Constructing a hierarchical MoS2/MXene heterostructure for efficient capacitive deionization of saline water

Abstract

Well-dispersed and few-layered molybdenum disulfide (MoS2) has been considered as a suitable electrode material for pseudocapacitive capacitive deionization (CDI) due to its lamellar structure, flexible interlayer intercalation, and high theoretical capacity. However, the serious aggregation, low electrical conductivity and poor hydrophilicity of MoS2 have limited its desalination application. To address these issues, few-layered MXene is used as a conductive and hydrophilic skeleton to support MoS2 nanosheets. In this study, a hierarchical MoS2/MXene heterostructure is fabricated for highly efficient CDI of saline water. The designed heterostructure effectively inhibits the agglomeration of MoS2 and MXene nanosheets, exposes more active electrochemical sites, and improves the wettability, thereby enhancing ion/charge transport. The MoS2/MXene heterostructure electrode exhibits low electrical resistance (3.2 Ω), along with a high specific capacitance of 171.8 F·g-1 at 2 A·g-1. Furthermore, the MoS2/MXene-based CDI electrode demonstrates an excellent desalination capacity of 55.8 mg·g-1 and a fast desalination rate of 13 mg·g-1·min-1. This study paves the way for novel applications in the CDI field.