Hydroxy double-walled carbon nanotubes are extensively used in the field of nanotechnology and materials science due to their unique structural and mechanical properties. They are commonly employed as reinforcing agents in composite materials to enhance strength, durability, and conductivity. These nanotubes are also utilized in the development of advanced sensors, where their high surface area and functional groups improve sensitivity and selectivity. In the energy sector, they play a crucial role in the fabrication of supercapacitors and batteries, offering improved charge storage and transfer capabilities. Additionally, their application in drug delivery systems is notable, as they can be functionalized to carry therapeutic agents directly to targeted cells, minimizing side effects and improving treatment efficacy. In environmental science, they are used for water purification and pollutant removal, leveraging their adsorption properties to capture harmful substances.