MXenes and Their Hybrids with Graphene for Energy Storage

2D carbides, nitrides, and carbonitrides of early transition metals known as MXenes are the most chemically and structurally diverse family of inorganic materials discovered this century. MXenes are among the few nanomaterials that have jumped into the limelight not only because of their exotic structure or attractive properties but also because of numerous practical applications [1]. The family of MXenes has been expanding rapidly since the discovery of Ti₃C₂ at Drexel University in 2011. IUPAC listed MXenes among its Top 10 emerging technologies in chemistry with a true potential to transform our world in 2024. The availability of solid solutions on M and X sites, multi-element high-entropy MXenes, control of surface terminations, and the discovery of out-of-plane ordered double-M o-MXenes (e.g., Mo₂TiC₂), as well as in-plane ordered i-MAX phases and their i-MXenes offer the potential for producing an almost infinite number of new 2D materials. Still, other materials like graphene and its derivatives offer properties that complement the properties of MXenes. Their hybridization in electrode structures can lead to unique multifunctional materials for structural energy storage, current-collector-free batteries, supercapacitors capable of operating under extreme conditions, etc. This presentation will describe the state of the art in synthesizing MXenes, their delamination into single-layer 2D flakes, and assembly into MXene and MXene-graphene electrode films [2-4]. The versatile chemistry of the MXene family renders their properties tunable for a large variety of energy-related applications.

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