C _(60)-mediated hydrogen desorption in Li-N-H systems

摘要

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.