C 60-mediated hydrogen desorption in Li-N-H systems

Abstract

Hydrogen desorption from a LiH+NH 3 mixture is very difficult due to the formation of the stable LiNH 4 compound. Using cluster models and first-principles theory, we demonstrate that the C 60 molecule can in fact significantly improve the thermodynamics of ammonia-mediated hydrogen desorption from LiH due to the stabilization of the intermediate state, LiNH 4. The hydrogen desorption following the path of LiNH 4-C 60→LiNH 3- is exothermic. Molecular dynamic simulations show that this reaction can take place even at room temperature (300K). In contrast, the stable LiNH 4 compound cannot desorb hydrogen at room temperature in the absence of C 60. The introduction of C 60 also helps to restrain the NH 3 gas which is poisonous in proton exchange membrane fuel cell applications. © 2012 IOP Publishing Ltd.