Double-walled carbon nanotubes (DWNTs) are widely used in electronics due to their excellent electrical conductivity and mechanical strength. They are incorporated into transistors, sensors, and conductive films, enhancing device performance and durability. In energy storage, DWNTs serve as key components in lithium-ion batteries and supercapacitors, improving charge capacity and cycle life. Their high surface area and thermal stability make them ideal for hydrogen storage and fuel cell applications. In composite materials, DWNTs reinforce polymers, metals, and ceramics, resulting in lightweight yet strong materials for aerospace, automotive, and construction industries. Additionally, DWNTs are utilized in biomedical applications, such as drug delivery systems and biosensors, due to their biocompatibility and ability to penetrate cell membranes. Their unique properties also enable their use in environmental applications, including water filtration and pollutant adsorption.