Boosting Capacitive Deionization in MoS₂ via Interfacial Coordination Bonding and Intercalation-Induced Spacing Confinement

Abstract

Capacitive deionization (CDI) is a green and promising technology for seawater desalination, with its capacity and industrial application being severely hindered by efficient electrode materials. Layered molybdenum disulfide (MoS₂) has garnered significant attention for CDI applications, while its performance is hampered by weak surface hydrophilicity, high interfacial resistance, and sluggish electron transport. Herein, we introduce an interfacial and intercalation dual-engineering strategy by covalently functionalizing the hydrophilic pyridine groups within the 1T-MoS₂ layer (Py-MoS₂); an electron-rich interface with an expanded interlayer spacing has been achieved synergistically. A state-of-the-art high desalination capacity of 43.92 mg g^-1 and exceptional cycling stability have been achieved, surpassing all of the reported existing MoS₂-based CDI electrodes. Comprehensive characterization and theoretical modeling reveal that covalently engineered pyridine groups enhance ion affinity via interfacial coordination, accelerate charge transfer, and expand ion-accessible sites within the MoS₂ interlayer spacing through intercalation-induced structural modulation. These synergistic effects dramatically boost the ion adsorption kinetics, mass transfer efficiency, and salt ion uptake capacity within Py-MoS₂ for CDI application. Our work presents an interfacial and intercalation dual-engineering strategy to promote the seawater desalination of 2D materials, paving new insights for next-generation high-performance CDI electrode development.