Papers by Keyword: UV-VIS

Abstract: Dye-sensitized solar cell (DSSC) is a well-known solar cell device because it can convert electrical energy from solar energy. In addition, DSSC has many benefits to offer humankind such as low cost in production, flexibility and eco-friendliness. However, the efficiency provided for DSSC operation is still low compared to the efficiency offered by semiconductor materials. Thus, four different solvents are used to extract natural dye from mangosteen pericarp in order to increase the efficiency in DSSC: pure ethanol, ethanol containing 20 % distilled water, ethanol containing 1 % hydrochloric acid (HCl) and ethanol containing 1 % acetic acid. Other than that, the dyes are examined to observe the optical properties by using Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible spectroscopy (UV-Vis). FTIR analysis resulted in the functional group presence in the dyes while UV-Vis shows that absorption activity exists in the mangosteen pericarp dyes. In addition, the efficiency of mangosteen pericarp dyes with pure ethanol, ethanol containing 20 % distilled water, ethanol containing 1 % hydrochloric acid (HCl) and ethanol containing 1 % acetic acid are calculated which are 0.080 x 10^-3 %, 0.554 x 10^-3 %, 0.126 x 10^-3 % and 0.102 x 10^-3 % respectively.

Abstract: L-asparagine and potassium chloride were used in a 2:1 ratio for the production of L-asparagine-based crystals such as L-asparagine admixture with potassium chloride (LAPC) utilizing deionized water as the solvent. The same process was used to synthesize L-asparagine admixtured with Glycine (LAG). To grow these crystals, the synthesized salts of its were used. The samples' saturated solutions were made separately, stirred vigorously for two hours, and then filtered separately. The solutions went through a slow evaporation process. Powder XRD studies reveals the various peaks present in the crystals. FTIR analysis provides the numerous functional groups connected to the produced crystals. The generated crystals are transmittable, according to studies of the UV-VIS spectrum. The mechanical behavior such the crystals belong to hard or soft category was also discussed.

Abstract: Computational research on the influence of the electron acceptor group position of cyano-3-acetic acid on γ-mangostin as a sensitizer in Dye-Sensitized Solar Cell (DSSC) has been carried out with variations in the positions of the atoms O-1, O-2, O-3 and O- 4. The photoelectric properties are known from the HOMO-LUMO energy parameters, UV-Vis absorption, |VRP|, ΔGinject, ΔGreg, τ, LHE and FEDAM. Geometry optimization uses Orca 4.2.1 with a 6-31G* basis set and interpretation uses Avogadro, Chemissian and GaussSum. Ground state optimization uses the DFT-B3LYP method and excited state optimization uses the TD-DFT-B3LYP method. The results showed that the difference in photoelectric properties affected the DSSC performance. O-2 has the best parameters for electron scattering and UV-Vis light with an absorption of 426 nm. O-3 has the best value for excited state lifetime (τ) and coupling constant (|VRP|). O-3 has a weakness in the LHE value. The LHE value for compounds without modification has the best value. Based on the qualitative parameters of the Full-Electron Donor-Acceptor Map (FEDAM) it was found that the ability of cyano-3-acetic acid as an electron acceptor is better at O-2.

Abstract: In this work, polystyrene/aluminium (PS/Al) nanocomposites were fabricated based on the various concentrations (0, 1, 5, 10, and 15 mg) of Al nanoparticles using the casting method. The resulting polymer/metal nanocomposites have good optical properties. The optical features such as transmittance and absorbance of the as-fabricated nanocomposites were investigated using the UV-Vis spectrophotometer. The effect of constriction of Al nanoparticles was noticed clearly on the transmittance and absorbance of PS/Al nanocomposites. The samples showed high absorption in the UVB range. Photoluminescence spectra (PL) revealed the UVB region of emission peak with the increasing concentration of Al NPs.

Abstract: In this study, silver-silica (Ag/SiO₂) was synthesized using the sol-gel method by silica from rice husks. Silica derived from rice husk waste was previously synthesized using the sol gel method. In addition, the Ag material used in this study was also performed into silver nanoparticles (AgNPs). This method was chosen to obtain an Ag/SiO₂ composite with nano size and high purity. AgNPs were synthesized using silver nitrate (AgNO₃) by reduction method at 90 °C. The reducing agent and stabilizer used is trisodium citrate. UV-Vis, FTIR, XRD, and SEM-EDX were used for the analysis Ag/SiO₂ composites. Uv-Vis analysis results Ag/SiO₂ has an absorption peak at a wavelength of 412 nm with a bandgap energy of 2.25 eV. These peaks indicate that AgNPs have formed in the SiO₂ membrane. The FTIR results revealed the Si-O-Si bonds which indicated the presence of silica and the Ag-O functional group, and the presence of AgNPs. The results of XRD analysis showed that the silica structure formed was cristobalite and silver crystals in the face center cubic (fcc) shape. The results of the SEM-EDX morphological analysis showed that the Ag/SiO₂ nanocomposite was shaped like sharp stone chips and the presence of small granules (granules) with different particle sizes and shapes, slightly porous and the composition of the compounds in the Ag/SiO₂ nanocomposite indicated the presence of various chemical elements in the sample, including carbon, oxygen, sodium, silica, and silver.

Abstract: Silver nano/micro particles have been successfully produced via biosynthesis using sambiloto (Andrographis paniculata) leaves extract as the reductor agent. The obejctive of current was to study the effect of four different AgNO₃ solution concentrations (i.e. 0.0125, 0.025, 0.05, 0.075 M) on the production of silver nano/micro particles via biosynthtesis. The sambiloto extract concentration used in this study was 0.5% w/v. The silver nano/micro particles produced via biosynthesis was characterized using UV-Vis spectrophotometer and Scanning Electron Microscopy (SEM). The UV-Vis analysis results showed that absorbance peaks for all four samples were observed at wavelength around 450 nm, which can be attributed to the presence silver nano/microparticles. The absorbance peak values for all samples were 0.1115; 0.0876; 0.052; 0.0424 for AgNO3 solution concentration of 0.0125; 0.025; 0.05; 0.075 M, respectively. The UV-Vis analysis results could also qualitatively conclude that the size of silver nano/micro particles produced at lower AgNO₃ solution concentration were smaller than the size of silver nano/micro particles produced at higher AgNO3 solution concentration. In the other hand, SEM image showed that the size of silver particles prepared using AgNO₃ solution concentration of 0.075 M was in the range of 5 – 10 μm, hence it can be called silver micro-particles. It was assumed that the size of silver nano/micro particles produced at higher AgNO₃ solution concentration were bigger than the size of silver nano/micro particles produced at lower AgNO₃ solution concentration.

Abstract: Silver nano-colloids have been generated via Laser Ablation Synthesis in Solution (LASiS) system. Nanoparticle formation with particle size below 50 nm in DI water was confirmed using UV-VIS spectroscopy, Dynamic Light Scattering (DLS) technique, and transmission electron microscopy (TEM). Supercapacitor structure, having dimension 11 mm x 10 mm, was successfully Aerosol Jet printed on an untreated polymer substrate using as produced LASiS silver nano-colloid.

Abstract: Polyaniline (PANI) thin films were successfully prepared from an aqueous electrolyte bath containing aniline and sulphuric acid (H₂SO₄) using electrodeposition method. The present study demonstrates that the properties of PANI thin film depends on the variation of pH and aniline concentration in prepared precursor. The optical and structural of PANI thin films were characterized using UV-Visible spectrometer (UV-Vis), X-ray diffraction spectrometer (XRD), Fourier Transform Infra-Red spectrometer (FTIR) and Raman spectrometer. PANI layer grown at pH 2.00 displayed green colour layer which denoted as emeraldine base (half oxidized state of PANI) while at pH 3.80 the colour of PANI layer was yellow representing the leucoemeraldine base (fully reduced state of PANI). Result obtained from FTIR confirmed the footprint of PANI and Raman spectrometer confirmed the half oxidized emeraldine base of PANI. Optical analysis using UV-Vis demonstrated the smallest energy band gap, E_g of PANI is 3.54 eV for sample with 0.50 M aniline concentration and pH 2.00. The trend shows that the bandgap of PANI is increased as the pH increased from 2.00 to 3.80. XRD result showed that all the deposited PANI layers were amorphous. Full characterization of this material is providing some information on PANI behavior due to pH and concentration in the prepared precursor.

Abstract: Generally, chemical fertilizer is considered as a one of the most significant materials for increasing food production. However, the fast release of the conventional fertilizer could effect negatively on the plants. Thus, the idea of using controlled release method in the agriculture application has emerged recently due to the efficiency of fertilizers can be improved by the controlled-release method. The objective of this work is to synthesize a new Slow Release Fertilizer from three different materials; the first one is urea, which is the conventional fertilizer, the second one is the rice husk (RH), which represents the carrier material, and the third one is epoxidized natural rubber (ENR-50), which represents the coating material. This work was divided into three series. The first series is the production of RH/Urea beads. RH was treated with alkaline NaOH at 1wt.% according to the weight of RH. The treated RH was then mixed with urea that produced treated RH/urea beads. In the second series, 200 mg of ENR-50 was applied to produce thicknes of coating material for treated RH/urea beads. In the third series, treated RH/urea beads coated with 200 mg of ENR-50 were subjected to the released behavior at different temperature in the water. After that, the prepared samples were characterized using Scanning Electron Microscopy (SEM) and UV-visible spectroscopy. Results suggested that the increasing of temperature has increased the rate of urea release of SRF samples in the water. Furthermore, the SRF sample at 35, 45, and 55 °C showed shorter time of release at 40, 34, and 17 day as compared to 47 day of SRF at room temperature.

Abstract: Nanostructured zinc oxide (ZnO) were successfully prepared by using phyto assisted solution immersion process. ZnO were grown on a glass substrate coated with ZnO nanoparticle thin-film as seed layer at annealing temperature of 450°C. The fabricated nanostructured ZnO exhibit absorption at ∼375 nm as revealed from the UV-visible absorption spectrum, and it is comparable with ZnO nanostructured synthesized from hexamethylenetetramine (HMTA). X-ray diffraction (XRD) measurement revealed a sharp peak corresponding to the hexagonal wurtzite structure of nanostructured ZnO. Field emission scanning electron microscopy (FESEM) showed average size of ZnO at 24.15 nm slightly smaller compared to synthesized from HMTA; 30.54 nm. It should also be highlighted that the needs of using this alternative green method are due to the advantages of low working temperature and cost-effective, and with the least possible damage to the environment.