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

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...

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Bibliographic Details
Published in:Small (Weinheim an der Bergstrasse, Germany) Germany), 2022-12, Vol.18 (50), p.e2204372-n/a
Main Authors: Wan, Kaiwei, Jiang, Bing, Tan, Ting, Wang, Hui, Liang, Minmin
Format: Article
Language:English
Subjects:
Catalysis
Catalytic activity
Coloring Agents
Ferric Compounds
Free Radicals
Hydrogen peroxide
Hydroxyl Radical
Hydroxyl radicals
iron oxide
Iron oxides
Nanoparticles
Nanotechnology
nanozymes
Oxidation
Peroxidase
Peroxidase - metabolism
peroxidase‐like activity
reaction mechanisms
Surface structure
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Summary: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. The peroxidase‐like catalytic reactions of Fe3O4 nanoparticles (NPs) under acid conditions are attributed primarily to both hydroxyl radicals (•OH) and high‐valent FeO rather than only being caused by the free •OH generated through the iron‐driven heterogeneous Fenton‐like reaction as previously thought. It is a good bridge between homogeneous catalysts and natural enzymes.
ISSN:1613-6810
1613-6829
DOI:10.1002/smll.202204372