Using DFTB method to investigate the magnetic and electronic properties of two-dimensional graphitic carbon nitride

2D graphitic carbon-nitride (C_xN_y) has drawn significant interest in recent years. It consists of a porous structure made from carbon and nitrogen covalently bonded. In particular, s-triazine and tri-triazine graphitic carbon nitride (g-C₃N₄) 2D materials have been successfully synthesized and they show fascinating characteristics. Moreover, defect formation was observed in graphitic carbon nitride and the properties were tailored by controlled defect formation.

Here, a detailed study of the effect of different types of defect creation, defect passivation by hydrogen and oxygen, and iron adsorption on the structure, electronic, and magnetic properties of g-C₃N₄ is conducted by using the density functional tight-binding method (DFTB) method based on the extended tight binding (xTB) Hamiltonian. We found that magnetism can be turned on by defect creation, hydrogen/oxygen passivation of the defects, and Fe adsorption. It is also shown that passivation leads to a semiconductor behavior with a band gap value higher than the bare C₃N₄ material.