▎ 摘　　要

Thermodynamic stability of graphene hydrides increases in an approximately linear way with the numbers of pi-bonds they contain. Thus, pi-bond maximization is the primary driving force for hydrogen addition reactions of graphene. The previously reported thermal preference of sp(2)/sp(3)-phase separation of graphene hydrides is a straightforward effect of pi-bond maximization. Although not well applicable to hydroxylation and epoxidation, the pi-bond maximization principle also holds approximately for the fluorination reactions of graphene. The findings can be used to help locate the lowest-energy structures for graphene hydrides and to estimate the hydrogenation energy without first-principles calculations.