3D heterostructure constructed by ion-doped polypyrrole coupled with MoS2@HCS and its highly efficient deionization performance

Capacitive deionization (CDI) is a hopeful alternative method in treating brackish water with low salt concentration. Molybdenum disulfide (MoS2) 2 ) has attracted widespread attention as a typical two-dimensional intercalation material, but its easy stacking structure and low conductivity greatly limit its practical application in CDI. This paper developed well-dispersed MoS2 2 nanosheets tightly attached to hollow carbon spheres (HCS), and the DBS-- ion doped polypyrrole (PPy-DBS) was coated on the surface of MoS2. 2 . HCS makes MoS2 2 nanosheets have improved dispersion and increased layer spacing which provide enough active sites for ion intercalation and transfer. Furthermore, the PPy-DBS provides a convenient electron transport path, accelerates ion transport, ensures good electrical conductivity and reduces ion diffusion resistance.The resulting PPy-DBS-MoS2@HCS 2 @HCS has a specific capacitance (168.77 F g- 1 ) which is 2.32 times that of MoS2 2 (72.9 F g-- 1 ). In addition, in 1.2 V, 500 mg L- 1 NaCl solution, the asymmetric CDI cell HCS//PPy-DBS-MoS2@HCS 2 @HCS displays an extremely high desalting capacity (53.4 mg g- 1 ) that is 2.9 and 2.4 times higher than HCS//MoS2 2 (18.3 mg g- 1 ) and HCS//MoS2@HCS 2 @HCS (22.3 mg g-- 1 ), respectively. Therefore, this unique 3D heterostructure (PPy-DBS-MoS2@HCS) 2 @HCS) provides a viable strategy for the development of CDI electrode materials.