Regular Article

Effect of electrolyte solution and deposition methods on TiO₂/CdS core–shell nanotube arrays for photoelectrocatalytic application

¹ Applied Sciences Department, University of Technology, Baghdad, Iraq
² Ministry of Science and Technology, Baghdad, Iraq

^* e-mail: salma_aljawad@yahoo.com

Received: 3 May 2020
Received in final form: 19 September 2020
Accepted: 23 September 2020
Published online: 30 October 2020

Abstract

In this work, TiO₂ nanostructure thin films were deposited by using anodization technique, while CdS thin films were deposited on TiO₂ films by two methods chemical bath deposition (CBD) and successive ionic layer adsorption and reaction (SILAR). The structure of TiO₂/CdS films were investigated and analyzed by XRD, SEM, and AFM, but the optical properties were investigated by UV–visible spectroscopy, PL spectroscopy, and spectral response. XRD analysis of all deposited films has confirmed the formation of two phases one is tetragonal phase (anatase, and rutile) for TiO₂, and second hexagonal phase which belong to CdS layer. SEM images of TiO₂ nanotubes arrays (NTAs)/CdS showed the TiO₂ NTs walls become decorated with aggregates of fine CdS nanoparticles that partly penetrate into the TiO₂ NTAs pores. AFM measurements displayed increase in the surface roughness compared with TiO₂ films. PL measurement results of TiO₂/CdS core–shell show two peaks, one is located at UV-region pointed to energy band gap for TiO₂ nano films, and second one is located at visible region pointing to recombination of photogenerated electron–hole pairs within CdS layers. Spectral response measurements showed photocurrent peaks for all TiO₂/CdS films deposited with different electrolyte solution have red-shift to visible region. When illuminated with a UV–Vis light source, the TiO₂/CdS core–shell films displayed high response. A higher response to UV–Vis light was attained with the use of TiO₂ NTAs/CdS films prepared by anodization /CBD. This approach offers a technique for fabricating photoelectrodes.