Solar-Light-Driven Improved Photocatalytic Performance of Hierarchical ZnIn₂S₄ Architectures

In the quest for developing novel narrow band gap semiconductor materials, the research in metal chalcogenides has gained a strong attraction. In the present investigation, a surfactant-free hydrothermal route has been followed to design hierarchical self-assembled flower-like ZnIn₂S₄ structures through control over precursor concentration and hydrothermal processing parameters. Uniform hexagonal marigold flower-like ZnIn₂S₄ architectures (∼4 μm) were formed with self-assembly of petals (thickness ∼8-12 nm) forming rose-like structures and finally forming marigold flowers in 24 h duration. The hierarchical ZnIn₂S₄ flower structure has been used as photocatalysts for the degradation of dye and chlorinated phenols. Photodegradation demonstrates that the high surface area from the porous flower architecture (∼72 m²/g) with an enhanced visible light absorption giving low band gap energy (2.15 eV) is responsible for higher photocatalytic performance. Complete degradation of the organic pollutants has been observed within 90 min in the presence of natural sunlight. To understand the participating reactive species contributing to degradation, scavenger studies were performed for deducing the plausible photocatalytic degradation pathways. This study might open new insights into the design of novel hierarchical structures.