The Origin of BC₇ Sheet Metallicity and the Tuning of its Electronic Properties by Hydrogenation

Using first-principles calculations, we investigate the structural, electronic and hydrogenated properties of the hexagonal BC₇ sheet. The computed energy bands and density of states indicate that the BC₇ sheet is a metal, and its metallicity mainly originates from the non-bonding p_z electrons of the diagonal carbon of the B atom. When these carbon atoms are fully passivated by H atoms, the BC₇ sheet becomes a semiconductor with a band gap of 2.41 eV. Our studies demonstrate that changing both the proportion of the boron atoms in the boron carbon sheet and its hydrogenation can tune the electronic properties of boron carbon two-dimensional material.