Chemically exfoliated MoS2 for capacitive deionization of saline water

Capacitive deionization (CDI) is a promising technology for removal of ions from saline water upon applying a voltage between two electrodes. In this work, chemically exfoliated MoS2 (ce-MoS2) has been explored as electrode material for CDI. The ce-MoS2 nanosheets demonstrate a good cycling stability, high ion quality removal capacity of 8.81 mg/g, and ion volume removal capacity of 16.51 mg/cm3 at 1.2 V applied voltage in 400 mM NaCl solution. Comparison with that of carbon materials and bulk MoS2, the ce-MoS2 nanosheets remain good removal capacity even at a low concentration of 50 mM salt. These results suggest that ce-MoS2 can be a promising candidate for CDI. The sound performance of ce-MoS2 in CDI can be attributed to the unique two-dimensional (2D) thin sheet structure of 1 T phase. The large layer-to-layer space and sound electric conductivity help ion intercalation and ion transportation, and the abundant negative charges on the surface of ce-MoS2 sheets enhance the electrostatic attraction of ion.