Preparation of fully coated PEDOT: PSS film on MXene for high reliability capacitive deionization

MXene (Ti3C2Tx) is a promising CDI electrode material with two-dimensional (2D) layer, which performs excellent capacitance, conductivity, interlayer reversibility and plentiful active sites. However, Ti layer of MXene is easily oxidized to TiO2 by dissolved oxygen in water, which causes structural instability and affects its desalting performance. In this paper, the sandwich PEDOT:PSS@MXene film electrode was prepared by uniformly coating PEDOT:PSS film on the surface of MXene through template-assisted polymerization. The film improves the stability of the composite by protecting the Ti layer. The specific capacitance of PEDOT:PSS@MXene performs 185.5 F g(-1) at 5 mV s(-1). The desalination capacity of hybrid AC//PEDOT:PSS@MXene cell in 500 mg L-1 NaCl solution is 35.8 mg g(-1). After 40 desalting cycles, the cell performs better retention rate than AC//MXene cell (82.5 %), which keeps 97.2 %. The morphology and structure of composite show no exists of TiO2 after 40 desalting cycles, indicating that PEDOT:PSS as a coating film can achieve high reliability capacitive deionization of MXene.