Fig. 1: Schematic representation of the degradation of (3,1)-chGNRs exposed to air and the prospective protection strategy by controlled hydrogenation.
From: Circumventing the stability problems of graphene nanoribbon zigzag edges

Hydrogenation of the most reactive carbon atoms at the centre of each zigzag segment14 would confer on the ribbons two extra Clar sextets (marked in grey) per unit cell; these are typically associated with larger bandgaps and increased stabilities.