DFT study of Se and Te doped SrTiO3 for enhanced visible-light driven phtocatalytic hydrogen production

H Bentour,M Houmad,A El Kenz,A Benyoussef,M El Yadari,M Boujnah

doi:10.1007/s11082-021-03214-1

Abstract

The pure STiO3 has been experimentally demonstrated to catalyze H2 production using water splitting, but the reaction can only be driven by Ultraviolet (UV) radiation due to the large band gap of SrTiO3. This motivated us to search efficient strategy to tune its band gap, so that it can function in the visible region of the solar spectrum. In this study, the electronic, optical and photocatalytic properties of Se-doped, and Te-doped SrTiO3 has been investigated using density functional theory (DFT) within the generalized gradient approximation (GGA). Our results reveal that the effect of doping can lead to band gap narrowing without introducing any isolated mid-gap states. This improves greatly the visible light activity of SrTiO3 and depresses the recombination of photogenerated electron–hole pairs. Furthermore, the locations of calculated band edges relative to the water reduction and oxidation levels for doped systems meet the water-splitting requirements. Consequently, our results show that the performance of SrTiO3 for hydrogen generation by photocatalytic water splitting is significantly enhanced with Se and Te doping. In particular, Te doping can enhance greatly the visible light photocatalytic activity of SrTiO3. We expect this study can provide a theoretical basis for a prospective experimental works.

Highlights

With the continuous increasing demand for the energy as a consequence of rapid demographic, economic and social developments, the energy supply should be permanently and sufficiently provided
Our findings show that the narrowing of band gap, absorption spectrum shifting into the visible light region and the photocatalytic performance of SrTiO3 is further improved with Te doping compared to our previous study about (S, Mn)-codoped SrTiO3 (Bentour, 2020).Our study serves to provide a theoretical basis for a possible experimental study
The increase of covalency strength of Ti-O bond and the decrease of iconicity strength of Sr-O bond through doping Se and Te atoms in O site may be the origin of observed band gap narrowing

Summary

Introduction

With the continuous increasing demand for the energy as a consequence of rapid demographic, economic and social developments, the energy supply should be permanently and sufficiently provided. Hydrogen energy is considered as a clean and sustainable energy carrier of the future.The most economic method to produce hydrogen is the photocatalytic splitting of water using sunlight. This has inspired large research efforts into designing and improving a wide range of photocatalytic systems over the past few decades. The main shortcoming which restricts their application at a large scale is their large band gap (superior to 3 eV) which makes them active only in the UV region of the solar spectrum This limitation can be overcome by employing adequate dopant elements. We are concerned with narrowing the band gap of SrTiO3 (3.15 eV), which has been investigated widely in the field of production of hydrogen from water splitting

Methods

Results

Conclusion