RESUMO
Transparent and amorphous yttrium (Y)/Sialon thin films were successfully fabricated using pulsed laser deposition (PLD). The thin films were fabricated in three steps. First, Y/Sialon target was synthesized using spark plasma sintering technique at 1500 °C in an inert atmosphere. Second, the surface of the fabricated target was cleaned by grinding and polishing to remove any contamination, such as graphite and characterized. Finally, thin films were grown using PLD in an inert atmosphere at various substrate temperatures (RT to 500 °C). While the X-ray diffractometer (XRD) analysis revealed that the Y/Sialon target has ß phase, the XRD of the fabricated films showed no diffraction peaks and thus confirming the amorphous nature of fabricated thin films. XRD analysis displayed that the fabricated thin films were amorphous while the transparency, measured by UV-vis spectroscopy, of the films, decreased with increasing substrate temperature, which was attributed to a change in film thickness with deposition temperature. X-ray photoelectron spectroscopy (XPS) results suggested that the synthesized Y/Sialon thin films are nearly homogenous and contained all target's elements. A scratch test revealed that both 300 and 500 °C coatings possess the tough and robust nature of the film, which can resist much harsh loads and shocks. These results pave the way to fabricate different Sialon doped materials for numerous applications.
RESUMO
An electrochemical sensor based on an indium tin oxide nanoparticle (ITONP)-modified glassy carbon electrode (ITONP/GCE) was developed for the detection of sulfides in alcoholic medium. The ITONP/GCE was prepared by simply dropping the aqueous solution of ITONP on the GCE surface and then drying at 40°C. The homogeneous distribution of ITONP on the GCE surfaces was confirmed by recording the camera photographs and field emission scanning electron microscopic images. The ITONP/GCE was further characterized with energy dispersive X-ray spectrometry, X-ray photoelectron spectroscopy and X-ray diffractometry to identify the surface chemical composition and crystallinity. The ITONP/GCE showed much better electrocatalytic properties toward sulfide electro-oxidation than that of bare GCE electrodes. The obtained amperometric detection limit of sulfide in alcoholic solutions of sodium acetate was 0.3 µM. The enhanced sensitivity, good selectivity and high stability are promising features of the ITONP/GCE for sulfide sensing.
RESUMO
The work presented here deals with the photoreduction in metallic silver nanoparticles onto the surface of Ag(3)PO(4) and resulting photocatalytic activity enhancement toward degradation of dye molecules, namely Rhodamine B (Rh. B) as a model compound, from aqueous solution under UV or visible light irradiation. Our results clearly indicated that the photoactivity of Ag(3)PO(4) was significantly enhanced by depositing an optimum amount of silver nanoparticles, even though the adsorption kinetics rate and capacity decreased after the silver nanoparticles agglomerate extensively. The surface plasmon resonance (SPR) excited between the silver nanoparticles and Rh. B interface is a physical origin and responsible for the boosted photoactivity, which strongly depends on the specific wavelength of the incident light. This work provides and suggests a novel scheme for Ag/Ag(3)PO(4) composites having plasmonic effect on the interface with detailed experimental and theoretical study.
