scholarly journals Pentavalent Vanadium Species as Potential Corrosion Inhibitors of Al2Cu Intermetallic Phase in the Sulfuric(VI) Acid Solutions

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1946 ◽  
Author(s):  
Przemysław Kwolek ◽  
Barbara Kościelniak ◽  
Magdalena Wytrwal-Sarna
Keyword(s):  
Photoelectron Spectroscopy ◽  
Inductively Coupled Plasma ◽  
Corrosion Inhibitors ◽  
Electrochemical Impedance ◽  
Intermetallic Phase ◽  
Open Circuit ◽  
Acid Solutions ◽  
Scanning Calorimetry ◽  
Electrochemical Impedance Spectra ◽  
X Ray

The objective of this work was to test vanadium isopolyoxoanions as potential corrosion inhibitors of the intermetallic phase Al2Cu in sulfuric acid solutions at pH = 1.3 and 2.5. The intermetallic was melted in an electric arc furnace. Its phase composition was confirmed using X-ray diffraction, light microscopy, and differential scanning calorimetry. Then Al2Cu corrosion kinetics was studied. Chemical composition of the solution after corrosion was determined using inductively coupled plasma-optical emission spectroscopy. The surface of corroded specimens was analyzed using scanning electron microscopy and X-ray photoelectron spectroscopy. Subsequent electrochemical studies involved determination of open-circuit potential, electrochemical impedance spectra, and polarization curves. It was found that the Al2Cu phase corrodes selectively and vanadium isopolyoxoanions increase this process both at pH = 1.3 and 2.5 with two exceptions. Corrosion inhibition was observed for 100 and 200 mM of Na3VO4 at pH 1.3, with inhibition efficiency 78% and 62% respectively, due to precipitation of V2O5.

Synthesis and Characterization of Li0.97K0.03FePO4/Graphene Composites by Carbonthermal Reduction Method

2014 ◽  
Vol 687-691 ◽  
pp. 4327-4330
Author(s):  
Yan Wang ◽  
Zhe Sheng Feng ◽  
Lu Lin Wang ◽  
Jin Ju Chen ◽  
Zhen Yu He
Keyword(s):  
Discharge Capacity ◽  
Photoelectron Spectroscopy ◽  
Reduction Method ◽  
Electrochemical Impedance ◽  
Impedance Spectra ◽  
X Ray Diffraction ◽  
Capacity Retention ◽  
Electrochemical Impedance Spectra ◽  
X Ray

Li0.97K0.03FePO4 and Li0.97K0.03FePO4/graphene composites were synthesized by carbothermal reduction method using acetylene black as carbon source. The structure and electrochemical properties of the prepared materials were investigated with X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, galvanostatic charge and discharge and electrochemical impedance spectra tests. The results indicated that K doping improves the cyclic stability of samples, the addition of small amounts of graphene results in better electronic properties on sample. Li0.97K0.03FePO4/graphene showed discharge capacity of 158.06 and 90.55 mAh g-1 at 0.1 C and 10 C, respectively. After the 50 cycle test at different rates, the reversible discharge capacity at 0.1 C was 158.58 mAh g-1, indicating the capacity retention ratio of 100.32%.

scholarly journals Croton lechleri Extracts as Green Corrosion Inhibitors of Admiralty Brass in Hydrochloric Acid

Molecules ◽  
2021 ◽  
Vol 26 (24) ◽  
pp. 7417
Author(s):  
Carlos Cevallos-Morillo ◽  
Pablo Cisneros-Pérez ◽  
Roxana Llive ◽  
Marvin Ricaurte ◽  
Carlos Reinoso ◽  
...  
Keyword(s):  
Natural Products ◽  
Photoelectron Spectroscopy ◽  
Surface Characterization ◽  
Corrosion Inhibitors ◽  
Electrochemical Impedance ◽  
Transfer Resistance ◽  
X Ray ◽  
Chemical Structures ◽  
Green Corrosion Inhibitors ◽  
Croton Lechleri

Croton lechleri, commonly known as Dragon’s blood, is a tree cultivated in the northwest Amazon rainforest of Ecuador and Peru. This tree produces a deep red latex which is composed of different natural products such as phenolic compounds, alkaloids, and others. The chemical structures of these natural products found in C. lechleri latex are promising corrosion inhibitors of admiralty brass (AB), due to the number of heteroatoms and π structures. In this work, three different extracts of C. lechleri latex were obtained, characterized phytochemically, and employed as novel green corrosion inhibitors of AB. The corrosion inhibition efficiency (IE%) was determined in an aqueous 0.5 M HCl solution by potentiodynamic polarization (Tafel plots) and electrochemical impedance spectroscopy, measuring current density and charge transfer resistance, respectively. In addition, surface characterization of AB was performed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy techniques. Chloroform alkaloid-rich extracts resulted in IE% of 57% at 50 ppm, attributed to the formation of a layer of organic compounds on the AB surface that hindered the dezincification process. The formulation of corrosion inhibitors from C. lechleri latex allows for the valorization of non-edible natural sources and the diversification of the offer of green corrosion inhibitors for the chemical treatment of heat exchangers.

scholarly journals Mechanism of Depression by Fe3+ During Hemimorphite Flotation

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 790
Author(s):  
Junbo Liu ◽  
Shuming Wen ◽  
Qicheng Feng ◽  
Qian Zhang ◽  
Yijie Wang ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Inductively Coupled Plasma ◽  
Electrochemical Impedance ◽  
Test Results ◽  
X Ray ◽  
Inductively Coupled ◽  
Adsorption Analysis ◽  
Plasma Mass Spectrometry ◽  
Local Electrochemical Impedance Spectroscopy ◽  
Ph Range

Sulfide hemimorphite can be depressed by Fe3+ during flotation. In this study, the depression mechanism was studied by microflotation, inductively-coupled plasma mass spectrometry, local electrochemical impedance spectroscopy (LEIS), and X-ray photoelectron spectroscopy (XPS). Flotation test results suggested that sulfated hemimorphite can be depressed by Fe3+ across the entire pH range. LEIS, adsorption analysis, and XPS indicated that S species were adsorbed on hemimorphite as ZnS. The sulfide film was attenuated and no adsorbed Fe species were found after treatment with Fe3+. The results indicate that Fe3+ reacts with the ZnS film, which decreases the number S species, and this leads to hemimorphite depression.

scholarly journals Crosslinked Polyethyleneimine Gel Polymer Interface to Improve Cycling Stability of RFBs

2022 ◽  
Vol 2022 ◽  
pp. 1-10
Author(s):  
Hyung-Seok Lim ◽  
Sujong Chae ◽  
Litao Yan ◽  
Guosheng Li ◽  
Ruozhu Feng ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Inductively Coupled Plasma ◽  
Electrochemical Impedance ◽  
Active Species ◽  
Cycling Stability ◽  
Vanadium Redox Flow Battery ◽  
Flow Battery ◽  
X Ray ◽  
Polymer Interface ◽  
Eis Measurements

Redox flow batteries are considered a promising technology for grid energy storage. However, capacity decay caused by crossover of active materials is a universal challenge for many flow battery systems, which are based on various chemistries. In this paper, using the vanadium redox flow battery as an example, we demonstrate a new gel polymer interface (GPI) consisting of crosslinked polyethyleneimine with a large amount of amino and carboxylic acid groups introduced between the positive electrode and the membrane. The GPI functions as a key component to prevent vanadium ions from crossing the membrane, thus supporting stable long-term cycling. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements were conducted to investigate the effect of GPI on the electrochemical properties of graphitic carbon electrodes (GCFs) and redox reaction of catholyte. X-ray photoelectron spectroscopy (XPS) and 1H nuclear magnetic resonance (NMR) spectra demonstrated that the crosslinked GPI is chemically stable for 100 cycles without dissolution of polymers and swelling in the strong acidic electrolytes. Results from inductively coupled plasma mass spectrometry (ICP-MS), Fourier-transform infrared (FTIR) spectroscopy, and energy-dispersive X-ray (EDX) spectroscopy proved that the GPI is effective in maintaining the concentration of vanadium species in their respective half-cells, resulting in improved cycling stability because of it prevents active species from crossing the membrane and stabilizes the oxidation states of active species.

scholarly journals Effect of immersion time at the stainless steel 304L/NaCl (0.01 M) interface

2019 ◽  
Vol 9 (2) ◽  
pp. 99-111
Author(s):  
Wejdene Mastouri ◽  
Luc Pichon ◽  
Serguei Martemianov ◽  
Thierry Paillat ◽  
Anthony Thomas
Keyword(s):  
Stainless Steel ◽  
Photoelectron Spectroscopy ◽  
Immersion Time ◽  
Surface Composition ◽  
Electrochemical Impedance ◽  
Open Circuit ◽  
Nacl Solution ◽  
Aisi 304L ◽  
X Ray ◽  
Steel Aisi

Stainless steels are broadly used thanks to their specific physical properties such as their high corrosion resistance in poorly aggressive solutions. However, only few studies have been reported in the literature concerning their electrochemical behavior in low concentration electrolytes medium. Accordingly, the present work aims to study the immersion time influence on the solid-liquid interface properties of the austenitic stainless steel AISI 304L, immersed in a low-concentrated (0.01 M) sodium chloride (NaCl) solution. The electroche­mical behavior of the interface was evaluated by electrochemical impedance spectroscopy (EIS) and open circuit potential (OCP) monitoring. The morphological features and the modification of the surface composition were evaluated by Optic Microscopy, Scanning Electron Microscopy, Energy Dispersive X-ray Spectrometry, Atomic Force Microscopy, White Light Interferometry and X-ray Photoelectron Spectroscopy. It was determined by OCP measurement that the characteristic time of the interface stabilization is very long (several months). After an immersion of 2 months in NaCl solution, a second time constant on impedance phase diagram appears. Surface characterizations reveal a significant modifi­cation of the morphology and chemistry of the AISI 304L surface that can be linked to OCP/EIS observations. It can be noticed that the repeatability deviation of the EIS method was about 1 % while its reproducibility deviation was estimated to 35 %.

scholarly journals Layered MoS2 Grown on Anatase TiO2 {001} Promoting Interfacial Electron Transfer to Enhance Photocatalytic Evolution of H2 From H2S

2020 ◽  
Vol 1 ◽  
Author(s):  
Qing Cai ◽  
Fang Wang ◽  
Jianglai Xiang ◽  
Meng Dan ◽  
Shan Yu ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Electrochemical Impedance ◽  
High Catalytic Activity ◽  
Interfacial Electron Transfer ◽  
Green Technologies ◽  
Electrochemical Impedance Spectra ◽  
X Ray ◽  
Production Of Hydrogen

The treatment of hazardous hydrogen sulfide (H2S) via photocatalysis technology has been known as one of the most promising green technologies. Photocatalytic production of hydrogen (H2) from H2S by two-dimensional (2D) semiconductor materials has gathered great attention owing to its large surface area and high catalytic activity. In this work, layered MoS2 has been successfully grown on TiO2 {001} surface to fabricate the 2D MoS2/TiO2 {001} composites for H2 evolution from H2S, which can be confirmed by the X-ray diffraction (XRD) and transmission electron microscopy (TEM) tests. Band structures and UV-Vis spectra provide important evidences that MoS2 loading can significantly narrow the band gap and broaden the light absorbance into the visible light region. Electron transfer is obviously visualized at the interface of MoS2/TiO2, resulting in the built-in potential from TiO2 to MoS2, which is determined by the density functional theory (DFT) calculations and X-ray photoelectron spectroscopy (XPS) test. Consequently, the photo-induced electrons and holes are accumulated at the sides of TiO2 and MoS2 under the illumination, respectively, which largely promote the interfacial electron transfer and prolong the lifetime of photo-generated electrons that participate in the photocatalytic reactions of H2 evolution from H2S. This efficient separation of photo-induced carriers can be further proved by photoluminescence (PL) spectra, photocurrent responses, and electrochemical impedance spectra. As a result, the photocatalytic activity of H2 evolution is largely increased by 9.4 times compared to the pristine TiO2. This study could offer a new and facile way to design highly efficient 2D photocatalysts for the application of H2S treatment.

scholarly journals The Influence of Rapid Solidification on Corrosion Behavior of Mg60Zn20Yb15.7Ca2.6Sr1.7 Alloy for Medical Applications

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5703
Author(s):  
Katarzyna Młynarek-Żak ◽  
Anna Sypien ◽  
Tomasz Czeppe ◽  
Anna Bajorek ◽  
Aneta Kania ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Cooling Rate ◽  
Corrosion Behavior ◽  
Photoelectron Spectroscopy ◽  
Open Circuit ◽  
Corrosion Products ◽  
Medical Applications ◽  
Scanning Calorimetry ◽  
X Ray ◽  
The Impact

Biodegradable magnesium alloys with Zn, Yb, Ca and Sr additions are potential materials with increased corrosion resistance in physiological fluids that ensure a controlled resorption process in the human body. This article presents the influence of the use of a high cooling rate on the corrosion behavior of Mg60Zn20Yb15.7Ca2.6Sr1.7 alloy proposed for medical applications. The microstructure of the alloy in a form of high-pressure die-casted plates was presented using scanning electron microscopy in the backscattered electrons (BSEs) mode with energy-dispersive X-ray spectrometer (EDX) qualitative analysis of chemical composition. The crystallization mechanism and thermal properties were described on the basis of differential scanning calorimetry (DSC) results. The corrosion behavior of Mg60Zn20Yb15.7Ca2.6Sr1.7 alloy was analyzed by electrochemical studies with open circuit potential (EOCP) measurements and polarization tests. Moreover, light microscopy and X-ray photoelectron spectroscopy were used to characterize the corrosion products formed on the surface of studied samples. On the basis of the results, the influence of the cooling rate on the improvement in the corrosion resistance was proved. The presented studies are novel and important from the point of view of the impact of the technology of biodegradable materials on corrosion products that come into direct contact with the tissue environment.

S-C3N4 Quantum Dot Decorated ZnO Nanorods to Improve Their Photoelectrochemical Performance

NANO ◽  
2017 ◽  
Vol 12 (05) ◽  
pp. 1750064 ◽  
Author(s):  
Haizhou He ◽  
Jie Li ◽  
Yang Liu ◽  
Qiong Liu ◽  
Faqi Zhan ◽  
...  
Keyword(s):  
Light Absorption ◽  
Photoelectron Spectroscopy ◽  
Seed Layer ◽  
Electrochemical Impedance ◽  
Solid Phase ◽  
Zno Nanorods ◽  
Phase Method ◽  
Photoelectrochemical Performance ◽  
Electrochemical Impedance Spectra ◽  
X Ray

S-doped C3N4 quantum dots (SCNQDs) were synthesized successfully by a low-temperature solid-phase method. The as-synthesised SCNQDs were decorated on ZnO nanorods by a dipping method. The ZnO nanorod films were prepared through a two-stage method, including pulse electrodeposition for depositing ZnO seed layer on fluorine doping SnO2 glass (FTO) and chemical bath for growing ZnO nanorods on the ZnO seed layer. The prepared samples were characterized via scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-vis absorption spectroscopy, X-ray photoelectron spectroscopy (XPS). The photoelectrochemical performances of the prepared samples were estimated using linear sweep voltammograms, electrochemical impedance spectra (EIS), Mott–Schottky, transient photocurrent and incident photon-to-current conversion efficiency (IPCE). The results show that the light absorption edge of the prepared SCNQDs increases from 326[Formula: see text]nm (CNQDs) to 349[Formula: see text]nm after S doping. The CNQD decorated ZnO photoanode film exhibits 1.34 times as high photocurrent as bare ZnO photoanode film. Importantly, the photocurrent increased to 1.79 times than bare ZnO photoanode film by S doping at 1.0[Formula: see text]V (versus Ag/AgCl), which is attributed to a wider light absorption of SCNQDs and a better efficiency of electron transfer in the interface between SCNQDs and ZnO.

scholarly journals Instrumental Techniques for Characterization of Molybdenum Disulphide Nanostructures

2020 ◽  
Vol 2020 ◽  
pp. 1-29
Author(s):  
Kabelo E. Ramohlola ◽  
Emmanuel I. Iwuoha ◽  
Mpitloane J. Hato ◽  
Kwena D. Modibane
Keyword(s):  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Analytical Techniques ◽  
Great Accuracy ◽  
Molybdenum Disulphide ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Electron Microscopies ◽  
Energy Applications ◽  
Transmission Electron

The excellent chemical and physical properties of materials (nanomaterials) with dimensions of less than 100 nm (nanometers) resulted in researchers and industrialists to have great interest in their discovery and applications in various systems/applications. As their sizes are reduced to nanoscale, these nanomaterials tend to possess exceptional properties differing from those of their bulk counterparts; hence, they have found applications in electronics and medicines. In order to apply them in those applications, there is a need to synthesise these nanomaterials and study their structural, optical, and electrochemical properties. Among several nanomaterials, molybdenum disulphide (MoS2) has received a great interest in energy applications due to its exceptional properties such as stability, conductivity, and catalytic activities. Hence, the great challenge lies in finding the state-of-the-art characterization techniques to reveal the different properties of MoS2 nanostructures with great accuracy. In this regard, there is a need to study and employ several techniques to accurately study the surface chemistry and physics of the MoS2 nanostructures. Hence, this review will comprehensively discuss a detailed literature survey on analytical techniques that can be used to study the chemical, physical, and surface properties of MoS2 nanostructures, namely, ultraviolet-visible spectroscopy (UV-vis), photoluminescence spectroscopy (PL), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, time-of-flight secondary ion mass spectroscopy (TOF-SIMS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning and transmission electron microscopies (SEM and TEM), atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDS/X), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and electroanalytical methods which include linear sweep (LSV) and cyclic (CV) voltammetry and electrochemical impedance spectroscopy (EIS).

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