Fuel cells, supercapacitors and lithium-ion batteries are the typical energy conversion and storage devices of great significance in which carbon-based nanostructures could play irreplaceable role.The functionalized carbon-based nanotubes/nanocages (CNTs/CNCs) could be applied to fuel cells to lower Pt loading by highly dispersing and immobilizing Ptbased nanoparticles, or to totally get rid of Pt with the metal-free electrocatalytic ability themselves.