期刊
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
卷 13, 期 38, 页码 8872-8878出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.jpclett.2c02331
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资金
- National Natural Science Foundation of China [21902138]
- Guangdong Basic and Applied Basic Research Foundation [2021A1515010064]
- Hong Kong Research Grants Council [CityU 21301719, 11300020, 11305721]
- Chow Sang Sang Group Research Fund - Chow Sang Sang Holdings International Limited [9229063]
This study resolves the debate on the activity of Fe3O4 nanoparticles as peroxidase mimetics and provides an atomic view into their origin. The redox between H2O2 and Fe(II) sites on the Fe3O4 surface was identified as the key step in producing OH radicals.
Although Fe3O4 nanoparticles were early reported to outperform horseradish peroxidase (HRP), recent studies suggested that this material bears a very poor activity instead. Here, we resolve this disagreement by reviewing the definition of descriptors used and provide an atomic view into the origin of Fe3O4 nanoparticles as peroxidase mimetics. The redox between H2O2 and Fe(II) sites on the Fe3O4 surface was identified as the key step to producing OH radicals for the oxidation of colorimetric substrates. This mechanism involving free radicals is distinct from that of HRP oxidizing substrates with a radical retained on its Fe-porphyrin ring. Surprisingly, the distribution and chemical state of Fe species were found to be very different on single- and polycrystalline Fe3O4 nanoparticles with the latter bearing not only a higher Fe(II)/Fe(III) ratio but also a more reactive Fe(II) species at surface grain boundaries. This accounts for the unexpected gap in the catalytic constant (k(cat)) observed for this material in the literature.
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