bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improved Photovoltaic Performances of Quasi-Solid Photoelectrochemical Solar Cells By Mitigating Charge Recombination Rate at Electrolyte and Photoanode Interface
Authors: Kim So-Eun , Kang Bo-Sung , Lee Ji-Eun , Song Hyeon-Bee , Kang Moon-Sung 
Published: February 2020

There has been much attention towards dye-sensitized solar cells (DSSCs) for the past decades due to their attractive features such as high energy conversion efficiency and low production cost etc. Recently, cobalt complexes have been suggested as one of the most promising candidates for replacing conventional iodine redox couples owing to their high voltage characteristics. Even though respectable energy efficiency exceeding 12% was reported by employing liquid electrolyte that consists of cobalt complex redox mediator and volatile solvent, the use of volatile liquid solvent cannot ensure the long-term stability of DSSCs. In this work, therefore, novel polymer gel electrolytes (PGEs) including cobalt complexes as redox couples have been prepared for efficient and long-term stable DSSCs. In addition, several ways to mitigate the charge recombination rate at the interface between PGE and photoanode have been systematically investigated. The electron transport properties in mesoporous TiO2 electrodes (i.e. electron lifetime and diffusion coefficients) have been evaluated through IMPS and IMVS analyses. In addition, the photovoltaic performances of DSSCs employing prepared PGEs have been evaluated via the J-V curve measurements and various electrochemical characterizations.
Acknowledgments:
This work was supported by a grant (No.2017000140002/ RE201702218) from the Environmental Industry Advancement Technology Development Project of Korea Environmental Industry & Technology (KEITI) funded by Korea Ministry of Environment (MOE).
Control of Interfacial Properties between Polymer Gel Electrolytes and Counter Electrodes for Efficient Quasi-Solid Photoelectrochemical Solar Cells
Authors: Kim So-Eun , Kang Bo-Sung , Lee Ji-Eun , Song Hyeon-Bee , Kang Moon-Sung 
Published: February 2020

There has been much attention towards dye-sensitized solar cells (DSSCs) for the past decades due to their attractive features such as reasonable energy conversion efficiency and low energy production cost. Recently, cobalt complexes have been suggested as one of the most promising candidates for replacing conventional iodine redox shuttles owing to their high voltage characteristics. Although high energy efficiency exceeding 12% was reported by employing liquid electrolyte that consists of cobalt complex redox mediator and volatile solvent, the use of volatile liquid solvent cannot ensure the long-term stability of DSSCs. In this work, therefore, novel polymer gel electrolytes (PGEs) including cobalt complexes as redox couples have been developed for efficient and long-term stable DSSCs. The physicochemical properties of PGEs were adjusted by selecting proper solvent and functional additives (for improving cobalt complex solubility and cation transference number etc.). Polyethers with polar groups (e.g. PEO and PMO) and polymers without polar groups (e.g. PVdF-HFP) were used as the polymer additives for the gelation of the liquid electrolytes with various blending ratios. Especially, various organic solvents with relatively high boiling points were tested to prepare long-term stable polymer gel electrolytes containing cobalt complex redox shuttles. Solvents with high donor number induced significant dissolution of dyes attached on TiO2 and therefore the low volatile solvents with moderate donor number and dielectric constant were utilized in this work. DSSCs employing PGEs with cobalt redox couples also showed better long-term stability compared with those of DSSCs filled with liquid electrolytes at 50 oC for 700 h. In addition, several types of conjugated polymer based counter electrodes have been prepared and used for the fabrication of DSSCs to decrease the high charge transport resistance occurred between the PGE and counter electrode. The photovoltaic and electrochemical performances of the DSSCs have been systematically analyzed via the J-V curve measurement and various electrochemical characterizations such as EIS and CV analyses.
Acknowledgments:
This work was supported by a grant (No.2017000140002/ RE201702218) from the Environmental Industry Advancement Technology Development Project of Korea Environmental Industry & Technology (KEITI) funded by Korea Ministry of Environment (MOE).
Luminescence Properties of Porous Silicon Influenced By Magnetic Metal Filling
Authors: Granitzer Petra , Rumpf Klemens , Poelt Peter , Reissner Michael 
Published: February 2020

In this work the influence of magnetic metal filling on the photoluminescence of luminescent porous silicon is presented. The metal deposits affect the optical properties but also give rise to specific magnetic behavior. Due to the metal filling of the porous silicon the photoluminescence is blue-shifted and furthermore an increase of the intensity is observed. The influence of the magnetic metal filling on the optical properties (photoluminescence, decay time) is discussed and the magnetic characterization of the nanocomposits is presented.
First the optical properties of the luminescent PSi are investigated, second Ni is deposited within the porous silicon samples and subsequently the nanocomposite specimens are characterized optically again and also magnetically. The samples are structurally characterized by SEM, EDX and TEM.
The optical properties are investigated with respect to the shift of the photoluminescence and their decay times due to the metal filling. Photoluminescence spectra of bare PSi show a maximum around 620 nm whereas in the case of Ni filled samples the peak is blue-shifted to around 580 nm and the luminescence intensity is increased.
Concerning the magnetic properties of the nanocomposite the embedded Ni structures can be superparamagnetic from the size of the pore diameters but due to the branched morphology the achieved deposits tend to be interconnected and thus do not offer necessarily a superparamagnetic behavior. Also temperature dependent magnetization measurements give no hint for superparamagnetism. Field dependent magnetization measurements performed with the magnetic field applied perpendicular and parallel to the sample surface show a high magnetic anisotropy. It can be clearly seen that the samples offer a film-like behavior due to the interconnected Ni structures which is represented by the easy axis parallel to the surface. In the frame of this work the optical characterization of luminescent PSi with respect to its photoluminescence compared with Ni filled samples is discussed in detail as well as the corresponding magnetic properties of the nanocomposites. Furthermore the influence of an external magnetic field on the optical properties is elucidated. The presented systems are promising candidates for applications in optoelectronics and also for magneto optical integrated devices.
Influence of Li+ on the Compact and Porous Anodizing of Ti: Achieving Porous Anodizing Conditions Just By the Addition of Li+ Ion
Authors: Dick Luís Frederico Pinheiro , Allongue Philippe , Knörnschild Gerhard , Maltez Rogerio Luis , Valente Renato Castro , Peñafiel-Castro Jhon Alexander , Meneses Carolina Remedi 
Published: February 2020

The incorporation of foreign atoms in trace amounts modifies electronic properties and spectral response by the so-called band gap engineering
1. Among different dopants, the incorporation of Li+ cations into TiO2 is important for expanding the oxide’s technological applications. Li+ and H+ doping of TiO2 was carried out using electrochemical processes or salt impregnation, which improved solar to electricity efficiency of Dye Sensitized Solar cells and Perovskite solar cells (where a TiO2 layer is used as electronic transporting layer), as well as photocatalytic performance 2-3. Thermochemical treatments, N and V doping by standard ion implantation or Ag doping by metal plasma ion implantation was also reported 4-6.
We recently reported 7 that Li+ is incorporated in the bulk of compact TiO2 layers during the anodization of Ti in lithium perchlorate (LiClO4), moving in the opposite direction expected for a cation under the applied electric field. Using Elastic Recoil Detection Analysis (ERDA) we observed that Li+ is accumulated in the form of more or less flat concentration profile along the thickness of compact layer (Fig. 1). Moreover, cell voltage profiles are strongly affected when Li+ is added to the electrolyte independent of anion of the salt. When the Li+ concentration is increased from 0.1 M to 0.5 M by addition of perchlorate or nitrate, the cell voltage transient changes from a curve typical for a compact anodizing with sparking to that of porous anodizing (Fig. 2). This transient change and the fact that the potential plateau during anodizing decreases as [Li+] is increased indicates that Li+ incorporation into the oxide greatly increases ionic conductivity and Ti oxide dissolution. Preliminary results show that a thick irregular tubular oxide structure is formed. The direct incorporation of Li+ into tubular TiO2 during its formation opens new possibilities for techniques of tubular oxide preparation. A mechanism for Li incorporation against the electric field is presented, as well as for the enhanced oxide dissolution.
1. Y.-C. Nah, I. Paramasivam and P. Schmuki, ChemPhysChem, 2010, 11, 2698–2713.
2. B. H. Meekins and P. V. Kamat, ACS Nano, 2009, 3, 3437–3446.
3. L. Tsui, M. Saito, T. Homma and G. Zangari, J Mater Chem A, 2015, 3, 360–367.
4. F. Giordano, A. Abate, J. P. Correa Baena, M. Saliba, T. Matsui, S. H. Im, S. M. Zakeeruddin, M. K. Nazeeruddin, A. Hagfeldt and M. Graetzel, Nat. Commun., 2016, 7, 10379.
5. N. A. Kyeremateng, N. Plylahan, A. C. S. dos Santos, L. V. Taveira, L. F. P. Dick and T. Djenizian, Chem Commun, 2013, 49, 4205–4207.
6. Y.-Y. Chang, Y.-N. Shieh and H.-Y. Kao, Thin Solid Films, 2011, 519, 6935–6939.
7. J. A. Penafiel-Castro, B. Hahn, R. L. Maltez, G. Knornschild, P. Allongue, and L. F. P. Dick, Chemical Communications , 2018, 54, 3251-3254.

Figure 1
Turning Nano Porous Aluminium Black: An in Situ High-Energy X-Ray Diffraction and X-Ray Fluorescence Study
Authors: Vinogradov Nikolay , Linpe Weronica , Harlow Gary Steven , Evertsson Jonas , Drnec Jakub , Lundgren Edvin 
Published: February 2020

Anodized aluminum, commonly used everyday applications, is effectively coloured by electro chemical deposition of materials into the nano-porous anodized aluminum oxide (NP-AAO). The colouring process is sensitive to the details of the nano-porous structure, and increased knowledge is essential to increase the effectiveness of the process to prevent cost, time and environmental losses.
To study the electro deposition of material into nano-scale objects and coloring as it happens in a harsh electrolyte is notoriously difficult. As a consequence, knowledge about the coloring process has been obtained from time consuming ex-situ studies, in which the composition of the sample may change upon exposure to ambient environments.
We have recently performed in situ studies of the formation of ordered NP-AAO using Grazing Transmission Small Angle X-ray Scattering (GTSAXS) [1].
The small x-ray beams produced by modern synchrotron radiation facilities provides the means for non-intrusive X-Ray Diffraction (XRD) and X-Ray Fluorescence (XRF) on a micron and sub-micron scale, allowing for high temporal and spatial resolution as the coloring process is occurring. In the present study, we have used micro XRD and XRF to study the electro deposition of Sn into the NP-AAO. An X-ray beam of 5 microns and an energy of 70 keV was used to penetrate the electrolyte and focused on the 20 micron thick layer of NP-AAO. Prior to deposition, the anodized alumina was pre-treated electrochemically in situ using a selected number of chemical procedures. The Sn deposition, which colours the aluminum black, was followed by XRF and initiates at the pore bottom and crystalizes as Sn metal nanowires along the pore height according to XRD.
References:
[1] N. A. Vinogradov, G. S. Harlow , F. Carlà, J. Evertsson, L. Rullik, W. Linpé, R. Felici and E. Lundgren, ACS Appl. Nano Mater. In Press. DOI: 10.1021/acsanm.7b00303

Figure 1
Mechanism of Tarnishing of Silver Alloys Under Sulphide
Authors: Ortiz-Corona Janette , Larios-Duran Erika Roxana , Rodriguez-Gomez Francisco Javier 
Published: February 2020

Silver and silver alloys is subject of corrosion in environments that contain sulphide (H2S). Thus, become tarnished and a blackish thin film is formed on the metallic surface. This problem is very important in the field of corrosion and conservation. Currently, there is growing attention in the study about tarnishing process in silver alloys, which allows supporting decision-making in the conservation of silver artefacts. However, previous works focused on the corrosion mechanisms and surface treatments of pure silver, more than on silver alloys.
This work investigates the corrosion mechanism on the tarnishing of silver alloys in a 0.07% v/v ammonium sulphide solution as an accelerator of the tarnishing process for 48 h. The Electrochemical Impedance Spectroscopy (EIS) and Scanning Electron Microscopy (SEM) are used as analysis techniques. The impedance measurements reveal that the copper content at the alloy modifies the kinetic of silver tarnishing. On the basis of experimental results, a reaction model for the tarnishing process of silver alloys in sulphide media is proposed. The reaction mechanism is depicted as that of silver modified by the copper content.
Influence of Uniaxial Deformation on Surface Morphology and Corrosion Performance of Trivalent Chromium Based Coatings for Packaging Steels
Authors: Whiteside Jordan William James , McMurray Hamilton Neil , de Vooys Arnoud C.A. 
Published: February 2020

The packaging steel industry has many products for the consumer market which are deformed to a required shape. Products produced in this way undergo different types of deformation, including uniaxial, biaxial and plane strain. In a situation where the steel is coated and then deformed, the coating must still offer a substantial level of protection for inhibiting corrosion.
An In Situ scanning kelvin probe (SKP) experiment was used to investigate the kinetics of organic coating disbondment on uniaxially deformed trivalent chromium coated steel. The studied material was a model trivalent chromium coated steel prototype, designed for over coatings with a lacquer or polymer laminate. The samples were uniaxially deformed to 5%, 10%, 20%, 25% strain using a Hounsfield/Tinius Olsen tensile tester prior to any further experimentation. The strain percentages selected corresponded to the yield point elongation zone, strain-hardening zone and early and late necking zones respectably. A model Poly(vinyl) butyral (PVB) coating was applied to the uniaxially deformed samples. A defect was created in the PVB coating and the sample exposed to aqueous sodium chloride electrolyte in 95% relative humidity. The disbondment kinetics of the polymer overcoat were measured every hour using the SKP, for up to 120 hours.
The disbondment kinetics have been quantified as a plot of distance (µm) vs time (tdel− ti), see Figure 1. The linear plots suggest as the strain percentage is increased the distance of delamination over a 24 hour period increases. Scanning electron microscope (SEM) images, shown in Figure 2, display cracking of the trivalent chromium coating. The availability of the underlying iron is estimated by studying the surface controlled hydrogen evolution curves. Increasing the uniaxial strain produced higher values for hydrogen evolution.
It is proposed that the increase in hydrogen evolution levels can be related to an increase in the exposure of iron caused by the cracking formations found on the surface. The cracking shown on the surface of the trivalent chromium coated steel (Figure 2) is also suggested to cause the increase in cathodic disbondment rates found during the SKP investigations. Cracking of the surface and exposure of iron is suggested to allow for a continuous cathodic front, causing an ingress of electrolyte underneath the PVB model coating. This investigation displays a link between surface cracking, caused by deformation, and the delamination rates of organic coatings on trivalent chromium coated steels.

Figure 1
Electrochemical Evaluation of Steel-Concrete Interaction after Application of Curing with SiO2-Based Nanoparticles
Authors: Esquivel Aldrhyn Miguel , Fajardo Gerardo , Acosta Andres 
Published: February 2020

The present work shows the progress of an ongoing research where, the influence of SiO2 –based nanoparticles (Nbs) ingress into hardened concrete specimens through the curing on the electrochemical behaviour of concrete-steel system was evaluated. For this, prismatic specimens of reinforced concrete were fabricated with two w/b ratios: 0.3 and 0.7. A suspension of 0.1 and 0.3% (by weight) of Nbs in water was applied during curing of specimens in periods of 1, 3 or 7 days.
Then, samples were separated in two different environments for at least 28 days: immersion in tap water and in laboratory conditions. Subsequently, specimens were exposed to penetration of chlorides using wetting and drying cycles as a simulation of conditions in a marine environment. The main techniques to evaluate the behaviour of embedded steel in specimens in this period were electrical resistivity, corrosion potential and linear polarization resistance. Also, chloride content and pH values of matrix concrete were assessed several times.
It was found, that the introduction of Nbs in hardened concrete can react with the cement matrix reducing its permeability, therefore, this phenomenon could get a great influence on initiation and propagation corrosion time.
The Role of Nitrate Ions in Repassivation of Crevice Corrosion on Type 316L Stainless Steel
Authors: Aoyama Takahito , Sugawara Yu , Muto Izumi , Hara Nobuyoshi 
Published: February 2020

In our previous studies, suppression of crevice corrosion for Type 316L stainless steel was confirmed to occur when the solution outside of the crevice was changed from 1 M NaCl to 1 M NaCl-1 M NaNO3
1. The repassivation inside crevice was thought to be caused by the active to passive transition produced by the increase in pH. The inhibition effect of NO3
- ions was expected to be attributed to increase in pH inside the crevice induced by reduction reaction of NO3
- ions. In this reduction process, there is possibility of the generation of NO2
- and/or NH4
+ ions inside the crevice. In this study, the role of NO3
- ions in the repassivation process for Type 316L was investigated.
A commercial Type 316L stainless steel was used as specimens. The specimens were heat-treated at 1373 K for 3.6 ks and then water-quenched. The specimens were polished down to 1 µm with a diamond paste. After that, ultrasonic cleaning was conducted in ethanol. Anodic polarization measurements were conducted in deaerated acidic 1 M NaCl, 1 M NaCl-0.01 M NaNO2 or 1 M NaCl-0.01 M NH4Cl at 298 K. The pH of the solutions was adjusted to 0.2 with HCl to simulate the solution inside the crevice. The surfaces of the specimen were coated with an epoxy resin, with the exception of the electrode area (ca. 10 × 10 mm). The potential scan rate was 3.8 × 10-4 V s-1 (23 mV min-1). The reference electrode was an Ag/AgCl (3.33 M KCl) electrode. All the potentials cited in this work refer to the Ag/AgCl (3.33 M KCl) electrode.
Figure 1 shows the anodic polarization curves measured in deaerated acidic 1 M NaCl, 1 M NaCl-0.01 M NaNO2 or 1 M NaCl-0.01 M NH4Cl at 298 K. In all the solutions, active and passive regions were observed. In this work, the potential range of which current density indicated over 1.0 A m-2 was defined as an active region. In 1 M NaCl, the active region was from -0.28 to -0.12 V, and the peak current density of the active region was 6.6 A m-2. In 1 M NaCl-0.01 M NaNO2 and 1 M NaCl-0.01 M NH4Cl, the active regions were from -0.26 to -0.20 V and -0.24 to -0.17 V, respectively. These results suggest the active region was narrowed by NO2
- or NH4
+ ions. The negative loop of current in 1 M NaCl-0.01 M NaNO2 was assumed to originate from narrowing the active region. In addition, the anodic peak current densities in 1 M NaCl-0.01 M NaNO2 (1.7 A m-2) and 1 M NaCl-0.01 M NH4Cl (1.3 A m-2) were lower than that in 1 M NaCl.
In addition to above results, in situ observations inside the crevice were performed, and the role of NO3
- ions in the repassivation process for Type 316L was determined.

Reference;

1. T. Aoyama, I. Muto, Y. Sugawara, and N. Hara, ECS Trans., 80(10), 519-526 (2017).

Figure 1
Local Electrochemistry on Thin Foils to Investigate Intergranular Corrosion in AA2024
Authors: Oltra Roland , Bonzom Remy 
Published: February 2020

Intergranular corrosion (IGC) on Al-Cu alloys, is controlled by the preferential anodic dissolution of the Cu depleted zone induced by the structural hardening treatments [1].The main dissolution process affects the active anodic head at the tip of the grain boundary and for a minor part the faces of the surface of the grain « crevice » behind the active anodic head [2]. Therefore it could be assumed that the measure of the anodic part of the total current during potentiostatic experiments would be useful to establish charge and mass balance to evaluate the IGC propagation rate. Actually electrochemical analysis is not largely spread in IGC studies of aluminum alloys and physical based methods like the foil penetration technique were preferred to define IGC propagation rate [3,4].
In a recent work [5], we combined local electrochemical probe and thin foil penetration techniques to select only one grain boundary propagating on the longitudinal direction (rolling induces long grains, up to 700µm length, leading to a columnar microstructure). In this presentation, the combination of the specially designed microelectrochemical cell controlled by a SECM stage with a direct optical interrogation of the backside of a 50µm thick foil AA2024 will be described. This local and “in volume” approach allowed us to analyze the current transient resulting from the full penetration of a well-selected intergranular path. By linking the 2D spatially resolved electrochemistry to optical observation on the backside of the foil (1D), it was possible to relate the total current to the successive steps involved during the “in volume” attack (3D) of a well-defined grain boundary trace.
It will be discussed how this approach could be applied to deduce the IGC propagation rate from mass balance using the Faraday law and could support more robust assumptions on the effect of microstructure on IGC propagation rate because it would be easier to manage a spatial control of the location of the IG attack.
Acknowledgements
This work is supported by French ANR-14-CE07-0027-01 – M-SCOT: Multi Scale COrrosion Testing.
References

[1]

J. R. Galvele, S. M. De Micheli, Mechanism of intergranular corrosion of Al-Cu alloys, Corros. Sci. 10 (1970) 795–807.

[2] S.P. Knight, M. Salagaras, A.R. Trueman, The study of intergranular corrosion in aircraft aluminium alloys using X-ray tomography,
Corros. Sci.
53 (2011) 727-734.

[3] W. Zhang, G.S. Frankel, Localized corrosion growth kinetics in AA2024 alloys,
J. Electrochem. Soc
149 (2002) B510-B519.

[4] A. Rota, H. Böhni, Contribution to the growth kinetics of the intergranular corrosion of age-hardened Al-Cu alloys – Part I : Results of the foil penetration technique,
Mater. Corros.
40 (1989) 219-228.

[5] R.Bonzom, R.Oltra, Droplet cell investigation of intergranular corrosion on AA2024, Electrochem. Commun. 81 (2017) 84–87

Figure 1