Fully coated WS2 antioxidant film with mesoporous structure for enhancing the structural stability and CDI performance of Mxene

Two-dimensional (2D) layer material MXene (Ti3C2Tx) is a promising electrode material in capacitive deionization (CDI) because of its advantages of large capacitance, high conductivity and abundant active sites. However, MXene nanosheets have a large number of metastable metal atoms, which are easy to react with dissolved oxygen and form metal oxides, resulting in structural instability and attenuation of electrochemical performance of MXene. Moreover, the inherent defects of MXene layered structure that are easy to stack, seriously limiting its application in CDI. In this paper, MXene fully coated by WS2 antioxidant film with mesoporous structure was designed and successfully prepared by hydrothermal method to form a 3D mutually supported heterostructure, so as to improve the structural stability and CDI performance of MXene. The heterostructure performs abundant mesoporous, excellent electrical conductivity, good hydrophilicity and excellent cyclic stability. Therefore, the WS2@MXene composite demonstrates high specific capacitance (217.0 F g−1) and retention rate of 90.51 % after 1000 GCD cycles. The hybrid AC//WS2@MXene cell composed of AC anode and WS2@MXene cathode shows excellent desalination capacity (39.1 mg g−1). The retention rate of the cell is still 94.9 % after 40 desalting cycles, which is better than that of AC//MXene cell (84.4 %).