First-Principles Study of Optoelectronic Properties of the Noble Metal (Ag and Pd) Doped BiOX (X = F, Cl, Br, and I) Photocatalytic System

Shixiong Zhou,Xin Wang,Zichuan Yi,Mingzhe Yuan,Lingling Shui,Guofu Zhou,Dmitri Kilin,Xiaobao Yang,Mingliang Jin,Tingting Shi,Qingguo Meng,Zhihong Chen,Nan Li

doi:10.3390/catal9020198

Abstract

To explore the photocatalytic performances and optoelectronic properties of pure and doped bismuth oxyhalides D-doped BiOX (D = Ag, Pd; X = F, Cl, Br, I) compounds, their atomic properties, electronic structures, and optical properties were systematically investigated using first-principles calculations. In previous experiments, the BiOX (X = Cl, Br) based system has been observed with enhanced visible light photocatalytic activity driven by the Ag dopant. Our calculations also show that the potential photocatalytic performance of Ag-doped BiOCl or BiOBr systems is enhanced greatly under visible light, compared with other Pd-doped BiOX (X = Cl, Br) compounds. Furthermore, it is intriguing to find that the Pd-doped BiOF compound has strong absorption over the infrared and visible light spectrum, which may offer an effective strategy for a promising full spectrum catalyst. Indicated by various Mulliken charge distributions and different impurity states in the gap when Ag or Pd was doped in the BiOX compounds, we notice that all D-doped BiOXs exhibit a p-type semiconductor, and all impurity levels originated from the D-4d state. The charge transfer, optoelectronic properties, and absorption coefficients for photocatalytic activities among D-doped BiOX photocatalysts caused by the electronegativity difference of halide elements and metal atoms will finally affect the photocatalytic activity of doped BiOX systems. Therefore, it is significant to understand the inside physical mechanism of the enhanced Ag/Pd-doped BiOX photocatalysts through density functional theory.

Highlights

The shortage of energy resources and the pollution of environments in the world have become hot topics nowadays
The variation of lattice parameters of the Ag and Pd doped BiOX models after optimization, such as average variation of bond length ∆d, bond angle ∆α, and lattice constant ∆a are listed in Table 1, and details in Table S1 to evaluate the effect of the doped metal atoms on the lattice structure of the BiOX models
In order to understand the photocatalytic mechanism of the D-doped BiOX compounds, especially the enhanced photocatalytic observed in the Ag-doped BiOX compound, the structural, electronic, and optical properties of Ag/Pd doped BiOX (X = F, Cl, Br, I) have been calculated based on the density functional theory (DFT) used generalized gradient approximation (GGA)-Perdew-Burke-Ernzerh for solids (PBEsol)

Summary

Introduction

The shortage of energy resources and the pollution of environments in the world have become hot topics nowadays. TiO2 photocatalysts under light [1], photocatalysts-based semiconductors have attracted extensive attention for developing new energy resources and eliminating pollutants [2,3]. This includes, for example, oxygen evolution, hydrogen evolution, CO2 reduction, nitrogen fixation, organic syntheses, disinfection, and organic pollutant removal [4,5,6]. Since the better performance of BiOCl over TiO2 at three cycles on the photocatalytic degradation of methyl orange (MO) dye was observed by Zhang et al in 2006 [15,16], a series of novel Bismuth oxyhalides (BiOX, X = Cl, Br, and I)

Methods

Results

Conclusion