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Searching advanced materials with high capacity and efficient reversibility for hydrogen storage is a key issue for the development of hydrogen as a clean energy. Here, we have explored the potential application of C 2 N monolayer using as a promising material for hydrogen storage through a comprehensive density functional theory (DFT) investigation. Our calculational results indicate that hydrogen molecule can only form weak interaction on neutral C 2 N monolayer with the adsorption energy of 0.06 eV. However, if extra charges (5 e − ) are introduced to the system, the adsorption energy of hydrogen molecule on C 2 N will be dramatically enhanced to 0.27 eV. Moreover, once the extra charges are moved from the system, the adsorbed hydrogen molecule will be spontaneously released from C 2 N monolayer without any barrier. Interestingly, the average adsorption energy for each of the 48 absorbed H 2 molecules is 0.28 eV with the charge injection (8 e − ). This adsorption energy meets the criterion of the Department of Energy (DOE) for hydrogen storage (0.2–0.6 eV). Moreover, C 2 N has a high hydrogen storage capacity of 10.5 wt %. Overall, this investigation demonstrates that the new fabricated C 2 N can be used as an efficient material for hydrogen storage with high capacity and reversibility by modifying the charges that it carried. The narrow band gap (1.70 eV) of C 2 N also ensures the electrochemical methods can be easily realized in experiment. [ABSTRACT FROM AUTHOR]