Water on Silicene: Hydrogen Bond Autocatalysis Induced Physisorption-Chemisorption-Dissociation Transition

TL;DR

This study reveals that water molecules on silicene undergo a transition from physisorption to chemisorption and dissociation due to hydrogen bond autocatalysis, with implications for sensors and catalysts.

Contribution

It demonstrates that water clusters on silicene exhibit a transition in adsorption behavior driven by hydrogen bonds, a novel insight into water-silicene interactions.

Findings

Water monomer shows physisorption on silicene.

Water dimer and trimer induce chemisorption and dissociation.

Hydrogen bonds catalyze the transition in water adsorption states.

Abstract

A single water molecule has nothing special. However, macroscopic water displays many anomalous properties at the interface, such as a high surface tension, hydrophobicity and hydrophillicity. Although the underlying mechanism is still elusive, hydrogen bond is expected to have played an important role. An interesting question is if the few-water molecule clusters will be qualitatively different from a single molecule. Using adsorption behavior as an example, by carefully choosing two-dimensional silicene as the substrate material, we demonstrate that water monomer, dimer and trimer show contrasting properties. The additional water molecules in dimer and trimer induce a transition from physisorption to chemisorption then to dissociation on silicene. Such a hydrogen bond autocatalytic effect is expected to have a broad application potential in silicene-based water molecule sensor and metal-free catalyst for water dissociation.