Achieving Exceptional Volumetric Desalination Capacity Using Compact MoS 2 Nanolaminates.

Capacitive deionization (CDI) has emerged as a promising technology for freshwater recovery from low-salinity brackish water. It is still inapplicable in specific scenarios (e.g., households, islands, or offshore platforms) due to too low volumetric adsorption capacities. In this study, we report a high-density semi-metallic molybdenum disulfide (1T'-MoS 2 ) electrode with compact architecture obtained by restacking of exfoliated nanosheets, which achieved high capacitance up to ∼277.5 F cm -3 under an ultrahigh scan rate of 1000 mV s -1 with a lower charge-transfer resistance and nearly ten-fold higher electrochemical active surface area than the 2H-MoS 2 electrode. Furthermore, 1T'-MoS 2 electrode demonstrates exceptional volumetric desalination capacity of 65.1 mg NaCl cm -3 in CDI experiments. Ex-situ X-ray diffraction (XRD) reveal that the cation storage mechanism with the dynamic expansion of 1T'-MoS 2 interlayer to accommodate cations such as Na + , K + , Ca 2+ , and Mg 2+ , which in turn enhances the capacity. Theoretical analysis unveils that 1T' phase is thermodynamically preferable over 2H phase, the ion hydration and channel confinement also play critical role in enhancing ion adsorption. Overall, this work provides a new method to design compact two-dimensional layered nanolaminates with high volumetric performance for CDI desalination. This article is protected by copyright. All rights reserved.