Reactant-induced dynamics of lithium imide surfaces during the ammonia decomposition process

Abstract

Ammonia decomposition on lithium imide surfaces has been intensively investigated owing to its potential role in a sustainable hydrogen-based economy. Here, through advanced molecular dynamics simulations of ab initio accuracy, we show that the surface structure of the catalyst changes on exposure to the reactants and a dynamic state is activated. It is this highly fluctuating state that is responsible for catalysis and not a well-defined static catalytic centre. In this activated environment, a series of reactions that eventually leads to the release of N2 and H2 molecules becomes possible. Once the flow of reagent is terminated, the imide surface returns to its pristine state. We suggest that by properly engineering this dynamic interfacial state one can design improved catalytic systems. The common static description of catalysts during turnover has often been challenged, but their specific nature under such conditions remains elusive. Now complex simulations reveal that ammonia decomposition on LiNH surfaces is catalysed by a highly dynamic, liquid-like interface that reversibly forms under operation.