Rational design of a Z-scheme RGO/CoFe₂O₄/Ag–AgBr heterostructure for high-efficiency visible-light-assisted photodegradation of cetirizine in simulated wastewater and antibacterial activity

Abstract

This work reports a novel Z-scheme RGO/CoFe₂O₄/Ag–AgBr photocatalyst designed for dual applications in pharmaceutical pollutant degradation and antibacterial role, addressing key challenges in sustainable water treatment. The rational integration of conductive RGO, magnetic CoFe₂O₄, and Ag–AgBr enables efficient visible-light harvesting, interfacial charge separation, and preserved redox activity. The composite was thoroughly characterized using FTIR, XRD, SEM, TEM, and XPS, confirming its successful fabrication and structural stability. The composite exhibits a narrow band gap of 2.26 eV and demonstrates superior suppression of charge-carrier recombination. Consequently, the photocatalyst achieved a high cetirizine degradation efficiency of 93.36% within 1 h. Band-structure and radical-scavenging studies supported a Z-scheme charge-transfer mechanism, with hydroxyl radicals (•OH) identified as the primary species responsible for pollutant breakdown. The photocatalyst performed optimally at pH 6, while humic acid concentrations below 2 ppm showed minimal impact on efficiency. LC–HR–MS analysis validated effective degradation and mineralization, allowing the proposal of a plausible reaction pathway. In addition, the composite exhibited strong antibacterial activity against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Salmonella typhi. Overall, the multifunctional RGO/CoFe₂O₄/Ag–AgBr nanocomposite shows excellent potential for sustainable water treatment through simultaneous chemical pollutant removal and microbial control.