scholarly journals Tailoring Mesoporous Silicon Surface to Form a Versatile Template for Nanoparticle Deposition

Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 699
Author(s):  
Nadzeya Khinevich ◽  
Mindaugas Juodėnas ◽  
Asta Tamulevičienė ◽  
Hanna Bandarenka ◽  
Sigitas Tamulevičius
Keyword(s):  
Current Density ◽  
Superficial Layer ◽  
Electrochemical Anodization ◽  
Nanoparticle Arrays ◽  
Pore Density ◽  
Mesoporous Silicon ◽  
Nanoparticle Deposition ◽  
Before And After ◽  
Pore Opening ◽  
Opening Process

Porous silicon (PS) can be used as a loading template in sensing or as a matrix to develop nanoparticle arrays. We present a comprehensive study of PS morphology and optical properties before and after the pore opening process, including the determination of thickness, pore size, and pore density of PS layers, its surface wettability, and reflectivity. The PS samples were fabricated by electrochemical anodization of monocrystalline silicon wafer in 5–20 wt.% hydrofluoric acid (HF) solution at a current density in the range of 20–200 mA/cm2. Anodization was followed by the pore opening process, i.e., the removal of a parasitic superficial layer with a “bottleneck” structure by reactive ion etching (RIE). The results illustrate that “bottleneck”-free PS allows to achieve a high pore density using a low HF concentration and a reduced current density. We established that this structure demonstrates higher hydrophobicity in comparison to the samples before RIE. The applicability of the developed “bottleneck”-free PS was tested via filling the pores with silver nanoparticles, indicating its potential use as a template for the fabrication of nanoparticle arrays.

Surface-Oriented Oxygen Mass Transport During Implantation

1995 ◽  
Vol 378 ◽  
Author(s):  
A. B. Danilin ◽  
L. A. Charnyi ◽  
A. W. Nemirovski ◽  
V. V. Saraikin
Keyword(s):  
Low Temperature ◽  
Oxide Film ◽  
Current Density ◽  
Superficial Layer ◽  
Concentration Profiles ◽  
X Ray ◽  
Oxygen Ions ◽  
Implantation Temperature ◽  
Thin Oxide Film ◽  
Concentration Peak

AbstractThe effect of implantation conditions on the localization of oxygen implanted with substoichiometric doses has been studied. Oxygen ions were implanted into Si wafers coated with a thin oxide film, which was etched off after the implantation. We used various implantation modes. After the implantation, the specimens were studied using SIMS and X-ray diffractometry. The concentration profiles suggest that at the lower implantation temperature, part of oxygen migrates toward the Si-SiO2 interface. The effect does not refer to the usual enhancement of SIMS signal at the surface because the concentration peak is at a depth of about 25 nm. Calculated deformation profiles indicate a compression at the same depth, the effect being the strongest for the low current density. The result suggests that the superficial layer is rich in vacancial-type defects. The coincidence of the deformation and oxygen concentration maxima leads to the conclusion that oxygen migrates toward the surface in the form of A-centers. A similar phenomenon has been observed for sequential low-temperature implantation of oxygen and nitrogen.

A Multiphysics Modeling Study of (Pr0.7Sr0.3)MnO3±δ∕8mol% Yttria-Stabilized Zirconia Composite Cathodes for Solid Oxide Fuel Cells

2004 ◽  
Vol 2 (1) ◽  
pp. 45-51 ◽  
Author(s):  
Ke An ◽  
Kenneth L. Reifsnider
Keyword(s):  
Fuel Cells ◽  
Ionic Conductivity ◽  
Solid Oxide Fuel Cells ◽  
Current Density ◽  
Composite Cathode ◽  
Solid Oxide ◽  
Yttria Stabilized Zirconia ◽  
Oxide Fuel ◽  
Stabilized Zirconia ◽  
Before And After

Solid oxide fuel cells (SOFCs) are expected to be a future power source. Simulation analyses of SOFCs can help to understand well the interactive functions among the multiphysics phenomena in the SOFC system. A three-dimensional multiphysics finite-element model was used to simulate the performance of a half-cell SOFC with (Pr0.7Sr0.3)MnO3±δ∕8mol% yttria-stabilized zirconia (8YSZ) composite cathode on one side of the 8YSZ electrolyte before and after aging. Multiphysics phenomena in the SOFC were considered in the modeling. The current/voltage curves simulated matched the experimental data before and after aging. The average current density was found to have a linear relationship to the logarithm of the effective exchange current density. The effect of the effective ionic conductivity of the composite cathode was more apparent for small total effective ionic conductivity values than for large ones.

scholarly journals Current density and residence time in the electrocoagulation process and its influence on Fe2+ reduction [Densidad de corriente y tiempo de residencia en el proceso de electrocoagulación y su influencia en la reducción de Fe+2]

2021 ◽  
Vol 5 (1) ◽  
pp. 29
Author(s):  
Freddy Waldir Gómez Escobedo ◽  
Jorge Edinson Gómez Escobedo ◽  
Erick Alexander Choton Cipriano ◽  
Dagner Marvin Castañeda Hilario ◽  
César Pol Arévalo Aranda ◽  
...  
Keyword(s):  
Acid Mine Drainage ◽  
Current Density ◽  
Mine Drainage ◽  
Research Work ◽  
Residence Times ◽  
Ph Values ◽  
Before And After ◽  
Initial Ph ◽  
Electrocoagulation Process ◽  
Evaluation Parameters

The present research work had as study variables the current density of 20, 40 and 80 mA/cm2 and residence times of 10, 20, 40 and 60 minutes, within these evaluation parameters values were taken of pH, conductivity and Fe2+ removal percentage before and after the electrocoagulation process of artisanal acid mine drainage samples (AMD), the amount of AMD sample per test was 350 mL per test, from the results obtained it could be observed that For the current density of 80 mA/cm2 and a time of 40 minutes, the highest percentage of removal was obtained (76.20%), likewise a minimum percentage of removal of 17.97% was obtained at 20 mA/cm2; The removal percentages are attributed to the effect of the current density of the electrocoagulation process, which allows increasing the initial pH values of the effluent, which in turn allows the formation of precipitates and co-precipitates, in this case of Fe2+.

scholarly journals Optimization of Wastewater Treatment Process on Energy Costs at Truck and Tractor Washing Posts

2019 ◽  
Vol 18 (5) ◽  
pp. 436-442
Author(s):  
A. V. Krutau ◽  
M. M. Dechko ◽  
M. A. Boika
Keyword(s):  
Current Density ◽  
Specific Energy ◽  
Specific Energy Consumption ◽  
Water Disinfection ◽  
Energy Costs ◽  
Laboratory Unit ◽  
Wastewater Treatment Process ◽  
Investigation Methods ◽  
Before And After ◽  
Degree Of Purification

The paper considers a process pertaining to purification of oily effluents while using electrocoagulation, electro-flotation and an electromagnetic hydro-cyclone, implemented with the help of a laboratory unit (Patent of the Republic of Belarus for the invention No 21229). The investigations have been carried out with the purpose to optimize specific energy consumption for the process of cleaning fuel and lubricants effluents. The following investigation methods have been applied – a literature review, a comparative analysis, an experiment execution, a mathematical modeling. Content of oil products in wastewater before and after treatment has been evaluated in the analytical laboratory of the Belarusian State Agrarian Technical University in accordance with standard methods. Purification of the oily effluents has been made with the help of a laboratory unit while using electroflotocoagulation method with removal of floated sludge in an electromagnetic hydrocyclone. This cleaning method makes it possible to increase a degree of water disinfection, provides a closed water supply, rational use of water resources, reduction of harmful effects of pollutants on the environment. An experimental design technique has been worked out and a three-level Box – Behnken design has been implemented in the paper. The problem concerning optimization of the purification process on energy costs has been solved without worsening the required concentration indices of petroleum products in water after treatment . Mathematical models have been obtained and optimal purification modes have been determined at the lowest specific energy costs and with sufficiently high degree of purification. Significance of regression coefficients has been estimated by Student criterion. It has been established that while using the proposed unit it is possible to obtain a degree of wastewater purification at automotive equipment washing stations with its performance G = 0.7 l/s, current density j = 150 A/m2. The degree of purification, determined by ratio of pollutant concentrations before and after purification, is up to 99.9 %. The results can be used in implementation of microprocessor control of cleaning mode while taking an initial concentration of pollution, unit capability, current density of an electroflotocoagulator as control action factors.

scholarly journals Effect of electrochemical parameters and working electrode material on the characteristics of bismuth (III) oxide obtained by electrodeposition and thermal oxidation

2019 ◽  
Vol 84 (5) ◽  
pp. 483-488
Author(s):  
Milica Petrovic ◽  
Slobodan Najdanovic ◽  
Milos Kostic ◽  
Miljana Radovic-Vucic ◽  
Nena Velinov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Chemical Composition ◽  
Thermal Treatment ◽  
Surface Morphology ◽  
Current Density ◽  
Electrode Material ◽  
Electrode Potential ◽  
Working Electrode ◽  
Electrochemical Parameters ◽  
Before And After

Bismuth (III) oxide was obtained by electrodeposition, followed by thermal treatment in air environment. The applied electrodeposition current density and electrode potential affect the surface morphology and chemical composition of the obtained deposit before and after the thermal treatment at 350?C, as well as its crystal structure after the thermal treatment at 350?C. The listed parameters affect the deposit?s morphology after the thermal treatment at 600?C, but do not affect its chemical composition and crystal structure. The conclusion is that investigated working electrode material does not affect the characteristics of synthesized material.

scholarly journals Visible Light Assisted Organosilane Assembly on Mesoporous Silicon Films and Particles

Materials ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 131 ◽  
Author(s):  
Chloé Rodriguez ◽  
Alvaro Muñoz Noval ◽  
Vicente Torres-Costa ◽  
Giacomo Ceccone ◽  
Miguel Manso Silván
Keyword(s):  
Electron Microscopy ◽  
Visible Light ◽  
Photoelectron Spectroscopy ◽  
Surface Oxidation ◽  
Spectroscopic Characterization ◽  
Surface Reactivity ◽  
Mesoporous Silicon ◽  
Tof Sims ◽  
Analytical Potential ◽  
Before And After

Porous silicon (PSi) is a versatile matrix with tailorable surface reactivity, which allows the processing of a range of multifunctional films and particles. The biomedical applications of PSi often require a surface capping with organic functionalities. This work shows that visible light can be used to catalyze the assembly of organosilanes on the PSi, as demonstrated with two organosilanes: aminopropyl-triethoxy-silane and perfluorodecyl-triethoxy-silane. We studied the process related to PSi films (PSiFs), which were characterized by X-ray photoelectron spectroscopy (XPS), time of flight secondary ion mass spectroscopy (ToF-SIMS) and field emission scanning electron microscopy (FESEM) before and after a plasma patterning process. The analyses confirmed the surface oxidation and the anchorage of the organosilane backbone. We further highlighted the surface analytical potential of 13C, 19F and 29Si solid-state NMR (SS-NMR) as compared to Fourier transformed infrared spectroscopy (FTIR) in the characterization of functionalized PSi particles (PSiPs). The reduced invasiveness of the organosilanization regarding the PSiPs morphology was confirmed using transmission electron microscopy (TEM) and FESEM. Relevantly, the results obtained on PSiPs complemented those obtained on PSiFs. SS-NMR suggests a number of siloxane bonds between the organosilane and the PSiPs, which does not reach levels of maximum heterogeneous condensation, while ToF-SIMS suggested a certain degree of organosilane polymerization. Additionally, differences among the carbons in the organic (non-hydrolyzable) functionalizing groups are identified, especially in the case of the perfluorodecyl group. The spectroscopic characterization was used to propose a mechanism for the visible light activation of the organosilane assembly, which is based on the initial photoactivated oxidation of the PSi matrix.

A novel electrochemical anodization cell for the synthesis of mesoporous silicon

2020 ◽  
Vol 91 (10) ◽  
pp. 105113
Author(s):  
N. Gostkowska-Lekner ◽  
D. Wallacher ◽  
N. Grimm ◽  
K. Habicht ◽  
T. Hofmann
Keyword(s):  
Electrochemical Anodization ◽  
Mesoporous Silicon

Nanostructured Aluminum Films: Deep Ultraviolet Absorption from Glancing Angle Physical Vapor Deposition

2019 ◽  
Author(s):  
Stephen Stagon ◽  
Ryan Scherzer
Keyword(s):  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Nanoparticle Arrays ◽  
Aluminum Films ◽  
Optical Absorbance ◽  
Glancing Angle ◽  
Before And After ◽  
Facile Fabrication ◽  
Deep Ultraviolet

This entry reports on the facile fabrication and characterization of aluminum (Al) nanoparticle arrays that absorb strongly in deep ultraviolet. First, Al nanoparticle arrays are fabricated using glancing angle physical vapor deposition and have average diameters of ~30 nm. After subsequent annealing, the structures become oxidized on the exterior with an Al metal core. Ultraviolet visible spectroscopy is performed to characterize the optical absorbance of the structures before and after annealing. The as-fabricated structures show strong and broad absorption centered near ~230 nm, and annealing in air at 400°C results in tightening and blue shifting of the absorption peak. Additionally, annealing results in a decrease in overall absorption intensity. These new results may be potentially useful for tandem or plasmon-assisted photovoltaics.

Nitrogen Loss and Structural Change of Nitrogen-incorporated SBA-15 Mesoporous Materials Under Different Treatment Conditions

2005 ◽  
Vol 20 (9) ◽  
pp. 2296-2301 ◽  
Author(s):  
Jiacheng Wang ◽  
Qian Liu
Keyword(s):  
High Temperature ◽  
Structural Change ◽  
Mesoporous Materials ◽  
Nitrogen Loss ◽  
Mesoporous Structure ◽  
Silicon Oxynitride ◽  
Mesoporous Silicon ◽  
Treatment Conditions ◽  
Before And After ◽  
Hydrolysis Of

Work on nitrogen loss and structural change of nitrogen-containing SBA-15 mesoporous materials after heat treatment in air or water treatment is described herein. The nitrogen-containing SBA-15 lost nitrogen after being treated in air at high temperature or in water, the mesoporous structure of which was very well maintained and did not collapse. HRTEM, N2 sorption, powder XRD, and SEM were used to study the structural ordering and morphology of the mesoporous silicon oxynitride materials before and after treatment. FTIR and C/N/H elemental analysis confirmed that nitrogen loss occurred after the mesoporous silicon oxynitride material was treated. Nitrogen was lost via hydrolysis of ammonium groups when mesoporous silicon oxynitride material was treated in water and by being substituted by oxygen from air when it was heated in air at high temperature.

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