Visible-light-driven dye degradation using a floriated ZnIn2S4/AgIn5S8 heteromicrosphere catalyst

Abstract

We report the synthesis of ZnIn₂S₄/AgIn₅S₈ (ZIS/AIS) heteromicrospheres with tailorable composition and controllable band gap via partial cation exchange for the first time. Detailed studies of the as-prepared samples were carried out using SEM, TEM, STEM-EDS, XRD and layer-by-layer depth XPS analysis. Based on these results, possible cation exchange was proposed, and a critical concentration of Ag⁺ in the crystals was identified, below which cation exchange cannot occur. Besides, an enhanced photodegradation mechanism was discussed by analyzing the UV-vis-NIR reflectance spectra and the band structure, illustrating that an appropriate thickness of the AIS layer is beneficial to the generation of active species thus favoring the degradation reaction. Further application of dye degradation demonstrated a remarkable photodegradation rate up to 99.2%. Our results shed light on how the cation exchange occurs between ternary and binary crystals, which may open a new avenue to the field for synthesizing materials at the micro-scale.