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

To nurture the full potential of hydrogen (H2) as a clean energy carrier, its efficient storage under ambient conditions is of great importance. Owing to the potential of material-based H2 storage as a promising option, we have employed here first principles density functional theory calculations to study the H2 storage properties of recently synthesized C3N monolayers. Despite possessing fascinating structural and mechanical properties C3N monolayers weakly bind H2 molecules. However, our van der Waals corrected simulations revealed that the binding properties of H2 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 H2 molecules to bind to the dopants through electrostatic interactions with adsorption energies that are within an ideal range. A drastically high H2 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 H2 storage material.