Synergistic microplastic degradation via Cu single atom-enhanced Janus BiOI/Fe₃O₄ microparticles with magnetic recyclability

Microplastic accumulation in water bodies is posing a serious threat to public health. Their chemical inertness impairs the effectiveness of current micro/nano-material-based remediation strategies. Especially in urban drinking water systems, microplastics constantly released and accumulated together with the complexity of pipeline networks challenges the recyclability and long-term stability of remediation materials and technology. To address this, Cu-single-atom magnetic Janus microparticles (CuMJMs) with flower-like crown morphology are engineered meticulously via a step-by-step strategy involving solvothermal growth and chemical deposition. The resulting CuMJMs feature a distinct Janus architecture composed of BiOI nanosheets and Fe 3 O 4 nanoparticles, thereby delivering synergistic magnetic and photocatalytic functionalities. When subjected to a rotating magnetic field, CuMJMs are able to locomote collectively and recover rapidly in confined microenvironments. The incorporation of atomically dispersed Cu single atom not only enhances the number of active sites, but also promotes the separation and migration of photogenerated charge carriers. Such abilities enable CuMJMs to degrade polyethylene (PE) efficiently, achieving a weight loss rate of 53.7 % beyond previous reports. This performance improvement is ascribed to singlet oxygen generation boosted by the Cu single atoms to facilitate oxidative degradation pathways, as supported by electron paramagnetic resonance and active species trapping test. While used in real water matrices, CuMJMs maintain both catalytic activity and magnetic responsiveness, underscoring their robustness and practical potential. This work establishes a new paradigm to active microplastic remediation, merging atomic-level catalytic precision with collective particle behavior to enable scalable and efficient environmental cleanup. • Cu Single Atom -decorated magnetic Janus microparticles (CuMJMs) are developed for efficient microplastic treatment. • The CuMJMs are fabricated via a scalable spray-coating and self-growth method. • Multifunctional Janus architecture enables simultaneous photodegradation and magnetic recovery. • Photodegradation mechanism enhanced by Cu single atoms is explored. • Efficient microplastic degradation is achieved and demonstrated with CuMJMs in real scenarios.