Impacts of r-GO and N-doping on the structural, magnetic, optical and photocatalytic properties of CuAl2O4: enhanced crystal violet removal under solar light irradiation

Abstract

Designing a magnetically recyclable and visible-light-driven photocatalyst is of great importance in environmental remediation. Realizing efficient removal of persistent azo dyes from industrial wastewater is still a major challenge for researchers. In this context, herein, novel CuAl₂O₄ and N/rGO nanohybrids, CA-N/GO(1–4), were synthesized via an ultrasonic method and assessed for their efficiency toward the photocatalytic removal of crystal violet (CV) dye from simulated polluted water under visible irradiation. Crystalline phase, morphology and functional groups of the synthesized materials were examined using XRD, SEM and FTIR spectroscopy, respectively, while their magnetic and optical behaviors were tested using VSM, PL and UV-visible spectroscopic techniques. XRD results showed that the cubic spinel phase of pure CuAl₂O₄ (CAO) exhibited a 57.32 nm mean crystallite size that was altered upon substitution of N/rGO in the composites. SEM images revealed the successful incorporation of CAO nanoparticles in N/rGO sheets. CuAl₂O₄-N/rGO4 (CA-N/GO4) catalyst exhibited excellent catalytic efficiency (i.e., 82.6% removal of dye in 90 min), which was significantly higher than those of pure CAO and N/rGO. After optimizing the reaction conditions, almost complete removal of dye was achieved for 30 mg L⁻¹ of catalyst dosage at pH = ∼10. This robust photocatalytic performance might be attributed to N/rGO, which hindered the recombination of electron–hole pairs, thus enhancing the surface area and providing more active sites for dye adsorption. A possible mechanism of CV degradation was proposed using different scavenging agents. Structural stability and practical utility of the used CA-N/GO4 catalyst were assessed after four continuous runs, which demonstrated good outcomes. Thus, these results reveal that the novel and magnetically separable CA-N/GO4 nanohybrid has a remarkable prospect for the elimination of toxic dyes from industrial sewage water under visible irradiation.