The Impact of Nitrogen Doping on Structural and Electronic Properties of Titanium Sesquioxide, Ti 2 O 3 : An ab-initio Study

TL;DR

This study uses ab-initio calculations to show that nitrogen doping in Ti2O3 significantly narrows its bandgap to 2.2 eV, enhancing its potential for visible-light photocatalysis.

Contribution

It provides the first detailed ab-initio analysis of nitrogen-doped Ti2O3, revealing improved electronic properties for photocatalytic applications.

Findings

Bandgap of Ti2N2O-P1 is 2.2 eV, suitable for visible light absorption.

Nitrogen doping removes in-gap states, increasing efficiency.

Ti2N2O-P1 outperforms TiO2 and TiO2:N in visible-light activity.

Abstract

Titanium-based oxides are abundant, chemically stable, non-toxic, and highly versatile materials, with applications ranging from photovoltaics to catalysis. For rutile and anatase phases of Titanium dioxide (TiO2), the bandgap ranges from 3.0-3.2 eV, which are too large to absorb in the visible range (400 nm - 700 nm), resulting in poor photo-catalytic efficiency. Nitrogen doping into TiO2 has been able to narrow its bandgap, forming an absorption tail in the visible-light region. However, TiO2 has limits to which it can be doped, suggesting investigations of the oxygen-deficient Ti203. Using the state-of-the-art Density Functional Theory (DFT) as implemented in the Quantum ESPRESSO package, we report on the structural and electronic properties of corundum-type Ti2N20 (an example TinN2O2n-3 compound with n=2). The most stable sample of the oxynitride (Ti2N2O-P1), has a bandgap of 2.2 eV, which is clearly near the middle of the visible light part of the electromagnetic spectrum, and has no in-gap states, suggesting that they are more efficient visible-light-driven materials for photocatalytic applications compared to TiO2, TiO2: N and Ti2O3.