Synthesis of transition metal and rare earth metal doped nanocrystalline CdAl2O4: An outstanding approach for photodegradation of harmful organic contaminants

Abstract

The development of novel, economical, eco-friendly and visible light-driven photocatalytic materials for industrial wastewater treatment remains a significant challenge for the scientific community. In this context, pure CdAl2O4 (CAO), Cu doped CdAl2O4 (Cu@CAO), Ce doped CdAl2O4 (Ce@CAO), and Cu-Ce co-doped CdAl2O4 (Cu-Ce@CAO) were fabricated by facile co-precipitation route. The XRD analysis of all prepared samples confirmed their hexagonal structure along with the increment of average crystallite size of Cu-Ce@CAO i.e. 18.5 nm as compared to CAO (15.2 nm), Cu@CAO (15.78 nm), and Ce@CAO (17.97 nm). The UV-Visible analysis revealed the decrement in bandgap of Cu-Ce@CAO i.e. 1.5 eV in comparison to CAO (3.42 eV), Cu@CAO (2.0 eV), and Ce@CAO (1.9 eV). This inverse relationship between bandgap and crystallite size (D) is attributed to the generation of quantum confinement effect after doping. The degradation efficacy of CAO, Cu@CAO, Ce@CAO, and Cu-Ce@CAO against bromocresol purple (BCP) was found to be 58 %, 66 %, 77 %, and 90 %, respectively. Moreover, about 44 %, 55 %, 64 %, and 71 % photodegradation of benzoic acid was observed by CAO, Cu@CAO, Ce@CAO, and Cu-Ce@CAO, respectively. The highest degradation efficiency of Cu-Ce@CAO among all photocatalysts is accredited to the quantum confinement effect produced by doping of Cu and Ce in CdAl2O4. Hence, doping of Cu and Ce in pristine spinel aluminates could be an efficient way to enhance their photocatalytic activities.

Keywords

• Spinel aluminate
• Cerium
• Co-doping
• Quantum confinement
• Photocatalysis
• Benzoic acid