How Does Structural Disorder Impact Heterogeneous Catalysts? The Case of Ammonia Decomposition on Non-stoichiometric Lithium Imide
Francesco Mambretti, Umberto Raucci, Manyi Yang, Michele Parrinello
Abstract
Among the many catalysts suggested for ammonia decomposition, Li 2 NH has been shown to be quite promising. In the recent past, we have performed extensive ab initio -quality simulations to explain the workings of this unusual catalyst. In the complex scenario that has emerged, surface dynamics and structural disorder enhanced by the interaction with the reacting ammonia molecules have played crucial roles. Non-stoichiometric lithium imide (Li 2– x (NH 2 ) x (NH) 1– x ) has been reported to have better catalytic performances than pure lithium imide. Stimulated by these findings, we follow up our previous study simulating the ammonia decomposition on such non-stoichiometric compounds. We attribute the enhanced reactivity to the fact that the compositional disorder further enhances the fluctuations in the topmost layers of the catalyst, strengthening our dynamic picture of this catalytic process.