Preparation and photocatalytic properties of novel composite CdIn₂S₄/ZnIn₂S₄ heterojunction

Exploring efficient and stable photocatalysts is an ongoing pursuit in effective solar photocatalytic degradation of pollutants. Through a chemical coprecipitation method, CdIn₂S₄/ZnIn₂S₄ microspheres were synthesized and then further annealed at 500℃ to obtain a CdIn₂S₄/ZnIn₂S₄ heterojunction that showed greater degradation performances. Characterizations of the samples through SEM, XRD, XPS, BET and UV-Vis DRS determined that the heterojunction had the spherical appearance and typical mesoporous structure. The surface photocurrent response and EIS showed significantly enhanced catalytic activity. CdIn₂S₄/ZnIn₂S₄ heterojunction catalysts displayed the best photocatalytic activity in the degradation of methylene blue (MB) after 90 min of illumination, yielding a degradation rate of 96.7%. Enhancement of photocatalytic activity is attributed to the increase of visible light absorption and excellent separation ability of h⁺-e⁻ pair. A control experiment revealed that the active species •O₂ ⁻ played a significant role in the degradation process. Based on these findings, a mechanism for the photocatalytic degradation of pollutants via CdIn₂S₄/ZnIn₂S₄ heterojunction was predicted. The composite CdIn₂S₄/ZnIn₂S₄ heterojunction synthesized in this study has reference significance for the preparation of high-efficient photocatalytic materials, and shows its good practicability in the degradation of pollutants.