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

Abstract 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.