2D/2D CoO/BiOCl nanocomposite with enhanced antibacterial activity under full spectrum: Synergism of mesoporous structure, photothermal effect and photocatalytic reactive oxygen species.

The overuse of antibiotics has caused the emergence of drug-resistant bacteria and even superbugs, which makes it imperative to develop promising antibiotic-free alternatives. Herein, a multimodal antibacterial nanoplatform of two dimensional/two dimensional (2D/2D) mesoporous CoO/BiOCl nanocomposite is constructed, which possesses the effect of "kill three birds with one stone": (1) the use of mesoporous CoO can enlarge the surface area of the nanocomposite and promote the adsorption of bacteria; (2) CoO displays remarkable full-spectrum absorption and photo-induced self-heating effect, which can raise the temperature of CoO/BiOCl and help to kill bacteria; (3) the p-type CoO and n-type BiOCl form a p-n heterojunction, which promotes the separation of photoelectrons and holes, thus producing more reactive oxygen species (ROS) for killing bacteria. The synergism of mesoporous structure, photothermal effect and photocatalytic ROS makes the developed CoO/BiOCl a promising antibacterial material, which shows outstanding antibacterial activity with an inhibition rate of nearly 100 % against Escherichia coli (E. coli) within 8 min. This work provides inspiration for designing multimodal synergistic nanoplatform for antibacterial applications.