In-situ sulfonated mesoporous silica as ZnO nanomaterial support for enhanced dyes photodegradation

• Mesoporous silica nanoparticles was synthesized from gelatin as low cost and environmentally materials • The addition of sulfonation process in mesoporous silica resulted to larger particle sizes • The sulfonation process enhance the degradation efficiency of 97.419% This study investigates the photocatalytic performance of sulfonated mesoporous silica impregnated with ZnO, focusing on its structural and functional properties. The ZnO crystal exhibited a dominant dimension of 14.627 nm with a crystallinity of 67.251%, while the sulfonated mesoporous silica sample demonstrated a remarkable ZnO growth of 22.156%. FTIR analysis identified key functional groups such as -CO₂, Si-O-Si, Si-OH, and sulfonation groups (S-OH, O=S=O), which were characterized by narrow absorption bands. SEM imaging revealed a well-defined rod-shaped morphology for the photocatalyst. The sulfonated mesoporous silica impregnated with ZnO exhibited a significantly higher surface area of 425.7 m²/g, in contrast to the 10.8 m²/g observed for pure ZnO. Band gap analysis indicated that the sulfonated silica impregnated with ZnO had a band gap of 5.69 eV, compared to the lower 3.20 eV of pure ZnO. Despite its smaller band gap, the photocatalytic activity of pure ZnO was limited due to particle agglomeration, which reduced its surface area and hindered active site accessibility. In contrast, the sulfonated mesoporous silica impregnated with ZnO maintained a high surface area and a uniform ZnO distribution, leading to improved photocatalytic performance. The composite material achieved a remarkable photocatalytic degradation efficiency of 97.419%, surpassing the performance of pure ZnO, which showed only 74.364% efficiency. The sulfonation process introduced sulfonic acid groups that enhanced the adsorption of methylene blue, while the mesoporous structure allowed for better accessibility of dye molecules to active sites. Over time, the degradation efficiency of the sulfonated mesoporous silica impregnated with ZnO showed consistent improvement, highlighting the critical role of its high surface area, uniform ZnO dispersion, and functional group contributions. Despite some fluctuations due to variations in crystallinity and particle size, the photocatalyst demonstrated superior stability and efficiency thus become a promising candidate for advanced photocatalytic applications.