Range separated hybrid exchange-correlation functional analyses of W and/or N(S) (co)doped anatase TiO_2

TL;DR

This study uses advanced hybrid DFT calculations to analyze how doping anatase TiO_2 with W, N, and S alters its electronic structure, band gap, and potential visible light activity, providing insights for photocatalyst design.

Contribution

It systematically investigates the electronic effects of W, N, and S doping in anatase TiO_2 using the HSE hybrid functional, highlighting band gap modifications and new hybrid states.

Findings

W/N codoping enhances charge carrier dynamics

W/S codoping causes significant band gap narrowing

W/S doped TiO_2 may exhibit strong visible light response

Abstract

Electronic properties and atomic structures of W, N, S, W/N, and W/S dopings of anatase TiO_2 have been systematically investigated using the density functional theory (DFT). The exchange and correlation effects have been treated with Heyd, Scuseria and Ernzerhof (HSE) hybrid functional. Mixing traditional semi-local and non-local screened Hartree-Fock (HF) exchange energies, the HSE method corrects the band gap and also improves the description of anion/cation derived gap states. Enhanced charge carrier dynamics, observed for W/N codoped titania, can partly be explained by the passivative modifications of N 2p and W 5d states on its electronic structure. Following this trend we have found an apparent band gap narrowing of 1.03 eV for W/S codoping. This is due to the large dispersion of S 3p states at the valance band (VB) top extending its edge to higher energies and Ti--S--W hybridized states appearing at the bottom of the conduction band (CB). W/S-TiO_2 might show strong visible light response comparable to W/N codoped anatase catalysts.