Construction of Sulfur-Vacancy-Modified 0D/2D S-Scheme Heterojunction for Enhancing Photocatalytic Cr(VI) Reduction

The rational design and construction of S-scheme heterojunctions represent an effective strategy for enhancing the photocatalytic efficiency. Nevertheless, the challenge of enabling efficient charge migration at the interface persists. Herein, a 0D/2D S-scheme heterojunction photocatalyst incorporating 0D Ag quantum dots and S-vacancy-modified Bi2S3 quantum dots with 2D MnFe2O4 ultrathin nanosheets (AgQDs/BQDs-SV/MFO) is designed and constructed via photoinduced decomposition-defect engineering strategy. Theoretical calculations and experimental results demonstrate the presence of quantum dots, S vacancies, and nanosheet structure in the AgQDs/BQDs-SV/MFO heterojunction significantly improves light harvesting, charge separation, and transfer dramatically, resulting in a high-efficiency photocatalytic degradation rate (99.5%) toward Cr(VI) under visible light irradiation (λ ≥ 420 nm) at 30 min with excellent stability. This work provides new insights for constructing effective photocatalysts for purifying Cr wastewater for environmental remediation.