C7N6 monolayer as high capacity and reversible hydrogen storage media: A DFT study

Searching advanced materials with high capacity and efficient reversibility for hydrogen storage is a key issue for the development of hydrogen energy. In this work, we studied systematically the hydrogen storage properties of the pure C7N6 monolayer using density functional theory methods. Our results demonstrate that H-2 molecules are spontaneously adsorbed on the C7N6 monolayer with the average adsorption energy in the range of 0.187-0.202 eV. The interactions between H-2 molecules and C7N6 monolayer are of electrostatic nature. The gravimetric and volumetric hydrogen storage capacities of the C7N6 monolayer are found to be 11.1 wt% and 169 g/L, respectively. High hardness and low electrophilicity provides the stabilities of H-2-C7N6 systems. The hydrogenation/dehydrogenation (desorption) temperature is predicted to be 239 K. The desorption temperatures and desorption capacity of H-2 under practical conditions further reveal that the C7N6 mono layer could operate as reversible hydrogen storage media. Our results thus indicate that the C7N6 monolayer is a promising material with efficient, reversible, and high capacity for H-2 storage under realistic conditions. (c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

The C7N6 monolayer shows promising hydrogen storage capacities and efficiencies for H-2 storage. The interactions between H-2 molecules and C7N6 monolayer are primarily electrostatic in nature. Predicted desorption temperatures indicate the C7N6 monolayer can operate as a reversible hydrogen storage medium.