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

Abstract

In this work, the MXene Ti₃C₂ with excellent electrical conductivity is obtained by etching Ti₃AlC₂ with NH₄HF₂ solution. The electrosorption performance, the?electrochemical?and?physicochemical properties of as-prepared Ti₃C₂ are characterized. The results demonstrate that NH₄HF₂-etched Ti₃C₂ 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 Ti₃C₂. In addition, the desalination capacity of NH₄HF₂-etched Ti₃C₂ enhances 35.5% than that of HF-etched Ti₃C₂. When the initial conductivity of NaCl is ~?1000?μS/cm, the desalination capacity of NH₄HF₂-etched Ti₂C₃ electrode is 12.1?mg?g^?1, and the pseudo-first-order model can well describe the electrosorption kinetics of NH₄HF₂-etched Ti₃C₂ electrode. Furthermore, the regeneration performance of the NH₄HF₂-etched Ti₃C₂ electrode is excellent. This study indicates a new kind of effective electrode material to improve the desalination performance of capacitive deionization (CDI) technology.