Comparative study on electrosorptive behavior of NH4HF2-etched Ti3C2 and HF-etched Ti3C2 for capacitive deionization

In this work, the MXene Ti 3 C 2 with excellent electrical conductivity is obtained by etching Ti 3 AlC 2 with NH 4 HF 2 solution. The electrosorption performance, the electrochemical and physicochemical properties of as-prepared Ti 3 C 2 are characterized. The results demonstrate that NH 4 HF 2 -etched Ti 3 C 2 possesses the better intercalation pseudo-capacity and the specific capacitance is up to 78 F∙g −1 , which is an increase of 34% than HF-etched Ti 3 C 2 . In addition, the desalination capacity of NH 4 HF 2 -etched Ti 3 C 2 enhances 35.5% than that of HF-etched Ti 3 C 2 . When the initial conductivity of NaCl is ~ 1000 μS/cm, the desalination capacity of NH 4 HF 2 -etched Ti 2 C 3 electrode is 12.1 mg∙g −1 , and the pseudo-first-order model can well describe the electrosorption kinetics of NH 4 HF 2 -etched Ti 3 C 2 electrode. Furthermore, the regeneration performance of the NH 4 HF 2 -etched Ti 3 C 2 electrode is excellent. This study indicates a new kind of effective electrode material to improve the desalination performance of capacitive deionization (CDI) technology.