First principles density functional theory (DFT) calculations have been performed to explore the stability, structural and electronic properties of Be and S codoped
graphene sheets. The band-gap of graphene has been tuned by co-doping with beryllium and sulphur at different sites. The results show that by codoping
graphene with Be and S, the band-gap increases from zero up to 0.58 eV depending on the doping sites. The cohesive and the formation energies of
the systems were also determined. All the isomers formed by exploring different doping sites differ notably in stability, bond length and band-gap.
Nevertheless, the planar structure of all the systems investigated was preserved even after geometry optimisation. Majority of the isomers that correspond
to co-doping at non-equivalent sites favour higher band-gap opening, but lesser stability, than the other set of isomers with equivalent doping sites. Bader
charge analysis was adopted to account for charges distribution in the systems. As a result of the difference in electronegativity among carbon atoms and
the impurities, it was observed that electrons accumulation occurred more on the carbon atoms in the proximity of Be and S than at any other position in
the graphitic systems investigated.