Self-assembled Co-doped β-Bi2O3 flower-like structure for enhanced photocatalytic antibacterial effect under visible light

A series of β-Bi2O3 with different Co doping amounts were prepared by a co-precipitation and pyrolysis process. A flower-like self-assembly of β-Bi2O3 sheets was realized by the doping of Co. Simulation results showed that an impurity state was introduced into the band gap of doped β-Bi2O3, mainly due to the Co 3d orbital. Co doping enhanced the visible light utilization rate by reducing the band gap and improving electrons holes separation efficiency. E. coli was used to evaluate the photocatalytic antibacterial ability of undoped and Co-doped β-Bi2O3 under visible light. β-Bi2O3 exhibited optimal efficiency for both electron-hole separation and antibacterial effect when doped with 0.4% Co (0.4%-CBO). Gradient experiments were performed to determine that reactive oxygen species (ROS) were the main factor behind the antibacterial effect of β-Bi2O3. The enhanced antibacterial properties of 0.4%-CBO were due to its increased production of O2–, OH, and H2O2, with scavenger experiments finding that O2– was the main contributor to its antibacterial effect. Through the detection of lipid peroxidation and bacterial respiratory chain dehydrogenase activity, it was determined that the antibacterial effect of ROS simultaneously occurred in the interior and exterior of E. coli and that this activity was enhanced by Co doping.