Nd,N,S-TiO2 Decorated on Reduced Graphene Oxide for a Visible Light Active Photocatalyst for Dye Degradation: Comparison to Its MWCNT/Nd,N,S-TiO2 Analogue

Neodymium, nitrogen, and sulfur tridoped titania (Nd,N,S-TiO2) was decorated on reduced graphene oxide (rGO) and multiwalled carbon nanotubes (MWCNTs) via a simple sol-gel method. The prepared photocatalysts were characterized by FE-SEM-EDX, TEM, UV-vis, BET, FTIR, Raman, and XRD. Aqueous solutions of eriochrome black T (EBT) and eosin blue shade (EBS) were used to evaluate the photocatalytic activity of the composites under simulated solar light irradiation. Degradation of the dyes was performed in single and mixed dye solutions. The reduced graphene based photocatalyst (rGO/Nd,N,S-TiO2) showed improved photocatalytic activity over the MWCNT/Nd,N,S-TiO2 composite in both single and mixed dye solutions. In the single dye solutions, a maximum degradation of 99.3% and 94.6% was achieved for EBS and EBT, respectively. Moreover, a maximum degradation efficiency of 65.7% and 58.9% was attained by rGO/Nd,N,S-TiO2 for EBS and EBT, respectively, from mixed dye solutions. These experimental results suggest the potential application of the composite photocatalysts for dye pollution remediation. Furthermore, radical scavenging experiments confirmed the superoxide and hydroxyl radicals as the active species during dye degradation. Total organic carbon analyses revealed a fairly high degree of complete mineralization of both dyes reducing the potential formation of toxic degradation byproducts.