Nadia Febiana Djaja

Transition-metal-doped ZnO nanoparticles: synthesis, characterization and photocatalytic activity under UV light.

ZnO nanoparticles doped with transition metals (Mn and Co) were prepared by a co-precipitation method. The synthesized nanoparticles were characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-rays, Fourier transform infrared spectroscopy, electron spin resonance spectroscopy and diffuse reflectance spectroscopy. The photocatalytic activities of the transition-metal-doped ZnO nanoparticles were evaluated in the degradation of methyl orange under UV irradiation. ZnO nanoparticles doped with 12 at.% of Mn and Co ions exhibited the maximum photodegradation efficiency. The experiment also demonstrated that the photodegradation efficiency of Mn-doped ZnO nanoparticles was higher than that of Co-doped ZnO nanoparticles. These results indicate that charge trapping states due to the doping were the decisive factor rather than the average particle size and energy gap. Moreover the effect of pH values on the degradation efficiency was discussed in the photocatalytic experiments using 12 at.% Mn- and Co-doped ZnO nanoparticles.

Photocatalytic Activity of Fe-Doped ZnO/Montmorillonite Nanocomposite for Degradation of Malachite Green

In this study, the photocatalytic activity of pure Fe- doped ZnO and Fe- doped ZnO/Montmorillonite nanocomposite has been investigated for the degradation of malachite green under UV light irradiation. Both photocatalysts were synthesized using co-precipitation method and characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, Fourier-transform infrared absorption, and electron spin resonance. The results showed that the photocatalytic efficiency is better in the presence of montmorillonite compared to pure Fe- doped ZnO. To detect the possible reactive species involved in degradation of organic dyes control experiments with introducing scavengers into the solution of organic dyes were carried out. It is found that electron plays an important role in the degradation of malachite green.

Synthesis, physical properties and catalytic activity of Cr-doped ZnO nanoparticles

The present work studies the photocatalytic degradation of Cr-doped ZnO nanoparticles toward aqueous mixture of organic dyes, such as methyl orange, methylene blue and congo red. Cr-doped ZnO nanoparticles were synthesized using co-precipitation method and characterized by several method of measurements. Photocatalytic mechanism was investigated by measuring the photocatalytic degradation rate in the presence of scavenger. The results revealed that hydroxyl radical plays an important role in photocatalytic activity.

Photocatalytic Activity of Zeolite Supported Transition Metal-(Co2+ and Cr2+) Doped ZnO: Comparative Study

Transition metal ions (Co and Cr) doped ZnO nanoparticles supported on natural zeolite were synthesized using co-precipitation method. The synthesized samples were characterized by means of X-ray diffraction, energy dispersive X-ray, Fourier-transform infrared absorption, and UV-visible diffuse reflectance spectroscopy. The samples were further used as photocatalyst for degradation of methyl orange and methylene blue in aqueous solutions under UV light irradiation. The results showed that zeolite supported Cr-doped ZnO nanoparticles is more efficient compared with zeolite supported Co-doped ZnO nanoparticles. It is also revealed that zeolite supported samples possessed higher photocatalytic efficiency compared to bare samples.

Comparative Study on Photocatalytic Performance of (La,Fe) and (Ce,Fe)-Codoped ZnO Nanoparticles

The present study evaluates the photocatalytic degradation of congo red as a model of organic pollutant over LaFe- and CeFe-codoped ZnO nanoparticles under UV light irradiation. Both photocatalysts were synthesized using co-precipitation method and characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, diffuse reflectance spectroscopy. The photodegradation efficiency of congo red using two 20W UV lamp was higher for LaFe-codoped ZnO nanoparticles compared with CeFe-codoped ZnO nanoparticles. Photocatalytic mechanism was investigated by measuring the photocatalytic degradation rate in the presence of ammonium oxalate, natrium sulfate, tert-butyl alcohol as photogenerated holes, photogenerated electrons and hydroxyl radical species scavenger. The results revealed that electrons are the main species in the photocatalytic process.

Comparative Study of Photocatalytic Activity of Ni-Doped ZnO and Zeolite Supported Ni-Doped ZnO Prepared by Co-Precipitation Method

The present study compares the photocatalytic degradation of methylene blue in the presence of natural zeolite supported Ni-doped ZnO and bare Ni-doped ZnO nanoparticles. The photocatalyst was prepared by co-precipitation method and the photocatalytic activity of the photocatalyst was investigated under UV light irradiation. The results showed that the photocatalytic efficiency of zeolite supported Ni-doped ZnO nanoparticles is better than that of bare Ni-doped ZnO nanoparticles. The influence of experimental parameters on the photodegradation of methylene blue was studied and it was observed that photocatalytic activity varied with pH, initial methylene blue concentration and the amount of photocatalyst. The scavenger technique shows that electron plays an important role in the bare Ni-doped ZnO, while in zeolite supported Ni-doped ZnO, ●OH is the prominent active species.

Natural Zeolite Incorporated in Zinc Oxide Nanoparticles Doped with Manganese for Degradation of Organic Dye in Water under UV Light Irradiation

In this study, the photocatalytic degradation of methylene blue has been investigated using natural zeolite modified Mn-doped ZnO nanoparticles synthesized by co-precipitation method. Comparison of degradation efficiency demonstrated that natural zeolite modifiedMn-doped ZnO exhibited higher activity than bare Mn-doped ZnO.