Computational investigation of mechanical properties and adsorption behavior of sulfur-doped h-BN nanosheets

Doping h-BN surface with sulfur has been shown to enhance its efficiency in photocatalytic reactions. Here, using density functional theory calculations, the various configurations of S-doped h-BN were investigated in terms of their formation energy, mechanical properties, structural, thermodynamic, and electronic properties, as well as their ability to adsorb metal atoms and hydrogen molecule. The formation energy of S-doped h-BN surfaces is only slightly more positive compared to the pristine surface. The band gap energy experiences the most significant changes when an S atom replaces an N atom. At low temperatures, the pristine h-BN surface has a higher vibrational Gibbs free energy compared to S-doped h-BN surfaces, but at high temperatures, it exhibits a lower value. The bulk modulus of S-doped h-BN surfaces was found to range from 151.2 to 163.0 GPa. Additionally, the Poisson's ratio of the S_N surface was found to be 0.237, which is slightly higher than that of the h-BN surface. The evaluated in-plane hardness of S-doped surfaces ranges from 221.8 to 196.1 GPa. Investigation into the adsorption of transition metals (Mo, Zn, Cd), post-transition metals (Ga), and metalloids (Ge, Se) on both pristine and S-doped h-BN surfaces revealed significantly enhanced binding energies on the S-doped surfaces. The strongest interactions occurred with the s-doped surface decorated with Mo and Ge metals. Hydrogen dissociatively adsorbs on the S_N surface. Also, the hydrogen molecule binds more strongly to metal-decorated surfaces. The results show that the S-doping of h-BN surface improves its electronic characteristics and adsorption capability without significantly altering its mechanical properties.