Few-Layer ZnIn 2 S 4 /Laponite Heterostructures: Role of Mg 2+ Leaching in Zn Defect Formation.

Designing nanostructures with extended light absorption via defect engineering is a useful approach for the synthesis of efficient photocatalysts. Herein, ZnIn ₂ S ₄ was grown hydrothermally in the modified interlayer space of Laponite, resulting in lamellae consisting of Zn-defective ZnIn ₂ S ₄ several unit cells thick. In the process it was found that Mg ²⁺ leached from Laponite during synthesis led to the formation of Zn defects in ZnIn ₂ S ₄ . This resulted in nanohybrids with light absorption extended across the visible spectrum and in improved charge transfer due to the layered structure formed via confined growth. Compared with pure ZnIn ₂ S ₄ , Zn-defective ZnIn ₂ S ₄ -Laponite hybrids have increased photocurrent generation and photocatalytic performance. The leaching of Mg ²⁺ and the resulting formation of Zn defects was attenuated by addition of 4 mM Mg ²⁺ to the reaction, due to a combination of shifting of the equilibrium of Mg ²⁺ leaching toward stability, and increased ionic strength. In summary, this work demonstrates the growth of ∼1 nm thick lamellae of ZnIn ₂ S ₄ , presents a unique strategy to generate cation defects in nanomaterials and the mechanism behind it, and also provides an approach to mitigate Mg ²⁺ leaching in such syntheses.