DBS−-doped polypyrrole/CNTs with 3D conductive architecture connected with MoS2 as symmetrical electrodes for boosted CDI capability

Molybdenum disulfide (MoS 2 ), as an appealing Faradaic material for efficient capacitive deionization (CDI), is limited by unsatisfactory electrical conductivity, inferior removal rate, and restacking. Herein, we develop a CNT/PPy/MoS 2 ternary composite using a robust 3D conductive interconnected structure CNT/PPy, constructed from multi-walled carbon nanotubes (MWCNTs) and polypyrrole (PPy) doped with dodecyl benzene sulfonate (DBS - ), as the growing substrate to mitigate the aggregation of MoS 2 nanoflakes. In this design, CNT/PPy ameliorates the wettability of the composite, provides convenient movement pathways, a fast charge transport rate, and facilitates ions diffusion process. Moreover, reinforced dispersibility and enlarged interlayer spacing of MoS 2 nanoflakes supply sufficient embedded sites for ion uptake and rapid transfer. Meanwhile, tight chemical coupling of Mo-N-C bonds can maintain the structural integrity of the composite electrode. Particularly, the symmetrical electrode configuration was established to address the kinetical unbalance of HCDI system. Consequently, the CNT/PPy/MoS 2 displays a large specific capacitance of 160.83 F g −1 at 5 mV s −1 , which is nearly 4.33 times that of MoS 2 (37.17 F g −1 ). The optimized CNT/PPy/MoS 2 cell achieves a maximum desalination capacity of 24.8 mg g −1 , ultra-high deionization rate of 5.24 mg g −1 min −1 , and superior capacity retention rate of 92.7% over 25 cycles. In addition, Na + ions were captured by the joint action of cation-exchange of DBS - -doped PPy, electrostatic adsorption of CNTs, and intercalation reaction of MoS 2 . The proposed composite structural design and electrode configuration should be a potential avenue to realize highly efficient deionization.