Catalyst-Free In Situ Carbon Nanotube Growth in Confined Space via High Temperature Gradient

Morphology and microstructure of the CR-wood and CL-wood. (a, b) Schematic indicating the two types of wood pieces obtained by slicing wood bricks along the radial or longitudinal directions before and after carbonization at 1000°C. (c-f) SEM images of CR-wood (c, d) and CL-wood (e, f) prove that the vessel structures are well maintained after the carbonization process.