Field Emission-scanning Microscopy Research Articles

Platinum‐promoted fibrous silica Y zeolite with enhanced mass transfer as a highly selective catalyst for n ‐dodecane hydroisomerization

A fibrous silica zeolite Y (HY@KCC-1) catalyst with a high surface area of 568 m2/g and unique core-shell morphology was successfully synthesized via a modified KCC-1 synthesis method. Characterization of the catalysts was achieved with X-ray powder diffraction (XRD), field emission scanning microscope (FESEM), N2 adsorption/desorption, and 2,6-dimethylpyridine adsorbed Fourier-transform infrared spectroscopy (FTIR). The Pt/HY@KCC-1 has displayed complete n-dodecane conversion coupled with an incredibly enhanced isomer yield of 72% at 350°C, nearly two-fold higher than that of unmodified Pt/HY catalyst. Remarkably, Pt/HY@KCC-1 had an internal effectiveness factor (η) of unity and negligible internal diffusion limitation, thus suggesting its potential application in hydroisomerization of higher hydrocarbons for enhancing fuel properties.

Defect assisted improved room temperature ferromagnetism in Ce doped SnO2 nanoparticles

In the present work, pure and Ce doped SnO2 have been prepared via sol-gel method and the effect of Ce doping on the structural, optical and magnetic properties of SnO2 are studied systematically. A detailed structural analysis has been carried out by X-ray diffraction (XRD), field emission scanning microscopy (FESEM), Fourier transform infrared (FTIR) spectroscopy, Raman scattering, X-ray photoelectron spectroscopy (XPS). These studies reveal that pure and Ce doped SnO2 NPs have a polycrystalline single phase tetragonal rutile structure without any detectable impurity phases and most of the dopant ions occupy the lattice site into the host structure of SnO2. The core level XPS spectrum of Ce 3d reveals that most of the Ce ions are in 3+ valence state. Simulated O K-edge based soft X-ray absorption analysis, high resolution O 1s XPS results and photoluminescence study reveal that oxygen vacancies are generated in the doped samples. Band gap of SnO2 is found to decrease with increase in Ce content. Magnetic measurements show that all the Ce doped samples clearly display the room temperature ferromagnetic behavior while pure SnO2 shows diamagnetic nature. Magnetic parameters have been determined from the fitted M-H loops and transition from diamagnetic to ferromagnetic is observed when Ce ions are doped into SnO2 structure.

Augmented physico‐chemical, crystalline, mechanical, and biocompatible properties of electrospun polyurethane titanium dioxide composite patch for cardiac tissue engineering

Although there is enormous growth in the technology for cardiovascular applications, remodeling of the damaged cardiac tissue is still a daunted task. Polymeric scaffold could be able to regenerate the human cardiomyocytes which facilitate the remodeling of the cardiac damage. The objective of the study is to fabricate polyurethane (PU) cardiac patch added with titanium dioxide (TiO2) nanofibers using electrospinning technique. The morphological investigation demonstrated the reduced fiber (666 ± 155 nm) and pore diameter (862 ± 75 nm) of the fabricated nanocomposite compare with the pristine PU (fiber diameter – 890 ± 117 nm and pore diameter – 1,064 ± 74 nm). Field emission scanning microscopy (FESEM), infrared (IR) spectrum, and thermal analysis confirmed the existence of titanium dioxide in the pristine PU. The wettability study showed the hydrophobic behavior (109° ± 1.53°) of electrospun PU/titanium dioxide nanocomposites than the pristine PU (100° ± 0.58°). X‐ray diffraction (XRD) study denoted the crystalline behavior of the pristine PU with the addition of titanium dioxide. Tensile (19.48 MPa) and surface (425 nm [Ra]) testing indicated that the addition of titanium dioxide improved the mechanical and surface roughness of the pristine PU (tensile strength – 7.12 MPa and roughness – 313 nm). The coagulation and cytotoxicity study depicted the enhanced anticoagulant behavior and improved cell viability of the developed nanocomposites than the PU. Hence, the developed novel patch exhibiting better physico‐chemical characteristics, enhanced blood compatibility parameters, and good cell viability rates hold to be a promising candidate for cardiac tissue repair. POLYM. COMPOS., 40:3758–3767, 2019. © 2019 Society of Plastics Engineers

Hydrophobic surface treatments for improving the corrosion resistance of anodized AA2024-T3 alloys

The present study investigates the use of hydrophobic sealing treatments to improve the corrosion resistance of anodized aluminium alloys. Alternative hydrophobic processes to the hydrothermal sealing were tested. One is based on a monocarboxylic acid, myristic acid, and others involve the deposition of hybrid sol-gel film. The samples characterization was performed by Field Emission Scanning Microscopy. The hydrophobic properties were assessed by contact angle measurements, and Electrochemical Impedance Spectroscopy was used to study the anticorrosive properties. All the hydrophobic treatments improved the corrosion resistance of the anodized samples with respect to the hydrothermal treatment. The best results were obtained using the hybrid sol-gel film, where high impedance values are measured after long immersion periods in a 0.1 M NaCl solution. Especially good behaviour was observed in samples sealed with the sol-gel film when the sol was previously heated at 70 °C. This temperature was necessary to dissolve the aggregates that formed at room temperature, which contribute to a more efficient sealing.

Construction of novel nonenzymatic Xanthine biosensor based on reduced graphene oxide/polypyrrole/CdO nanocomposite for fish meat freshness detection

A novel nonenzymatic voltammetric Xanthine biosensor was constructed based on a three-dimensional porous nanocomposite of reduced graphene oxide/polypyrrole/CdO nanocomposite modified glassy carbon electrode (GCE/rGO/PPy/CdO) for measuring of Xanthine. The structure and morphology of rGO/PPy/CdO nanocomposites were characterized by field emission scanning microscopy, Raman spectroscopy, X-ray diffraction, UV–vis spectroscopy, Fourier transform infrared and X-ray photoelectron spectroscopy. The GCE/rGO/PPy/CdO based biosensor exhibited excellent electrocatalytic activity and high stability for Xanthine oxidation. Under optimized conditions, the linearity between the current response and the Xanthine concentration was obtained in the range of 1–800 µM with a detection limit of 0.11 μM (S/N = 3). The biosensor was used to determine the Xanthine in fish meat with satisfactory results.

Hydrothermal synthesis of MoS2 with controllable morphologies and its adsorption properties for bisphenol A

The effect of preparation conditions (molar ratio of S/Mo, hydrothermal temperature and time) on the morphologies of MoS2 was investigated. The as-synthesized materials were characterized by X-ray diffraction (XRD), field emission scanning microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectra and Brunauer–Emmett–Teller’s (BET) surface area measurement. Results showed that the three kinds of morphologies of MoS2 were obtained. Morphologies varied gradually from the coral-like aggregated particles to flower-like spheres to wrapped nano-sheet structure with increasing hydrothermal temperature and time. It is meaningful for specific morphology demand in different fields. Moreover, the prepared materials were used as tentative adsorbents for the removal of bisphenol A (BPA) as a representative of endocrine disruptors. The results showed that the prepared MoS2 materials with wrapped nano-sheet structure had good adsorption capacity (39.03 mg/g) and fast adsorption rate (0.0053 g/(mg/min). The adsorption process was thermodynamically exothermic and spontaneous. The study indicated that electrostatic interaction is strong and π-π interaction between BPA and the MoS2 materials play an important role for BPA adsorption.

Correlation between morphology and magnetic properties in Zr doped BiFeO3 nanoparticles

Multiferroic gained attention in the past decade owing to their fascinating properties and applications. Herein, we implemented flash combustion method to synthesize BiZrxFe1−xO3; 0 ≤ x ≤ 0.07. The X-ray data analysis revealed the dependence of the unit cell volume on the Zr4+ concentration, where it decreased with increasing the later. The change in the lattice parameters aR of the rhombohedral unit cell with Zr content follows the same trend of the c-axis in the hexagonal system, in which the angle (α) is increased up to x = 0.05 and then decreased in accordance with the behavior of a. Platelets of hexagonal shape with slight agglomeration were observed using field emission scanning microscope. Homogenous size distribution is the main feature of the nanocrystals. For the samples with x = 0.01, some nanofibers were grown on the surface of the existed hexagonal platelets. The magnetic hysteresis loops indicated antiferromagnetic trend. The saturation magnetization Ms increased significantly from 0.2 emu/g at x = 0 to 1.4 emu/g at x = 0.03. The values of Hc were found to increase sharply from 83 Oe at x = 0 to about 192 Oe at x = 0.01 due to shape anisotropy.

Optimization and characterization of magnetite-reduced graphene oxide nanocomposites for demulsification of crude oil in water emulsion.

Oily wastewater from the oil and gas industry negatively affects the environment. Oily wastewater typically exists in the form of an oil-in-water emulsion. Conventional methods to treat oily wastewater have low separation efficiency and long separation time and use large equipment. Therefore, a simple but effective method must be developed to separate oil-in-water emulsions with high separation efficiency and short separation times. Magnetite–reduced graphene oxide (M–RGO) nanocomposites were used as a demulsifier in this work. Magnetite nanoparticles (Fe3O4) were coated on reduced graphene oxide (rGO) nanosheets via an in situ chemical synthesis method. The synthesized M–RGO nanocomposites are environmentally friendly and can be recovered after demulsification by an external magnetic field. M–RGO characterization was performed using X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, field emission scanning microscopy, Raman spectroscopy, and vibrating sample magnetometry. Demulsification performance was evaluated in terms of M–RGO dosage, effects of pH, and brine concentration. The demulsification capability of M–RGO was determined based on the residual oil content of the emulsion, which was measured with a UV-vis spectrometer. The response surface method was used to determine the optimum conditions of the input variables. The optimum demulsification efficiency achieved at pH 4 and M–RGO dosage of 29 g L−1 was approximately 96%. This finding demonstrates that M–RGO nanocomposites are potential magnetic demulsifiers for oily wastewater that contains oil-in-water emulsions. Also, the recyclability of this nanocomposite has been tested and the results shown that it is a good recyclable demulsifier.

Albumen Assisted Green Synthesis of NiFe2O4 Nanoparticles and Their Physico-Chemical Properties

Spinel ferrites with general formula AB2O4 possess fascinating magnetic and electrical properties due to their thermal and chemical firmness. Nickel ferrite (NiFe2O4) is one of the most vital spinel ferrite having inverse spinel structure showing ferrimagnetism that originates from magnetic moment of anti-parallel spins linking the metal ions (Ni2+ and Fe3+). Here a simple technique of self-combustion with aid of albumen is made to synthesize nano crystalline Nickel ferrite (NiFe2O4) particles. The egg white (albumen) used in the synthesis process plays the role of fuel in the combustion process. The powder X-ray diffraction (PXRD) and Fourier Transform Infrared Spectroscopy (FTIR) results indicated that the synthesized nanoparticles are of single phase and show evidence of spinel structure. The Photoluminescence studies showed a doublet peat at 360-380nm. Also the functional groups present in the synthesized nanoparticles was found using FTIR. EDX results give account of the percentage composition of the elements Fe, Ni and O present in the synthesized sample. The Field Emission Scanning Microscope (FESEM) reveals the agglomerated nature of ferrite nanoparticles. Magnetic moment and retentivity of the as synthesized nickel ferrite (NiFe2O4) nanoparticles were obtained using Vibrating Sample Magnetometer (VSM). Dielectric properties of the as prepared samples were measured by two-probe method for various frequencies ranging from 100Hz-1MHz

Micro-Spectroscopy in the Low-Energy Regime:Secondary Electron Detection and Energy Analysis in the Scanning Field-Emission Microscope

Micro-Spectroscopy in the Low-Energy Regime:Secondary Electron Detection and Energy Analysis in the Scanning Field-Emission Microscope

Electrodeposited Cu/MWCNT composite-film: a potential current collector of silicon-based negative-electrodes for Li-Ion batteries.

With the aim of developing the potential high theoretical capacity of Si as a negative electrode material for Li-ion batteries, a new type of composite current collector in which multi-walled carbon nanotubes (MWCNTs) are immobilized on a Cu surface was developed using an electroplating technique. For the Si electrode with a flat-Cu substrate, voltage plateaus related to the stepwise electrochemical lithiation were observed below 0.27 V (vs. Li/Li+), whereas the Cu/MWCNT substrate distinctly decreased the overvoltage to enhance charge/discharge capacities to approximately 1.6 times that obtained in the flat-Cu system. Field-emission scanning microscopy revealed that MWCNTs immobilized on the Cu surface extended inside the active material layer. Adhesion strength between the substrate and electrode mixture layer was reinforced by MWCNTs to increase the reversibility of change in electrode thickness before and after cycling: the expansion ratio was 200% and 134% for flat-Cu and Cu/MWCNT systems, respectively. Electrochemical impedance analysis demonstrated that MWCNTs served as an electron conduction pathway inside the electrode. By controlling the upper cutoff voltage from 2.0 V to 0.5 V, synergetic effects including improved adhesion strength and a more developed conduction pathway became noticeable: a reversible capacity of 1100 mA h g−1 with 64% capacity retention was achieved even after the 100th cycle. The results indicate that the Cu/MWCNT is a promising current collector for expansion/contraction-type active materials for rechargeable batteries.

Facile growth of novel morphology correlated Ag/Co-doped ZnO nanowire/flake-like composites for superior photoelectrochemical water splitting activity

In this paper, novel morphology correlation between silver nanowires (AgNWs) and cobalt (Co)-doped ZnO (Co-ZnO) flake-like thin films (nanowire/flake-like) has been proposed for enhanced photoelectrochemical (PEC) water splitting activity. Here in, high-quality AgNWs/Co-ZnO heterostructures enabled superior visible light water splitting activity compared to the pure ZnO and AgNWs/ZnO. To address the strategic effect of AgNWs coupling and transition metal (Co-2 at%) doping into the ZnO host lattice, we have carried out the X-ray diffraction, field emission scanning microscopy, X-ray photoelectron spectroscopy, UV–Vis transmittance, water contact angle and PEC analyses. In this way, PEC water splitting activity was mainly examined by linear sweep voltammetry (I-V), amperometric I-t and photoconversion efficiency (η) studies. The experimental results provide clear evidence of morphology correlation between AgNWs and Co-ZnO flake-like structures for strong visible light absorption. Specifically, AgNWs/Co-ZnO composites exhibited significant enhancement in the photocurrent density (7.0 × 10−4 A/cm2) than AgNWs/ZnO (3.2 × 10−4 A/cm2) and pure ZnO (1.5 × 10−6 A/cm2). As a result, detailed AgNWs/Co-ZnO geometry has great potential for photoconversion efficiency (0.73%). In a word, the merits of controllable AgNWs/Co-ZnO heterostructure are proposed to improve the visible light harvesting and charge carrier generation for energy conversion devices.

Enhanced visible photocatalytic activity of tree-like ZnO/CuO nanostructure on Cu foam

Novel tree-like ZnO/CuO composite, composed of CuO nanowire trunks and ZnO nanorod branches, have been successfully synthesized on Cu foam substrate. Single-crystalline CuO nanowires and ZnO nanorods are obtained by thermal oxidation and hydrothermal processes, respectively. The morphological, crystal and optical properties of the as-prepared samples have been studied by field-emission scanning microscopy, X-ray diffractometer, transmission electron microscopy, and UV–vis spectrophotometer. The resultant tree-like ZnO/CuO composites on Cu foam show excellent photocatalytic activity with a rate constant of about 0.0073 min−1 in the photo-degradation of Rhodamine B (RhB) under visible light (λ > 420 nm). The Cu foam not only provides extra-large surface area for the growth of tree-like CuO/ZnO composites, but also acts as an effective frame to support the catalysts. Furthermore, tree-like ZnO/CuO composite catalysts show high recovery yield for the recycling during the degradation of organic pollutants. This work provides an insight view into the design and synthesis of composite photocatalyst effectively supported by a substrate.

Improved photoelectrical performance of single crystalline rutile TiO2 nanorod arrays incorporating α-alumina for high efficiency dye-sensitized solar cells

Novel architecture like TiO2 nanorod arrays (TNR) incorporating α-alumina (ATNR) thin film have been fabricated on the fluorine-doped tin oxide (FTO) by a modest and flexible doctor-blade technique based hydrothermal method. α-Al2O3, TNR and ATNR were used as a photoanode in dye-sensitized solar cells (DSSCs) and their photovoltaic performance was evaluated. The crystallinity, presence of α-Al2O3 on TNR and morphology of the photoanodes were characterized by X-ray diffraction, field emission scanning microscopy and high-resolution transmission scanning microscopy. DSSCs fabricated with 1.0 wt% α-Al2O3 added TNR exhibited an improved open-circuit photo voltage of 0.68 V, short-circuit current density of 15.23 mA cm−2, fill factor of 0.63 and photo-electric conversion efficiency (PCE) of 6.5%.

Natural Minerals as Support of Silicotungstic Acid for Photocatalytic Degradation of Methylene Blue in Wastewater

In this paper, silicotungstic acid (HSiW) was impregnated on natural minerals such as clinoptilolite (HSiW/Clin), mordenite (HSiW/Mord), bentonite (HsiW/Bent) and kaolinite (HSiW/Kaoln) and were evaluated towards photocatalytic degradation of methylene blue in wastewater. The as-prepared photocatalysts were characterized by X-ray powder diffraction (XRD), Field Emission Scanning Microscopy (FESEM), Fourier transform infrared (FTIR) and UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS). The results showed that the crystallinty of HSiW was different on above mentioned minerals and HSiW on clinoptilolite had the most crystallinty and the smallest crystallite size. FESEM showed that the supported HSiW had nanometric spherical particles with narrow and uniform distribution. FTIR revealed Keggin structure of HSiW in all photocatalysts and a strong interaction between HSiW and minerals. DRS studies showed HSiW/Clin and HSiW/Mord had photoactivity in both visible and ultraviolet regions while HSiW/Bent and HSiW/Kaoln photocatalysts were just active in UV region. More studies indicated that HSiW/Clin had the lowest band gap of 3.1 eV among studied nano photocatalysts. This sample could degrade 92% of methylene blue after 90 min of UV irradiations and HSiW/Mord, HSiW/Bent and HSiW/Kaoln were in the next positions. Kinetic studies illustrated photocatalytic degradation of methylene blue followed a pseudo first order reaction and the highest rate constant belonged to HSiW/Clin and other photocatalysts had much lower rate constants. Effect of operation parameters like wastewater pH, initial dye concentration, photocatalyst loading and successive runs of HSiW/Clin was investigated and at the end a new mechanism for this photocatalyst was proposed.

Visible-Light-Driven Photocatalytic N-Doped TiO2 for Degradation of Bisphenol A (BPA) and Reactive Black 5 (RB5) Dye

Bisphenol A (BPA) and reactive black 5 (RB5) dye are among the most persistent and non-biodegradable contaminants in water which require an urgent need for the development of effective removal method. The ubiquitous existence of both contaminants could interfere with the human health and aquatic environmental balance. Photocatalytic process as one of advanced oxidation processes (AOPs) has shown high performance for degradation of organic compounds to the harmless materials under sensible condition. Therefore, this study aims to develop a visible-light-driven photocatalyst that can efficiently degrade BPA and RB5 present in household water. N-doped TiO2 were successfully synthesized via simple and direct sol–gel method. The prepared TiO2 nanoparticles were characterized by field emission scanning microscope (FE-SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and Brunauere Emmette Teller (BET) analysis. The incorporation of nitrogen in TiO2 lattice exhibited excellent optical responses to visible region as revealed by UV–Vis–NIR spectroscopy absorption capability at 400–600 nm. The photocatalytic activity of the N-doped TiO2 nanoparticles was measured by photocatalytic degradation of BPA and RB5 in an aqueous solution under visible-light irradiations. Degradation of BPA and RB5 was 91.3% and 89.1%, respectively after 360 min illumination. The degradation of BPA and RB5 by N-doped TiO2 was increased up to 89.8% and 88.4%, respectively under visible-light irradiation as compared to commercial TiO2 P25. This finding clearly shows that N-doped TiO2 exhibits excellent photocatalytic degradation of BPA and RB5 under visible irradiation, hence have a promising potential in removing various recalcitrant contaminants for water treatment to fulfill the public need to consume clean water.

Performance of γ-aluminium oxide nanoparticles for arsenic removal from groundwater

The present study aims to investigate the applicability of γ-Al2O3 nanoparticles (NPs) adsorbent for removal of arsenite and arsenate from aqueous solution. The nano-adsorbent was characterized using zeta potential analysis, dynamic light scattering, field emission scanning microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy and X-ray diffraction. Batch adsorption studies were carried out to optimize adsorption parameters such as contact time, stirring speed, initial arsenic concentration, adsorbent dose, pH and effect of different competing anions. Langmuir adsorption capacities obtained at 298 K are 769.23 µg/g and 1000 µg/g for As(III) and As(V) removal correspondingly. The adsorption mechanism was well established by pseudo-second-order kinetic model. Negative values of enthalpy (ΔH°) obtained during adsorption [− 29.12 kJ/mol and − 35.55 kJ/mol for As(III) and As(V), respectively] confirmed the process was exothermic in nature. The negative values of ΔG° [− 6.14 to − 3.86 kJ/mol for As(III) and − 9.32 to − 6.68 kJ/mol for As(V)] further affirmed that the adsorption process is spontaneous in nature. There was no requirement of additional external energy supply for the enhanced removal as the adsorption was less favoured at high temperature. Phosphate and sulphate had the profound effect on reduction in the removal efficiency. Good regenerating efficiency of γ-Al2O3 NPs up to fourth cycle implied economic feasibility of the adsorbent. The effectiveness of γ-Al2O3 was also proved for removal of arsenic from real arsenic-contaminated groundwater.

Facile synthesis of hydroxyapatite nanoparticles mimicking biological apatite from eggshells for bone-tissue engineering.

A facile synthesis of hydroxyapatite (HAp) nanoparticles that mimicked biological apatite by utilizing eggshells as a bio-calcium precursor was presented via the hydrothermal method and with the assistance of cetyltrimethylammonium bromide for bone-tissue engineering. The synthesized HAp was characterized by the X-ray powder diffraction method, Fourier transform infrared spectroscopy, field emission scanning microscopy, energy-dispersive X-ray spectroscopy, and nitrogen adsorption-desorption isotherms. The HAp nanoparticles were produced in film and pellet forms to determine their biomineralization and protein adsorption through in vitro studies in simulated body fluids and minimum essential medium supplemented with fetal bovine serum, respectively. A pure HAp nanocrystalline phase with rod-shaped nanoparticles of 161 nm in mean length and 52 nm in mean diameter was produced. The HAp was revealed to be a carbonated HAp exhibiting A- and B- type CO32- substitutions with CO32- content of 2.14 ± 1.36 wt.%, trace amounts of some important elements (Mg, Na, and K), and Ca/P atomic ratio of 1.54, thereby confirming that the HAp resembled the biological apatite in terms of morphology, structure, and composition. The HAp showed high biomineralization capability with the quick release of a double layer of bone-like apatite after 3 days in SBF and extremely high protein adsorption with 1213 ± 178 μg of proteins adsorbed on the HAp surface after 24 h. The HAp material had high bioactivity and cell affinity (cell adhesion, spreading, and proliferation). Thus, it has potential as a biomaterial for fabrication of BTE scaffolds. To our knowledge, this article is the first detailed study on biological tests of the HAp material derived from eggshells.

Adsorptive mercaptan removal of liquid phase using nanoporous graphene: Equilibrium, kinetic study and DFT calculations

This research investigated the adsorption of tertiary butyl mercaptan (TBM) from liquid phases by using nanoporous graphene. Nanoporous graphene synthesized through chemical vapor deposition method was characterized using Brunauer–Emmett–Teller method, transmission electron microscopy, field-emission scanning microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy techniques. The TBM adsorption equilibrium was investigated by using Langmuir, Freundlich, and Tempkin models. The obtained results were in good agreement with the Freundlich isotherm. The adsorption kinetics of this process was modeled by the pseudo-first-order, pseudo-second-order, and intraparticle models. The adsorption rate was obtained according to the pseudo-second-order model. The satisfactory results indicated that nanoporous graphene can be used as a good carbon nanostructure sorbent in mercaptan removal. The process reduced the sulfur content from 300 ppm to less than 10 ppm which was the standard level in environmental regulations. The capacity for TBM removal was achieved at 4.4 gr S/gr adsorbent. The desulfurization efficiency was revealed about 96.3% for nanoporous graphene at 298 K and 24 h. Moreover, density functional theory calculations were used to determine the stable configuration, adsorption energy, and electronic structure of different configurations of TBM adsorbed onto a graphene surface. TBM physically adsorbed onto the graphene surface with adsorption energies of approximately − 25 kJ/mol was indicated from DFT calculations.

Corrosion behaviors of bioactive element coatings on PEO-treated Ti-6Al-4V alloys

In this study, the corrosion behaviors of bioactive element coatings on plasma electrolytic oxidation (PEO)-treated Ti-6Al-4V alloys were researched using various instruments for measurement of coated elements from PEO-treated surface in the solution of simulated fluid.For this research, Ti-6Al-4V ELI disks were prepared as the substrates for PEO treatment. PEO treatment was carried out using pulsed DC power supply at 280 V for 3 min in electrolytes containing bioactive ions such as silicon, zinc, manganese, magnesium, strontium, calcium, and phosphorus. To analyze the electrochemical properties of the PEO film as a function of added ions in the electrolyte, potentiodynamic and AC impedance tests were performed using a potentiostat in 0.9% NaCl solution. The alloy surface after performing a corrosion test of the PEO-treated specimen on the Ti-6Al-4V alloy was observed using a field-emission scanning microscope, energy dispersive X-ray spectrometer, and X-ray diffractometer (XRD).When a bioactive element was added during the PEO process, the pore size decreased and a precipitate containing a high Mn content was formed around the pores. The XRD results of the PEO-treated surface with bioactive elements showed that the anatase and HA phase contents increased while the Ti peak intensity decreased. When Mn was added to the electrolyte, a second anodic peak appeared, and the precipitates on the surface and pore edges were dissolved in the 0.9% NaCl solution. The results of AC impedance tests revealed a decrease in the polarization resistance of the PEO-treated surface.