Showing papers on "Fourier transform infrared spectroscopy published in 2020"

Tunable and Ultraefficient Microwave Absorption Properties of Trace N-Doped Two-Dimensional Carbon-Based Nanocomposites Loaded with Multi-Rare Earth Oxides

Abstract: A high efficiency and great tunability of bandwidth and absorption-range electromagnetic wave absorber is proposed without precedent. A series of 2D carbon-based nanocomposites with the loading of cerium oxide (CN-Ce) and other types of rare earth oxides (CN-REOs) can be successfully synthesized by a simple solvothermal-sintering method. As-synthesized 2D nanocomposites with local graphite-like C3 N4 structure and trace N-doped are identified by transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy. The CN-REOs and polyvinylidene fluoride composite absorbers with reflection loss values above -40 dB are obtained in C-band, X-band, and Ku-band, respectively. The empirical rules on effective bandwidth and frequency range are discovered and summarized, which can be successfully realized by simply tuning the doping amount or type of REO. The mechanism is explained by enhanced attenuation and tunable impedance matching. In addition co-filled samples by two types of CN-REOs nanocomposites are prepared to support these findings and inspire the preparation of absorber with desirable frequency band in the range of 2-18 GHz.

Biogenic synthesis of iron oxide nanorods using Moringa oleifera leaf extract for antibacterial applications

Abstract: Biogenic synthesis of iron oxide nanorods (FeO-NRs) from FeCl3 capped with Moringa oleifera (MO) has been developed in this work. The facile, cost effective, and eco-friendly FeO-NRs formulated were characterized using various techniques. The change in the visible color which leads to the formulation of FeO-NRs was confirmed by the UV–visible spectroscopy analysis. The crystallinity of FeO-NRs was observed in the X-ray diffraction spectroscopy pattern indexed to the spinel cubic lattice in the tetrahedral hematite structure. A rod-like morphology of FeO-NRs with the average particle size of 15.01 ± 6.03 nm was determined by the scanning and transmission electron microscopies. Fourier transform infrared spectroscopy analysis shows the various functional groups in the formulatedFeO-NRs. Vibrating sample magnetometer shows that the formulated FeO-NRs are superparamagnetic with good saturation magnetization. The formulated FeO-NRs inhibit the growth of six human pathogens with a higher activity at lower concentrations. It is noteworthy that the bacterial strains show strong and effective susceptibility to the formulated FeO-NRs at lower concentrations compared to the conventional antibacterial drugs. Hence, the formulated FeO-NRs proved to be a good, efficient, and promising antibacterial agent due to its cost-effectiveness, non-toxicity, and facile synthesis procedures in therapeutic biomedical fields.

Green-Synthesized Rice-Shaped Copper Oxide Nanoparticles Using Caesalpinia bonducella Seed Extract and Their Applications.

Abstract: Copper oxide nanoparticles (CuO Nps) were synthesized using Caesalpinia bonducella seed extract via a green synthetic pathway and were evaluated for electrocatalytic properties by carrying out electrochemical detection of riboflavin [vitamin B2 (VB2)]. The seeds of C. bonducella are known to have strong antioxidant properties arising due to the presence of various components, including citrulline, phytosterinin, β-carotene, and flavonoids, which serve as reducing, stabilizing, and capping agents. The synthesized CuO Nps were characterized using UV-visible spectroscopy, Fourier transform infrared spectroscopy, thermogravimetrc analysis-differential thermal analysis, X-ray diffraction spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy and further used as a modifier for a graphite electrode surface. The modified electrode was electrochemically characterized by cyclic voltammetry, square-wave voltammetry, and chronoamperometry techniques and then assessed for electrocatalysis by carrying out the detection of VB2. The electrochemical sensor could be used for nanomolar detection of VB2 with an observed linear range of 3.13-56.3 nM with a limit of detection of 1.04 nM. The electrode showed good stability and reproducibility over a period of 120 days. The CuO Nps were further analyzed for antibacterial effect with Gram-positive and Gram-negative bacteria, and in both cases, high antibacterial activity was clearly observed. The newly synthesized nanoparticles, thus, proved to be an interesting material for electrochemical and biological studies.

Green synthesis of zinc oxide nanoparticles from the leaf, stem and in vitro grown callus of Mussaenda frondosa L.: characterization and their applications

Abstract: Biosynthesis of zinc oxide nanoparticles (ZnO-NPs) was achieved by utilizing the reducing and capping potential of leaf, stem and callus aqueous extracts of Mussaenda frondosa.The bioreduced ZnO-NPs were characterized using powder X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–Vis spectroscopy), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), fourier transform infrared spectroscopy (FTIR) and dynamic light scattering (DLS) techniques. UV–visible spectra of ZnO-NPs showed a strong absorption peak at 370, 376 and 373 nm corresponding to the band gap energy of 3.33, 3.27 and 3.30 eV for ZnO-NPs obtained from leaf (L-ZnO-NP), stem (S-ZnO-NP) and callus (C-ZnO-NP) aqueous extracts, respectively. XRD analysis confirmed the formation of hexagonal wurtzite structures having an average grain size between 5 and 20 nm in diameter. FTIR spectra revealed the presence of stretching vibrations of –O–H, C–H, C–N, C = O groups involved in reduction and stabilization of nanoparticles. SEM images recognize the presence of spongy, spherical, porous agglomerated nanoparticles. DLS analysis and zeta potential values validated the stability of ZnO-NPs. The present investigation puts light on the photocatalytic activity and biological (antioxidant, anti-inflammatory, antidiabetic, antimicrobial, anticancerous) applications of ZnO-NPs. The current study is an attempt to describe an effective, simple and eco-friendly method of ZnO-NP synthesis and to evaluate its potential for various industrial and medical applications.

Synthesis, characterization and photocatalytic dye degradation capability of Calliandra haematocephala-mediated zinc oxide nanoflowers.

Abstract: An environmentally sound approach towards the green synthesis of zinc oxide nanostructures has been achieved with an aqueous extract of Calliandra haematocephala leaves. The nanoparticles were characterized using various analytical techniques to substantiate the structural details. An absorption band at 358 nm corresponds to the formation of zinc oxide nanoparticles. Scanning electron microscopy revealed the nanoflower morphology of the nanoparticles. Energy dispersive spectral analysis portrayed the strong presence of zinc and oxygen, while X-ray diffraction showed the nanoparticles to conform to hexagonally-formed wurtzite structure. The crystallite size of the nanoflowers was estimated to be 19.45 nm. Vibrational frequencies, typical of zinc‑oxygen and other functional groups, were revealed using Fourier transform infrared spectroscopy. BET analysis revealed that the pores were of mesoporous nature with an estimated specific surface area of 9.18 m2/g. The photocatalytic nature of the nanoparticles was established by the degradation of methylene blue (MB) dye, under solar radiation. Up to 88% degradation was achieved in a duration of 270 min. Kinetic data from the studies proved that the reaction was compliant with first-order model, with rate constant as 0.01 min−1. The study illustrated the synthesis of zinc oxide nanoparticles using a novel source, viz., the leaves of C. haematocephala.

Magnetic and spectroscopic properties of Ni–Zn–Al ferrite spinel: from the nanoscale to microscale

Abstract: This article presents the annealing effect on the structural, elastic, thermodynamic, optical, magnetic, and electric properties of Ni0.6Zn0.4Fe1.5Al0.5O4 (NZFAO) nanoparticles (NPs). The samples were successfully synthesized by the sol–gel method followed by annealing of the as-synthesized at 600, 800, 900, 1050, and 1200 °C. This approach yielded the formation of a highly crystalline structure with crystallite size ranging from 17 nm to 40 nm. X-ray diffraction (XRD), scanning electron microscopy (SEM) techniques, as well as energy disperse spectroscopy (EDS), Fourier transform infrared (FTIR) and Raman spectroscopy, were used in order to determine the structural and morphological properties of the prepared samples. Rietveld XRD refinement reveals that Ni–Zn–Al ferrite nanoparticles crystallize in inverse cubic (Fdm) spinel structure. Using FTIR spectra, the elastic and thermodynamic properties were estimated. It was observed that the particle size had a pronounced effect on elastic and thermodynamic properties. Magnetic measurements were performed up to 700 K. The prepared ferrite samples present the highest Curie temperature, which decreases with increasing particle size and which is consistent with finite-size scaling. The thickness of the surface shell of about 1 nm was estimated from size-dependent magnetization measurements using the core–shell model. Besides, spin resonance, magnetostriction, temperature coefficient of resistance (TCR), and electrical resistivity properties have been scientifically studied and appear to be different according to their size. The optical properties of synthesized NZFAO nanoparticles were investigated, and the differences caused by the particle sizes are discussed on the basis of the phonon confinement effect. This effect was also inspected by the Raman analysis. Tuning of the physical properties suggests that the Ni–Zn–Al ferrite samples may be promising for multifunctional diverse applications.

Microstructure, optical and photocatalytic properties of MgO nanoparticles

Abstract: The present work is focused on the synthesize of MgO nanoparticles using combustion method. The magnesium nitrate is used as a precursor with urea as a fuel. The precursor material is dissolved in 50 ml DI water along with the fuel and the solution is heated at 80 °C for 2 h. Then, the solution is transferred to crucible and kept it in the temperature of 500 °C. The as-synthesized MgO nanopowders are analyzed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), photoluminescence (PL) and photocatalytic studies. The XRD results of MgO nanoparticles indicated the cubic structure with the crystallite size of 27 nm. The FESEM studies indicated the formation of MgO crystallites in spherical shape. In addition, MgO nanoparticles are porous and agglomerated. PL spectrum of MgO materials exhibit emission peaks, which indicates the occurrence of band to band transition with the bandgap of 2.9 eV. The photocatalytic degradation of methylene blue dye is evaluated using the as-prepared MgO nanoparticles under UV light. The photocatalytic studies indicate the 75% degradation efficiency of the catalyst after 120 min irradiation. Hence, the MgO Nanoparticles (NPs) can be used for the treatment of effluents from the dye industries.

Cobalt-Based MOF-on-MOF Two-Dimensional Heterojunction Nanostructures for Enhanced Oxygen Evolution Reaction Electrocatalytic Activity.

Abstract: Two-dimensional (2D) Co-based MOF-on-MOF heterojunction nanostructures with improved electrocatalytic activity were successfully constructed via a mild two-step solution route, employing Co2+ ions as the center atoms, and 1,4-benzenedicarboxylate (BDC) and 4,4'-biphenyldicarboxylate (BPDC) as ligands. The as-obtained heterojunction nanostructures were characterized by field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Brunauer-Emmett-Teller (BET) surface area analysis, thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS) technologies. Electrochemical measurements showed that as-prepared Co-BPDC/Co-BDC heterojunction nanostructures presented markedly enhanced OER electrocatalytic activity, compared with single Co-BPDC, Co-BDC, and/or their physical mixture. Also, the Co-BPDC/Co-BDC-3 heterojunction prepared after treatment for 3 h exhibited the strongest catalytic activity. To reach the current density jgeo = 10 mA cm-2, the Co-BPDC/Co-BDC-3 heterojunction-modified glassy carbon electrode required an overpotential of 335 mV in 1 M KOH, which was reduced by 57 and 93 mV, compared to the electrodes modified by Co-BDC and Co-BPDC, respectively. Simultaneously, the heterojunction catalyst also displayed better long-term stability. The improvement of the above performances should be attributed to the increased structure stability, BET surface area, ECSA, and electron transfer ability of the heterojunction.

Hydrothermal Synthesis of Silver Decorated Reduced Graphene Oxide (rGO) Nanoflakes with Effective Photocatalytic Activity for Wastewater Treatment

Abstract: Graphene oxide (GO) was obtained through modified hummers method, and reduced graphene oxide (rGO) was acquired by employing heat treatment. Various concentrations (2.5, 5, 7.5, and 10 wt. %) of silver (Ag) were incorporated in GO nanosheets by adopting hydrothermal approach. Synthesized Ag decorated rGO photocatalyst Ag/rGO was characterized using X-ray diffraction (XRD) to determine phase purity and crystal structure. XRD patterns showed the formation of GO to Ag/rGO. Molecular vibration and functional groups were determined through Fourier Transform Infrared spectroscopy (FTIR). Optical properties and a decrease in bandgap with insertion of Ag were confirmed with UV-Visible (Uv-Vis) spectrophotometer and photoluminescence (PL). Electronic properties and disorders in carbon structures were investigated through Raman spectroscopy that revealed the existence of characteristic bands (D and G). Surface morphology of prepared samples was examined with field emission scanning electron microscope (FESEM). Homogeneous distribution, size, and spherical shape of Ag NPs over rGO sheets were further confirmed with the help of high-resolution transmission electron microscope (HR-TEM). Dye degradation of doped and undoped samples was examined through Uv-Vis spectra. Experimental results indicated that photocatalytic activity of Ag@rGO enhanced with increased doping ratio owing to diminished electron-hole pair recombination. Therefore, it is suggested that Ag@rGO can be used as a beneficial and superior photocatalyst to clean environment and wastewater.

Elaboration of novel polyaniline@Almond shell biocomposite for effective removal of hexavalent chromium ions and Orange G dye from aqueous solutions

Abstract: A novel polyaniline@Almond shell (PANI@AS) biocomposite was synthesized via facile in situ chemical polymerization method. The as-synthesized adsorbent was characterized using various analytical techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), and potentiometric titration. A batch adsorption system was applied with the aim of investigating as-synthesized adsorbent ability to remove Cr(VI) ions and Orange G (OG) textile dye from aqueous solutions. Obtained results revealed that adsorption process was strongly depended upon the physicochemical parameters. The adsorption of Cr(VI) and OG dye onto PANI@AS was better described by the pseudo second-order-kinetic model and followed the Freundlich isotherm model. The maximum uptakes were 335.25 for Cr(VI) and 190.98 mg g−1 for OG dye. We further evaluated that PANI@AS biocomposite could be regenerated easily with NaOH solution and efficiently reused for Cr(VI) and OG dye removal from aqueous media. Thus, these results indicated the potential practical application of PANI@AS biocomposite for wastewater treatment.

Highly efficient g-C3N4/Cr-ZnO nanocomposites with superior photocatalytic and antibacterial activity

Abstract: Currently, fabricating a narrow bandgap photocatalyst that can degrade pollutants in natural sunlight is critical but inspiring. In this study, a hybrid g-C3N4/Cr-ZnO nanocomposite was synthesized by a simple chemical co-precipitation method and its photocatalytic and antimicrobial properties were explored. In the first step, the photocatalytic efficiency of Cr-ZnO (1−9 wt. %) nanoparticles were carried out to find out the optimum doping of Cr into ZnO. The as-prepared 5% Cr-ZnO nanoparticles demonstrated the best optical absorption of sunlight and methylene blue degradation and in the second step; these were dispersed on g-C3N4 nanosheets as an active component to form ternary heterostructured photocatalyst. The nanoparticles and composite photocatalysts were characterized by X-ray diffraction spectroscopy, energy-disperse X-ray spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and ultraviolet-visible spectroscopy. The optimized composite (60 %g-C3N4/5%Cr-ZnO) performed enhanced harvesting of solar energy compared to ZnO, g-C3N4 and g-C3N4/ZnO composite, achieving 93 % methylene blue dye degradation in 90 min. The improved photocatalytic activity of composite can be attributed to the better absorption and electron-hole pair separation between g-C3N4 and Cr-ZnO. The photocatalytic stability of the composite was testified by cyclic tests. The antibacterial aptitude of the samples was investigated against Gram-negative (Escherichia coli) and Gram-positive (Bacillus subtilis, Staphylococcus aureus and Streptococcus salivarius) bacteria applying diffusion well method. The 60 %g-C3N4/5%Cr-ZnO nanocomposite exhibits higher antibacterial activity compared to other samples. The enriched photocatalytic and antimicrobial activities of the composite may be predominantly ascribed to the synergistic effect of the heterojunction developed between g-C3N4 and Cr-ZnO.

Experimental and molecular dynamics study on dye removal from water by a graphene oxide-copper-metal organic framework nanocomposite

Abstract: In this study, a novel copper-based metal-organic framework (Cu-MOF), immobilized on graphene oxide (GO), was fabricated via ultrasonication method. The synthesized GO-Cu-MOF was used as an adsorbent, and the kinetics data for the removal of dye molecules investigated along with the molecular dynamics simulations. Various parameters such as solution temperatures and pH, dye, and adsorbent concentrations were studied to evaluate the performance of the adsorbent in removing a model contaminant based on the real-world water treatment conditions. The synthesized adsorbent was characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Ultraviolet-visible spectroscopy (UV–vis), Brunauer–Emmett–Teller (BET) analysis, and Zeta Potential. The characterization results showed full exfoliation of GO in Cu-MOF. The adsorption kinetic results followed the rapid adsorption process with a pseudo-second-order characteristic. The GO-Cu-MOF exhibited higher adsorption capacity of 173, 251, and 262 mg/g at 25 °C, 45 °C and 65 °C compared to 106, 117 and 142 mg/g adsorption capacity of Cu-MOF at the same temperature. The dye removal experiments suggest that the acidic condition and the higher temperature (65 °C) favors the adsorption of Methylene blue (MB) on GO-Cu-MOF compound. The molecular dynamics simulation performed to calculate the adsorption energy for Cu-MOF and GO-Cu-MOF. The calculated adsorption energy of -323 (kCal/mol), and -119 (kCal/mol) for GO-Cu-MOF and Cu-MOF was in agreement with the experimental data.

FTIR, Raman and XRD analysis of graphene oxide films prepared by modified Hummers method

Abstract: Graphene oxide (GO) is a promising material for energy storage device applications. Modified Hummers method (MHM) has been used to prepare GO films from graphite flakes by Sol-Gel method. With the aid of bridging agent dimethyldichlorosiline, structurally fine GO films were prepared. Fourier transform and infra-red (FTIR) spectrum of the GO thin film possesses absorption bands at 461, 594, 670, 803, 1020, 1243, 1457, 1544, 1627, 2850, 2926 and 3429 cm−1. A sharp OH− absorption band was revealed at 3429 cm−1. Two vibrational bands were noticed in the Raman spectrum for pure graphite flakes at 1578 and 2718 cm−1. However, for GO, five Raman vibrational bands were unveiled at 413, 1344, 1597, 2697 and 2945 cm−1. Among these bands, the mode at 1344 cm−1 was assigned to D-band and 1597 cm−1 was assigned to G-band. Compared to D-band, G-band was dominated for the GO films. Several times of centrifugation and ultra-sonication process have aided to obtain more intensity of G-band. In addition, 2D and D + G bands were also revealed in the GO films. X-ray diffraction (XRD) analysis was confirmed that a sharp peak at 10.64 degrees leads to the formation of GO thin film.