An Eco-Friendly and Cost-Effective Strategy for the Synthesis of High-Purity MXene

Abstract

Conventional hydrofluoric acid (HF)-based etching methods have been widely utilized to synthesize MXene materials from the MAXPhase. This study explores the advantages of electrochemical etching to establish a new eco-friendly, cost-effective, facile, and time-saving etching process, and it has been developed with high purity compared to traditional chemical etching methods. The electrochemical etching is carried out using a less corrosive and cheaper electrolyte containing 1 M KCl-0.3 M KOH. By applying 5 V for 4 h at room temperature, we synthesized MXene. Moreover, by using MAXPhase pellets, uniform and efficient etching was achieved with an 80% yield. The synthesized MXene possesses the highest d-spacing value of 1.3 nm with single-layered nanosheets, and it is revealed by field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscope (HRTEM) to have several nanometers in lateral size compared to the early reports without affecting the core structure of Ti₃C₂T_x. The synthesized MXene possesses an electrical conductivity of 17831.66 S cm^–1. For the first time, MXene prepared by our electrochemical etching method has a slightly higher atomic % of –Cl terminal groups in addition to common –O and –OH terminal groups compared with MXene obtained earlier by electrochemical methods.