Sulfur vacancy-rich (α/β-CdS)/SiO photocatalysts for enhanced visible-light-driven photocatalytic degradation of rhodamine B.

The development of highly efficient photocatalysts for visible-light-driven degradation of organic pollution is of great interest for wastewater purification. In this work, a sulfur vacancy-rich (α/β-CdS)/SiO (α: hexagonal & β: cubic) photocatalyst with a high catalytic activity was novelly synthesized on a nano-SiO carrier by the reaction of Cd with a CS storage material (CSSM) as sulfur source and crystalline modifiers. The dispersion of α/β-CdS on the nano-SiO carrier significantly enhanced the visible-light-driven catalytic activity of (α/β-CdS)/SiO photocatalyst, and 93.37 % rhodamine B (RhB) conversion was determined over 50 mg (α/β-CdS)/SiO photocatalyst for 30 mL 400 mg/L RhB solution at light intensity of 150 mW/cm and 298.15 K. After five cycle tests, the (α/β-CdS)/SiO photocatalyst still owned excellent visible-light-driven catalytic degradation stability (>90 %). The characterizations of morphology, functional groups, and photo-electrochemistry of (α/β-CdS)/SiO photocatalyst demonstrated that nano-SiO as a carrier played meaningful role in dispersing α/β-CdS and reducing agglomeration, thus increasing the active site of photocatalytic degradation reaction, and the presence of α/β hetero-phase junctions and sulfur vacancies allows the rapid separation of photo-generated carriers and inhibits photo-generated electron-holes recombination. Meanwhile, the electron paramagnetic resonance (EPR) and free radical masking test have also proved that the main active species is ·O for the oxidation of RhB. Therefore, the work is providing a new reference to the visible-light-driven degradation of wastewater with high RhB concentration at room temperature.