CeO2 nanoparticles dotted on NiAl-LDHs as Z-scheme heterojunction: synergistic enhancement of adsorption and photocatalytic properties

Conventional adsorption technologies face significant challenges in dye wastewater treatment, particularly in achieving effective mineralization and reducing toxicity. To address these limitations, we have developed novel nanomaterials that integrate both adsorption and photocatalytic functions, thereby enhancing treatment efficiency. The composite materials were synthesized by co-precipitating CeO2 onto the surface of NiAl-Layered Double Hydroxides (NiAl-LDHs). These composites were then employed for the degradation of Naphthol Blue Black (NBB) effluent. The results revealed that the optimized CeO2@NiAl-LDHs achieved a 96.2% removal of NBB, which represents a 67.9% improvement compared to pure NiAl-LDHs. The primary mechanisms of NBB adsorption onto CeO2@NiAl-LDHs were identified as ligand exchange and electrostatic attraction. Additionally, CeO2@NiAl-LDHs form a direct Z-scheme heterojunction, which promotes efficient electron–hole separation and enhances the generation of ·OH and O2·⁻, key species involved in NBB degradation. After 8 h of treatment, the CeO2@NiAl-LDHs system reduced biological toxicity of wastewater, while improving its biodegradability (BOD/COD increased to 0.41). Even after 5 cycles, the composite material’s removal rate for NBB only slightly decreased from 96.2% to 88.6%. This study provides a practical approach for developing CeO2@NiAl-LDHs-based photocatalysts with excellent adsorption and photocatalytic properties, presenting a novel solution for wastewater treatment.