Ti interstitial flows giving rutile TiO$_2$ reoxidation process enhanced in (001) surface

TL;DR

This study uses refined ab initio methods to analyze defect diffusion in rutile TiO2, revealing that Ti interstitials primarily diffuse along the c-axis towards the [001] surface, explaining enhanced photocatalytic activity.

Contribution

It provides a revised understanding of defect diffusion pathways in rutile TiO2 by accurately considering self-interaction cancellation, contradicting previous theoretical predictions.

Findings

Ti interstitials hop along the c-axis towards [001] surface

Revised diffusion pathway explains superior photocatalytic activity

Previous models overestimated defect radii due to poor self-interaction cancellation

Abstract

We revisited ab initio evaluations of the energy barriers along the possible diffusion paths of the defects in rutile TiO$_2$. By using a method carefully considering the cancellation of the self-interaction, Ti interstitials hopping along $c$-axis are identified as the major diffusion directing to [001] surface. The conclusion is contradicting to any of previous theoretical works, and the discrepancy is explained by the overestimation of the radius of defects due to the poor cancellations in the previous works. The updated prediction here can explain the superior photocatalysis activity in [001] surface to [110].