Preparation of magnetically separable and recyclable carbon dots/NiCo2O4 composites with enhanced photocatalytic activity for the degradation of tetracycline under visible light

Abstract

Utilizing photocatalysis to remove antibiotics from aqueous solution is a promising technology for environmental remediation. In this work, we successfully fabricated a visible-light-responsive and magnetically recycled carbon dot (CD)/NiCo₂O₄ composite photocatalyst through a one-step simple calcination method for the first time. Compared with pristine NiCo₂O₄, CDs/NiCo₂O₄ composites exhibit significantly enhanced photocatalytic activity for the degradation of tetracycline (TC) (100 mL, 10 mg L⁻¹) under visible-light irradiation. The photodegradation rate constant data reveal that CDs/NiCo₂O₄ with 3 wt% CD loading content (CDs/NiCO-3) exhibited the highest photocatalytic activity (0.02134 min⁻¹), which is about 6-fold in comparison with pristine NiCo₂O₄ (0.0036 min⁻¹). The enhanced photocatalytic activity of the CDs/NiCo₂O₄ composite corresponds to the synergetic effect of CDs and NiCo₂O₄ that improves not only the light absorption capacity but also the separation efficiency of photo-induced charge carriers. Additionally, the CDs/NiCo₂O₄ composites showed good recyclability without loss of apparent photocatalytic activity after five successive cycles, and more importantly, CDs/NiCo₂O₄ could be recovered magnetically.