ZnIn2S4 thin films with hierarchical porosity for photocatalysis

Abstract

Optimizing the activity of photocatalysts is of great interest for the chemical industry and the renewable energy sector. Zinc indium sulfide is a promising photocatalyst due to its absorption in the visible and UV range and its suitable energy levels. Immobilized heterogeneous catalysts, known for their ease of handling and integration into flow reaction systems, often suffer from low surface areas, limiting reaction sites. To address this, we combined microsphere lithography with a single-source precursor method using metal xanthates to fabricate zinc indium sulfide thin films with hierarchical porosity. The resulting films feature macropores around 300 nm and micropores of approximately 2 nm in diameter. This hierarchical porosity increases the surface area, providing more active catalytic sites and reducing charge transport distances. In dye degradation tests with Rhodamine B, the porous films exhibited specific photocatalytic activity over 3 times higher than for planar films and comparable dispersed powder systems reported in the literature. Our findings suggest that multiscale porosity is a promising strategy for enhancing the activity of photocatalysts.