Steps on Rutile TiO2(110): Active Sites for Water and Methanol Dissociation

TL;DR

This study investigates the structure and catalytic activity of monoatomic steps on TiO2(110), revealing that certain step edges facilitate dissociative adsorption of water and methanol, thus contributing to surface reactivity.

Contribution

It introduces an automated genetic algorithm to identify stable reconstructed step structures and demonstrates their enhanced reactivity compared to flat surfaces.

Findings

Reconstructed <1-11> step edges are more stable than bulk truncated structures.

Oxygen vacancies are more easily formed along step edges.

Step edges significantly enhance water and methanol dissociation activity.

Abstract

We present a detailed investigation of the structure and activity of extended defects namely monoatomic steps on (1x1)-TiO2(110). Specifically, the two most stable <001> and <1-11> step edges are considered. Employing an automated genetic algorithm that samples a large number of candidates for each step edge, more stable, reconstructed structures were found for the <1-11> step edge, while the bulk truncated structures were recovered for the <001> step edge. We demonstrate how oxygen vacancies along these defects have lower formation energies than on flat terraces and how water and methanol molecules adsorb dissociatively on reduced <1-11> step edges. Our findings are in agreement with earlier experimental results and indicate an important contribution from step edges to the reactivity of the TiO2(110) surface.