scholarly journals A Comparative Study of Cerium- and Ytterbium-Based GO/g-C3N4/Fe2O3 Composites for Electrochemical and Photocatalytic Applications

2021 ◽  
Vol 11 (19) ◽  
pp. 9000
Author(s):  
Nosheen Farooq ◽  
Rafael Luque ◽  
Mahmoud M. Hessien ◽  
Ashfaq Mahmood Qureshi ◽  
Farzana Sahiba ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Organic Dyes ◽  
Electrochemical Techniques ◽  
Environmental Pollutants ◽  
Ytterbium Oxide ◽  
Storage Devices ◽  
Major Interest ◽  
Physicochemical Studies ◽  
The Difference ◽  
Photocatalytic Applications

The design of sustainable and efficient materials for efficient energy storage and degradation of environmental pollutants (specifically organic dyes) is a matter of major interest these days. For this purpose, cerium- and ytterbium-based GO/g-C3N4/Fe2O3 composites have been synthesized to explore their properties, especially in charge storage devices such as supercapacitors, and also as photocatalysts for the degradation of carcinogenic dyes from the environment. Physicochemical studies have been carried out using XRD, FTIR, SEM, and BET techniques. Electrochemical techniques (cyclic voltammetry, galvanic charge discharge, and electrochemical impedance spectroscopy) have been employed to measure super-capacitance and EDLC properties. Results show that the gravimetric capacitance calculated from GCD results is 219 Fg−1 for ytterbium- and 169 Fg−1 for cerium-based nanocomposites at the current density of 1 A/g and scan rate of 2 mV/sec. The specific capacitance calculated for the ytterbium-based nanocomposite is 189 Fg−1 as compared to 125 Fg−1 for the cerium-based material. EIS results pointed to an enhanced resistance offered by cerium-based nanocomposites as compared to that of ytterbium, which can be assumed with the difference in particle size, as confirmed from structural studies including XRD. From obtained results, ytterbium oxide-based GO/g-C3N4/Fe2O3 is proven to be a better electro-catalyst as compared to cerium-based nanocomposites. Photocatalytic results are also in agreement with electrochemical results, as the degradation efficiency of ytterbium oxide-based GO/g-C3N4/Fe2O3 (67.11 and 83.50% for rhodamine B and methylene blue dyes) surpasses values observed for cerium-based GO/g-C3N4/Fe2O3 (63.08 and 70.61%).

scholarly journals Electrochemical Detection of Environmental Pollutants Based on Graphene Derivatives: A Review

2021 ◽  
Vol 7 ◽  
Author(s):  
Coster Kumunda ◽  
Abolanle S. Adekunle ◽  
Bhekie B. Mamba ◽  
Ntuthuko W. Hlongwa ◽  
Thabo T. I. Nkambule
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Electrochemical Detection ◽  
Heavy Metal Ions ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Environmental Pollutants ◽  
Electrochemical Sensing ◽  
Graphene Synthesis ◽  
Graphene Derivatives

Population-driven socioeconomic urban expansion, industrialization, and intensified modern agricultural practices are interlinked to environmental challenges culminating in compromised water quality due to pollution by toxic, persistent, and bioaccumulative heavy metal ions, pesticides, nitroaromatics, and other emerging pollutants. Considering the detrimental impact of pollutants on human health and ecosystem, their detection in different media including water is paramount. Notably, electrochemical techniques are more appealing owing to their recognized advantages. This research summarizes and evaluates the most recent advances in the electrochemical sensing of environmental pollutants such as heavy metal ions, pesticides, nitroaromatics, and other distinct emerging contaminants. Besides, the review focuses on the application of electrochemical detection of the selected pollutants through analysis of representative reports in the five years from 2016 to 2020. Therefore, the review is intended to contribute insights and guidelines to contemporary progress in specific electrochemical application practices based on graphene derivatives, toward the aforenamed pollutants. Thus, it focused on sensing methods such as cyclic voltammetry, anodic stripping voltammetry, and electrochemical impedance spectroscopy employing different sensing elements incorporating graphene. Moreover, the review also highlighted graphene synthesis pathways, sensor design strategies, and functionalization. Furthermore, the review showed that there is congruence in the literature that functionalized graphene and its derivatives remain as viable modifiers in electrochemical sensing of pollutants. Nonetheless, the study also appraised the absence of literature reports on electrochemical detection of natural organic matter substances like humic acid and fulvic acid using a graphene-based sensor. In reckoning, current challenges related to graphene synthesis and applicability, envisaged opportunities, and future perspectives are outlined.

Performance of coatings containing treated silica fume in the corrosion protection of reinforced concrete

2018 ◽  
Vol 47 (4) ◽  
pp. 350-359 ◽  
Author(s):  
Nivin M. Ahmed ◽  
Mostafa G. Mohamed ◽  
Reham H. Tammam ◽  
Mohamed R. Mabrouk
Keyword(s):  
Reinforced Concrete ◽  
Silica Fume ◽  
Corrosion Protection ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Dual Function ◽  
Core Shell ◽  
Protection Efficiency ◽  
Content Type ◽  
Anticorrosive Pigments

Purpose This study aims to apply novel anticorrosive pigments containing silica fume-phosphates (Si-Ph), which were prepared using core-shell technique by covering 80-90 per cent silica fume (core) with 10-20 per cent phosphates (shell) previously, to play dual functions simultaneously as anticorrosive pigments in coating formulations and as an anticorrosive admixture in concrete even if it is not present in the concrete itself. Two comparisons were held out to show the results of coatings on rebars containing core-shell pigments in concrete, and concrete admixtured with silica fume can perform a dual function as anticorrosive pigment and concrete admixture. The evaluation of corrosion protection efficiency of coatings containing core-shell pigments and those containing phosphates was performed. Design/methodology/approach Simple chemical techniques were used to prepare core-shell pigments, and their characterization was carried out in a previous work. These pigments were incorporated in solvent-based paint formulations based on epoxy resin. Different electrochemical techniques such as open-circuit potential and electrochemical impedance spectroscopy were used to evaluate the anticorrosive efficiency of the new pigments. Findings The electrochemical measurements showed that concrete containing coated rebars with core-shell pigments exhibited almost similar results to that of concrete admixtured with silica fume. Also, the anticorrosive performance of coatings containing Si-Ph pigments offered protection efficiency almost similar to that of phosphates, proving that these new pigments can perform both roles as anticorrosive pigment and concrete admixture. Originality/value Although the new Si-Ph pigments contain more than 80 per cent waste material, its performance can be compared to original phosphate pigments in the reinforced concrete.

scholarly journals Corrosion of Steel Rebars in Anoxic Environments. Part I: Electrochemical Measurements

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2491
Author(s):  
Elena Garcia ◽  
Julio Torres ◽  
Nuria Rebolledo ◽  
Raul Arrabal ◽  
Javier Sanchez
Keyword(s):  
Corrosion Rate ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Chloride Content ◽  
Offshore Platforms ◽  
Anoxic Conditions ◽  
Current Limit ◽  
Anoxic Environments ◽  
Corrosion Of Steel ◽  
Steel Rebars

The number of reinforced concrete structures subject to anoxic conditions such as offshore platforms and geological storage facilities is growing steadily. This study explored the behaviour of embedded steel reinforcement corrosion under anoxic conditions in the presence of different chloride concentrations. Corrosion rate values were obtained by three electrochemical techniques: Linear polarization resistance, electrochemical impedance spectroscopy, and chronopotenciometry. The corrosion rate ceiling observed was 0.98 µA/cm2, irrespective of the chloride content in the concrete. By means of an Evans diagram, it was possible to estimate the value of the cathodic Tafel constant (bc) to be 180 mV dec−1, and the current limit yielded an ilim value of 0.98 µA/cm2. On the other hand, the corrosion potential would lie most likely in the −900 mVAg/AgCl to −1000 mVAg/AgCl range, whilst the bounds for the most probable corrosion rate were 0.61 µA/cm2 to 0.22 µA/cm2. The experiments conducted revealed clear evidence of corrosion-induced pitting that will be assessed in subsequent research.

Application of Electrochemical Techniques to Characterization of the Corrosion Behaviors of GW63 Alloys

2007 ◽  
Vol 546-549 ◽  
pp. 571-574
Author(s):  
Xing Wu Guo ◽  
Jian Wei Chang ◽  
Shang Ming He ◽  
Peng Huai Fu ◽  
Wen Jiang Ding
Keyword(s):  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Open Circuit ◽  
Cyclic Polarization ◽  
Time Curve ◽  
Completely Monotonic ◽  
Treatment Conditions ◽  
Impedance Variation ◽  
Corrosion Behaviors

The corrosion behavior of GW63 (Mg-6wt.%Gd-3wt.%Y-0.4wt.%Zr) alloys in 5% NaCl aqueous solution has been investigated by PARSTAT 2273 instrument. The Open Circuit Potential (ECORR) vs. time curve, cyclic polarization (Pitting Scans) curve and Electrochemical Impedance Spectroscopy (EIS) was measured for the GW63 alloys in as-cast and T6 heat treatment conditions. The EIS results indicated that the tendency of impedance variation for as-cast condition was monotonic decreasing, however, the tendency of variation for T6 condition was not completely monotonic but the total tendency was decreasing. The values of impedance of GW63 alloy at 0.1 Hz are about 103 ohm-cm2 for as-cast and T6 condition.

Ferrite

2021 ◽  
Keyword(s):  
High Frequency ◽  
Biomedical Applications ◽  
Organic Dyes ◽  
High Tech ◽  
Hexagonal Ferrites ◽  
Wastewater Remediation ◽  
Structure Synthesis ◽  
Synthesis Properties ◽  
Photocatalytic Applications ◽  
Classification Structure

Ferrites are highly interesting high-tech materials. The book covers their classification, structure, synthesis, properties and applications. Emphasis is placed an biomedical applications, degradation of organic pollutants, high frequency applications, photocatalytic applications for wastewater remediation, solar cell applications, removal of organic dyes and drugs from aquatic systems, and the synthesis of hexagonal ferrites.

Effect of Nano-Silica Volume Reinforcement on the Microstructure, Mechanical, Phase Distribution and Electrochemical Behavior of Pre-Alloyed Titanium-Nickel (Ti-Ni) Powder

2021 ◽  
Vol 875 ◽  
pp. 60-69
Author(s):  
Syed Abbas Raza ◽  
Muhammad Imran Khan ◽  
Mairaj Ahmad ◽  
Danish Tahir ◽  
Asim Iltaf ◽  
...  
Keyword(s):  
Phase Distribution ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Microstructural Analysis ◽  
Furnace Cool ◽  
Neutral Salt ◽  
Nano Silica ◽  
Corrosion Properties ◽  
Volume Percentage ◽  
Titanium Nickel

Titanium-Nickel pre-alloyed powder was reinforced with Nano-Silica in 2%, 4% , 6% and 8 wt. % due to effectiveness of Nanoscale ceramic Reinforcement in improving the properties of Metals and Alloys. The compositions of the Pre-Alloyed powders and Nano Silica Approximately 50 nm in diameter and spherical in shape were weighed and mixed in Planetary Ball Mill followed by compaction at 50 MPa using a Uniaxial Compaction machine The green pellets obtained were sintered in Argon Environment for 5 hrs and allowed to furnace cool. The pellets were then sectioned through their cross-section for slices 3 mm thick followed by Cold-mounting and Soldering followed by cold mounting additionally. The Samples were analyzed via X-Ray Diffraction (XRD) for phase distribution as a function of variation in nano-Silica reinforcements and Microstructural analysis was performed via Optical Microscope. The effect of Volume percentage on the densification was determined via Archimedes principle and Micro-Vickers hardness was used for mechanical Evaluation. The Electrochemical Properties were evaluated using Potentio-Dynamic Polarization and Electrochemical Impedance Spectroscopy (EIS) in neutral salt solution (3.5% NaCl). The results indicated increasing dissolution of the TiNi phase into intermetallic Titanium-rich and Ni-rich phases in the matrix and hardening due to the Nano-Silica effect of Grain Boundary impingement and phase dissolution of Equiatomic phase and mixed behavior in Corrosion properties as determined by the electrochemical techniques whereas densification decreased due to poor plasticity of Nano-Silica and hinderance in diffusion during the sintering process.

scholarly journals Protection of Petroleum Pipeline Carbon Steel Alloys with New Modified Core-Shell Magnetite Nanogel against Corrosion in Acidic Medium

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Gamal A. El Mahdy ◽  
Ayman M. Atta ◽  
Amro K. F. Dyab ◽  
Hamad A. Al-Lohedan
Keyword(s):  
Carbon Steel ◽  
Sulfonic Acid ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Core Shell ◽  
Magnetite Nanoparticle ◽  
Potassium Peroxydisulfate ◽  
Redox Initiator ◽  
Initiator System ◽  
First Time

New method was used to prepare magnetite nanoparticle based on reduction of Fe(III) ions with potassium iodide to produce Fe3O4nanoparticle. The prepared magnetite was stabilized with cross-linked polymer based on 2-acrylamido-2-methylpropane sulfonic acid (AMPS to prepare novel core-shell nanogel. In this respect, Fe3O4/poly(2-acrylamido-2-methylpropane sulfonic acid) (PAMPS) magnetic nanogels with controllable particle size produced via free aqueous polymerization at 65°C have been developed for the first time. The polymer was crosslinked in the presence of N,N-methylenebisacrylamide (MBA) as a crosslinker and potassium peroxydisulfate (KPS) as redox initiator system. The structure and morphology of the magnetic nanogel were characterized by Fourier transform infrared spectroscopy (FTIR) and transmission and scanning electron microscopy (TEM and SEM). The effectiveness of the synthesized compounds as corrosion inhibitors for carbon steel in 1 M HCl was investigated by various electrochemical techniques such as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed enhancement in inhibition efficiencies with increasing the inhibitor concentrations. The results showed that the nanogel particles act as mixed inhibitors. EIS data revealed thatRctincreases with increasing inhibitor concentration.

Gel Electrolyte Based Supercapacitors with Higher Capacitances and Lower Resistances than Devices with a Liquid Electrolyte

MRS Advances ◽  
2018 ◽  
Vol 3 (22) ◽  
pp. 1261-1267 ◽  
Author(s):  
Belqasem Aljafari ◽  
Arash Takshi
Keyword(s):  
Polymer Electrolytes ◽  
Room Temperature ◽  
Electrochemical Impedance ◽  
Liquid Electrolyte ◽  
Gel Electrolyte ◽  
Superior Performance ◽  
Energy Storage Devices ◽  
Storage Devices ◽  
Gel Electrolytes ◽  
Further Development

ABSTRACTRecently, gel polymer electrolytes (GPEs) have been drawn noteworthy attention for different applications, specifically, for supercapacitors. GPEs could become an excellent substitute to liquid electrolytes (LEs) for making flexible and more durable devices. The performance of two different electrolytes (GPEs and LEs) in multi-wall carbon nanotube based supercapacitors were investigated. In spite of significantly lower conductivity of GPEs than LEs, devices with the gel electrolyte presented a superior performance. More focused has been given in this work on demonstrating the performance of supercapacitors based on GPEs and LEs at different concentrations of the acids ranging from 1M to 3M. Both electrolytes have been characterized at room temperature by making supercapacitors and using cyclic voltammetry, charging-discharging, electrochemical impedance spectroscopy, and leakage tests. The experimental results showed that GPE devices had much better capacitances and resistances compare to the LE based devices. Moreover, the capacitances of all devices were increased proportionally with the increase in the concentration from 1M to 3M, and the resistances were increased inversely with the decreased of concentration. The promising results from the gel electrolytes is encouraging for further development of flexible and high capacitance energy storage devices.

Characterization and Electrochemical Performances of Vanadium Oxide Films Doped with Metal Ions

2013 ◽  
Vol 537 ◽  
pp. 174-178
Author(s):  
Ji Chao Wang ◽  
Guang Ming Wu ◽  
Guo Hua Gao ◽  
Xiao Wei Zhou
Keyword(s):  
Metal Ions ◽  
Vanadium Oxide ◽  
Volume Fraction ◽  
Electrochemical Impedance ◽  
Sol Gel ◽  
Electrochemical Techniques ◽  
Oxide Films ◽  
Dip Coating ◽  
Electrochemical Performances ◽  
Vanadium Oxide Films

Vanadium oxide films were prepared via the sol–gel process and dip coating method, using V2O5as raw materials and H2O2(volume fraction 30) as the solvent. Mn and Ni ions were added to vanadium oxide sol to prepare doping vanadium oxide films. The films were characterized by atomic force microscopy, FT-IR, X-ray diffraction and electrochemical techniques. The add-on of Metal ions will not affect the morphology of the vanadium oxide films, but change the valence of vanadium ion and vanadium oxide crystal phase. Furthermore, cyclic voltammetry curves show that metal ions doping vanadium oxide films exhibit reversible electrochemical reaction. But electrochemical impedance spectroscopy indicates pure vanadium oxide film has a better diffusion rate.

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