Interface engineered cascade-type electronic structure of 2D/0D/2D CdS-CdCO₃/SnO₂ quantum dots/g-C₃N₄ nanocomposite for boosting solar-driven photocatalysis

A rational design of heterojunctions with high-quality contacts is essential for efficiently separating photogenerated charge carries and boosting the solar-driven harvesting capability. Herein, we fabricated a novel heterojunction of SnO₂ quantum dots-anchored CdS-CdCO₃ with g-C₃N₄ nanosheets as a superior photocatalyst. SnO₂ quantum dots (SQDs) with positively charged surfaces were tightly anchored on the negatively charged surface of CdS nanosheets (NSs). The resulting CdS@SnO₂ was finally decorated with g-C₃N₄ NSs, and a new crystalline phase of CdS-CdCO₃ was formed during the hydrothermal decoration process, g-C₃N₄ decorated CdS-CdCO₃@SnO₂ (CdS-CdCO₃@SnO₂@g-C₃N₄). The as-synthesized photocatalysts were evaluated for the degradation of methyl orange dye under solar light conditions. The CdS-CdCO₃@SnO₂@g-C₃N₄ exhibited 7.7-fold and 2.3-fold enhancements in photocatalytic activities in comparison to those of the bare CdS and CdS@SnO₂ NSs, respectively. The optimal performance of CdS-CdCO₃@SnO₂@g-C₃N₄ is primarily attributed to the cascade-type conduction band alignments between 2D/0D/2D heterojunctions, which can harvest maximum solar light and effectively separate photoexcited charge carriers. This work provides a new inspiration for the rational design of 2D/0D/2D heterojunction photocatalyst for green energy generation and environmental remediation applications.