Reactivity of shape-controlled crystals and metadynamics simulations locate the weak spots of alumina in water

R. Réocreux (1) , E. Girel (2, 3) , P. Clabaut (1) , A. Tuel (3, 4) , M. Besson (3, 5) , A. Chaumonnot (2) , A. Cabiac (2) , P. Sautet (6) , C. Michel (1)

1 LC - Laboratoire de Chimie - UMR5182
2 IFPEN - IFP Energies nouvelles
3 IRCELYON - Institut de recherches sur la catalyse et l'environnement de Lyon
4 ING - IRCELYON-Ingéniérie, du matériau au réacteur
5 CDURABLE - IRCELYON-C'Durable
6 UCLA - University of California [Los Angeles]

The kinetic stability of any material in water relies on the presence of surface weak spots responsible for chemical weathering by hydrolysis. Being able to identify the atomistic nature of these sites and the first steps of transformation is therefore critical to master the decomposition processes. This is the challenge that we tackle here: combining experimental and modeling studies we investigate the stability of alumina in water. Exploring the reactivity of shape-controlled crystals, we identify experimentally a specific facet as the location of the weak spots. Using biased ab initio molecular dynamics, we recognize this weak spot as a surface exposed tetra-coordinated Al atom and further provide a detailed mechanism of the first steps of hydrolysis. This understanding is of great importance to heterogeneous catalysis where alumina is a major support. Furthermore, it paves the way to atomistic understanding of interfacial reactions, at the crossroad of a variety of fields of research.

Keywords: Theoretical chemistry; Materials for energy and catalysis; Heterogeneous catalysis

Domains: Chemical Sciences; Catalysis

R. Réocreux, E. Girel, P. Clabaut, A. Tuel, M. Besson, et al.. Reactivity of shape-controlled crystals and metadynamics simulations locate the weak spots of alumina in water. Nature Communications, 2019, 10 (1), ⟨10.1038/s41467-019-10981-9⟩. ⟨hal-02275963⟩