Sunflower-disc-inspired vertical growth of 2D ZnIn2S4 on ultra-thin TiO2: Constructing a 3D porous photocatalytic glass film for ultra-efficient organic pollutant degradation

Thin-film catalysts show immense potential for photocatalytic applications due to their versatility and ease of recovery. However, their stability is often compromised by detachment and poor surface utilization. In this study, inspired by the architecture of sunflower discs, we present a novel 3D porous photocatalytic film by vertical growth of 2D ZnIn2S4 on ultra-thin TiO2/glass for ultra-efficient degradation of organic pollutants. Crucially, ZnIn2S4 nanosheets were vertically grown on the stable TiO2/glass substrate to form a 3D porous structure, and the vertical growth mechanism is demonstrated by DFT. In contrast, when directly grown on glass, only aggregated ZnIn2S4 spheres formed. The enhanced surface area of the 3D ZnIn2S4 structure allows for maximum light absorption, while the rapid separation and transfer of photogenerated charges follow a Z-scheme charge transfer mechanism in the ZnIn2S4/TiO2 heterojunction. This synergy significantly improves the photocatalytic performance, surpassing most previously reported semiconducting films.