Facile Formation of Bi2O2CO3/Bi2MoO6 Nanosheets for Visible Light-Driven Photocatalysis.

Junlei Zhang,Zhen Ma,Zhendong Liu

doi:10.1021/acsomega.8b03699

Abstract

Bi2O2CO3/Bi2MoO6 heterojunction catalysts were prepared by treating Bi2MoO6 sheets with aqueous NaHCO3 solutions at room temperature. All the Bi2O2CO3/Bi2MoO6 heterojunctions exhibited higher activities than pristine Bi2MoO6 in the photocatalytic degradation of rhodamine B (RhB), methyl orange, and ciprofloxacin under visible-light irradiation, and the most active photocatalyst was found to be the one with a C/Bi molar ratio of ∼1/2.3. Relevant samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, N2 adsorption–desorption, Fourier transform infrared spectroscopy, and UV–vis spectroscopy. The higher activity of Bi2O2CO3/Bi2MoO6 than pristine Bi2MoO6 is explained by the enhanced separation and transfer of photogenerated electron/hole pairs, as verified by transient photocurrent densities, photoluminescence spectroscopy, and electrochemical impedance spectroscopy. Photogenerated holes (h+) and superoxide radical anions (•O2–) were found to be the main active species. The good reusability of Bi2O2CO3/Bi2MoO6 was testified by cycling degradation of RhB and tetracycline hydrochloride.

Highlights

TiO2, a benchmark photocatalyst, works efficiently under UV light that merely accounts for a very small fraction of sunlight.Seeking new catalysts that can make full use of sunlight, especially the visible light portion, is a meaningful topic.Bi2MoO6, conductor, a nontoxic and visible light-responsive semiis promising for making photocatalysts.[1−4]Bi2MoO6 photocatalysts with different morphologies or structures have been developed
The presence of residual NaHCO3 can be excluded because the Bi2O2CO3/Bi2MoO6 samples were thoroughly washed by water and our later X-ray photoelectron spectroscopy (XPS) characterization excludes the presence of residual Na
Bi2MoO6 nanosheets modified with Bi2O2CO3 were prepared by chemical deposition

Summary

Introduction

TiO2, a benchmark photocatalyst, works efficiently under UV light that merely accounts for a very small fraction of sunlight.Seeking new catalysts that can make full use of sunlight, especially the visible light portion, is a meaningful topic.Bi2MoO6, conductor, a nontoxic and visible light-responsive semiis promising for making photocatalysts.[1−4]Bi2MoO6 photocatalysts with different morphologies or structures (e.g., nanoparticles,[5] nanotubes,[6] nanosheets,[7] flowerlike structures,[8,9] and hollow microspheres10,11) have been developed. TiO2, a benchmark photocatalyst, works efficiently under UV light that merely accounts for a very small fraction of sunlight. Bi2MoO6, conductor, a nontoxic and visible light-responsive semiis promising for making photocatalysts.[1−4]. Bi2MoO6 photocatalysts with different morphologies or structures (e.g., nanoparticles,[5] nanotubes,[6] nanosheets,[7] flowerlike structures,[8,9] and hollow microspheres10,11) have been developed. The recombination of photogenerated carriers is still a serious problem when using pristine Bi2MoO6 as a photocatalyst.[12] It is of great interest to develop Bi2MoO6-based modified photocatalysts with enhanced photocatalytic performance. Bi2MoO6-based modified photocatalysts can be prepared by depositing metals (e.g., Pt,[13] Pd, and Ag15) onto Bi2MoO6, doping Bi2MoO6 with metal ions (e.g., Er3+,16 Gd3+,17 Ho3+,17 and Yb3+17), and integrating Bi2MoO6 with other substances such Ag2M as TiO2,18 oO4,23,24

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