Ti3C2Tx MXene@carbon dots hybrid microflowers as a binder-free electrode material toward high capacity capacitive deionization

Abstract

Owing to the exceptional electrical conductivity and high hydrophilic surface area, MXene is regarded as one of the most glaring capacitive deionization (CDI) electrode materials. However, the self-stacking of pure MXene nanosheets though van der Waals forces seriously hinders its electrochemical performance. Therefore, a novel pathway to prepare flexible and binder-free MXene@carbon dots (MXene@CDs) electrodes materials for CDI is presented, which was based on the electrostatic self-assembly between negatively charged Ti3C2Tx MXene and positively charged CDs. The 2D MXene nanosheets are bent with CDs and formed hybrid microflowers. This unique structure can reduce the self-stacking of MXene during film formation, accelerate ion transport and increase ion storage. The binder-free electrode MXene@CDs-2 shows an excellent deionization capacity of 86.4 mg/g in 10 mM NaCl solution. Moreover, the relativity low energy consumption (0.13 kWh/kg-NaCl) and high energy recovery (12.61%) are achieved. This strategy of combining zero-dimensional and two-dimensional nanomaterials to form microflowers can promote the performance of MXene-based CDI.