Insight into the mechanism and toxicity assessment of a novel Co3O4/BiOBr p-n heterojunction driven by sunlight for efficient degradation of glyphosate

The environmental stresses posed by glyphosate, an organic phosphorus herbicide with inert CP and CN bonds, necessitate its effective degradation. Herein, we present a novel p-type Co3O4/n-type BiOBr heterojunction (COBB) photocatalyst as an efficient solution for this challenge. Owing to the built-in electric field as well as the synergistic matching band potentials of the p-Co3O4 and n-BiOBr, the COBB considerably enhances the separation efficiency and transfer rates of photogenerated carriers. As a result, it displays remarkable activity in degrading 16.9 mg/L of glyphosate under simulated sunlight with 88.5 % efficiency, outperforming both the pure Co3O4 and BiOBr by 51.8 and 3.3 times, respectively. In addition, COBB also demonstrates promising performance under natural sunlight and maintains a high level of stability in four cycles. Furthermore, intermediate product and toxicity analyses illustrate that the toxicity of glyphosate is greatly reduced in the COBB system. Altogether, this study provides renewed opportunities for the use of heterojunction photocatalysts in natural environments.