2D TiO₂ Nanosheets Decorated Via Sphere-Like BiVO₄: A Promising Non-Toxic Material for Liquid Phase Photocatalysis...

An in-depth investigation was conducted on a promising composite material (BiVO₄/TiO₂), focusing on its potential toxicity, photoinduced catalytic properties, as well as its antibiofilm and antimicrobial functionalities. The preparation process involved the synthesis of 2D TiO₂ using the lyophilization method, which was subsequently functionalized with sphere-like BiVO₄ through wet impregnation. Finally, we developed BiVO₄/TiO₂ S-scheme heterojunctions which can greatly promote the separation of electron-hole pairs to achieve high photocatalytic performance. The evaluation of concentration- and time-dependent viability inhibition was performed on human lung carcinoma epithelial A549 cells. This assessment included the estimation of glutathione levels and mitochondrial dehydrogenase activity. Significantly, the BiVO₄/TiO₂ composite demonstrated minimal toxicity towards A549 cells. Impressively, the BiVO₄/TiO₂ composite exhibited notable photocatalytic performance in the degradation of rhodamine B (k=0.135 min^-1) and phenol (k=0.016 min^-1). In terms of photoinduced antimicrobial performance, the composite effectively inactivated both gram-negative E. coli and gram-positive E. faecalis bacteria upon 60 minutes of UV-A light exposure, resulting in a significant log 6 (log 10 CFU/mL) reduction in bacterial count. In addition, a 49 % reduction of E. faecalis biofilm was observed. These promising results can be attributed to the unique 2D morphology of TiO₂ modified by sphere-like BiVO₄, leading to an increased generation of (intracellular) hydroxyl radicals, which plays a crucial role in the treatments of both organic pollutants and bacteria. This research has significant potential for various applications, particularly in addressing environmental contamination and microbial infections.