Strain-Induced Water Dissociation on Supported Ultrathin Oxide Films

TL;DR

This study demonstrates that substrate-induced tensile strain on ultrathin MgO films significantly enhances their ability to dissociate water molecules, offering new ways to control catalytic reactions on insulating surfaces.

Contribution

It reveals the critical role of lattice mismatch and tensile strain in promoting water dissociation on ultrathin MgO films supported on Mo(100).

Findings

Water dissociation is enhanced by tensile strain.

Three low-energy dissociative configurations are identified.

Structural transition from molecular to dissociative water is barrierless.

Abstract

Controlling the dissociation of single water molecule on an insulating surface plays a crucial role in many catalytic reactions. In this Letter, we have identified the enhanced chemical reactivity of ultrathin MgO(100) films deposited on Mo(100) substrate that causes water dissociation. We reveal that the ability to split water on insulating surface closely depends on the lattice mismatch between ultrathin films and the underlying substrate, and substrate-induced in-plane tensile strain dramatically results in water dissociation on MgO(100). Three dissociative adsorption configurations of water with lower energy are predicted, and the structural transition going from molecular form to dissociative form is almost barrierless. Our results provide an effective avenue to achieve water dissociation at the single-molecule level and shed light on how to tune the chemical reactions of insulating surfaces by choosing the suitable substrates.