▎ 摘　　要

We demonstrate two unusual electronic properties of semihydrogenated graphene with variable sized A- or B-hydrogenated domains within the tight-binding formalism as follows: (i) a universal band gap scaling law which states that the band gap depends linearly upon the ratio of the number of A- to B-hydrogenated atoms, N-A/N-B, reaching zero gap at N-A=N-B, but independent of the domain size, and (ii) an insulating state with zero band gap at N-A=N-B, a rare phenomenon in nature. We confirm this gapless insulator state by the zero optical conductance at low frequencies. (C) 2010 American Institute of Physics. [doi:10.1063/1.3469941]