A DFT+U study of Rh, Nb codoped rutile TiO2

TL;DR

This study uses DFT+U calculations to analyze how Rh and Nb doping affect the electronic structure and photocatalytic efficiency of rutile TiO2, highlighting improved stability and reduced recombination centers.

Contribution

It provides a detailed computational analysis of Rh and Nb codoping effects on TiO2's electronic properties, revealing mechanisms for enhanced photocatalytic performance.

Findings

Rh doping causes a red shift in optical absorption edge.

Nb codoping suppresses Rh4+ formation, reducing recombination centers.

Codoping reduces band gap by 0.5 eV, improving photocatalytic efficiency.

Abstract

A systematic study of electronic structure and band gap states is conducted to analyze the mono doping and charge compensated codoping of rutile TiO2 with Rh and Nb, using the DFT+U approach. Doping of rutile TiO2 with Rh atom induces hybridized O 2p and Rh 4d band gap states leading to a red shift of the optical absorption edge, consistent with previous experimental studies. Since Rh mono-doping may induce recombination centers, charge-compensated codoping with Rh and Nb is also explored. This codoping induces an electron transfer from Nb induced states to Rh 4d states which suppresses the formation of Rh4+, thereby leading to a reduction in recombination centers and to the formation of more stable Rh3+. A combination of band gap reduction by 0.5 eV and the elimination of band gap states that account for recombination centers makes (Rh,Nb)- codoped TiO2 a more efficient and stable photocatalyst.