Direct Z-Scheme Xylan-Based Carbon Dots@TiO2-x Nanocomposites for Visible Light Driven Photocatalytic of Dye Degradation and Antibacterial

TiO 2 photocatalysis has gained attention as a cost-effective way of degrading contaminants. However, it relies on UV excitation and experiences rapid carrier recombination. To address these drawbacks, novel xylan-based carbon dots@hydrogenated TiO 2 (CDs@TiO 2-x ) composited by direct Z-scheme heterojunction is fabricated as a visible light-driven photocatalytic material, which broadens the range of light absorption to visible light and suppresses the recombination of photogenerated carriers. The spindle-shaped CDs@TiO 2-x has C/N/O/S groups, positive charges, and oxygen vacancies on its surface, and can degrade 89% of methylene blue and 87% of methyl orange within 90 min, and 99% of rhodamine B within 60 min in visible light. It also eradicates 99.9% of E. coli in 2 h and 97.1% of S. aureus in 2.5 h. These performances surpass CDs and TiO 2-x , and exhibit advantages in similar composite materials. The degradation pathways of dyes and the specific antibacterial processes induced by ROS are thoroughly investigated through LC-MS testing and related enzyme activity assays. DFT calculations study the role of oxygen vacancies, heterojunction mechanism, and catalytic sites. This study has developed a novel nanocomposite with applications in both dye degradation and sterilization, offering insights for multifunctional materials based on photocatalysis and heterojunction.