Surface Protolysis and Its Kinetics Impact the Electrical Double Layer
Résumé
vide insights into reaction mechanisms, energy barriers 66 and adsorption energies, the small system sizes in these 67 approaches [O(10-100 atoms)] are insufficient to study 68 the fluid response [13-17]. On the other hand, classi-69 cal molecular dynamics (MD) simulations [O(10 3 − 10 5) 70 atoms] probe the fluid response, but they generally do 71 not account for chemical reactions. Only recently, the 72 computational power has increased to allow atomistic 73 MD simulations to probe chemical reactions and fluid re-74 sponses. In this context, the reactive force field ReaxFF 75 [18] is an important landmark but parameters for protol-76 ysis are not available. In contrast, the dissociative force 77 field MGFF [19, 20] allows reproducing OH bond dis-78 sociation/formation involved in proton reactions. Using 79 this force field, when set in contact with water, protolysis 80 rates up to 2×10 5 mol/m 2 /s were found for hydroxylated 81 silica surfaces containing strained sites (Si(OH)Si and 82 SiOH 2 defects), while smaller rates between 900 and 1750 83 mol/m 2 /s were assessed when only considering silanol 84 sites (SiOH) [21, 22]. The OH bond lifetime was found 85 to be broadly distributed from fs to ns with an average of 86 the order of ps. Despite its ability to model silanol disso-87
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