Novel Cd0.5Zn0.5S/Bi2MoO6 S-scheme heterojunction for boosting the photodegradation of antibiotic enrofloxacin: Degradation pathway, mechanism and toxicity assessment

The artificial S-scheme photocatalysis system, mimicking natural photosynthesis, has shown eminent potential for the photocatalytic destruction of pharmaceuticals and personal care products (PPCPs). Here, S-scheme heterostructures were fabricated by coupling Cd0.5Zn0.5S nanoparticles and Bi2MoO6 microspheres as efficacious photocatalyst for antibiotic oxidation. The optimum Cd0.5Zn0.5S/Bi2MoO6 attains the highest enrofloxacin degradation efficiency of 76.3 % within 40 min, with a significant promotion of 1.8 and 2.6 folds compared to Cd0.5Zn0.5S and Bi2MoO6, respectively. The integration of Cd0.5Zn0.5S with Bi2MoO6 to gain the Cd0.5Zn0.5S/Bi2MoO6 S-scheme heterojunction can availably achieve the effective spatial photo-carrier dissolution and optimize the photo-redox capacity, leading to the significant optimization of photocatalytic performance and stability. The primary reactive species, enrofloxacin degradation pathways and photocatalysis mechanism were illustrated basing on the scavenging tests, ESR characterization, and the HPLC-MS analyses etc. The computational toxicology analysis unravels the weakened bio-toxicity of most intermediates than parent enrofloxacin. Significantly, it also manifests a preeminent catalytic efficacy for annihilating enrofloxacin in authentic water systems, manifesting its vast potential for annihilating PPCPs. This study underlines the impetus of S-scheme heterojunction fabrication and hierarchical heterostructure configuration for the development of high-performance photocatalysts for efficient purification of PPCPs.