An investigation on the thermo-mechanical properties of boron-doped g-C3N4

Abstract

Graphitic carbon nitride (g-C3N4) has been receiving special attention because of its significant physical properties and wide application areas. In this study, using molecular dynamics (MD) simulations, the mechanical properties and thermal conductivity (TC) of boron (B)-doped g-C3N4 (B-g-C3N4) were systematically investigated for two different cases. In the first case, B atoms were substituted at five specific (C1, C2, N1, N2, and N3) sites. The results of MD simulations indicated that when the B-doping concentration was increased, the mechanical properties of B-g-C3N4 at the C2 site improved. However, other B-doping sites did not show a positive effect on the mechanical properties of g-C3N4. In addition, the TC of B-g-C3N4 at these sites decreased by increasing the B concentration of B doping. When both results were evaluated, B-g-C3N4 at the C2 site was found to be the most mechanically and thermodynamically favorable site, whereas B doping at the N3 site the most unfavorable. In the second case, B atoms were occupied at three specific (B1, B2, and B3) sites in the open hollow of g-C3N4. The results of this study showed that the mechanical properties of B-g-C3N4 at these sites improved with the increasing B concentration. However, the TC of B doping at the B2 site of the g-C3N4 decreased. In addition, the TC of B-g-C3N4 at the B1 and B3 sites showed similar behavior, and also the variation in the TC between these two sites and undoped g-C3N4 indicated a small change with the increasing B concentration. The results of MD simulations of both situations demonstrated that the location of the B3 site was the most suitable B-doping site for the mechanical properties and TC of g-C3N4. On the other hand, the most thermodynamically and mechanically unfavorable site was specified as B2. The results of this study may be considered helpful for future works of mechanical and thermal management of B-carbonitride materials.