Surface-Mediated Production of Complexed •OH Radicals and Fe=O Species as a Mechanism for Iron Oxide Peroxidase-Like Nanozymes

Kaiwei Wan, Bing Jiang, Ting Tan*, Hui Wang*, Minmin Liang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)

Abstract

Fe3O4 nanoparticles (NPs) with intrinsic peroxidase-like properties have attracted significant interest, although limited information is available on the definite catalytic mechanism. Here, it is shown that both complexed hydroxyl radicals (•OH) and high-valent Fe-O species are attributed primarily to the peroxidase-like catalytic activity of Fe3O4 NPs under acid conditions rather than only being caused by free •OH radicals generated through the iron-driven Fenton/Haber–Weiss reactions as previously thought. The low energy barrier of O-O bond dissociation of H2O2/•OOH (0.14 eV) and the high oxidation activity of surface Fe-O (0 eV) due to the reduced state of Fe on the surface of Fe3O4 NPs thermodynamically favor both the •OH and Fe-O pathways. By contrast, high-valent Fe-O species are the key intermediates in the catalytic cycles of natural peroxidase enzymes. Moreover, it is demonstrated that the enzyme-like activity of Fe3O4 NPs can be rationally regulated by modulating the size, surface structure, and valence of active metal atoms in the light of this newly proposed nanozyme catalytic mechanism.

Original languageEnglish
Article number2204372
JournalSmall
Volume18
Issue number50
DOIs
Publication statusPublished - 15 Dec 2022

Keywords

  • iron oxide
  • nanozymes
  • peroxidase-like activity
  • reaction mechanisms

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