Photo-Fenton Degradation of AO7 and Photocatalytic Reduction of Cr(VI) over CQD-Decorated BiFeO3 Nanoparticles Under Visible and NIR Light Irradiation

Tao Xian,Hongqin Li,Lijing Di,Yongjie Zhou,Xiaofeng Sun,Hua Yang

doi:10.1186/s11671-019-3206-5

Tao Xian, Hongqin Li + Show 4 more

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https://doi.org/10.1186/s11671-019-3206-5

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Abstract

In this work, the carbon quantum dot (CQD)–decorated BiFeO3 nanoparticle photocatalysts were prepared by a hydrothermal method. The TEM observation and XPS characterization indicate that the CQDs are well anchored on the surface of BiFeO3 nanoparticles. Acid orange 7 (AO7) and hexavalent chromium (Cr(VI)) were chosen as the model pollutants to investigate the photocatalytic/photo-Fenton degradation and photocatalytic reduction performances of the as-prepared CQD/BiFeO3 composites under visible and near-infrared (NIR) light irradiation. Compared with bare BiFeO3 nanoparticles, the CQD/BiFeO3 composites exhibit significantly improved photocatalytic and photo-Fenton catalytic activities. Moreover, the composites possess good catalytic stability. The efficient photogenerated charges separation in the composites was demonstrated by the photocurrent response and electrochemical impedance spectroscopy (EIS) measurements. The main active species involved in the catalytic degradation reaction were clarified by radicals trapping and detection experiments. The underlying photocatalytic and photo-Fenton mechanisms are systematically investigated and discussed.

Highlights

In recent decades, wastewater containing heavy metal ions and organic compounds brings serious damages for environment and human beings
The results indicate that the high-purity BiFeO3 is obtained and the introduction of Carbon quantum dots (CQDs) and hydrothermal treatment do not obviously change the crystal structure of BiFeO3
From the X-ray powder diffraction (XRD) pattern of CQDs, one can see that a broad diffraction peak is observed at ~ 23.5°, which is mainly attributed to the amorphous structure of CQDs

Summary

Introduction

Wastewater containing heavy metal ions and organic compounds brings serious damages for environment and human beings. Many techniques have been developed to eliminate organic pollutants and reduce Cr(VI) to Cr(III) [3,4,5]. Among these methods, photocatalytic and photo-Fenton-like catalytic techniques are regarded to be the promising methods for efficient degradation of organic contaminants and Cr(VI) reduction in wastewater because of. The iron-contained catalysts with narrow bandgap are considered as ideal candidates in the photocatalytic and photo-Fenton-like catalytic applications [21,22,23,24,25]

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