Heri Sutanto

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.

Preparation and characterization of double layer thin films ZnO/ZnO:Ag for methylene blue photodegradation

Double layer (DL) thin films of zinc oxide and silver-doped zinc oxide (ZnO/ZnO:Ag) were deposited on glass substrate by sol-gel spray coating technique. The prepared thin films were subjected for optical and photocatalytic studies. UV-visible transmission spectra shows that the subtitution of Ag in ZnO leads to band gap reduction. The influence of Ag doping on the photocatalytic activity of ZnO for the degradation of methylene blue dye was studied under solar radiation. The light absorption over an extended visible region by Ag ion doping in ZnO film contributed equally to improve the photocatalytic activity up to 98.29%.

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.

Morphology and Degradation Kinetics of N-Doped TiO 2 Nano Particle Synthesized Using Sonochemical Method

Nano particle of N-doped TiO2 with the size of 21.42 nm was successfully created using sonochemical method. Concentration of Nitrogen (N) doping on TiO2 was calculated using mole ratio of Urea and TTiP. Doping variations were performed by doping 5% to 9% N, and did not change the crystallite size and strain. The nanoparticle produced has a polycrystalline structure with a dominant diffraction peak (101). Doping N into TiO2 affects the morphology of particle surface, thus tending to shrink. Results of photo catalysis on liquid samples of MB 20 ppm dye indicate that the addition of N improves the degradation ability of TiO2, with the highest value on sample T5 of 85% and with a rate of degradation kinetics of 0.024 ppm/minute.

The Influence of Nitrogen Doping Concentration on the Strain and Band Gap Energy of N-Doped Zinc Oxide Prepared Using Spray Coating Technique

N-ZnO thin layer is widely used in application of wastewater photo catalyst. N-ZnO thin films have been successfully deposited on glass substrate using spray coating technique at 450 °C with varying concentrations of N from Urea source. XRD test results showed that the N-ZnO has a polycrystalline structure with diffraction field (100), (002), (101) and (110). The presence of nitrogen atoms in the lattice of ZnO causes a shift in diffraction angle between 0.08o - 0.18o. N-ZnO thin layer showed the occurrence of tensile strain. Surface morphology of N-ZnO is shaped like mine (like root). All samples have band gap energies lower than that of ZnO and the smallest is sample N6 with Eg = 3.249 eV. The presence of nitrogen atom increases surface roughness and decreases band gap energy.

Encapsulation of phycocyanin-alginate for high stability and antioxidant activity

The aim of this study was to obtain optimal condition of phycocyanin-alginate encapsulation, encapsulation efficiency and phycocyanin load, physicochemical properties of beads, in vitro release study, stability and antioxidant activity. The result product with alginate content 1,5% (w/v) and 2% (w/v) produced were in spherical shape than product with alginate content 2,5% (w/v) by ratio of phycocyanin 1:1. Increasing alginate content on encapsulation process will increase of encapsulation efficiency and phycocyanin load. In vitro released study showed that phycocyanin-alginate beads were more resistant in simulated gastric fluid, while rapidly release in simulated intestinal fluid. The antioxidant activity showed that phycocyanin antioxidant activity decreased after encapsulation process due to duration of storage and the possibility of a cracking which will cause reduced stability of phycocyanin.

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.