Abstract

The structural and electronic properties of iron-fluorine (Fe-F) and iron-sulfur (Fe-S) codoped anatase TiO2are investigated by first-principles based on density functional theory. Our results show that the formation energy of codoped system is lower than that of single-element doping, which indicates the synergic effect of codoping on the stability of the structure. Codopants introduced impurity gap states resulting in the electron transition energy reduction and thus the visible light absorption observed in the samples. It is concluded that Fe-S should be a better codoping pair because Fe-S codoping introduces extended impurity states resulting in stronger visible light absorption than that of Fe-F codoped compounds. This work gives understanding to the recent experiment and provides the evidence of choosing the more effective co-dopants in TiO2.

Highlights

  • Titanium dioxide has been extensively studied as a promising photocatalyst due to its cheap, stable, and nontoxic characteristics

  • We examine the microscopic electronic structures of Fe-S and Fe-F codoped anatase TiO2 to explore the synthetic effects of the dopants by means of the firstprinciples density function theory (DFT) calculations

  • We have examined the crystal structures and electronic and optical properties of Fe-F and Fe-S codoped anatase TiO2 based on DFT calculations

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Summary

Introduction

Titanium dioxide has been extensively studied as a promising photocatalyst due to its cheap, stable, and nontoxic characteristics. Liu et al [18] found that iron-fluorine (FeF) codoped TiO2 displays excellent photocatalytic activity under visible light irradiation. Fluorine atom has one more valence electron than oxygen, and sulfur has the same outer-shell electron as oxygen atom; it is interesting to explore the origin of the high photocatalytic activity under visible light concerning these two kinds of codoped anatase TiO2. Our theoretical calculations may provide a comprehensive explanation for experimentally observed visible-light photocatalytic activity in the metal and nonmetal codoped TiO2 and may offer some helpful theoretical information for exploiting new effective photocatalysts

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