Material-enhanced
heterogonous peroxymonosulfate (PMS) activation
on emerging organic pollutant degradation has attracted intensive
attention, and a challenge is the electron transfer efficiency from
material to PMS for radical production. Herein, an interface architecture
of Co(OH)2 nanosheets growing on the KNbO3 perovskite
[Co(OH)2/KNbO3] was developed, which showed
high catalytic activity in PMS activation. A high reaction rate constant
(k
1) of 0.631 min–1 and
complete removal of pazufloxacin within 5 min were achieved. X-ray
photoelectron spectroscopy, X-ray absorption near edge structure spectra,
and density functional theory (DFT) calculations revealed the successful
construction of the material interface and modulated electronic structure
for Co(OH)2/KNbO3, resulting in the hole accumulation
on Co(OH)2 and electron accumulation on KNbO3. Bader topological analysis on charge density distribution further
indicates that the occupations of Co-3d and O-2p orbitals in Co(OH)2/KNbO3 are pushed above the Fermi level to form
antibonding states (σ*), leading to high chemisorption affinity
to PMS. In addition, more reactive Co(II) with the closer d-band center
to the Fermi level results in higher electron transfer efficiency
and lower decomposition energy of PMS to SO4
•–. Moreover, the reactive sites of pazufloxacin for SO4
•– attack were precisely identified based
on DFT calculation on the Fukui index. The pazufloxacin pathways proceeded
as decarboxylation, nitroheterocyclic ring opening reaction, defluorination,
and hydroxylation. This work can provide a potential route in developing
advanced catalysts based on manipulation of the interface and electronic
structure for enhanced Fenton-like reaction such as PMS activation.
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