We prepared binder-free monoliths of carbon nanohorns(CNHs), hole-opened nanohorns (CNHoxs), multi-walled nanotube(MWCNT), and single-walled nanotube(SWCNT)using spark plasma sintering(SPS)method at 1800℃ 80 MPa in vacuum. The density the SPS-treated SWCNT is 1.8 g/cm3, which close to that graphite, while those CNHs, CNHoxs, MWCNT remained 1.1-1.3 g/cm3 even after SPS treatment. evaluated using...