Papers by Keyword: UV-VIS Spectroscopy

Abstract: This paper presents an in-depth spectroscopic analysis of Al₂O₃-40%TiO₂ coatings deposited via HVOF thermal spraying on a 10CrMo9.10 heat-resistant steel substrate. The study aims to correlate the optoelectronic and structural properties of the coatings with their composition and microstructure. Spectroscopic investigations revealed intense absorption in the visible (VIS) region due to electronic transitions from the valence band to the conduction band of the ceramic materials and high reflectivity in the ultraviolet (UV) region. These properties make the coatings particularly useful for protective systems in solar thermal power plants. The detailed characterization of the optical properties of the Al₂O₃-40%TiO₂ coatings obtained through HVOF technology was made possible by corroborating spectroscopic results. These insights are essential for understanding the mechanisms that govern the performance of these coatings in protective applications under high temperatures and aggressive environments.

Abstract: In this work, the co-precipitation method is used for the synthesis of copper sulfide (CuS) nanoparticles for use in solar cells. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDX), UV-Visible spectroscopy (UV-Vis), photoluminescence spectroscopy (PL), and Fourier transform infrared spectroscopy (FTIR) are used to analyse the synthesized CuS nanoparticles. CuS nanoparticles with hexagonal phases and crystallite sizes ranging from 19 nm to 24 nm are identified by X-ray. The morphology of the SEM images changes from being asymmetrical to spherical. UV-Vis spectroscopy was carried out for the optical analysis of the synthesized powder. The band gap of the samples is determined using a tauc plot, and it is found to be decreasing with an increase in sulfur concentration, going from 2.01 eV to 1.88 eV. Surface imperfections and green emission bands related to electro-hole recombination are visible in PL spectra. Cu-S stretching vibrations are present at 618 cm^-1, according to FTIR spectra.

Abstract: Tris [4-(diethylamino) phenyl] amine (TDAPA) is an organic molecular semiconductor generally used to enhance the charge transport of the devices for some time now. TDAPA is dissolved in various Polar and Non-polar solvents like DMF, Acetone, Acetonitrile, Ethanol, Methanol, Toluene and Chloroform. Absorption spectrum of solution is recorded using UV-Vis spectroscopy and absorption peak for different solvents were observed in UV and Near-UV region. PL study and Pl Excitation study is also carried out for these solvents. Results for absorption and photoluminescence show some interesting phenomenon of Stokes’ shift. The colour coordinates for respective emission are represented by CIE 1931. The study is successfully carried out for better understanding of effect of these solvents on the optical properties of TDAPA.

Abstract: Silver nanoparticles were synthesized using locally purchased honey and silver nitrate solution. This method provides a simplistic and straightforward approach to the formation of silver nanoparticles. The silver nanoparticles with varying amounts of silver nitrate solution were characterized using ultraviolet-visible spectroscopy and Fourier transform infrared spectroscopy. In addition, dynamic light scattering characterization was used to determine the average size and size distribution of silver nanoparticles. Experimental results revealed that varying the amount of silver nitrate solution can control the size and absorption spectra of silver nanoparticles. A large amount of silver nitrate solution will exhibit a peak in the higher wavelength. The shifting of the absorption peaks at 401, 406, 407, 408, and 409 nm are believed to be related to the wavelength of the surface plasmon resonance. Moreover, a larger amount of silver nitrate solution also results in an increasing size with 27.2, 57.9, and 63.4 nm as revealed in the size distribution via dynamic light scattering. This green synthesis method of silver nanoparticles will provide a cost-effective production as an alternative to commercial antibacterial agents.

Abstract: Thin film of cobalt ferrite has been deposited on glass substrate by a chemical spray pyrolysis technique using methanol solutions at 400^◦C substrate temperature. The uniformly deposited thin film were annealed at 500 ^◦C and studied their structural, infrared and optical properties using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and UV-Vis spectroscopy (UV-Vis), respectively. The X-ray diffraction patterns revealed single phase cubic spinel structure with space group Fd-3m. The fundamental absorption bands related to octahedral and tetrahedral sites were confirmed by Fourier-transform infrared spectroscopy (FTIR) spectrum.The formation of cubic spinel crystal structure of the CoFe₂O₄ thin filmwere confirmed from exhibited strong absorption peaks around 530.21 and 451.48 cm⁻¹ by FT-IR spectra.The optical properties of the deposited thin film were studied by an absorbance spectrum found at 315 nm. The value of energy bandgap (2.4 eV) wasinvestigated by Tauc plot.The obtained results indicate the fabricated thin film is promising material for various applications.

Abstract: Reduced Graphene Oxide (rGO) is a promising material as an active electrodes material for supercapacitors. However, in its application, rGO can only store electrostatic charges so there is no electron transfer between surface of the electrode and electrolyte. In order to improve electrode performance, rGO can be composite with conductive polymers such Polyaniline (PANi). It was reported that rGO-PANi composite can increase conductivity of rGO and support pseudocapacitance of the material so the electron transfer can be carried out actively through reduction-oxidation (redox) reactions. In this work we study preparation of rGO-PANI composite using UV oven spraying method. Thin layers of rGO-PANi composite were prepared from mixture of 0.5 mg/ml GO dispersion (Graphenia) and PANi-HCl solution with a ratio of 1:1. PANi-HCl solution were prepared from PANi Emeraldine Base and 1 M HCl with mole ratio of 1:2. The samples were spray coated onto quartz substrates under photo-irradiation using UV Oven Spraying apparatus. In order to obtain a proper thickness for electrode application we varied deposition repetition. The optical characteristics of the rGO-PANi composites were measured using UV-Vis Spectroscopy. The results were compared with the optical spectra of rGO and PANi, respectively. Acknowledgement This work was funded by Hibah Kemenristek Dikti Indonesia, contract no: 1827/UN6.3.1/LT/2020 date 12 May 2020.

Abstract: Anatase/brookite nanocomposites were fabricated by the classical method of hydrolysis, additionally using hydrothermal treatment of preformed titanium dioxide sol with tetrabutyl orthotitanate. The influence of hydrothermal processing the buffer solution of TiO₂ synthesis on the average particle sizes, specific surface area, pore sizes distributions, optical and photocatalytic properties investigated by X-ray diffraction, low-temperature nitrogen adsorption and UV-Vis spectroscopy. It has been determined that the hydrothermal treatment of pre-prepared titania sol as hydrolysis product leads to rutile formation after annealing at 400°C. Respective model of forming anatase/brookite/rutile nanocomposites was proposed. The changes of bang gap energy of TiO₂ were observed and explained by effect of change phase composition and particles size of nanocomposite particles. Methylene blue (MB) photo-oxidation reactions using titanium dioxide nanocomposite were analyzed. Maximal photocatalytic activity of MB oxidation was detected for material with the ratio of the titania phases (anatase : brookite : rutile – 2 : 2 : 1). Synergistic effect between crystallinity, phase ratio, morphology of oxide material, band gap and photocatalytic activity in the anatase/brookite nanocomposites was established.

Abstract: In this study, we report structural, morphological and optical properties of Fe-doped SnO₂ thin layers. Fe doping concentration has evaluated from 0 to 0.6 wt.%. XRD and SEM results revealed a polycrystalline structure for Fe-doped SnO₂ thin layers. The optical transmittance of all thin layers displayed high transparency reach to 80% in the visible region. The optical gap of these layers decreases from 3.87 to 3.58 eV. The grain sizes decrease from 35 to 30 nm. The electrical resistivity of layers increases from 1.2×10^-2 to 6.8×10^-2 Ω.cm.

Abstract: The flexibility in replacing the organic part of the organic-inorganic hybrid material has become an interesting material parameter to tune the functionality of their inorganic part. Based on the optical absorption in the UV-VIS region, we are able to observe the d-d transition of the Mn²⁺ in (C₆H₅CH₂CH₂NH₃)₂-MnCl₄, and (NH₂CH₂CH₂NH₂)₂-MnCl₄ hybrid compounds. The results of this the experiment clearly indicate that there are six transitions related to the d-d transition of the Mn²⁺ from the high spin state, ⁶S, to the excited states of ⁴G, ⁴D and ⁴P. The transition energies are fitted to the Tanabe-Sugano diagram. The different in organic part change its Racah parameters and crystal field energy. This shows that the organic part could modify the bond strength between the Mn and the Cl as well as the electronic interaction.

Abstract: This work reported the influence of seaweed (Sargassum crassifolium) extract on the absorption of magnetic iron oxide nanoparticles (MIONPs) via green synthesis route. The seaweed extract acted as reducing and capping agent. Ultraviolet-visible (UV-Vis) spectra revealed the presence of sharp peaks at around 366 nm to 371 nm which corresponds to the absorption spectra of MIONPs. The absorption peaks corresponding to MIONPs was significantly affected by the varying amount of seaweed extract. On the other hand, Fourier Transform-Infrared (FTIR) spectra revealed the presence of the vibration mode around 532 cm^-1 to 551 cm^-1 which corresponds to Fe-O bands suggesting the successful formation of MIONPs. Thermogravimetric (TGA) spectra showed that the produced MIONPs stabilizes at 400 °C. The synthesized MIONPs are spherical in shape with an estimated average diameter of 20 nm as revealed by the Field Emission Scanning Electron Microscopy (FESEM). Finally, the produced MIONPs exhibit magnetic property via attraction with an external magnet. This straight forward green synthesis of MIONPs can be a good route for possible industrial and environmental application.