The construction of p-n heterojunction in nanozyme for improved peroxidase-like activity and “point-of-use” water disinfection

Abstract

Pathogenic bacteria are widely distributed in water environments globally, causing numerous waterborne diseases and posing significant threats to human health. Fe₃O₄, as a nanozyme with peroxidase-like (POD-like) activity, has been recognized as an inherent bactericidal agent. To enhance the POD-like activity and antibacterial properties of n-type Fe₃O₄, a p-n heterojunction was constructed with p-type NiO. The Fermi level difference between Fe₃O₄ and NiO induces a built-in electric field in NiO/Fe₃O₄, optimizing the interfacial structure for POD-like catalysis. This material exhibits a unique hollow morphology with promising POD-like activity. Mechanistic calculations further confirm the charge distribution and the formation of the internal electric field within the p-n heterojunction. The d-band center of NiO/Fe₃O₄ is positioned close to the Fermi level, enhancing the interaction between NiO/Fe₃O₄ and H₂O₂, facilitating O-O bond cleavage, and improving POD-like activity. Additionally, NiO/Fe₃O₄ demonstrates excellent antibacterial performance against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Furthermore, it achieves effective “point-of-use” water disinfection in practical water systems. This study highlights that the synergistic effects of the p-n heterojunction and the built-in electric field can significantly enhance POD-like activity, providing a novel approach for developing nanozymes with POD activity for “point-of-use” water disinfection.