Two-dimensional Mo1.33C MXene with divacancy ordering prepared from parent 3D laminate with in-plane chemical ordering

TLDR

The exploration of two‑dimensional solids is an active area of materials discovery, encompassing structures from graphene to dichalcogenides and recently 2D transition metal carbides (MXenes). The study aims to master ordering within atomic sheets of MXenes. The authors use a top‑down, high‑yield, facile route that designs a parent 3D laminate (Mo₂/₃Sc₁/₃)₂AlC with in‑plane chemical ordering and selectively etches Al and Sc to produce 2D Mo₁.₃₃C sheets with ordered divacancies and high electrical conductivity. The resulting 2D Mo₁.₃₃C exhibits a volumetric capacitance of ~1,100 F cm⁻³, 65 % higher than vacancy‑free Mo₂C, ranking among the highest reported, and the atomic‑scale design may broaden property‑tailoring of 2D materials.

Abstract

Abstract The exploration of two-dimensional solids is an active area of materials discovery. Research in this area has given us structures spanning graphene to dichalcogenides, and more recently 2D transition metal carbides (MXenes). One of the challenges now is to master ordering within the atomic sheets. Herein, we present a top-down, high-yield, facile route for the controlled introduction of ordered divacancies in MXenes. By designing a parent 3D atomic laminate, (Mo 2/3 Sc 1/3 ) 2 AlC, with in-plane chemical ordering, and by selectively etching the Al and Sc atoms, we show evidence for 2D Mo 1.33 C sheets with ordered metal divacancies and high electrical conductivities. At ∼1,100 F cm −3 , this 2D material exhibits a 65% higher volumetric capacitance than its counterpart, Mo 2 C, with no vacancies, and one of the highest volumetric capacitance values ever reported, to the best of our knowledge. This structural design on the atomic scale may alter and expand the concept of property-tailoring of 2D materials.