Architectures of flower-like MoS2 nanosheet coated N-doped carbon sphere electrode materials for enhanced capacitive deionization

• Published in: Desalination 2022-10, Vol.540, p.115979, Article 115979
• Main Authors: Nguyen, Thi Kim Anh, Wang, Tzu-Heng, Doong, Ruey-an
• Format: Article
• Language: English
• Subjects: Capacitive deionization (CDI); CDI Ragone plot; Flow-like heterostructures; Modified Donna model; Molybdenum disulfide nanosheet (MoS2); N-doped carbon sphere (NCS)
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/j.desal.2022.115979

The development of promising nanomaterials for capacitive deionization (CDI) is an emerging energy-efficient technology for water recovery and purification. Herein, the nanoarchitecture of deposition of molybdenum disulfide nanosheets onto N-doped carbon sphere (MoS2@NCS) has been successfully developed using hydrothermal processes for CDI applications. The morphological and fine structural analyses clearly indicate that the hexagonal structure of MoS2 nanosheets are homogeneously dispersed onto the 300-nm NCS to form the flower-like MoS2@NCS heterostructure. After calcination for 2 h at 800 °C, the MoS2@NCS exhibits a large specific surface area of 82 m2 g−1 and interconnected meso-macroporous channels for rapid ion and electron transfer, resulting in the superior electrochemical behaviors with the specific capacitance of 340 F g−1 at 5 A g−1 in 1 M Na2SO4 solution. Moreover, the electrosorption performance of MoS2@NCS-800 was investigated under different conditions in terms of initial NaCl concentration and voltage, and the superior specific electrosorption capacity of 59.9 mg g−1 is obtained at 2000 mg L−1 NaCl and applied voltage of 1.4 V. The experimental data is then well-fitted with the modified Donnan model, signifying that the electrosorption performance is highly dependent on the formation of electrical double layers and homogeneous potential distribution throughout the diffuse layer of the porous electrodes. The excellent cyclic durability of MoS2@NCS electrode is also highlighted after 100 electrosorption-desorption cycles. These results elaborate that MoS2@NCS composites are promising electrochemical materials for CDI application, which can open a pathway to design the 2D/3D hybrid nanoarchitectures as a highly potential material for green and sustainable water purification and ion removal in grey and salty waters. [Display omitted] •The nanoarchitecture MoS2@NCS for the enhanced capacitive deionization (CDI) is well developed.•The enlarged meso-macropores of MoS2@NCS enhance adsorption and charge transfer rates.•The superior specific electrosorption capacity (SEC) of 59.9 mg g−1 is obtained.•The desalination mechanism of using MoS2@NCS and its stability in CDI are addressed.•The modified Donnan model can well explain the nechanism for superior CDI performances.