Fabrication of a novel Z-scheme g-C3N4/Bi4O7 heterojunction photocatalyst with enhanced visible light-driven activity toward organic pollutants

Meng Sun; Yu Wang; Yu Shao; Yunhui He; Qi Zeng; Huikai Liang; Tao Yan; Bin Du

doi:10.1016/j.jcis.2017.04.047

Fabrication of a novel Z-scheme g-C₃N₄/Bi₄O₇ heterojunction photocatalyst with enhanced visible light-driven activity toward organic pollutants

J Colloid Interface Sci. 2017 Sep 1:501:123-132. doi: 10.1016/j.jcis.2017.04.047. Epub 2017 Apr 19.

Authors

Meng Sun¹, Yu Wang², Yu Shao³, Yunhui He³, Qi Zeng², Huikai Liang², Tao Yan², Bin Du⁴

Affiliations

¹ School of Resources and Environment, University of Jinan, Jinan 250022, PR China. Electronic address: smlcu@163.com.
² School of Resources and Environment, University of Jinan, Jinan 250022, PR China.
³ State Key Laboratory of Photocatalysis on Energy and Environment, Research Institute of Photocatalysis, Fuzhou University, Fuzhou 350116, PR China.
⁴ School of Resources and Environment, University of Jinan, Jinan 250022, PR China. Electronic address: bindu61@gmail.com.

PMID: 28448832
DOI: 10.1016/j.jcis.2017.04.047

Abstract

In this work, highly efficient g-C₃N₄/Bi₄O₇ heterojunction photocatalysts have been successfully fabricated by a facile method. Compared with the bare photocatalysts, the obtained g-C₃N₄/Bi₄O₇ hybrid photocatalysts exhibited efficient degradation activity toward methylene blue (MB), phenol, rhodamine B (RhB), and bisphenol A (BPA) under visible light irradiation. The influences of different g-C₃N₄ contents on the photocatalytic efficiency of the hybrid photocatalysts have been investigated. The results revealed that the g-C₃N₄/Bi₄O₇ with g-C₃N₄ mass ratio of 30% exhibited the best photocatalytic activity. The activity enhancement should be ascribed to the improved visible light adsorption as well as the effective Z-scheme charge transfer according to the energy band theory. The UV-vis diffuse reflectance spectra (DRS) shows that the absorption edge of g-C₃N₄ move towards longer wavelength with the increment of Bi₄O₇ component. The strong connection between g-C₃N₄ and Bi₄O₇ was investigated using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Subsequently, the effective Z-scheme charge transfer has also been verified by using transient photocurrent measurements and electrochemical impedance spectroscopy. Controlled experiments proved that active species of O₂^- and h⁺ were produced in the degradation system, which played the major role in the degradation of MB. A possible Z-scheme degradation mechanism over g-C₃N₄/Bi₄O₇ hybrid photocatalysts was proposed.

Keywords: Degradation; Heterojunction; Photocatalysis; Visible light; g-C(3)N(4)/Bi(4)O(7).