Study on the synergistic enhancement of photocatalytic degradation of carbendazim by Co-doped BiOBr induced spin polarization and OVs

Abstract

Bismuth bromide oxide (BiOBr) has been widely used in water purification areas due to its unique layered structure, suitable bandgap value and excellent photocatalytic performance. In this work, a Co doped BiOBr (Co–BiOBr) photocatalyst was successfully synthesized using the solvothermal method, and the photocatalytic performance of Co–BiOBr was studied by photocatalytic degradation and mineralization of pesticide carbendazim (CBZ). The effects of the Co doping amount, Co–BiOBr dosage, concentration and pH of pesticide CBZ aqueous solution and common inorganic anions on the photocatalytic degradation performance of CBZ were deeply studied. The results showed that 5% Co–BiOBr exhibited an excellent photocatalytic performance under conditions of xenon lamp (350–780 nm) irradiation when the pH is 7 and the concentration of the CBZ pesticide aqueous solution is 10 mg L⁻¹. After 90 minutes of photocatalytic degradation, the degradation efficiency and TOC removal efficiency of CBZ reached 92.1% and 88.1%, respectively. Additionally, the degradation efficiency of CBZ reached 82.1% even after being reused 4 times. The crystal structure of 5% Co–BiOBr remained almost unchanged after reuse, indicating excellent photocatalytic performance and stable structure. Meanwhile, through free radical capture experiments and ESR analysis, it was demonstrated that h⁺, ˙O₂⁻ and ¹O₂ free radicals played an extremely important role in the photocatalytic degradation of CBZ pesticides with 5% Co–BiOBr. Finally, based on the DFT calculation results and combined with the analysis of the catalyst's morphology, specific surface area, optical properties, and active free radicals, the mechanism of enhanced photocatalytic performance of 5% Co–BiOBr was revealed.