Field Emission Scanning Electron Microscopy Images Research Articles

Impact of voltage variation on topography, hydrophobicity, and corrosion behavior of the CeO2-TiO2 nanocomposite coating on AM60B Mg alloy prepared by plasma electrolyte oxidation

Abstract A superhydrophobic oxide layer on AM60B magnesium alloy was created by using a plasma electrolytic oxidation (PEO) technique and subsequent surface modification. PEO was applied in an electrolyte with/without CeO2-TiO2 nanoparticles (NPs) by two different voltages of 350 and 450 V. Atomic force microscopy (AFM) and field emission scanning electron microscopy (FE-SEM) were used to evaluate the roughness and morphology of the surface. Water contact angles on the surface were measured to investigate the surface wettability. Potentiodynamic polarization tests in a 3.5 wt.% NaCl solution were used to assess the corrosion resistance of the coating. Also, the FE-SEM images showed that increasing applied voltage, decreases the numbers and size of the pores on the surface. Results showed that applying PEO, increased the corrosion resistance of the bare AM60B because corrosion rate (C.R.) decreased from 1.523805 (bare AM60B) to 1.432107 mpy (PEO-450 V). Furthermore, using CeO2-TiO2 NPs effectively enhanced the corrosion resistance of the bare AM60B by decreasing the corrosion rate from 1.523805 to 1.286469 mpy.

Magnetically retrievable carbon-wrapped CNT/Ni nanospheres as efficient catalysts for nitroaromatic reduction.

We present a facile strategy for synthesizing magnetically retrievable carbon-wrapped CNT/Ni nanospheres (C-wrapped CNT/Ni) that enhance the catalytic performance of metals for environmental pollutant reduction. Structural and compositional analyses using X-ray diffraction (XRD), Raman spectroscopy, energy-dispersive X-ray spectroscopy (EDS), and field emission scanning electron microscopy (FESEM) confirmed the phase purity, morphology, and structure of the C-wrapped CNT/Ni. XRD, Raman, and EDS data validate the formation of the nanospheres, while FESEM images reveal uniform Ni nanospheres wrapped with a carbon layer through interconnected, evenly dispersed CNTs. Initially, Ni nanoparticles were anchored onto multiwalled carbon nanotubes to form magnetic CNT/Ni nanospheres, which were then coated with a carbon layer to prevent aggregation, improve Ni particle stability, and introduce additional surface functionalities. The catalytic efficacy of C-wrapped CNT/Ni was assessed through the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The reaction rate constant (k app = 0.6167 min-1) with C-wrapped CNT/Ni is approximately six times higher than that with bare Ni nanospheres (k app = 0.1056 min-1). This enhanced catalytic activity is attributed to the synergistic effect between the spherical Ni core and the wrapped carbon layer, mediated by the interconnected CNT, which promotes efficient hydride formation. Additionally, C-wrapped CNT/Ni demonstrates exceptional reusability in the 4-NP reduction process. The integration of these features within a single framework suggests its significant potential for diverse engineering and environmental applications.

TiO2/NiFe2-xCexO4/rGO ternary magnetic nanocomposite as separable and recyclable photocatalyst

This study investigates the synthesis and application of a TiO2/NiFe2-xCexO4/rGO ternary magnetic nanocomposite as an efficient and recyclable photocatalyst. The nanocomposite was characterized using Fourier-transform infrared(FTIR), X-ray diffraction(XRD), Field emission scanning electron microscopy(FE-SEM), magnetic measurements, UV–Vis diffuse reflectance spectroscopy(DRS), and X-ray photoelectron spectroscopy (XPS). FTIR analysis confirmed the formation of the inverse spinel cubic structure, with significant vibrational bands related to metal–oxygen complexes. XRD patterns showed successful incorporation of Ce3+ ions into the NiFe2O4 lattice, with shifts in diffraction peaks indicating changes in crystallite size and lattice parameters. FE-SEM images revealed a well-dispersed distribution of TiO2 and NiFe2O4 nanoparticles on the reduced graphene oxide (rGO) surface, enhancing the nanocomposite’s structural integrity. Energy dispersive X-ray(EDX) analysis demonstrated the presence of Ti, Ni, Fe, Ce, O, and C elements in the ternary nanocomposite without impurities, confirming the high purity of the material. Magnetic measurements indicated increased magnetization due to Ce3+ doping. DRS revealed optical band gaps (Bg), and XPS provided detailed insights into the surface chemical composition and valence states. XPS analysis confirmed the presence of Ni2+, Fe3+, Ti4+, and Ce3+ ions, and verified the reduction of graphene oxide to rGO. Importantly, the XPS data also indicated a reduction in the binding energy of oxygen species, which suggests effective electron trapping. The photocatalytic performance was assessed by the degradation of methylene blue (MB) under UV and Vis light. The TiO2/NiFe2-xCexO4/rGO nanocomposite demonstrated superior photocatalytic activity with high degradation rates. The enhanced photocatalytic efficiency is attributed to efficient electron trapping, which reduces electron-hole recombination. Furthermore, the nanocomposite showed excellent reusability, maintaining high photocatalytic efficiency over multiple cycles of use, which underscores its potential for practical applications in environmental remediation.

Studies on the retarded recrystallization of tungsten in CIMPLE-PSI exposed under very-high target temperature and long He+-fluence

Abstract Experiments are carried out in CIMPLE-PSI, to understand the recrystallization behavior of tungsten (W) exposed under very-high target temperature and ITER relevant long He+-fluence. The effect of helium bubbles on possible retardation of the recrystallization process is also studied. W samples were simultaneously exposed under He plasma and annealed by the plasma heat-load, in contrast to previously reported experiments in literature, which were carried out sequentially. Exposed samples are characterized by field emission scanning electron microscopy (FESEM), Vickers surface micro-hardness, nano-hardness and electron backscattered diffraction (EBSD). It is observed that the sample exposed to plasma under the highest temperature (1866 K) suffered acute retarded grain growth. This also contained small, unrecovered grains on the exposed surface. FESEM imaging of the cross-sections confirms that relatively smaller helium bubbles still form even at very high temperature conditions, which can impede the grain growth locally, whenever they are forming right on the grain boundaries. This results in an inhomogeneous mixture of surface grains with sizes ranging from a few micrometers to a few tens of micrometers. EBSD estimates that the plasma exposed surface was only 34% recrystallized. The second sample exposed at a lower temperature (1699 K) but for three times higher fluence (ion fluence: 1.19 × 1027 m−2) was almost fully recrystallized, which shows retardation diminishes very fast with the duration of the exposure. Hardness measurements were undertaken to understand the variation with plasma exposure/annealing temperature and the extent of recrystallization, with three different probing length scales, spanning from a few hundred nanometers to several micrometers. Both helium plasma exposed W samples are observed to undergo retarded softening up to a depth of a few hundred nanometers from the surface, compared to when the metal may be recrystallized by simple heating, without any plasma exposure.

Mechanistic Insights into the Reaction of Wulfenite with Aqueous Sodium Sulfide Solution and Its Industrial Implications.

The purpose of this study was to investigate the reaction mechanism of wulfenite with an aqueous sodium sulfide solution and thereby provide guidance for the sulfidization flotation and sodium sulfide leaching of wulfenite. For this purpose, dissolution/leaching behavior analysis, X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and field-emission scanning electron microscopy (FESEM) were performed. The dissolution/leaching analysis indicated that sodium sulfide can induce the dissolution of PbMoO4. The XRD and Raman spectra results demonstrated that PbMoO4 was replaced by PbS at the wulfenite-sodium sulfide solution interface, and the sulfidized wulfenite particles had a PbMoO4/PbS core-shell structure. The XPS results also indicated the transformation of PbMoO4 to PbS. The FESEM images showed the growth of PbS nanoparticles on the surface of wulfenite and the dissolution pits after treatment with sodium sulfide solution. These findings showed that wulfenite sulfidization proceeds through an interface-coupled dissolution-precipitation mechanism. In the presence of sodium sulfide solution, the less stable PbMoO4 dissolves, and the more stable PbS phase precipitates, both of which are coupled at the wulfenite-sodium sulfide aqueous solution interface.

Phase-selective fabrication of Cu-based films by magnetic field-assisted sparking process for improved photocatalytic dye degradation and CO2 reduction

Copper-based films (Cu2(OH)3NO3, Cu2O, and CuO) were successfully synthesized using a sparking process under an external magnetic field, without requiring an annealing process. We thoroughly investigate the impact of magnetic field orientation on the structural, morphological, and optical properties of the films, along with their performance in photocatalytic degradation of methylene blue (MB) and carbon dioxide (CO2) reduction. Field-emission scanning electron microscopy (FE-SEM) images reveal that the CuEB(S) sample displays secondary particles forming spherical, dense clusters, whereas the CuEB(N) sample exhibits larger, loosely packed clusters. In contrast, the cluster-like structures disperse in the CuEB(P) sample, resulting in a smoother film surface aligned with the parallel magnetic flux direction. Upon close observation, rice-shaped particles of varying sizes (26.3–60.3 nm) were found stacked together. This study presents a facile method to selectively fabricate films comprising single-phase Cu2(OH)3NO3, a CuO/Cu2O composite, or a combination of all phases by manipulating the external magnetic field orientation during the sparking process. All synthesized materials exhibit photocatalytic activity, with the heterojunction composed of CuO, Cu2O, and Cu2(OH)3NO3 demonstrating superior performance. This heterostructure achieved up to a 180 % enhancement in MB degradation and approximately doubled the CO2-to-CO conversion rate to 16.09 μmol g–¹ h–¹ compared to the sample prepared without a magnetic field.

Biosynthesis and investigation of antibacterial properties of green silver nanoparticles using fruit extracts of Wild barberry, Medlar (Mespilus germanica L.), and Hawthorn

The biological method of synthesizing nanoparticles is a valuable alternative to traditional chemical synthesis methods, offering a fast, environmentally friendly, and cost-effective technique. In this study, the synthesis of silver nanoparticles (AgNPs) was carried out using fruit extracts of Wild barberry (Bar-Ag), Medlar (Mespilus germanica L.) (Med-Ag), and Hawthorn (Haw-Ag) as reducing and stabilizing agents. AgNPs were characterized by various analysis methods, including X-ray diffraction (XRD), UV-vis spectroscopy, Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), and Dynamic Light Diffraction (DLS). The XRD results showed the presence of pure silver crystals with average sizes of 35.6, 23.7, and 35.6 nm for Bar-Ag, Med-Ag, and Haw-Ag, respectively. FESEM and TEM images illustrated the formation of nearly spherical and stable particles with sizes ranging from 30 to 80 nm. In addition to confirming the particle sizes, the DLS result indicated their uniform distribution. FTIR analysis revealed that AgNPs contain three main groups of agents: phenols, carboxylic acids, and amines, which play a role in the synthesis of nanoparticles. Evaluating the antibacterial activity against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria showed that AgNPs synthesized with these fruit extracts exhibited significant antibacterial performance. The results of this study demonstrate that AgNPs biosynthesized with fruit extracts have considerable potential for biomedical applications.

One-pot synthesis of graphene nanosheets‑nickel cobalt LDHs nanocomposite for electrocatalysis of oxygen evolution reaction

Oxygen evolution reaction (OER) is known as a bottleneck for the overall water-splitting process due to its slow kinetics. In this regard, constructing a high-performance, cost-effective electrode material may act as a game changer. Here, a 2D/2D nanocomposite has prepared out of graphene nanosheets and nickel‑cobalt layered double hydroxide (NiCo LDH) by a simple solvothermal method. The 2D flower-like structures of NiCo LDH attached to graphene nanosheets have observed in field-emission scanning (FE-SEM) and transmission (TEM) electron microscopy images. The X-ray diffraction (XRD) patterns have revealed the formation of Ni(OH)2 and Co(OH)2 lattices along with hexagonal graphene crystals. The energy-dispersive X-ray spectroscopy (EDS) has noted the 2.2:1 ratio of nickel to cobalt in the graphene/NiCo LDH nanocomposite. X-ray elemental maps have shown the uniform distribution of elements in the sample, and the corresponding functional groups have observed in the Fourier-transform infrared (FTIR) and Raman spectra. X-ray photoelectron spectroscopy (XPS) has determined the coexistence of divalent and trivalent metals in the nanocomposite. The N2 adsorption-desorption study has shown signs of slit-shaped ion-accessible micro and mesopores with high specific surface area for the nanocomposite. It has benefited the ion diffusion process during the exposure of the modified electrode to the electrolyte. The graphene/NiCo LDH nanocomposite has provided the onset potential of 1.56 V, overpotential of 338 mV at 10 mA cm−2, Tafel slope of 69 mV dec−1, charge-transfer resistance (Rct) of 27 Ω, double layer capacitance (Cdl) of 24 μF, electrochemically active surface area (ECSA) of 0.6 cm2, and roughness factor (RF) of 20. The electrode has maintained 98.3 % of its initial signal after 10 h continuous measurement at OER potential. This electrocatalytic activity refers to the sheet-like morphology, effective hydroxide ion transfer through interlayer spaces, enhanced conductivity, and high chemical stability achieved by a constructive synergy between graphene nanosheets and NiCo LDH.

Formamidinium Lead Iodide‐Based Perovskite Solar Cell Fabrication With an Electrospun‐Reduced Graphene Oxide Back Electrode: A Novel Approach

AbstractIn this work, low‐cost and simple structure perovskite solar cells (PSCs) were fabricated using formamidinium lead iodide (FAPbI3) as the light absorber and reduced graphene oxide nanofibers (rGO NFs) as the counter electrode (CE). The FAPbI3 light absorber was prepared using a two‐step solution process, whereas the rGO NFs were synthesized through a simple electrospinning method. The as‐prepared FAPbI3 and rGO NFs were characterized by high‐resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and X‐ray diffraction (XRD) pattern analysis. The surface morphology of the as‐prepared FAPbI3 and rGO NFs showed crystalline and bead‐free fiber structures, as confirmed by HRTEM and FESEM image analysis. The AFM topographical images of FAPbI3 and rGO NFs further reveal the crystalline and fiber structures. XRD pattern analysis confirmed the cubic crystalline phase of FAPbI3 and the graphitic nature of rGO NFs. From the electrochemical impedance spectroscopy studies, the PSC assembled with the FAPbI3 light absorber and rGO NFs‐based CE demonstrated an electrical conductivity of 3.64 × 10−4 S cm−1. The fabricated PSC device achieved an efficiency of 8.78% compared to the 7.49% efficiency of the device with a sputtered gold CE. This work uniquely integrates advanced materials, cost‐effective manufacturing, and enhanced efficiency in PSCs using FAPbI3 light absorbers and rGO NFs, addressing key challenges in cost and sustainability in solar technology.

Fabrication of Zinc Oxide Thin Films by Sol-Gel Dip Coating Process

Zinc oxide (ZnO) is a non-toxic material known for its distinctive physical and chemical properties, including a direct band gap energy of 3.37 eV and a large exciton binding energy of 60 meV, which contribute to its significant thermal and chemical stability at room temperature. Due to these characteristics, ZnO plays a critical role in various applications, such as UV light emitters, transparent conducting thin films in electronic devices, gas sensors, piezoelectric materials, transducers, and as a transparent conductive oxide (TCO) layer in thin-film photoelectrochemical cells. Numerous fabrication techniques have been employed to produce ZnO thin films. However, many of these methods require costly equipment, high vacuum environments, and elevated temperatures. In contrast, the sol-gel process stands out as a convenient, cost-effective, and versatile method for ZnO thin film fabrication. It offers advantages such as simplicity, low crystallization temperature, ease of reproducibility, molecular-level homogeneity, and precise compositional control. In this study, ZnO thin films were deposited onto Indium Tin Oxide (ITO) glass substrates using the sol-gel dip coating method, with varying preparative parameters: sol concentrations and annealing temperatures. The resulting samples were characterized using a UV-visible spectrophotometer, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray spectroscopy (EDX). The results demonstrated that the unique properties of ZnO thin films are highly dependent on the preparative parameters. Specifically, the band gap energy decreased from 3.25 eV to 3.18 eV with increasing sol concentration and also showed a similar decline with higher annealing temperatures. XRD patterns revealed a smaller full width at half maximum (FWHM) of the most intense peak (002) at higher sol concentrations and annealing temperatures, indicating an increase in crystallite size. FESEM images highlighted distinct morphological changes corresponding to the variations in sol precursor concentration and annealing temperature, while EDX analysis confirmed the formation of highly pure ZnO thin films on ITO glass substrates.

Effects of Pt doping on surface properties and quenching of band edge emission in ZnO

Pt doped ZnO thin films were synthesized on soda-lime glass substrates using a cost-effective sol-gel method, followed by spin coating and thermal annealing at various temperatures. Several characterization techniques such as UV–Vis absorption spectroscopy, photoluminescence (PL), field emission scanning electron microscopy (FESEM), time-of-flight secondary ion mass spectroscopy (ToF-SIMS), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) are exploited to investigate the Pt doping effects on surface and optical properties of ZnO thin films. UV–Vis analysis demonstrated a slight decrease in the optical band gap from 3.3 eV to 3.2 eV with increased annealing, indicating enhanced suitability for optoelectronic applications. FESEM imaging revealed distinct worm-like structures and small Pt metal nanoparticles in unannealed samples, while thermal treatment supported the formation of spherical Pt nanoparticles and improved conductive pathways in the films. The Wagner diagram, coupled with Auger line transitions from XPS, quantified the oxidation states and chemical environments of Zn and Pt, respectively. Notably, the observed changes in the binding energy of the Zn-2p junction and the kinetic energy of the Zn-LMM Auger junction were significantly influenced by the Pt doping and the electronic properties of the substrate. The Wagner diagram provided a comprehensive visual representation of the parameters, facilitating a deeper understanding of electronic interactions and structural dynamics at the atomic level. XPS results confirmed the presence of ZnO, Zn(OH)2, Pt0 and PtO2 phases, indicating stability and constutient's interactions. ToF-SIMS also validated the uniform distribution of Pt nanoparticles within the ZnO thin film, confirming the effectiveness of the sol-gel method. As a result of Pt doping, PL studies revealed a large quenching effect on band edge emission in the UV and visible emission region of ZnO thin film, which is due to Pt acting as a recombination center for photogenerated carriers. Overall, our results highlight the influence of annealing and Pt incorporation on the optical and structural properties of ZnO thin films and highlight their potential applications for photonics and catalysis.

Effect of Various Carbon Coating Techniques on the Electrochemical Performance of Li4Ti5O12 Synthesized by Sol-Gel Method

This study aimed to prepare spinel carbon-coated Li4Ti5O12 (LTO/C) via sol-gel reaction and applied as a high-performance lithium-ion battery anode. The LTO powder was coated using various carbon sources, super P (SP), sugar and PVDF-assisted SP. The crystal structure, morphology, conductivity and electrochemical performance of the samples were examined using X-ray diffraction (XRD), Field Emission scanning electron microscopy (FESEM), Fourier Transform Infrared (FTIR) spectroscopy, Electrochemical Impedance Spectroscopy (EIS) and Cyclic Voltammetry/Charge-discharge (CV/CD), respectively. The XRD analysis results showed that the samples contain highly crystalline spinel LTO as the main phase and rutile as impurity. The FESEM image showed that SP covers the entire LTO surface more homogenous than sugar. However, sugar carbon makes roughness on the LTO surface. FTIR spectra showed that the coating using sugar and PVDF still contain hydrocarbon element. Electrochemical performance evaluations showed that SP carbon-coated-LTO possesses higher lithium diffusion and specific capacity than pure LTO, while sugar-coated-LTO shows the lowest specific capacity. Moreover, the SP carbon-coated-LTO sample high-rate capability has improved during full cell evaluation, delivering a discharge capacity of 249, 231, 211, 194, 58, and 23 mAhg-1 at the charge or discharge current density of 0.05, 0.1, 0.5, 1, 5, and 10 C, respectively.

Multifunctional 3D-Printed Thermoplastic Polyurethane (TPU)/Multiwalled Carbon Nanotube (MWCNT) Nanocomposites for Thermal Management Applications

In this work, multiwalled carbon nanotubes (MWCNTs) were melt-compounded into a novel thermal energy storage system consisting of a microencapsulated paraffin, with a melting temperature of 6 °C (M6D), dispersed within a flexible thermoplastic polyurethane (TPU) matrix. The resulting materials were then processed via Fused Filament Fabrication (FFF), and their thermo-mechanical properties were comprehensively evaluated. After an optimization of the processing parameters, good adhesion between the polymeric layers was obtained. Field-Emission Scanning Electron Microscopy (FESEM) images of the 3D-printed samples highlighted a uniform distribution of the microcapsules within the polymer matrix, without an evident MWCNT agglomeration. The thermal energy storage/release capability provided by the paraffin microcapsules, evaluated through Differential Scanning Calorimetry (DSC), was slightly lowered by the FFF process but remained at an acceptable level (i.e., >80% with respect to the neat M6D capsules). The novelty of this work lies in the successful integration of MWCNTs and PCMs into a TPU matrix, followed by 3D printing via FFF technology. This approach combines the high thermal conductivity of MWCNTs with the thermal energy storage capabilities of PCMs, creating a multifunctional nanocomposite material with unique thermal management properties.

Anticorrosion and rheological properties of Calyptocarpus vialis extract as a green coating for mild steel in 2MH2SO4

This study assesses the rheological properties and corrosion inhibition efficacy of Calyptocarpus vialis (CV) extract, a wild plant in Asteraceae family. Shear and dynamic rheology studies show that CV extract has shear-thinning behaviour, with viscosity changes occurring at higher shear rates, most likely owing to aggregate formation. These aggregates may develop due to certain solvent characteristics and a jamming tendency is due to the presence of extract phytochemicals. Dynamic rheology confirms its viscoelastic nature. Corrosion inhibition effectiveness was investigated using Mild Steel (MS) in 2 M H2SO4, resulting in an 82.69 % inhibition with an extract concentration of 1 g/L. Adsorption isotherm indicates phytochemical adsorption on MS surface. Contact angles of polished MS (87.30°), with extract (80.10°), and without extract (51.25°) show decrease in wetting and increase in hydrophobicity which indicates that a thin protective layer is formed at MS surface. FE-SEM (Field Emission Scanning Electron Microscopy) images reveal that the CV extract forms a protective barrier on the MS surface, significantly reducing corrosion as compared to the unprotected surface exposed to the mild acid solution. Theoretical calculations, including Density Functional Theory (DFT) simulations, Monte Carlo (MC), and Molecular Dynamics (MD) simulations, support the experimental findings, elucidating phytochemicals adsorption on the MS surface. Further research is required to examine the scalability of CV extracts for industrial applications, as well as their long-term stability and efficacy in various corrosive conditions.

In-situ polymerized boehmite/ cashew gum/ polyvinyl alcohol/ polypyrrole blend nanocomposites with tunable structural, electrical, and mechanical properties for enhanced energy storage applications

This study describes the successful synthesis of boehmite (BHM) nanofiller-reinforced ternary blend nanocomposite films composed of polyvinyl alcohol (PVA), cashew gum (CG), and polypyrrole (PPy) using in-situ polymerization with water as the environmentally friendly solvent. The blend nanocomposites were characterized using Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). FTIR analysis revealed chemical bonding between BHM and the biopolymer matrix at1071 cm-1. FE-SEM images exhibited a uniform distribution of BHM nanofillers within the CG/PVA/PPy matrix, particularly at a 10 wt% concentration. The addition of BHM significantly enhanced the thermal stability and the glass transition temperature of the nanocomposites. The temperature-sensitive AC conductivity, activation energy, and dielectric properties were examined using an impedance analyzer. AC conductivity analysis revealed reduced activation energy (1.277 × 10⁻5 eV at 7 wt% BHM) and increased dielectric constant (from 565.28 to 4411.22). The ternary blend nanocomposite demonstrated a significant 60.2 % increase in tensile strength, reflecting enhanced force resistance, while hardness values ranged from 26 to 30, classifying the films as soft and flexible. Overall, the study highlights significant enhancements in the morphological, electrical, thermal, dielectric, and mechanical properties of the nanocomposite films, emphasizing their promising potential for energy storage applications.

New hybrid organic-inorganic conversion coating applied on the Al2024 substrate: Electrochemical, adhesion and surface study

Health problems caused by chromate conversion coatings promoted new research for discovering environmentally-friendly conversion coatings. In this study, Ti-Zr conversion coating (Ti-Zr) was deposited on the aluminum surface in the presence of nickel sulfate (Ti-Zr-Ni) and adipic acid (Ti-Zr-AA). Polarization and electrochemical impedance spectroscopy (EIS) measurements were employed to evaluate the anti-corrosion properties. Surface analysis was carried out using field emission scanning electron microscope (FE-SEM) and Atomic force microscopy (AFM). The results revealed that the Ti-Zr-Ni treatment inhibited the corrosion progression to a significant degree. The polarization resistance showed a significant increase (Rp= 58835 ohm.cm2) in Ti-Zr-Ni treatment in comparison with Ti-Zr conversion coating (Rp= 4450 ohm.cm2) and Ti-Zr-AA sample (Rp= 15058 ohm.cm2). The presence of Ni in the Ti-Zr composition, not just gave rise to the synergism but also played an important role as catalyst to further help avoiding further material degradation. Moreover, the presence of additives (nickel sulfate and adipic acid) enhanced the anti-corrosion resistance of coating by modification of surface morphology according to FE-SEM and AFM images. Anti-corrosion properties and adhesion strength of samples in a fully coated system were also investigated by EIS and pull-off tests, respectively, which revealed that the delamination of the Ti-Zr-Ni sample was lowest among others, and this sample showed better barrier performance even after 6 weeks of immersion in the corrosive environment.

Mechanochemical synthesis and characterization of poly[(aniline-co-N-(4-sulfophenyl) aniline] nanofibers and its nanocomposite with titanium dioxide nanoparticles and study of their efficiency in hybrid solar cell

The advantages of polyaniline for application in new generation solar cells include its cost-effectiveness, environmentally friendly synthesis, remarkable stability, and the ability to modify the bandgap through the synthesis of its nanocomposites. But a challenge for its nanostructures is the limited solubility in non-toxic solvents, including water, which limits their processability in coating techniques. We overcame this challenge by synthesizing its copolymer with diphenylamine-4-sulfonate and its nanocomposite with titanium dioxide nanoparticles (TiO2NPs). So through a solid-state and template-free technique and using sodium diphenylamine-4-sulfonate, aniline hydrochloride salt, TiO2NPs, and FeCl3∙6 H2O as an oxidant, poly(N-(sulfophenyl)aniline) nanoflowers (PSANFLs), poly [(aniline-co-N-(4-sulfophenyl) aniline] nanofibers (PAPSANFs), poly(N-(sulfophenyl)aniline) nanofibers/titanium dioxide nanoparticles (PSANFs/TiO2NPs), and poly (aniline-co-N-(4-sulfophenyl)aniline nanofibers/titanium dioxide nanoparticles (PAPSANFs/TiO2NPs) were synthesized. Characterization of the synthesized samples was carried out through field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectra, ultraviolet-visible spectra (UV-Vis), cyclic voltammetry (CV), and elemental analysis (CHNS). The FE-SEM images clearly illustrate that the synthesized samples are of nanoscale dimensions. The band gap values of 2.23 eV for PSANFs/TiO2NPs and 1.96 eV for PAPSANFs/TiO2NPs nanocomposites were determined through electrochemical calculations based on cyclic voltammetry curves, showcasing the complementary properties of n and p semiconductors. Using doctor blade method to prepare films from synthesized materials and the architectural pattern of ITO│TiO2NPs│semiconductor sample│Al, all hybrid solar cells are fabricated. The I-V characteristics and power conversion efficiency (PCE) of the samples were examined and discussed. The PCE values for the four samples were found to be in the range of 0.20–0.82 %.

Low magnetic field alignment of carbon fibers in a polymer matrix for high-performance thermal interface materials

Carbon-based materials like carbon nanotubes, graphene nanoplatelets, graphite, and carbon fibers (CF) are highly promising fillers for enhancing the thermal conductivity of thermal interface materials (TIMs) due to their high thermal conductivity and low thermal expansion. Aligning these fillers can further improve thermal conductivity, but current alignment methods using high magnetic fields are impractical for industrial use. In this study, we investigated the enhancement of the thermal conductivity of CF–polymer composites by aligning CF fillers with a low magnetic field. We observed up to 17 times enhancement of the thermal conductivity (from 3.1 to 52.8 W/mK) in a CF–graphene–polymer composite film by vertically aligning the CF fillers with a magnetic field of 0.75 T. The analysis of the structural properties of the films using X-ray diffraction and field-emission scanning electron microscopy imaging confirmed that the crystalline c-axis of the graphite plates in the CF was oriented perpendicular to the magnetic field direction. The large anisotropy in the diamagnetic susceptibility of the laminated graphene structure of the CF flakes is at the origin of the filler alignment. Furthermore, the thermal conductivity of the composites showed a strong correlation with the degree of filler alignment, which was dependent on the CF–graphene hybridization and the type of polymer matrix. This study provides a scalable and cost-effective method for enhancing the physical properties of carbon composites by controlling their microarchitecture using a low magnetic field.

Integration of orange peel derived carbon quantum dots with TiO2 for enhanced photocatalytic degradation of brilliant green dye

Brilliant green (BG) dye is a non-biodegradable, highly venomous and coloured pigment. BG dye possesses remarkably high visibility even at small concentration that causes diarrhea and abdominal pain in humans when being ingested. In addition, it is harmful to living organisms and polluting aquatic environments. Hence, eliminating BG dye from contaminated water is an urgent need. In this report, a photocatalyst encompasses hydrothermally prepared titanium dioxide (TiO2) integrated with orange peel derived oxygenated carbon quantum dots (O-CQDs) was developed for effective removal of BG dye. The O-CQDs were prepared using a single step eco-friendly hydrothermal process and an intense green fluorescence was observed upon exposing the O-CQDs to far UV light irradiation (254 nm). The formation of TiO2/O-CQDs nanohybrid was confirmed through UV–Visible spectrophotometer, X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM) and X-ray photoelectron spectroscopy (XPS) analyses. A random distribution of spherical shaped O-CQDs on the surface of TiO2 was clearly observed in FESEM images. The carboxyl groups present in O-CQDs not only increased interlayer spacing but also led to the attachment of TiO2 effectively. The TiO2/O-CQDs nanohybrid showed 94.70 % efficiency towards photocatalytic degradation of BG dye under UV light irradiation that was ∼20 % higher than the efficiency of pristine TiO2 photocatalyst. The presence of O-CQDs in the TiO2/O-CQDs nanohybrid boosted the photocatalytic degradation efficiency by enhancing UV light absorption and suppressing photo-generated electron–hole recombination. The integration of agricultural waste derived carbon with TiO2 by a facile synthesis method paves a way for large scale synthesis of TiO2/O-CQDs nanohybrid, which is anticipated to broaden its application potential in environmental remediation through photocatalytic degradation of organic compounds.

Influence of Calcination Temperature on the Physicochemical Properties of Synthesized Hydroxyapatite from Cow Bone Waste

The chemical similarity found in hydroxyapatite (HA) with natural bone makes it a popular choice for bone replacement. Therefore, in recent years, there has been an increasing tendency towards manufacturing HA from biological sources or waste, such as animal bone waste. Using naturally derived HA can benefit the economy, the environment, and human health. Therefore, this paper reports on the extraction of HA from cow bone waste using a simple and cost-effective technique. The bone powder was calcined in a furnace at temperatures ranging from 700°C to 1000°C for two hours. Then, the synthesized HA was characterized using a Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-ray Spectroscopy (EDX), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray diffraction (XRD). FESEM images revealed that HA particles with non-uniform spherical morphology were produced where the size increases with the calcination temperature. This finding is consistent with the average value of particle diameter measured at a temperature of 1000°C (0.783±0.268 µm) which is much greater than at a temperature of 700°C (0.272±0.128 µm). EDX analysis revealed that the Ca/P ratio value obtained in this study indicates non-stoichiometric HA production. XRD analysis shows that only the HA phase is present and there is no secondary phase generated from the calcination process. Meanwhile, FTIR analysis can detect the main group elements of the HA which were OH- and PO43-. The findings obtained in this study prove the effectiveness of this method in producing highly crystalline HA powder from cow bone waste using the thermal treatment method.