronics applications. This categorization is not a uniform one, and it might differ from author to author. In one popular convention, organic additives in the so-called three-component plating bath are named accelerator, suppressor and leveler, with their names hinting at how they influence Cu deposition. Ultimately, it is thanks to these additives that defect-free Cu features ranging from tens of nanometers to hundreds of micrometers can be economically fabricated.
However, it is not enough to successfully fill a given single feature. The same has to be done for all the features on a 300 mm wafer, and then performed reproducibly over and over again. So, one needs to monitor the state of the electrolyte, i.e. of all the bath constituents, and either replace or replenish the electrolyte when the need arises. Additives could also have a strong influence on the physical properties of the deposit and therefore have a strong influence on the post-plating processing results. An additive that promotes void-free deposition of Cu structures in the end might not be used in a production line if it creates issues in the processing steps following electrodeposition.
In our presentation we focus on a number of specific examples showing the effect of additives on nucleation and growth of Cu, propagation of Cu fronts on resistive substrates, post-plating processing, and their use in substrate surface modifications. A closer look is taken into in situ microscopic and electrochemical techniques and their use in studies of electrochemical nucleation and growth of Cu. We discuss advantages and drawbacks of potential step and galvanostatic deposition techniques in determining nucleation and growth parameters, and selection criteria for additive sets for a given plating task. We demonstrate that substrate surface modifications prior to plating could help simplify bath composition, i.e. eliminate need for some additives in the electrolyte, or improve the filling performance of the given plating bath. We also give examples of additives that promoted void-free filling of features but also influenced physical/mechanical properties of the final product in such a way that rendered it unusable in a specific application.
Observation of Additive Behavior in Copper Electroplating Using Microfluidic Device
Authors: Tomie Mineyoshi , Akita Takanori , Ikuta Ryo , Hayase Masanori 
Published: February 2020

Nowadays, high performance of integrated circuits is owing three-dimensional packaging technologies and TSV (through silicon via) came into use in commercial products. TSV is formed by bottom-up filling of conductor in the deep hole and copper electroplating with several additives is usually employed for the filling. However, many trial-and-error processes are needed to obtain optimal recipe for the filling and understanding of the bottom-up filling is not satisfying yet.
Suppression behavior of additive is considered as an essential factor for the bottom-up filling, but critical suppression behavior is not well observed by conventional electrochemical measurements. Desorption of suppressing additive from plating surface seems to have important role, because suppression breakdown occurs from the TSV bottoms where the additive supply is most limited. In this study, we made a microfluidic device to realize precise mass transport and quick switching of plating solutions, and in-situ observation of plating surface was performed. Figure 1 shows a result with a commercial leveler. Initially, VMS (virgin make-up solution) with no additive was supplied into the micro channel, and copper plating was performed on Pt working electrode with 100μm in diameter for 5 s. Then, the solution containing leveler was supplied for 10 s. Finally, the solution was switched to VMS again and additive desorption was monitored. With small overpotential (-550 mV vs. MSE), plating surface was covered by the leveler and strong suppression was observed. After the plating solution was switched to VMS with no additives, localized depositions were observed all over the plating surface. While with large overpotential (-600 mV vs. MSE), strong suppression was observed only on up-stream region of the plating surface where bright smooth surface was kept during the leveler supply. After the solution change, suppression breakdown with localized depositions were observed gradually from the lower-stream region. Identical experimental procedure was applied to several additives and the behaviors were compared.

Figure 1
Selective Metalization of Non-Conductive Materials By Macropatterning of Catalytic Particles and the Application of a Gradient Magnetic Field
Authors: Danilova Sofya , Graves John Edward , Pellicer Eva , Sort Jordi , Cobley Andrew J 
Published: February 2020

Photolithography is commonly used in various manufacturing sectors to achieve metal patterning of non-conductive materials. However, the high cost and toxicity of reagents used in this process have prompted the investigation of alternative approaches to selective metallisation. The present work shows a novel approach that utilizes a gradient magnetic field to achieve selective metallization on the millimeter scale. The magnetic field is applied during the seeding (catalysation) stage, which is required to initiate electroless copper deposition. Subsequent copper deposition occurs selectively according to the pre-defined pattern of the magnetic field.
The modified approach uses a new type of magnetic catalyst i.e. a Fe­3O4-Ag composite material, which was obtained by a wet chemical synthesis method. The Fe component of these particles enables them to be arranged on the substrate in a way that directly corresponds to the pattern of the magnetic field and therefore subsequent electroless copper plating will follow this pattern. The magnetic and catalytic properties of particles for the initiation of electroless copper deposition were characterised by vibrating sample magnetometry and cyclic voltammetry measurements. The Fe3O4-Ag composite colloid solution was optimized by varying the pH, mixing approach and particle concentration.
This paper will demonstrate the potential for selective catalysation in a magnetic field to compete with the commonly used photolithography and ink-jet printing approaches for macroscale selective metallisation of non-conductive materials.

Figure 1. The schematic representation of standard electroless copper plating process and modified process of selective metalization in a gradient magnetic field.

Figure 1