bluuebunny/crossref_metadata_2025_split huggingface dataset:
BaFeO3-Δ-Based Materials for Intermediate-Temperature Solid Oxide Fuel Cells and Beyond
Authors: Ciucci Francesco 
Published: February 2020

Energy conversion and storage is a central problem to modern society, requiring the deployment of novel “green” technologies. Solid oxide fuel cells (SOFCs) are very promising because they can convert chemical energy directly to electricity with efficiencies as high as 60%. However, one of the bottlenecks of this technology is the limited activity of typical cathode materials. In this presentation, we will overview doped-BaFeO3-δ (BFO) as a potential high-activity SOFC cathode material.
We first fabricate Ba0.95La0.05FeO3-δ (BLF) single crystal thin films by pulsed laser deposition (PLD) on yttria-stabilized zirconia (YSZ) substrates. The phase structure, surface morphology and roughness of the BLF thin films are characterized by X-ray diffraction and atomic force microscopy. X-ray photoelectron spectroscopy is used to analyze the elemental composition and chemical state of the deposited thin film [1-2]. Electrochemical impedance spectra measurements obtained from the symmetric cells with the configuration of BLF /SDC/YSZ/SDC/ BLF reveal that polarization resistance of BLF (001) thin films (100 nm) is as low as ~0.1 Ω cm2 at 700 °C and 0.21 atm oxygen pressure. The polarization resistances of BLF are lower than those of other perovskite electrodes. Furthermore, our computational results, including density functional theory and molecular dynamics simulations, show that the BLF has a low vacancy formation energy and fast oxygen transport [3-4].
The effect of various A- and B-site substitutions on the BFO’s activity from both an experimental [5, 6] and computational [7] perspective are then explored. Finally, opportunities to develop ferrites are discussed together with their use as low temperature electrocatalysts.

Acknowledgements

The authors gratefully acknowledge the Research Grants Council of Hong Kong for support through the project 16207615 and 16227016.

References

[1] D. Chen, C. Chen, F. Dong, Z. Shao, F. Ciucci, J. Power Sources, 250, 188-195 (2014)
[2] C. Chen, D. Chen, Y. Gao, Z. Shao, & F. Ciucci. J. Mater. Chem. A, 2, 14154-14163 (2014)
[3] Z.M. Baiyee, C. Chen, & F. Ciucci. Phys. Chem. Chem. Phys. Phys. Chem. Chem. Phys., 17, 23511-23520 (2015)
[4] C. Chen, Z.M. Baiyee, & F. Ciucci. Phys Chem Chem Phys., 17, 24011-9 (2015)
[5] J. Wang, M. Saccoccio, D. Chen, Y. Gao, C. Chen, & F. Ciucci, J. Power Sources, 297, 511-518 (2015)
[6] J. Wang, K.Y. Lam, M. Saccoccio, Y. Gao, D. Chen, & F. Ciucci. J. Power Sources, 324, 224–232 (2016)
[7] C. Chen & F. Ciucci. Chem. Mat. 28 (19), 7058-7065 (2016)
[8] H. Zhao, C. Chen, D. Chen, M. Saccoccio, J. Wang, Y. Gao, T.H. Wan, & F. Ciucci, Carbon, 90, 122-129 (2015)
Development of Bi-Functional Oxygen Electrode By Low Temperature Roll Press Method for Aqueous Air Secondary Battery
Authors: Kino Shizuki , Kawaguchi Kenji , Morimitsu Masatsugu 
Published: February 2020

A bi-functional oxygen electrode is the key component of aqueous air secondary batteries, and a low overpotential for oxygen evolution and reduction and a bi-functionality for a long-term charge-discharge cycles are required. The oxygen electrode often consists of carbon material as the conducting matrix, oxygen catalyst, and PTFE, which are mixed, pressed to form a sheet, and finally heated at the temperature close to the melting point of PTFE, e.g., 370 oC, and oxygen in air is reduced during discharge and oxygen evolution occurs during discharge inside of the electrode. For the reactions, the electrode’s structure needs to be porous and optimized for oxygen permeability, and the inside should provide active sites for O2 and OH-. The polarization behaviors of the bi-functional oxygen electrode strongly depend on not only the materials but also the process and condition of the electrode preparation. The purpose of this study is to control and improve the gas diffusion behaviors of the oxygen electrode prepared by low temperature roll press at 80 oC, which was developed by our group [1].
The electrode used graphite as conductive material, Bi2-xRu2O7-z as bi-functional catalyst, and PTFE as binder, which were mixed and pressed to form a sheet by heated roller at 80 oC, and pressed again onto a nickel mesh. The polarization behaviors of the electrode were examined by cyclic voltammetry using a three-electrode cell, in which one side of the electrode was exposed to air and the other side to 6 mol/L KOH solution. The surface and cross section of the electrodes were examined by SEM.
SEM observation of the obtained electrodes at various roll press conditions indicated that the shape of PTFE changed depending on the pressure, temperature, and clearance of the rollers, and PTFE particles were fiberized even at 80 oC when the clearance between the two rollers was reduced at constant pressure. The cathodic polarization curves of the electrodes revealed that the onset potential of oxygen reduction hardly depended on the preparation condition, while the polarization in the potential region under mass transfer control, i.e., oxygen diffusion inside of the electrode, was strongly affected by the preparation condition. Oxygen evolution was also seen differently in polarization depending on the electrode, suggesting that the oxygen permeability seems to affect anodic polarization because evolved oxygen should be discharged from the electrode. In this work, detailed relationship between the internal structure of the electrode and the polarization behaviors for oxygen reactions will be presented.
Reference
[1] Y. Ujino, M. Morimitsu, TMS 2017, San Diego (2017).
Corrosion Behavior of Highly As-Doped <100> Oriented Si-Wafer Anodes in Alkaline Si–Air Batteries
Authors: Durmus Yasin Emre , Montiel Guerrero Saul Said , Tempel Hermann , Hausen Florian , Kungl Hans , Eichel Rüdiger-Albert 
Published: February 2020

One line of development to establish resource-efficient metal–air batteries is focusing on silicon materials as anode electrodes. While operation of primary Si–air batteries with ionic liquid electrolytes is one possible approach [1], employing conventional alkaline electrolyte is also considered by the recent investigations [2]. At the current state of development, the alkaline Si–air batteries suffer from high corrosion rates that reduce the theoretical specific capacity of 3820 mAh/g to 120 mAh/g [3]. Thereby, corrosion as being the major challenge has to be overcome in order to establish practical application of primary alkaline Si–air batteries.
The objective of the present work is to investigate the corrosion behavior of highly As-doped <100> oriented silicon wafer anodes in alkaline solutions for a scope of conditions that may arise in battery operation. Firstly, the influence of the immersion times on the open-circuit corrosion rates are discussed in combination with the surface morphology development in 72 h. Secondly, the impact of KOH electrolyte concentration on the open-circuit corrosion rates is investigated and three ranges of KOH concentrations are identified with different limiting mechanisms. Moreover, basing on the electrochemical corrosion rates obtained from potentiodynamic polarization method, the comparison between the chemical and electrochemical corrosion mechanisms are pointed out. Further investigations are carried out on the corrosion behavior of Si wafers under anodic voltages as present during the discharge of batteries. The dependency of the discharge characteristics as the discharge voltage, corrosion rates, and mass conversion efficiencies on the KOH concentrations and current densities are analyzed and accordingly, optimum conditions for the battery application are discussed.

References:

[1] Cohn, G., Ein-Eli, Y., Journal of Power Sources, 195, 4963–4970 (2010).

[2] Zhong, X., Zhang, H., Liu, Y., Bai, J., Liao, L., Huang, Y., Duan, X., ChemSusChem 5, 177–180 (2012).

[3] Durmus, Y.E., Montiel Guerrero, S.S., Aslanbas, Ö., Tempel, H., Hausen, F., de Haart, L.G.J., Ein-Eli, Y., Eichel, R.-A., Kungl, H., Electrochimica Acta 265, 292–302 (2018).
(Invited) Emerging Applications of Nanostructured Porous Silicon
Authors: Koshida Nobuyoshi 
Published: February 2020

Porous silicon (PS) prepared by the appropriate electrochemical anodization consists of a nanopore structure and residual quantum-size nanocrystalline silicon (nc-Si). It has tunable physical properties that can be radically different from those of single-crystalline bulk silicon and plays a role as a platform of functional devices. Possible applications are discussed here and some recent developments highlighted: efficient route for nc-Si colloid formation, quasiballistic electron emission, and thermo-acoustic effect.
Using self-standing PS layer flakes as a base material, nc-Si dot colloid has been formed efficiently by either optical or thermal energy. Highly luminescent (35% in quantum efficiency) colloidal nc-Si dots can be produced with a considerably higher yield (85%) from target than the values (1-10%) in the conventional processes.
A multiple-tunneling transport mode through nc-Si dot chain induces efficient quasiballistic hot electron emission from an nc-Si diode. Being a relatively low operating voltage device compatible with silicon planar fabrication process, the emitter is applicable to mask-less parallel lithography under an active matrix drive. It has been demonstrated that the integrated 100×100 PS emitter array is useful for multibeam lithography and that the selected emitter pattern is delineated corresponding to the activated emitters [1]. In addition, highly reducing activity of emitted electrons is applicable to liquid-phase thin film deposition of metals and semiconductors under a printing mode [2,3]. Both the efficiency and the energy distribution are remarkably improved by using monolayer graphene as a surface electrode [4].
Due to a complete thermal insulating property of nc-Si layer retaining a low volumetric heat capacity, on the other hand, thermo-acoustic conversion is significantly enhanced. When a temperature fluctuation is produced at the surface of nc-Si layer, an acoustic wave is generated near the device surface without any mechanical vibrations. The non-resonant and broad-band emissivity with no harmonic distortions makes it possible to use the emitter for generating audible sound under a full digital drive [5] and reproducing complicated ultrasonic communication calls between mice [6].
References
1. A. Kojima et al., Proc. SPIE Adv. Lithography Symp. 9777, 977712 (2016).
2. R. Suda et al., J. Electrochem. Soc. 163(6), E162 (2016).
3. R. Suda et al., Mater. Sci. Semicond. Process 70, 44 (2017).
4. A. Kojima, R.Suda, and N. Koshida, Appl. Phys. Lett. 112 (2018) (accepted for publication).
5. N. Koshida et al., Appl. Phys. Lett. 102, 123504 (2013).
6. K. Mogi et al., Behav. Brain Res. 325, 138 (2017).
Cryogelated Superstructures for Electrochemical Applications
Authors: Müller Dennis , Freytag Axel , Bigall Nadja 
Published: February 2020

The cryogelation method represents a simple and sophisticated way for producing highly porous aerogel materials of nanoparticles with extremely large specific surface areas. Therefore, an aqueous dispersion of nanoparticles, which are serving as building blocks, is frozen rapidly by the use of liquid nitrogen. A sudden crystallization of the solvent leads to a formation of many small ice crystals. In this process, the previously dispersed particles are excluded from the ice, so that a network of crystal boundaries filled with nanoparticles is formed. In a subsequent step, the solvent is sublimed and removed by lyophilization, to finally obtain a self-supported monolith. Providing a sufficiently high nanoparticle concentration, the shape of the resulting aerogel resembles the frozen colloid.[1] This fact offers the opportunity to prepare thin films on substrates by means of doctor blading or, on the other hand, to use molds for the fabrication of other macroscopic shapes.[2] Besides, a time-consuming hydrogelation step, which would be necessary for a conventional chemical gelation, is avoided. In the end, this procedure is applicable for a variety of nanoparticle systems, due to the fact that there is no chemical selectivity.[3] Here, we will present the chemical and physical properties of these superstructures and discuss their benefits in consideration of applications in the field of electrochemistry.
[1] A. Freytag, M. Colombo, N. C. Bigall, Z. Phys.
Chem., 2017, 231(1), 63-75.
[2] T. Kodanek, Axel Freytag et al., Z. Phys. Chem.,
2018, aop.
[3] A. Freytag et al., Angew.
Chem. Int. Ed., 2016, 55, 1200-1203.

Figure 1
(Invited) Light Enhanced Metal Assisted Chemical Etching of Silicon
Authors: Quiroga-González Enrique , Juárez-Estrada Miguel Ángel , Gómez-Barojas Estela 
Published: February 2020

The study of electrochemicl porosification of silicon has allowed the production of different kinds of porosities in it, ranging from micropores to macropores, and directed by cristallographic planes, or electrical current lines. Additional studies have been on the use of different kinds of electrolytes, to etch faster, or with lower branching. Pore modulation has been also an important development, for a range of applications from photonics to energy storage devices. The modulation can be of either different porosities or different pore diameters, and has been accomplished by the use of different current densities [1], or by the use of different light intensities (mainly for n-type Si) [2].
In particular, the use of light allows the production of electron-hole pairs in semiconductors. This is necessary in n-type Si, since electronic holes are part of the etching reaction, and they are scarce in n-type wafers. Having the availability of more of fewer electronic holes, one can etch wider or narrower pores respectively [1].
Metal Assisted Chemical Etching (MACE) is an alternative etching method, which does not use a power source (it is an electroless method). Nobel metal (commonly Au, Ag or Pt) particles or films are deposited on the surface of Si, and the metallized samples are immersed in an etching solution afterwards. The regions with metal are commonly etched much faster, thus they work as a catalyst [3]. At the metal-semiconductor interface, space-charge-region (SCR) is formed, accelerating electronic holes formed at the electrolyte-metal interface. In this way, there is a higher availability of holes for etching in (or close to) the regions where the metal is present.
Having an internal electric field (given by the SCR) in MACE, which is external in the case of electrochemical etching, it is strightforward to think that light may work in a similar way in both etching methods. However, there are just a few reports on the use of light for MACE, and it has been used just at the front-side (the etched face). There are no reports on the use of back-side illumination for MACE. In the present work, evidences of pore modulation or etching conditions through the use of alternating illumination at the back-side will be presented. Illumination induces either lateral or vertical etching, depending on the doping type of Si.
[1] E. Quiroga-González, J. Carstensen, C. Glynn, C. O’Dwyer, H. Föll, Phys.Chem.Chem.Phys., 16, 255 (2014).
[2] S. Matthias, F. Müller, J. Schilling, U. Gösele, Appl. Phys. A, 80(7), 1391 (2005).
[3] X. Li and P.W. Bohn, Appl. Phys. Lett.77, 2572 (2000).
(Invited) 3D Multifunctional Carbon Nanotube Networks
Authors: Scarselli Manuela 
Published: February 2020

In the field of nanomaterials research, carbon nanotubes (CNTs), proved to possess unique physicochemical properties, owing to their nanoscale dimensions, that have been applied to improve the performance of existing processes or even design novel technologies.
Recently, there has been a growing interest in obtaining natural and synthetic three-dimensional (3D) architectures instead of two-dimensional ones to increase the active surface-to-volume ratio throughout the entire 3D structure, which proves to be advantageous in several applications. The 3D macroscopic structures can be obtained from the assembly of nanomaterials like graphene, carbon nanotubes, polymers and similar others, following chemical and physical routes and the resulting properties derive from the combination of those of the nano-constituents and those due to the complex architecture (like porosity, lightweight and others).
In this paper, we show that is possible to promote a direct self-assembly of CNTs to obtain 3D networks following a chemical vapor deposition route. The self-supporting internal structure consist of interconnected CNTs and to lesser extent of carbon fibers that form a random skeleton with micrometer-size open pores. The porous nature of the network is directly responsible for its lightweight and the hydrophobic and lipophilic behavior, therefore the material is called CNT-sponge (figure 1). In addition, the macroscopic assembly shows high structural stability and good electrical conductivity, and mechanical response. The experimental results obtained in our laboratory, demonstrate that this 3D new material can be successfully applied in different applications. In particular, they can be applied as active material to address some environmental challenges involving water treatment, energy production, and contaminant sensing. Other potential applications include their use as pressure-sensors, in photon-energy conversion devices and as guides in reconnection of segregated spinal explants.
References
Scarselli M., et al. Beilstein J. Nanotechnol.
6 (2015) 792–798;
Camilli L., Scarselli, M. et al., Appl. Phys. Lett.
102, (2013) 183117;
Camilli, L.; Scarselli, M. et al., Nanotechnology 25, (2014) 065701.

Figure 1
Electrodeposited Inconel and Stellite like Coatings for Improved Corrosion Resistance in Biocombustors
Authors: Hall Timothy D , Vijapur Santosh H. , Wang Dan , Taylor E. J. , Inman Maria , Snyder Stephen , Brady Michael 
Published: February 2020

Biomass embodies tremendous potential as a renewable energy resource. According to the biomass thermal Energy Council (BTEC), biomass energy is renewable, carbon neutral, domestic and technologically mature. In addition, the low cost per BTU of wood chips and pellets relative to fossil fuels makes biomass an attractive thermal energy source. Furthermore, ~7% of global energy consumption comprises small-scale biomass combustion,[1] representing a tremendous market for technologies that facilitate enhanced biomass utilization. However, a major challenge associated with utilization of biomass is its combustion behavior. The moisture content, chemical composition, and combustion efficiency varies depending on the source of biomass. Small scale biomass combustors (Figure 1) which for cost reasons are often constructed of mild or low-alloy steels, during operation are subjected to corrosive environments which include alkali halides (borne, e.g., by fly ash particulates), mineral/halogen acids and water; as well as various others such as sulfur and nitrogen oxides. There is a need to create more efficient, longer lasting, cleaner, and cost effective cookstoves for use in burning biomaterials. The materials used for cookstoves must improve burning efficiency, must be able operate at higher temperatures, and should be low cost material systems to durably perform in the corrosive environments. Within this context, Faraday Technology Inc. is working on developing low cost and high value corrosion-resistant alloy coatings for existing bio-combustors or lower cost steels with the goal of increasing their functional lifetime, while reducing the component cost. The manufacturing process involves electrodeposition of binary/ternary/quaternary alloys consisting of [Ni/Co]-Cr-[Mo/Fe] onto a low cost substrate and subsequent accelerated high temperature corrosion evaluation. A wide array of electrolytes and processing parameters were evaluated in order to understand these effects on the deposit composition, structure, and high-temperature corrosion resistance properties towards the goal of developing an ideal alloy coating. Specifically, 60 wt% Ni – 40 wt% Cr (NiCr) binary and 25 wt% Ni – 20 wt% Cr – 55 wt% Co (NiCoCr) ternary alloy coatings demonstrated enhanced corrosion resistance when exposed to an aggressive environment (~700°C, 1000 hr, coating surface salted with ~1 mg/cm2 every 100 hours). When compared to the 441 SS base material the NiCoCr coating exhibited an significant lifetime improvement over its base material and other alloys.

Acknowledgements: The financial support of DOE Contract No. DE-SC0013870 is acknowledged.
[1] Biomass Production Now 10 Percent of World Energy, http://www.realclearenergy.org/charticles/2013/09/26/biomass_production_now_10_percent_of_world_energy_107257.html. Accessed 12 Jan 2015.

Figure 1
Chemical Conversion Treatment on Stainless Steel 316L By Using TiO2 Thin Films Via Sol-Gel Technique and Adding Niobium and Vanadium As Inhibitors to Enhance Corrosion Resistance
Authors: Herrera-Hidalgo Alan Damian , Rodriguez-Gomez Francisco Javier 
Published: February 2020

Stainless steel has been used in a wide variety of industries due to its mechanical, anticorrosion and biocompatibility properties. However, its passive layer can be compromised under aggressive environments leading to corrosion. There are several chemical conversion treatments that are applied on the steel’s surface to improve its corrosion resistance. The most commonly used conversion coatings are based on hexavalent chromium, a compound that is carcinogenic and very hazardous pollutant. The new researches are looking for alternatives that achieve the same or better corrosion inhibition. As an alternative less toxic method, this work presents the use of the sol-gel as a chemical conversion treatment to obtain TiO2 thin films on a stainless steel 316L..
The sol-gel was prepared with titanium butoxide as a precursor; adding niobium and vanadium salts as corrosion inhibitors. Once prepared, the sol-gel was aged for 24 hours. The substrate (stainless steel 316L) was cut in 5x2cm pieces to be ground and polished. Each piece was rinsed with water and finally with acetone. The method dip-coating was used to apply the sol-gel on the surface of the substrate. The dipping was done at three different speeds using a device previously designed and built in the laboratory. After the sol-gel is applied, the pieces are heat treated at different temperatures: 300°C, 500°C and 700°C. The films were characterized by X- Ray Fluorescence and Raman Spectroscopy. These techniques showed the presence of TiO2, with different structures depending on the thermal treatment temperature: amorphous, anatase and rutile. The corrosion behavior was studied in a 3% NaCl solution by Potentiodynamic Polarization Curves and Electrochemical Impedance Spectroscopy. The effect of the dipping speed and the actual TiO2 structures on the anticorrosive properties were reported.