Enhancement of photocatalytic and photoelectrochemical properties of TiO2 nanotubes sensitized by SILAR - Deposited PbS nanoparticles

Abstract

The aim of this work is to improve the photocatalytic and photoelectrochemical properties of TiO2 nanotubes (TiO2-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 TiO2 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 TiO2 NTAs without damaging the tubular ordered structure. The photocatalytic activity of the PbS/TiO2 NTAs system, toward Amido Black (AB), showed significant enhancement compared to the bare untreated TiO2 NTs. At 30 SILAR deposition cycles the PbS-NPs/TiO2 NTAs structure is able to remove 75% of BA under simulated solar light, considerably higher than the 40% removal obtained with unloaded TiO2 NTAs. A significant improvement of the Photoelectrochemical (PEC) efficiency has been also demonstrated for the PbS-NPs/TiO2 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 well-organized morphology of the TiO2 NTAs. Keywords: TiO2 nanotubes, PbS nanoparticles, Amido black degradation, Photoelectrochemical performance