Defect Engineering: Synthesis and Electrochemical Properties of Two‐Dimensional Mo1.74CTz MXene

The creation of vacancies and/or pores into two‐dimensional materials, like graphene and MXenes, has shown to increase their performance for sustainable applications. However, a simple and affordable method with controlled and tailorable vacancy concentration and/or pores size remains challenging. Herein, a simple and reproducible method is presented for controlled synthesis of Mo 1.74 CT z MXene with randomly distributed vacancies and pores, obtained from selective etching of both Ga and Cr in the Cr‐alloyed MAX‐phase like precursor Mo 1.74 Cr 0.26 Ga 2 C. Structural and compositional analysis of the 3D alloy show ≈13% Cr on the metal site, homogeneously distributed between different particles and within the atomic structure. After etching, it translates to Mo 1.74 CT z MXene, exhibiting defect‐rich sheets. Notably, the incorporation of Cr facilitates a shorter etching time with an improved yield compared to Mo 2 CT z . The Mo 1.74 CT z MXene displays excellent electrochemical properties, almost doubling the capacitance values (1152 F cm −3 and 297 F g −1 at 2 mV s −1 scan rate), compared to its pristine counterpart Mo 2 CT z . The presented method and obtained results suggest defect engineering of MXenes through precursor alloying as a pathway that can be generalized to other phases, to further improve their properties for various applications.