Hydrophilic MoS2/polydopamine (PDA) nanocomposites as the electrode for enhanced capacitive deionization

[Display omitted] •A series of MoS2/polydopamine nanocomposites were facilely prepared.•The incorporation of PDA rendered MoS2/polydopamine nanocomposites the better water wettability.•MoS2/PDA-4 exhibited the highest specific capacitance, lowest inner resistances and best electrochemical stability.•MoS2/PDA-4 exhibited a highly enhanced desalination performance compared to original MoS2. Because of its special architectures and excellent capacitive property, molybdenum disulfide (MoS2) showed great potential in electrochemical-related applications. Nevertheless, the poor water wettability remains one of the primary weaknesses of MoS2 for its application in capacitive deionization (CDI). In this work, MoS2 was facilely modified by hydrophilic polydopamine (PDA) in a self-polymerization pathway to ameliorate the wettability of MoS2. With the soak time being carefully adjusted, MoS2 modified by PDA for 4 h (MoS2/PDA-4) could exhibit not only lower inner resistances due to its better wettability, but also much higher specific capacitance because of the incorporation of electroactive PDA compared to original MoS2, resulting in the enhanced electrosorption rate (less than 9 min) and desalination capacity (14.80 mg/g). Moreover, the electrochemical stability of MoS2/PDA-4 guaranteed the nanocomposites a good regenerability. The results suggested the MoS2/PDA-4 electrodes a promising material for CDI device.