Constructing Z-scheme charge separation in 2D layered porous BiOBr/graphitic C3N4 nanosheets nanojunction with enhanced photocatalytic activity

Article abstract of DOI:10.1016/j.jallcom.2017.07.003

In the present work, a series of layered BiOBr/g-C₃N₄ heterojunction photocatalysts were prepared via a simple reflux process, and their photocatalytic performance was investigated by the degradation of rhodamine B (RhB) and bisphenol A (BPA) under visible light irradiation. It was found that BiOBr nanoplates were deposited on the external surface of g-C₃N₄nanosheets (CNNS) and the tightly contacted interface was formed between two components, giving rise to a 2D porous layered heterojunction structure with a high specific area. It was found that BiOBr nanoplates coupled with the proper amount of CNNS exhibited an excellent photocatalytic performance due to the combined effects of layered heterojunction, high specific surface area and porous structure, which lead to the high efficiency of light harvesting and charge separation. The active species of [rad]OH is the most crucial one while h⁺ and O₂^[rad]?contributed to a lesser extent in RhB and BPA photocatalytic degradation. Based on the direct evidence of the formed [rad]OH, O₂^[rad]? and h⁺ active species detected by active species capture experiment and ESR spectra, a Z-scheme photocatalytic mechanism was proposed for the charge separation. The present work may provide an insight for designing novel layered Z-scheme heterojunction photocatalysts with a high performance.

Full text of DOI:10.1016/j.jallcom.2017.07.003

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Constructing Z-scheme charge separation in 2D layered porous BiOBr/graphitic C N
3 4
nanosheets nanojunction with enhanced photocatalytic activity
Chao Liu, Qisheng Wu, Mingwei Ji, Huajun Zhu, Haijun Hou, Qihang Yang, Cuifeng
Jiang, JingJing Wang, Liang Tian, Jing Chen, Wenhua Hou
PII:
S0925-8388(17)32358-7
10.1016/j.jallcom.2017.07.003
JALCOM 42419
DOI:
Reference:
To appear in: Journal of Alloys and Compounds
Received Date: 31 March 2017
Revised Date: 29 June 2017
Accepted Date: 1 July 2017
Please cite this article as: C. Liu, Q. Wu, M. Ji, H. Zhu, H. Hou, Q. Yang, C. Jiang, J. Wang, L. Tian, J.
Chen, W. Hou, Constructing Z-scheme charge separation in 2D layered porous BiOBr/graphitic C N
3 4
nanosheets nanojunction with enhanced photocatalytic activity, Journal of Alloys and Compounds
(2017), doi: 10.1016/j.jallcom.2017.07.003.
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ACCEPTED MANUSCRIPT
Constructing Z-Scheme Charge Separation in 2D Layered Porous
BiOBr/Graphitic C3N4 Nanosheets Nanojunction with Enhanced Photocatalytic
Activity
Chao Liu,a Qisheng Wu,a Mingwei Ji,a Huajun Zhu,a Haijun Hou,a Qihang Yang,a
Cuifeng Jiang,a JingJing Wang,a Liang Tian,a Jing Chen,b,* Wenhua Houc,*
a
School of Materials Engineering, Yancheng Institute of Technology, Yancheng,
224051, P. R. China.
b College of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing,
211816, P.R. China
c
Key Laboratory of Mesoscopic Chemistry of MOE, School of Chemistry and
Chemical Engineering, Nanjing University, Nanjing, 210093, P. R. China
*Corresponding author. Tel: (+86)-25-83686001.
E-mail address: whou@nju.edu.cn

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ACCEPTED MANUSCRIPT
Constructing Z-Scheme Charge Separation in 2D Layered Porous
BiOBr/Graphitic C3N4 Nanosheets Nanojunction with Enhanced
Photocatalytic Activity
Chao Liu,a Qisheng Wu,a Mingwei Ji,a Huajun Zhu,a Haijun Hou,a Qihang Yang,a
Cuifeng Jiang,a JingJing Wang,a Liang Tian,a Jing Chen,b,* Wenhua Houc,*
a
School of Materials Engineering, Yancheng Institute of Technology, Yancheng,
224051, P. R. China.
b College of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing,
211816, P.R. China
c
Key Laboratory of Mesoscopic Chemistry of MOE, School of Chemistry and
Chemical Engineering, Nanjing University, Nanjing, 210093, P. R. China
*Corresponding author. Tel: (+86)-25-89686001.
E-mail address: whou@nju.edu.cn
Abstract:
In the present work, a series of layered BiOBr/g-C3N4 heterojunction
photocatalysts were prepared via a simple reflux process, and their photocatalytic
performance was investigated by the degradation of rhodamine B (RhB) and
bisphenol A (BPA) under visible light irradiation. It was found that BiOBr nanoplates
were deposited on the external surface of g-C3N4nanosheets (CNNS) and the tightly
contacted interface was formed between two components, giving rise to a 2D porous
layered heterojunction structure with a high specific area. It was found that BiOBr
nanoplates coupled with the proper amount of CNNS exhibited an excellent
photocatalytic performance due to the combined effects of layered heterojunction,
high specific surface area and porous structure, which lead to the high efficiency of
•
light harvesting and charge separation. The active species of OH is the most crucial
•−
one while h+ and O2 contributed to a lesser extent in RhB and BPA photocatalytic
•
•−
degradation. Based on the direct evidence of the formed OH, O2 and h+ active
1

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ACCEPTED MANUSCRIPT
species detected by active species capture experiment and ESR spectra, a Z-scheme
photocatalytic mechanism was proposed for the charge separation. The present work
may provide an insight for designing novel layered Z-scheme heterojunction
photocatalysts with a high performance.
KeywordsꢀBiOBr, g-C3N4, Layered heterojunction, Photodegradation, Z-scheme
1. Introduction
As a green and effective method, semiconductor photocatalysis has provided an
alternative way to effectively use solar energy for solving ever-increasing
environmental and energy crises, especially for the removal of hazardous organic dyes
from wastewater [1-3]. However, there are still many shortcomings needed to be
overcome in order to enhance visible light photocatalytic activity, such as limited
utilization of solar energy and low separation efficiency of photogenerated
electron-hole pairs [4].
Till now, many strategies, including doping, morphology engineering,
heterojunction and so forth, have been developed to overcome the above mentioned
shortcomings [5]. Especially, the construction of heterojunction photocatalysts has
attracted considerable attention due to its effectiveness in improving the
photocatalytic activity [6].
Basically, two types of heterojunctions, namely type-II heterojunction and
solid-state Z-scheme system, have been well established, showing the different
pathways for interfacial charge transfer [7-9]. In a type-II heterojunction, the redox
ability of photogenerated electrons and holes will be reduced due to the transfer of the
photogenerated electrons to a less negative conduction band (CB) and holes to a less
positive valence band (VB), respectively. However, in a Z-scheme system, the
photoinduced electrons in less negative CB from one semiconductor and holes in less
positive VB from the other semiconductor will recombine at their interfaces, leaving
behind the electrons and holes with stronger redox ability separately on two
semiconductors. Therefore, the construction of Z-scheme system with dual
2