Fabrication of oxygen vacancy-rich BiO2−x/multi-walled carbon nanotubes with enhanced photothermal catalytic antibacterial performance

Abstract

Photothermal catalytic sterilization technology is a promising approach due to its high efficiency, environmental friendliness, and stability. Herein, the composites of oxygen vacancy-rich BiO_2−x and multi-walled carbon nanotubes (BiO_2−x/CNTs) were prepared, and their photothermal bactericidal ability under near-infrared (NIR) light was investigated. The experimental results showed that the photothermal response of BiO_2−x was significantly improved after CNT combination. And the surface of the catalyst reached nearly 60 °C in a short time under NIR light irradiation. The photothermal catalytic activity of BiO_2−x/CNTs was tested with Escherichia coli as the target pathogen. It was observed that BiO_2−x/CNTs exhibited excellent sterilization effects, killing 99% of E. coli within three hours, which was attributed to the reactive oxygen species produced by the lattice oxygen release of BiO_2−x. The results of radical quenching experiment and electron paramagnetic resonance (EPR) indicated that the main active substance was a superoxide free radical (˙O₂⁻), which caused the complete irreversible death of E. coli K-12 by destroying the cell membrane function. The BiO_2−x/CNT catalyst showed excellent photothermal and bactericidal properties under NIR light, which provided a new idea for the application of solar-driven photothermal catalysis in bactericidal processes.