Core-Shell Mn- and Cu-Doped CoFe₂O₄@Co₃O₄ Hollow Spheres with Dual Adsorption and Catalytic Function

Area of Science:

• Materials Science
• Environmental Chemistry
• Nanotechnology

Background:

• Developing efficient materials for water treatment is crucial to address pollution.
• Hollow sphere structures offer high surface area and enhanced reactivity.
• Doping magnetic spinel ferrites can improve their catalytic and adsorption properties.

Purpose of the Study:

• To synthesize and characterize Mn- and Cu-doped CoFe2O4@Co3O4 hollow spheres.
• To evaluate their performance as bifunctional adsorbent-catalysts for removing Congo Red (CR) and oxytetracycline (OTC) from water.
• To investigate the role of doping on material properties and pollutant removal mechanisms.

Main Methods:

• Solvothermal synthesis of core-shell hollow spheres.
• Characterization using X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS).
• Evaluation of adsorption and Fenton-like degradation performance for CR and OTC removal.

Main Results:

• Successful synthesis of Mn- and Cu-doped CoFe2O4@Co3O4 hollow spheres with high surface area (up to 115 m²/g).
• Mn-doping primarily enhanced adsorption, while both dopants improved catalytic activity.
• Mn-3 sample achieved 99% OTC removal in 30 min and complete CR removal in 40 min.
• Identification of Co, Mn, and Cu as redox-active centers responsible for pollutant degradation.
• Singlet oxygen and hydroxyl radical generation were confirmed as key reactive species.

Conclusions:

• Mn- and Cu-doped cobalt ferrite hollow spheres are promising for water treatment.
• The doping strategy effectively enhances pollutant removal via combined adsorption and catalytic degradation.
• Material recyclability is demonstrated, though stronger chemisorption affects OTC removal over cycles.