Designing advanced S‐scheme CdS QDs/La‐Bi2WO6 photocatalysts for efficient degradation of RhB

Abstract

Abstract Finding effective strategies to design efficient photocatalysts and decompose refractory organic compounds in wastewater is a challenging problem. Herein, by coupling element doping and constructing heterostructures, S‐scheme CdS QDs/La‐Bi2WO6 (CS/LBWO) photocatalysts are designed and synthesized by a simple hydrothermal method. As a result, the RhB degradation efficiency of the optimized 5% CS/LBWO reached 99% within 70 min of illumination with excellent stability and recyclability. CS/LBWO shows improvement in the adsorption range of visible light and promotes electron–hole pair generation/migration/separation, attributing the superior degradation performance. The degradation RhB mechanism is proposed by a free radical capture experiment, electron paramagnetic resonance, and high‐performance liquid chromatography‐mass spectrometry results, indicating that h+ and •O2– play a significant role during four degradation processes: de‐ethylation, chromophore cleavage, ring opening, and mineralization. Based on in situ irradiated X‐ray photoelectron spectroscopy, Mulliken electronegativity theory, and the work function results, the S‐scheme heterojunction of CS/LBWO promotes the transfer of photogenerated electron–hole pairs and promotes the generation of reactive radicals. This work not only reports that 5% CS/LBWO is a promising photocatalyst for degradation experiments but also provides an approach to design advanced photocatalysts by coupling element doping and constructing heterostructures.

Keywords

• CdS quantum dots
• density functional theory
• La‐Bi2WO6
• photocatalytic degradation
• S‐scheme heterojunction