In various embodiments, the present disclosure describes processes for preparing functionalized graphene nanoribbons from carbon nanotubes. In general, the processes include exposing a plurality of carbon nanotubes to an alkali metal source in the absence of a solvent and thereafter adding an electrophile to form functionalized graphene nanoribbons. Exposing the carbon nanotubes to an alkali metal source in the absence of a solvent, generally while being heated, results in opening of the carbon nanotubes substantially parallel to their longitudinal axis, which may occur in a spiralwise manner in an embodiment. The graphene nanoribbons of the present disclosure are functionalized on at least their edges and are substantially defect free. As a result, the functionalized graphene nanoribbons described herein display a very high electrical conductivity that is comparable to that of mechanically exfoliated graphene.