Structural phases and electrochemical properties of 2D MoS₂ for supercapacitor applications

Supercapacitors (SCs) are becoming popular as electrochemical energy storage devices because they have a high-power density, fast charge and discharge rates, and good cycling stability. The materials used in the electrodes have a big effect on how well supercapacitors work overall. Two-dimensional molybdenum disulfide (2D MoS₂) has gotten a lot of attention among a number of other electrode materials, such as carbon-based materials, metal oxides, and conducting polymers. This is mostly because of its layered structure, large surface area, and ability to change its electrical properties. MoS₂ shows strong links between structure and properties. The bulk form of MoS₂ has an indirect bandgap of about 1.2 eV, while the monolayer form has a direct bandgap of about 1.8 eV. This difference in bandgap affects how well it works in optoelectronic and electrochemical applications. MoS₂ also comes in different forms, such as the semiconducting 2H, the metallic 1T, and the rarer 3R. Each of these has its own unique atomic structure. Alkali metal intercalation, mechanical strain, or doping with elements like Re, Tc, or Mn can cause phase changes from 2H to 1T. This makes the material more conductive and improves the performance of supercapacitors. This review thoroughly examines recent advancements in phase engineering and the electrochemical performance of 2D MoS₂-based supercapacitor electrodes, highlighting the effects of intrinsic modifications (phase engineering) and extrinsic modifications (composite formation) on the charge-storage characteristics of MoS₂.