Iis Nurhasanah

Ag Doped ZnO Thin Films Synthesized by Spray Coating Technique for Methylene Blue Photodegradation under UV Irradiation

Silver (Ag) substituted ZnO thin films were successfully deposited onto glass substrates by spray coating technique. Structure, morphology, and optical properties were evaluated by X-ray diffractometer (XRD), scanning electron microscopy (SEM), and UV-Vis spectrophotometer, respectively. XRD spectra had polycrystalline wurtzite structure; SEM images showed that thin films had different surface morphology at different Ag doping concentration. From transmittance spectra, thin films transparency decreased as well as band gap energy along with increase of Ag doping concentration. Methylene blue (MB) solution was used as a pollutant in the photodegradation studies. Under UV light irradiation, the optimal Ag doping is 25%, with 83% of the decolorizing efficiencies after 3 h irradiation time and apparent constant () about 9.69 × 10−3 min−1.

Deposition of Ag 2~6 mol%-Doped ZnO Photocatalyst Thin Films by Thermal Spray Coating Method for E.coli Bacteria Degradation

ZnO doped with 2~6 mol% Silver (Ag) photocatalyst thin films has been deposited on glass substrate by thermal spray coating with temperature deposition of 250°C. A gel of ZnO:Ag precursor has been synthesized by sol-gel route from aqueous/alcoholic solution of zinc acetate dehydrate and silver nitrate mixture at room temperature. The morphology of ZnO:Ag films were investigated scanning electron microscopy (SEM). 3D SEM images of ZnO:Ag thin films show the rough morphology with roughness mean square (rms) of 150 to 195 nm. The grain size of ZnO:Ag films were found in the range 76,5 to 304,8 nm. The photoactivity examination of ZnO:Ag photocatalyst films show the E. Coli bacteria degraded up to 99.99% under sunlight irradiation for 4 hours.

Synthesis and characterization of ZnO:TiO2 nano composites thin films deposited on glass substrate by sol-gel spray coating technique

In this work, (ZnO)x:(TiO2)1-x nano composites thin films, with x = 1, 0.75, 0.5, 0.25, and 0, have been prepared by sol–gel spray coating technique onto glass substrate. Pure TiO2 and ZnO thin films were synthesized from titanium isopropoxide-based and zinc acetate-based precursor solutions, respectively, whereas the composite films were obtained from the mixture of these solutions at the specific % vol ratios. The properties and performance of nano composite ZnO, TiO2 and ZnO:TiO2 thin films at different composition have been investigated. Ultraviolet – Visible (UV-Vis) Spectrophotometer and Scanning Electron Microscopy (SEM) were employed in order to get morphology and transmittance of thin films. Testing the ability of photocatalytic activity of obtained films was conducted on photodegradation of methylene blue (MB) dye and organic pollutants of wastewater under a 30 watt UV light irradiation, then testing BOD, COD and TPC were conducted. Using the Tauc model, the band-gap energy decreased from 3.12 e...

The Physical and Photocatalytic Properties of N-Doped TiO2 Polycrystalline Synthesized by a Single Step Sonochemical Method at Room Temperature

Titanium dioxide (TiO2) is one of popular semiconductor materials that usually used for photocatalytic application. Recent studies show the improvement of TiO2 photocatalytic activity through nitrogen doping (N-doped TiO2). In this study, we focused on the synthesis and characterization of N-doped TiO2. Ultrasonic assisted synthesis or sonochemical method was used to prepare N-doped TiO2 polycrystalline powder under room temperature. X-ray diffractometer (XRD), and diffuse reflectance ultraviolet-visible spectrophotometer (DR-UV) were employed to evaluate physical properties of N-doped TiO2. XRD pattern exhibited that all samples have anatase crystalline phase and crystallite size decrease with increase of N dopant concentration. The absorbance spectra showed the slight shift toward higher wavelength (red shift) and from Kubelka-Munk function the band gaps were getting smaller with increase of N content. The increase of photocatalytic activity under solar radiation was achieved by N-doped TiO2 samples with highest efficiency about 81 % for 5% of N doping concentration.

Optical Properties of Zn-Doped CeO2 Nanoparticles as a Function of Zn Content

CeO2 and Zn-doped CeO2 nanoparticles were synthesized by simple precipitation method in water/isopropanol mixed solvent from cerium nitrate and zinc nitrate with various mole ratios. The precipitates were then calcined at 300°C for 4 hours and characterized by X-ray diffraction (XRD) and uv-vis spectroscopy. Characterization by x-ray diffraction shows that high crystallinity of cubic fluorite structure of CeO2 with crystallite size in the range 6 12 nm depending on Zn content. CeO2 nanoparticles exhibits tranparent in the visible region and strong absorbance in the ultra-violet region. It was also found that significant effect of Zn content on transmittance and optical band gap. In addition, Zn substitution into Ce suppressing photocatalytic activity of pure CeO2 nanoparticle under sunlight irradiation. These results suggest that Zn-doped CeO2 nanoparticle is more prommising for safer optical UV-absorbers.

Optical and microstructure of thin film of Ag-doped ZnO synthesized by sol-gel

One of semiconductor materials that can be used as a photocatalyst is zinc oxide (ZnO). Many studies show that the addition of silver content (Ag) to ZnO solid can increase the photocatalytic activity. In this study, we developed Ag-doped ZnO thin film on a glass substrate, which was prepared by sol-gel spray coating method. The structure, morphology, and optical properties were studied by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and UV-Vis spectrophotometer, respectively. The XRD data showed that all thin films had a strong preferred orientation toward the c-axis. The SEM images indicated that the presence of Ag affects the morphology of thin film. The transmittance spectra exhibited that Ag addition slightly shifted the band edge toward the visible light region. Transparency of Ag-doped ZnO increased and showed fringes on its spectra.

UV-Light Absorption and Photocatalytic Properties of Zn-Doped CeO2 Nanopowders Prepared by Ultrasound Irradiation

Ceria (CeO2) nanopowders doped with various Zinc (Zn) compositions were synthesized from solution by irradiating ultrasound waves. Ultrasound waves were irradiated to aqueous/isopropanol solution of cerium nitrate and zinc nitrate mixtures. Aqueous solution of ammonium hydroxide was droped into that solution until pH becomes 10. Dried precipitates were calcinated at 100°C to form CeO2 nanopowders. X-ray Diffraction (XRD) analysis shows the CeO2 nanopowder possess fluorite cubic structure. Ultrasound irradiation resulted in nanometric powder of CeO2 with spherical in shape. The addition of Zn into CeO2 reduces the particle size and shows strong absorbance in the ultra–violet (UV) region. Moreover, the addition of 20 mol% Zn is inhibiting photocatalytic activity of CeO2 under sunlight irradiation. These results suggest that Zn-doped CeO2 is more promising for UV radiation protection with no presence photocatalytic activity.

Growth and UV Absorption of 5 mol% Zn-Doped CeO2 Nanoparticle Synthesized with a Simple Precipitation Process

Nanoparticles of the 5 mol% Zn-doped CeO2 have been synthesized by simple precipitation process from aqueous/alcoholic solution of cerium nitrate and zinc nitrate mixture at room temperature. Dried precipitates were calcined at 300-700°C for 2 hours. The structure and growth of 5 mol% Zn-doped CeO2 was investigated using X-ray diffraction measurement. All the peaks in X-ray diffraction patterns are identified and indexed as single crystalline phase of cubic fluorite CeO2. The enhancement in calcination temperature increases the crystallite size from 5.51 to 15,56 nm and improves crystallinity of that nanoparticle. The low activation energy for crystallite growth of the 5 mol% Zn-doped CeO2 is found to be 10.85 kJ/mol. The UV-Vis spectrophotometer measurement shows the UV absorption property of the 5 mol% Zn-doped CeO2 enhanced with the increasing calcination temperature. The 5 mol% Zn-doped CeO2 nanoparticle calcined at temperature 600°C is found to be more effective as UV-blocker.

The Influence of Mn/Ga Solution Mole Fraction on the Solid Composition and Microstructure of GaN:Mn Thin Film Deposited on Silicon Substrate by Spin Coating Technique

The influence of Mn/Ga solution on the characteristics of solid composition and microstructure of GaN:Mn thin film was studied. GaN:Mn thin films were deposited on Si (111) substrate by the Chemical Solution Deposition (CSD) method using the spin coating technique. Variations of the Mn/Ga mole fraction were 4%, 6%, 8%, and 10% respectively. The GaN:Mn thin films were then heated at a temperature of 900°C for 2 hours in an N2 environment with a constant flow rate of 120 sccm. Atomic composition, crystal structure, and surface morphology of GaN:Mn thin films were characterized using X-Ray Diffraction (XRD), Energy Dispersive of X-ray (EDX), and Scanning Electron Microscope (SEM). EDX results showed that the larger the Mn/Ga mole fraction solution, the higher the Mn At percentage is. The correlation of At Mn percentage and Mn/Ga solution mole fraction is represented by the formula y = 0.023x3 - 0.352x2 - 1.742x -2.81. All of the GaN:Mn thin films still have nitrogen vacancy, carbon impurity and maintain the wurtzite polycrystalline structure. Lattice parameter a, which is in the range of 3.2077Å – 3.2621Å, and lattice parameter c, which is in the range of 5.1094Å – 5.3038Å, depend on Mn atomic percentage of the film. The Root Mean Square (RMS) of GaN:Mn thin film surface roughness is in the range of 15.3nm – 29.90nm. The grain size for the 6% Mn/Ga mole fraction thin film is homogeneous.

The precipitation synthesis of broad-spectrum UV absorber nanoceria

In this paper the possibility of nanoceria as broad-spectrum UV absorber was evaluated. Nanoceria were synthesized by precipitation process from cerium nitrate solution and ammonium hydroxide as precipitant agent. Isopropanol was mixed with water as solvent to prevent hard agglomeration. The structure of resulting nanoceria was characterized by x-ray diffractometer (XRD). The transparency in the visible light and efficiency of protection in UV A region were studied using ultraviolet-visible (UV - Vis) spectrophotometer. The results show that nanoceria possess good tranparency in visible light and high UV light absorption. The critical absorption wavelenght of 368 nm was obtained which is desirable for excellent broad-spectrum protection absorbers. Moreover, analysis of photodegradation nanoceria to methylene blue solution shows poor photocatalytic activity. It indicates that nanoceria suitable for used as UV absorber in personal care products.