bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Photogenerated Cathodic Protection of Steel Using the Thin Layers of Photoactive Nanocomposite Fabricated By Electrophoretic Deposition
Authors: Park Ji Hoon 
Published: February 2020

The photogenerated cathodic protection of steel can be achieved by a photoactive coating layer. It is recently attracting attention because it can overcome the limitations of the sacrificial cathodic protection method. In theory, it can provide permanent cathodic protection because it used energy from solar light rather than to consume itself to protect against corrosion of steel. In the present work, a novel nano-structured layer for the photogenerated cathodic protection was coated on steel using electrophoretic deposition (EPD). Through EPD, thin photoactive composite films can effectively be fabricated on conductive substrates using the colloidal suspension of functional nanoparticles with the simple application of an electrical field. Firstly, crystalline TiO2 nanoparticles were deposited on a steel substrate by the EPD process for the photo-generated cathodic protection. To improve the cathodic protection ability of the photo-stimulated layer, graphene nanoplatelets were incorporated into the TiO2 composite layer by the simultaneous co-deposition of graphene and TiO2 nanoparticles using EPD. Despite the superior cathodic protection afforded by a photo-stimulated TiO2 EPD layer, the coating only works when exposed to solar irradiation during the daytime. However, steel suffers from corrosion at all times. There have been many attempts to overcome this drawback. The incorporation of various photo-electron storing materials into the coating layer is the most promising strategy for maintaining the efficacy of the cathodic protection that is provided by TiO2 in the absence of sunlight. WO3 nanoparticles were used in this study to impart photo-generated cathodic protection to the EPD layer at all times. Moreover, the graphene was exploited as a barrier to protect steel from corrosion because it forms a better barrier to molecules. A graphene film was prepared on steel using EPD with a suspension of graphene oxide in water. When graphene was used as an underlying film for the organic coating, the corrosion resistance of the coated steel improved significantly.
Gravimetric Measurement of Hydrogen Evolution on Magnesium
Authors: Fajardo Santiago , Frankel Gerald 
Published: February 2020

The aim of this work is to study the suitability and limitations of a new gravimetric hydrogen evolution (HE) collection method for corrosion rate determination on pure Mg. This method, originally developed by Curioni [1], is based on the real-time weight measurement of the H2 produced during dissolution and exhibits a higher accuracy level as well as better collection efficiency than the traditional volumetric method. The gravimetric HE collection method overcomes some of the limitations exhibited by the traditional volumetric HE method, where hydrogen gas tends to accumulate at the walls of the funnel and the burette, leading to a lower determination of the amount of H2 produced and thus, an underestimation of the HE rate. The gravimetric HE collection method also exhibits good suitability for the study of Mg alloys with high corrosion resistance and for short experimental times, where the low levels of H2 produced prevents reliable measurements of the amount of gas evolved by the volumetric HE collection method. The gravimetric HE collection method is also applicable for dynamic measurements, i.e. potentiodynamic and galvanodynamic polarizations. The gravimetric method was evaluated for the study of anodic HE on pure Mg (also termed Negative Difference Effect (NDE)), which is characteristic of Mg and its alloys when they are forced to dissolve at anodic potentials from the E
corr. Possible artifacts and experimental limitations of the gravimetric experimental method will be discussed.
[1] M. Curioni, The behaviour of magnesium during free corrosion and potentiodynamic polarization investigated by real-time hydrogen measurement and optical imaging, Electrochim. Acta 120 (2014) 284-292.
Cathodic Activation of Magnesium
Authors: Birbilis Nick 
Published: February 2020

The cathodic activation of magnesium has been studied in a wide range of conditions using electrochemical cycling.
The are several key characteristics of cathodic activation, including pH dependence, and its manifestation in several metals (other than magnesium).
Cathodic activation implies an enhanced ability to support water reduction (i.e. the cathodic reaction) on surfaces that have undergone anodic exposure or some dissolution. This activation is capable of leading to superfluous hydrogen, which is then also a key contributor to the so-called ‘negative difference effect’, or, persistent hydrogen evolution.
A number of experiments are combined in order to provide a holistic description of the cathodic activation effect, and its physical origins – which is of key significance to understanding electrochemistry of reactive metals.
Mg Corrosion Control By Biopolymer-Polyelectrolyte Membranes
Authors: Wilson Benjamin Paul , Yliniemi Kirsi , Singer Ferdinand , Höhn Sarah , Kontturi Eero , Murtomäki Lasse , Virtanen Sannakaisa 
Published: February 2020

Mg and Mg alloys offer a great potential for use as a biomedical material for temporary implant applications: its lack of toxicity, ability to easily dissolve in aqueous environments, and its bone-like bulk properties. One of the key drawbacks however, that prevents the more widespread use of magnesium-based materials is their fast and often uncontrollable corrosion within the human body that impedes its utilisation in a wide range of orthopaedic components1,2. The possibility to control this dissolution is vital if Mg alloys are to be considered as a practical, temporary biomedical implant materials. In this study we detail how this aim can be attained by the use of biocompatible polymeric membrane materials. For example, by using a polyelectrolyte like poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) to modify cellulose acetate (CA) membranes it is possible to achieve Mg dissolution control.
Commercially pure magnesium surfaces were spin-coated with differing concentrations of PDMAEMA to create a number of cellulose based surfaces that were subsequently exposed to an aqueous solution. On immersion it was observed that the CA film distends and begins to function like a membrane that can control both ion flow and H2 gas evolution. Electrochemical measurements (open circuit potential, polarisation and linear sweep voltammograms) demonstrate that by varying the CA:PDMAEMA ratio, the rate of Mg corrosion can be controlled. Additional measurements of pH and with ICP-OES clearly demonstrate that the accumulation of corrosion products between the membrane and the sample also reduces the undesirable effects of H2 formation and high local pH that takes place during the corrosion process3.
Furthermore, SECM studies (with ferrocenemethanol as a redox mediator and using a custom-made cell set-up) were performed in order to determine membrane permeability: knowledge over the permeability of the membrane is crucial when designing the membrane for dissolution control.
Overall, these findings demonstrate that the presence of polyelectrolyte modified cellulose membranes have the potential to control Mg corrosion in physiological environments and that the permeability of the membrane can be controlled by additions of a cationic polyelectrolyte like PDMAEMA.
(1) F. Witte, N. Hort, C. Vogt, S. Cohen, K. U. Kainer, R. Willumeit, F. Feyerabend, Current Opinion in Solid State and Materials Science, 2008, 12, 63-72.
(2) S. Virtanen, Mater. Sci. Eng. B, 2011, 176, 1600-1608.
(3) K. Yliniemi, B. P. Wilson, F. Singer, S. Höhn, E. Kontturi S. Virtanen, ACS Applied Materials and Interfaces, 2014, 6, 22393-22399.
Investigation of Pitting on Stainless Steel Using Scanning Electrochemical Microscopy
Authors: Souto Ricardo M. 
Published: February 2020

Metallic materials are usually employed in a state of passivation with an oxide layer formed on their surface acting as a barrier to ionic migration effectively separating the underlying metal from its environment. As a result, the release of metal ions from the substrate into the electrolytic phase is greatly hindered, and the material is regarded to be stable for sufficiently long service periods. Unfortunately, passivity breakdown and localized pitting corrosion are common phenomena to many materials in chloride solutions. In that event, though most of the material remains passive, effectively experiencing very slow corrosion rates, pits propagate very rapidly penetrating into the bulk of the material. Failure and even catastrophic destruction of the material often occurs as result of such penetration, which is the motivation for the significant research efforts investigating the causes and mechanisms of pitting. Though pit nucleation can often be correlated to heterogeneities in the material, pits can also be nucleated on homogeneous metallic surfaces, producing random distributions as a result. Significant progress in the knowledge of the origins of corrosion has been gathered from electrochemical measurements in the micrometer range, in order to greatly reduce the number of pitting events simultaneously occurring on the investigated section of the substrate. In this way, the electrochemical signal obtained from the sample could eventually arise from individual pits.
The inherently localized nature of the pitting process requires methods capable to gain information about the generation and evolution of the pit formation in the micrometer range with high spatial resolution, preferably in real time. In situ measurements during the corrosion process performed in the actual corroding media under study are mandatory, especially for the analysis of the initial stages of the process. In this regard, scanning electrochemical microscopy (SECM) is highly attractive for corrosion studies, and various experimental procedures have been developed for studying corrosion phenomena.
Diffusion-Limited 1D Pit Growth of S13Cr in Brine at Elevated Temperature
Authors: Jun Jiheon , Frankel Gerald , Sridhar Narasi 
Published: February 2020

Diffusion-limited pit growth of Super 13Cr stainless steel (S13Cr) was studied using one-dimensional (1D) pit electrodes in 0.1 – 3 M NaCl solutions at 85 °C. Applied potential (Eapp) was controlled in four different steps to achieve a target pit depth and measure the anodic current density for S13Cr dissolution under potentiostatic polarization and during a backward scan. For pits with similar depths, the diffusion-limited current density (ilim) of anodic dissolution decreased with increasing NaCl concentration. A characteristic potential, below which the current density started to decay from steady ilim, was found during the backward scan. This potential is associated with dissolution of a salt film at the pit bottom and was defined as the potential of salt film dissolution (Esfd). Esfdalso decreased with increasing NaCl concentration.
To explain the dependence of ilim and Esfd on NaCl concentration, the diffusion coefficient of metal ions (D) and saturation concentration of FeCl2 (Csat), which are directly associated with the product of pit depth and ilim, were calculated using model concentration profiles in a pit and a thermodynamic database software. Both D and Csat were predicted to decrease as NaCl concentration increased, indicating slower diffusion and easier precipitation of salt film, which both increase the stability of a salt film. The product of the calculated D and Csat values was used to predict ilim for certain pit depths, and the predicted ilim values were in the range of experimentally-measured ilim in different NaCl concentrations, which validated the model.
Susceptibility of 5xxx Aluminum Alloys to Localized Corrosion in Natural Waters
Authors: Lee Jason S , Little Brenda J. 
Published: February 2020

Future ship designs and modernization of existing platforms rely on lightweight Al, particularly 5xxx series Al-Mg alloys. Fatigue damage, stress corrosion cracking and microstructure instability are the major degradation mechanisms for ship structures. It is our hypothesis that microorganisms can control the rate and mechanism of degradation for 5xxx Al. Field and laboratory testing will be designed to answer the following questions related to aqueous corrosion: 1) Can naturally occurring microorganisms influence pitting and/or crevice corrosion in 5xxx Al? 2) Are microorganisms attracted to anodic sites and does their presence stabilize localized corrosion propagation? 3) Does degree of sensitization influence biofouling and its effect on open circuit potential?
Vibrio neocaledonicus Sp., a Novel Marine Bacterium with the High Corrosion Inhibition Efficiency
Authors: Moradi Masoumeh , Song Zhenlun , Xiao Tao 
Published: February 2020

Many marine steel structures, such as harbor and oil exploration facilities become corroded over time and need to be renovated or modified, which is expensive. Therefore, it is essential to extend the service life of the existing structures using appropriate methods. Current corrosion protection techniques usually involve toxic or expensive applications, such as volatile organic compounds, which are considered to be a major human health issue or expensive elements incorporated for a stainless steel effect. These limitations have prompted a greater interest in developing alternative methods for corrosion protection. The most promising approaches to achieve effective environmentally friendly corrosion control are to avoid the use of biocides or other traditional strategies. The inhibitory effects of bacteria were shown for the first time in 1988 in that bacteria could reduce corrosion rate of carbon steel. In this study, from a marine environment, we isolated a new inhibitory bacterium namely Vibrio
neocaledonicus sp. which increased the corrosion resistance by more than 60-fold. This is the highest corrosion inhibitory effect that has been reported by bacteria. This inhibitory effect is stable as long as the growth medium is refreshed. This capacity was comparable with some industrial coatings such as electroless Ni-P or Ni-P-PTFE. FTIR analysis confirmed the formation of iron-EPS complexes on a metal surface as EPS is adsorbed on the surface as an inhibitory layer and provides the first inhibitory effect. EPS adhered to metal surfaces by the functional groups of an exopolymer substance. FTIR spectra detected the presence of carbohydrates and amide groups in the EPS structure which enable EPS adhere irreversibly to metal surfaces.

Figure 1
(Invited) Bright Light Emitting Silicon/Germanium Nanostructures
Authors: Lockwood David J 
Published: February 2020

Light emission from Si and Ge nanostructures has been of great interest for some time now owing to the need for silicon-based light sources for applications in silicon opto-electronics and photonics. Optical interconnects are required now for on-chip technology as an alternative to metal wires, because of data transmission bottlenecks introduced by their unavoidable delay times, significant signal degradation, problems with power dissipation, and electromagnetic interference. Two major avenues toward optical interconnects on a chip include a hybrid approach with III-V densely packaged optoelectronic components and the all-group-IV approach (mainly Si, Ge and SiGe), where the all major components, e.g., light emitters, modulators, waveguides and photodetectors, are monolithically integrated into the CMOS environment. Both Si and Ge possess indirect band gaps, which makes them very inefficient light emitters. Band gap engineering employing quantum wells, quantum wires or quantum dots has been proposed as one way to overcome this limitation and Si/Ge or Si/SiGe-alloy thin-multilayer quantum well structures grown on Si have been produced on this principle, and although light emission with greatly improved efficiency has been obtained at low temperatures the emission at room temperature is still very weak, because of exciton dissociation. Recently, through employing novel band-gap engineering strategies, we have prepared several different entirely new bright light-emitting Si/Ge nanostructures including one possessing a direct gap. The latter structure is based on constructing a new super unit cell comprised of multiple planar epitaxial layers of Si and Ge grown on (001) Si0.4Ge0.6. Others are based on silicon-germanium layers grown epitaxially on silicon in in such a way as to form multiple layer three-dimensional nanostructures (quantum dots). Lastly, we have developed a simple and efficient electrochemical process that combines galvanic reaction and focused-ion-beam lithography to selectively synthesize gold nanoparticles that are consequently used for the growth of ordered SiGe nanowire arrays with predefined diameter (200 nm) and position. Here we report on the optical properties of such Si/Ge nanostructures, which are found to luminesce efficiently at wavelengths in the important spectral range of 1.1–1.6 μm.
This work has been carried out in collaboration with J.-M. Baribeau and N.L. Rowell, National Research Council, Ottawa, Canada; L. Tsybeskov, New Jersey Institute of Technology, Newark, USA; and I. Berbezier, Institut Matériaux Microélectronique Nanosciences de Provence, Marseille, France.
Plasmonic Mesostructures Prepared by Oriented Mesoporous Materials as a Template
Authors: Murai Shunsuke , Uno Shiguma , Kamakura Ryosuke , Fujita Koji , Tanaka Katsuhisa 
Published: February 2020

Recent progress in top-down nanolithography now allows to fabricate plasmonic metallic structures on the scale comparable to the lightwaves. However, it is still a challenge to fabricate structures one-order smaller than the lightwaves in a large scale. On the other hand, bottom-up strategies, such as self-assemblies and electrochemical etching, have been studied to fabricate smaller structures as a complementary to top-down techniques.
In this study, mesoporous silica was used as a template to fabricate metallic meso-structures. Highly-oriented mesoporous silica thin films with hexagonally-packed meso-cylinders aligned parallel to the surface were prepared on rubbing-treated silicon and silica substrates following ref.[1]. The meso-cylinders are exposed on the surface by the wet-etching treatment[2]. Oblique angle deposition of metals on the substrates results in the discrete metallic mesostructures with rod-like islands aligning along the meso-cylinders. Figure shows the top-view image of Pt meso-grating. We have measured optical transmission for the gold meso-gratings. The transmission is highly polarization-sensitive, reflecting its anisotropic morphology.
Acknowledgement
We gratefully acknowledge Dr. Hirokatsu Miyata (Canon inc.) for the supply of rubbing-treated substrates.
References

S. Hayase et al.,
Langmuir
29, 7096 (2013). 2. M. Kobayashi et al., Chem. Lett.
43, 846 (2014).

Figure 1
Semi-Metallic TiO2 Nanotubes: Growth, Properties and Applications
Authors: Hahn Robert , Schmuki Patrik 
Published: February 2020

Self organized nanotubular structures of transition metal oxides grown on their metallic substrates, especially titanium, have attracted great scientific and technological interest due to the possibility to exploit their functional properties (such in photo-catalysis, electro-catalysis, solar energy conversion, DSSCs and as host for Li storage) in nanotubular morphology. In contrast to the conventional way to grow anodic TiO2 nanotubes, which is an optimized electrochemical treatment of Ti in fluoride containing electrolyte (for an overview see [1]) this work reports on the growth of nanotubes by so-called RBA (rapid breakdown anodization).[2] This nanotube growth-process is in comparison extremely fast (seconds instead of hours) and seems to be initiated by a pit. This leads to surface coatings consisting of dense packed bundles of nanotubes with very high aspect ratios (tube length up to 50 micrometer, tube diameter of ~40 nanometer). In addition, this method provides a new route for an insitu electrochemical doping during the growth of TiO2 nanotubular layers with various transition metals to adjust the electronic levels in the material which is important for charge transfer reactions through the semiconductor/electrolyte interface [3]. The second part of the presentation will demonstrate that alternatively the electronic and optical properties [4] of these TiO2 nanotubes can be significantly modified, showing semi-metallic behavior by a high temperature reduction treatment in acethylene or ammonia creating a suitable platform for highly conductive surface area electrodes which is important i.e. sensing, methanol oxidation or supercap applications [5]
References:
[1] S. Berger, R. Hahn, P. Roy, P. Schmuki Phys. Status Solidi B247, 10,2424 (2010).
[2] R. Hahn, J. M. Macak, P. Schmuki, Electrochem. Commun.,9, 947 (2007).
[3] M. Stark, R. Hahn, M.S. Killian, P. Schmuki Catal. Sci. Technol., 3, 1765 (2013).
[4] R. Hahn, F. Schmidt-Stein, J. Salonen, S. Thiemann, Y.Y. Song, J. Kunze, V.-P. Lehto, P Schmuki, Angewandte Chemie - International Edition 48(39), 7236 (2009).
[5] S. A. Al-Thabaiti, R. Hahn, N. Liu, R. Kirchgeorg, S. So, P. Schmuki, S. N. Basahel, S. M. Chemistry Communication 50, 7960 (2014).
Dealloying of Few Coating: From Disorder to Order
Authors: Ling Yunhan , Zhang Jun , Yu Siqi , Liu Weifeng 
Published: February 2020

Oxide semiconductors are widely used as photocatalysts in environmental purification as well as energy harvesting and transformation. Thanks to its narrow energy band gap, WO3 (2.7eV) and Fe2O3 (2.2eV) is recognized as one of the most promising n-type semiconductors resistant to photocorrosion in acidic and alkaline aqueous solution respectively, and shows interesting properties both in visible light absorption and its good charge transport abilities. To pursue higher quantum efficiency, nanostructures are a favorable choice, many WO3 and Fe2O3 nanostructures in the form of powders, nanowires, nanorods, nanobelts and nanochannels have been synthesized and reported.
Precisely controlled conditions and complicated fabrication methods have been needed in the preparation of WO3 and Fe2O3-based photocatalysts for water decomposition. Dealloying was considered to be a simple, mild and economical method to fabricate nanostructures, such as nanoporous structures, nanowires, nanocages, etc. As determined by their chemical potentials, the more active (less noble) component is selectively dissolved, while the other phase represents simultaneously a self-assembling action, which is controlled by atom diffusion and the materials’ intrinsic properties.
In this work, we propose a more facile and efficient way to nanostructures by dealloying the as-electrodeposited FeW amorphous alloy coating in an acidic and alkaline environments. It was found that highly ordered WO3 and Fe2O3nanoflake arrays were successfully synthesized and remarkable photoelectrochemical performance in water splitting of the novel nanostructure photoanode can be achieved by this disorder to order transformation.
References
[1] J. Zhang, Y. H. Ling, W. B. Gao, S. Wang and J. T. Li, J. Mater. Chem. A, 2013, 1, 10677–10685
[2] Z. F. Liu, T. Yamazaki, Y. B. Shen, D. Meng, T. Kikuta, N. Nakatani and T. Kawabata, J. Phys. Chem. C, 2008, 112,1391.
[3] J. Su, X. Feng, J. D. Sloppy, L. Guo and C. A. Grimes, Nano Lett., 2011, 11, 203.