C3N monolayer decorated with single-atom Y for outstanding and reversible hydrogen storage: A DFT study

First-principles density functional theory (DFT) calculations were conducted to investigate the feasibility of single-atom Y decoration on the C3N monolayer and its consequent interactions with H2 molecules. The Y atom preferably and firmly dispersed over a hexatomic-carbon ring within the C3N monolayer, exhibiting a high binding energy of −5.124 eV. The Y atom decorated on the C3N monolayer demonstrated the capability to adsorb and store one to five H2 molecules through a typical Kubas interaction, featuring reasonable average adsorption energies ranging from −0.361 eV to −0.265 eV. All the adsorbed H2 molecules could be fully desorbed from the Y-decorated C3N at a temperature approximately reaching 500 K. Moreover, the single-atom Y on the C3N showcased a high diffusion energy of 1.976 eV, energetically preventing cluster effects of the dispersed Y atoms. Elevating the number of decorated Y atoms to four on each side of the C3N substantially improved the stored H2 to 40. Consequently, the hydrogen storage capacity of the C3N decorated with eight Y atoms surged to an impressive 6.76 wt% with a suitable average adsorption energy of −0.249 eV, meeting the requirements of the U.S. DOE. These results demonstrate that the Y-decorated C3N monolayer could be an excellent substrate for exhibiting outstanding and reversible hydrogen storage performance.