Ce-doped nano-Fe–TiO2 composites for photocatalytic degradation of naphthol blue black in aqueous medium

Abstract

In this study, the effectiveness of Ce-doped nano-Fe–TiO₂ composites as photocatalysts for the degradation of Naphthol Blue Black (NBB) dye present in water was investigated. Several TiO₂ nano-photocatalysts were synthesized using the sol–gel method, including undoped TiO₂, TiO₂ doped with Fe (TF), and co-doped with Fe₂O₃–CeO₂ (TFC), Fe₂O₃–Ag₂O (TFA), and Fe₂O₃–CeO₂–Ag₂O (TFCA). Characterizations of the synthesized catalysts were performed using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) to understand their structural and morphological properties. Photocatalytic performance was evaluated by measuring the degradation of NBB dye under ultraviolet (UV) light irradiation in a suspension configuration. The results demonstrated a significant enhancement in the light-absorption properties of TiO₂ nanoparticles upon Fe doping, with a 71% degradation of NBB observed. Subsequent co-doping with CeO₂ further enhanced the degradation efficiency by an additional 18% degradation achieved by TF, within a 5.5 h duration. Among the synthesized composites, TFC nanocomposites exhibited the highest photodegradation efficiency, reaching 89% for NBB dye at a concentration of 50 ppm. The kinetics of the photocatalytic degradation process could be well-described by the pseudo-second-order model, with TFC nanocomposites having a reaction rate constant of 9.5 × 10⁻⁴ g mg⁻¹ min⁻¹. Furthermore, the point of zero charge for the TFC catalyst was determined to be pH 6.4, indicating its favorable surface charge properties. Analysis of the electronic band structure revealed a calculated band gap of 2.60 eV. This study introduces a scalable, co-doped Ce–Fe–TiO₂ nanocomposite with enhanced photocatalytic efficiency, demonstrating a ∼25% improvement over TiO₂, a promising direction for advanced dye remediation.