Exploring the Influence of Etching media on the Electrochemical Behavior of Cr₂CT_x MXene

Abstract MXenes, a class of 2D materials, have garnered significant attention for energy applications due to their unique properties. This study investigates the influence of different etching media on the synthesis of 2D Cr₂CT_x MXene derived from cost‐effective Cr₂AlC MAX phase. Three etching solutions‐ hydrofluoric acid (HF), HF‐forming (lithium fluoride + Hydrochloric acid, LiF+HCl), and non‐fluoride (sodium hydroxide, NaOH) have been used to treat ternary carbide Cr₂AlC MAX phase under varied reaction conditions. The MXenes, Cr₂CT_x‐HF, Cr₂CT_x‐LiF/HCl, and Cr₂CT_x‐NaOH are structurally, and morphologically characterized using XRD, Raman spectroscopy, TGA, XPS, SEM‐EDX, and BET‐BJH analysis. The electrochemical performance of Cr₂CT_x MXene is assessed, focusing on its performance in water splitting and supercapacitive applications. The materials exhibit lower overpotential values for hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and demonstrate improved pseudocapacitive behavior, with enhanced energy and power densities. The introduction of surface termination groups in Cr₂CT_x MXene (T_x = ─F, ─OH, ─O) resulted in a more open and accessible layered structure with an appreciable surface area, without any modifications. This enhanced electrochemical kinetics, improved ion transport, diffusion, and storage capacity, which are beneficial for electrochemical energy storage and production.