Incorporation of Non-metal Impurities at the Anatase TiO$_2$(001)-(1$\times$4) Surface

TL;DR

This study uses first-principles calculations to explore how non-metal impurities like nitrogen and carbon incorporate into the reconstructed anatase TiO2(001) surface, revealing pathways and sites crucial for impurity integration.

Contribution

It provides detailed insights into impurity binding sites, pathways, and the role of subsurface oxygen vacancies in impurity incorporation on TiO2(001).

Findings

Identification of subsurface interstitial binding sites.

Surface structure influences impurity pathways.

Subsurface oxygen vacancies facilitate impurity incorporation.

Abstract

We use first-principles calculations to investigate the adsorption and incorporation of non-metal impurities (N, C) at the anatase TiO$_2$(001)-(1$\times$4) reconstructed surface. We analyze in detail the influence of the surface structure and local strain on the impurity binding sites and incorporation pathways and identify important intermediates which facilitate impurity incorporation. We find various subsurface interstitial binding sites and corresponding surface $\rightarrow$ subsurface penetration pathways on the reconstructed surface. This surface also favors the presence of subsurface oxygen-vacancies, to which adsorbed species can migrate to form substitutional impurities. Most notably, we show that the non-exposed oxygen sites just below the surface have a key role in the incorporation of nitrogen and carbon in TiO$_2$(001).