Simultaneous Desalination and Bacteria Inactivation via Synergistic MoS₂-ε-poly-L-lysine Nanocomposites in Capacitive Deionization

The coexistence of pathogenic bacteria and ionic contaminants in water resources poses significant threats to public health. Capacitive deionization (CDI) offers a promising approach to simultaneously address this dual purification challenge. Here, we present a novel CDI electrode material comprising molybdenum disulfide (MoS₂) nanosheets functionalized with the cationic antimicrobial peptide ε-poly-L-lysine (EPL) through electrostatic self-assembly. The MoS₂/EPL composite integrates the bactericidal properties of MoS₂ nanosheets and EPL, exhibiting synergistic disinfection through dual mechanisms. Physical membrane penetration occurs via the sharp edges of MoS₂, while direct contact killing is mediated by EPL. The optimized composite demonstrates exceptional desalination performance, including a significant salt adsorption capacity (53.94 mg g⁻¹) and robust regeneration stability over 20 cycles. Remarkably, the MoS₂/EPL electrode achieves ultra-efficient bacterial disinfection (>99.99%) against highly pathogenic-resistant bacteria. This efficacy is maintained in both laboratory settings and real lake water tests. Electrochemical analyses further confirm the superior capacitive behavior and cycling stability of the composite. This work presents the integration of antimicrobial peptides with two-dimensional nanomaterials for CDI systems, offering a scalable and resistance-resistant strategy to concurrently mitigate microbial hazards and ionic pollution in water purification.