Entropy-driven difference in interfacial water reactivity between slab and nanodroplet
Shiwei Chen, Jiabao Zhu, Jiaze Li, Pan Guo, Jinrong Yang, Xiao He
Abstract
Interfacial water activity plays a critical role in governing chemical reactivity and catalytic efficiency, yet a quantitative understanding of how hydrogen-bond (H-bond) network structure influences this reactivity remains limited. Herein, we employ ab initio molecular metadynamics simulations to delineate the relationship between the H-bond network and the reactivity of interfacial water molecules at the slab and nanodroplet systems. Interfacial water at nanodroplets, characterized by microscopic inhomogeneity, tends to adopt a donor–acceptor dimer configuration, in contrast to the more homogeneous H-bond network at the slab. This disparity in local structure, corroborated by the quantified differences in solvation configurational entropy, results in a reduction of the reaction free energy barrier by 1–2 kcal·mol⁻1 at the slab interface, corresponding to an order-of-magnitude enhancement in reaction rate. These results provide a fresh perspective to understand the interfacial water reactivity and highlight the critical role of H-bond network in optimizing catalytic performance. Water behaves different at interfaces and under confinement compared to the bulk. Here the authors use metadynamics simulations and show that water interfacial reactivity also differs between nanodroplet and thin film confinements due to entropy effects.