Engineering and Technology Journal

In recent years, biologists, chemists, materials scientists, and engineers have become interested in Nano-sized particles because of their unique properties. In this paper, ZnO nanoparticles were synthesized using an Nd: YAG laser with 800 mJ at 1064 nm and 532 nm (the fundamental and second harmonic wavelengths). The characteristics of optical, morphological, structural, wettability and antibacterial activity have been studied. The used technique of PLAL was successful in nanoparticle formation. It was proved in color changes, which was an indication of ZnO nanoparticle formation. The optical measurements show a decrease in absorption wavelength and an increase in the band gap, an indication of the formation of quantum confinement due to nanoparticle formation. The XRD involves the formation of polycrystalline ZnO at both wavelengths. Also, the FE-SEM proved the formation of nanoparticles with a semispherical shape and little agglomeration on the surface. However, the EDX shows Zn and O in the film, which means the formation of ZnO. The low contact angle indicates high wettability, which means that the material has high biocompatibility. Finally, the antibacterial test was done on two types of bacteria (E. coli and S. aurous) and showed an antibacterial effect on both types with different NP concentrations.

In this present study, Pulsed Laser Ablation in Liquid (PLAL) experiment setup for synthesis colloidal solution of silver-NPs. The laser system was used in this study, a (Nd-YAG) nanosecond laser system with optimal pulse duration of 10 ns and repetition rate 1-6 Hz. The Laser wavelengths were: 1064 nm, 532 nm and 355 nm. The spot size of the laser beam on the surface of metal plate was varied in the range of 1.4-1.5 mm in diameter by changing the distance between the focusing lens and the metal plate.The ablation process was typically done for 1 minute. The average particle size has been characterized by TEM, SEM and UV-Vis investigation. From morphologyresults for colloidal silver nanoparticles images were spherical shape and average size of the particles is 55-60 nm at wavelength (λ =1064 nm), average size of the particles is 35-40 nm at(λ =532 nm) and average size of the particles is 28 nm at(λ =355 nm).

In this research, AuNPs prepared by laser ablation in liquid (PLAL) at 750 mJ energy and 90 pulses. They have been added to N719-dye to form (Au-N719) mixture. TiO2 paste was deposited on FTO substrates and immersion in a mixture dye and AuNPs. DSSC was fabricated and enhancement of the DSSC conversion efficiency was achieved. Scanning electron microscope, X-ray diffraction and UV-Visible spectrophotometer were used to characterize and study the DSSC components. The UV-Vis data show high absorbance of AuNPs+N719 dye compared to N719 dye only; that means the immersion of AuNPs in the N719-dye solution tend to increase the total absorbance of the dye. The XRD pattern of AuNPs has diffraction peaks at 38.2° and 44.4° which can be indexed by (111), (200) plane of Au in the cubic phase. The shape and size distribution shows spherical AuNPs with particle size about (50-60) nm. The relative increase of short circuit current density after the adding gold nanoparticles was about 76%. In the same way the relative increase of open circuit voltage after adding gold nanoparticles was about 6.7%. The total photon-to-current energy conversion efficiency for the standard DSSC is 1.75 while its 2.8 of the enhanced DSSC with gold NPs.The maximum enhancement is about 60 % under illumination (105 mW/cm2, (AM1.5).

In this work preparation and characterization of a zinc metal target in isopropanol liquid at room temperature is carried out by PLAL technique at different laser fluency. The effect of laser fluencies during laser ablation process on the structure properties of the NPs is investigated.
We have use UV-visible spectroscopy, Atomic force microscopy and Energy dispersive X-ray (EDX) was used to evaluate the bulk atomic composition of NPs. The absorption peak of samples prepared in isopropanol solution is seen to be substantially blue shifted relative to that of the bulk zinc oxide due to the strong confinement effect. The technique offers an alternative for preparing the nanoparticles of active metal. The morphological investigation, carried out using (AFM), showed thatthe root mean square roughness is increased and the grain size of the obtained NPs are found to increase with the laser fluency.The use of isopropanol as solvent yielded spherical nanoparticles of 30–60 nm.