Constrained by the strong Coulombic
interaction of electron–hole
pairs in semiconductor photocatalysts, the charge carrier separation
and the resultant photocatalytic capability are greatly compromised.
In this work, we rationally construct a built-in electric field (BEF)
from the (111) facet of CdTe quantum dots (CdTeQDs) to the (200) facet
of two-dimensional Bi2WO6 (2DBWO) nanosheets
by the formation of a Te–O
x
bond.
We validate experimentally and theoretically that the BEF can profoundly
promote the dissociation of a photoexcited exciton and separation
of a charge carrier, resulting in the formation of a Z-scheme electronic
structure of the CdTeQDs/2DBWO photocatalyst. Benefiting from the
role of the BEF, the photoinduced generation of the superoxide anion
radical and hydroxyl radical is significantly promoted, based on which
photodegradation performances of the CdTeQDs/2DBWO photocatalyst are
6.64, 1.95, and 5.4 times those of pure 2DBWO for tetracycline, phenol,
and rhodamine B, respectively. This work provides a mechanistic insight
into the design and optimization of semiconductor heterojunction photocatalysts
for efficient charge carrier separation and environmental remediation.
The modification of biochar is essential for the development of multifunctional biochar materials with enhanced remediation effects on contaminated water. In this work, a biochar-based microcatalyst with sunlight sensitivity was synthesized by a creative modification method that involved the rapid fabrication of MnO2 microspheres by high-energy electron beam (HEEB) irradiation, and loading them into corn straw-derived honeycomb-like KOH-modified biochar (MBC) to obtain a sunlight-sensitive microcatalyst (SSM). The honeycomb-like structure of MBC facilitated the improvement in MnO2 dispersion and photocatalytic property through confinement effect. The effects of photocatalyst dosage, initial chlortetracycline (CTC) concentration, solution pH, temperature and coexisting ions on the photocatalytic performance of SSM were systemically investigated. The results indicated that SSM could efficiently degrade CTC in water and swine urine under sunlight, and exhibited high stability against coexistence of urea, Cl− and SO42−. Moreover, SSM showed good reusability in regeneration studies. This work provides a novel method for degrading CTC with potential application prospect.
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