Structural and optical characteristic features of RF sputtered CdS/ZnO thin films

In this study,CdS/ZnO(2:3 mol%)thin films are successfully deposited on quartz substrates by using the sputtering technique.Good images on the structural and optical characteristic features of CdS/ZnO thin films before and after annealing are obtained.The CdS/ZnO thin films are annealed respectively at temperatures of 373 K,473 K,and 573 K and the structural features are examined by XRD,ATR-FTIR,and FESEM.The optical properties of CdS/ZnO thin films such as refractive indices,absorption coefficients,optical band gap energy values,Urbach energy values,lattice dielectric constants,and high frequency dielectric constants are determined from spectrophotometer data recorded over the spectral range of 300 nm-2500 nm.Dispersion parameters are investigated by using a single-oscillator model.Photoluminescence spectra of CdS/ZnO thin films show an overall decrease in their intensity peaks after annealing.The third-order nonlinear optical parameter,and nonlinear refractive index are also estimated.

Enhancement of photocatalytic and photoelectrochemical properties of TiO_(2) nanotubes sensitized by SILAR-Deposited PbS nanoparticles

The aim of this work is to improve the photocatalytic and photoelectrochemical properties of TiO_(2) nanotubes(TiO_(2)-NTAs)by sensitizing them with PbS nanoparticles(NPs)prepared by the Successive Ionic Layer Adsorption and Reaction method(SILAR).The Microstructure,surface morphology,phase composition and optical properties of the prepared structure were characterized using X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM and High-resolution mode HRTEM)and X-ray photoelectron spectroscopy(XPS).The TiO_(2) NTAs were loaded by PbS NPs,which contents increase by increasing the number of SILAR cycles.The PbS NPs,which have a size in the order of ~20 nm,were found to be uniformly distributed in the TiO_(2) NTAs without damaging the tubular ordered structure.The photocatalytic activity of the PbS/TiO_(2) NTAs system,toward Amido Black(AB),showed significant enhancement compared to the bare untreated TiO_(2) NTs.At 30 SILAR deposition cycles the PbS-NPs/TiO_(2) NTAs structure is able to remove 75% of BA under simulated solar light,considerably higher than the 40% removal obtained with unloaded TiO_(2) NTAs.A significant improvement of the Photoelectrochemical(PEC)efficiency has been also demonstrated for the PbS-NPs/TiO_(2) NTAs hybrid system.This improvement is mainly related to visible-light harvesting and reduced recombination of photo-generated electron-hole pairs due to the synergistic effect of the heterojunction and to the wellorganized morphology of the TiO_(2) NTAs.