First-principles study of the role of strain and hydrogenation on C3N

C3N has been synthesized recently and demonstrated to possess specific physical and chemical properties. In this work, we investigated the strain effect on it's electronic and phonon properties and on the adsorption property of Li atom through first-principles calculations. Phonon dispersions demonstrate that the crystal structure of C3N is dynamical stable under tensile strain up to 14%. Calculation results show that C3N is always an indirect gap semiconductor as the applied tensile strain is 0%–12% and the band gap reaches its maximum at strain = 9%. While when strain is 13% and 14%, C3N become metallic. Li atom prefers to occupy the C-C hexagonal sites on C3N surface with a diffusion barrier of 0.43eV and the adsorption energies of different adsorption configurations increase with strain. What's more, phonon dispersion calculations and ab initio molecular dynamics simulations reveal that the fully hydrogenated extension of C3N, C3NH3 has two stable conformations, in which one is an indirect semiconductor with band gap of 4.09eV while the other possesses a direct band gap of 2.88eV suitable for photocatalytic application. The strained and hydrogenated C3N with diverse structures and electronic properties provide new prospects in the applications of lithium ion batteries and photoelectrochemistry.