Perspectives on Two-Dimensional Heterostructures: Pioneering the Future of High-Energy Supercapacitors

Abstract

Two-dimensional materials are a class of materials consisting of nanosized dimensions resembling thin sheetlike structures. Some trending 2D materials include metal–organic frameworks (MOF), MXenes, and hexagonal boron nitride (h-BN). MOFs belong to a new class of materials with numerous merits, such as uniform distribution of tunable pore size, ultrahigh porosity, accessibility of production, and structural alteration ability. Nevertheless, the insulating nature of MOFs is regularly recognized as a bottleneck factor in the expansion of their applications, specifically in the field of electronics. MXenes have been a recent boom in material science research. These sheetlike structures are produced by customizable etching of Al from Ti₃AlC₂. These new classes of materials have tremendous applications in energy storage, and hexagonal boron nitride is another emerging class of 2D materials. The utilization of 2D materials in supercapacitor electrodes has demonstrated enhanced electrochemical characteristics, including higher energy density, prolonged charging–discharging cycles, exceptional capacitive properties, and increased specific capacitance. This Review details the utilization of 2D MOFs, h-BN, and MXenes in supercapacitors. 2D MOFs and MXenes offer significant surface areas and a high proportion of surface atoms rich in redox activities, facilitating improved pseudocapacitive performance by enabling interactions with electrolyte ions. Additionally, the intercalation of 2D structures such as MXene, h-BN, and MOFs with other compounds, hybrid designs for additional electrochemical active sites, and suggestions for overcoming limitations are discussed in detail.