Tailoring the capability of carbon nitride (C3N) nanosheets toward hydrogen storage upon light transition metal decoration

To nurture the full potential of hydrogen (H-2) as a clean energy carrier, its efficient storage under ambient conditions is of great importance. Owing to the potential of material-based H-2 storage as a promising option, we have employed here first principles density functional theory calculations to study the H-2 storage properties of recently synthesized C3N monolayers. Despite possessing fascinating structural and mechanical properties C3N monolayers weakly bind H-2 molecules. However, our van der Waals corrected simulations revealed that the binding properties of H-2 on C3N could be enhanced considerably by suitable Sc and Ti doping. The stabilities of Sc and Ti dopants on a C3N surface has been verified by means of reaction barrier calculations and ab initio molecular dynamics simulations. Upon doping with C3N, the existence of partial positive charges on both Sc and Ti causes multiple H-2 molecules to bind to the dopants through electrostatic interactions with adsorption energies that are within an ideal range. A drastically high H-2 storage capacity of 9.0 wt% could be achieved with two-sided Sc/Ti doping that ensures the promise of C3N as a high-capacity H-2 storage material.