Optimal thermodynamic conditions for hydrogen storage in Li ‐modified graphene oxide

Thermodynamic properties are of great significance for evaluating and optimizing hydrogen storage systems. In this work, the hydrogen storage performance of Li‐modified graphene oxide and the thermodynamic properties of their hydrogen storage reaction are investigated. The calculations show that the adsorption energy of H 2 in Li‐modified graphene oxide containing a single O/OH group lies within −0.19 to −0.42 eV, and the maximum hydrogen storage capacity can reach 12.6 wt%. The calculations on the adsorption state, vibration frequency, and entropy reveal that the zero‐point energy correction accounts for 17%–46% of the adsorption energy, which indicates that the influence of the zero‐point energy cannot be ignored. There is a good linear relationship between the entropy of adsorbed hydrogen and that of gaseous H 2 . The entropy of hydrogen decreases by 10.6R to 12R after adsorption. Based on the Langmuir adsorption model, Li‐modified graphene oxide can achieve maximum cyclic adsorption capacity in the operating temperature of 250 to 260 K and ∆ S range of −89 to −93 J mol −1 K −1 .