Ph.D. Thesis

Development of Z-scheme heterojunction Type II
photocatalysts for efficient degradation of pollutants
under solar light irradiation

Graduate School of Yeungnam University

Department of Chemical Engineering
Major in Chemical Engineering

NGUYEN VAN QUANG

Advisor: Prof. Jae-Jin Shim

August 2021

Ph.D. Thesis

THƯ VIỆN TRƯỜNG ĐẠI HỌC BÁCH KHOA – ĐẠI HỌC ĐÀ NẴNG.

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Development of Z-scheme heterojunction Type II
photocatalysts for efficient degradation of
pollutants under solar light irradiation

Advisor: Prof. Jae-Jin Shim

Presented as Ph.D. Thesis

August 2021

Graduate School of Yeungnam University
Department of Chemical Engineering
Major in Chemical Engineering

NGUYEN VAN QUANG

THƯ VIỆN TRƯỜNG ĐẠI HỌC BÁCH KHOA – ĐẠI HỌC ĐÀ NẴNG.

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Nguyen Van Quang’s Ph.D. Dissertation is
approved
Committee member Prof. Moonyong Lee,
Ph.D _____________
_____________
Committee member Prof. Jae-Jin Shim, Ph.D
_____________
Committee member Prof. Taeho Yoon, Ph.D
Committee member Prof. Jinwoo Lee, Ph.D
_____________
Committee member Prof. Dohyung Kang, Ph.D _____________

August 2021

Graduate School of Yeungnam University



Acknowledgments
Firstly, I would like to express gratitude from the bottom of my heart to my supervisor Prof.
Jae-Jin Shim for his guidance, sincere advice, and supports during my stay for combined Master
and Ph.D program at Nano Energy Materials and Processing lab (formerly, Supercritical Fluids
and Nano Processing Lab). I would also like to thank the committee members: Prof. Moonyong
Lee, Prof. Taeho Yoon, Prof. Jinwoo Lee (KAIST), and Prof. Dohyung Kang for useful and
valuable recommendation on my dissertation and final defense.
Secondly, I would like to give my gratitude to postdocs and research professors in
NanoEMAP lab: Dr. Hoa, Dr. Ranjith, Dr. Amr, Dr. Rabie, Dr. Manjiri, Dr. Shafi, Dr. Darshna,
Dr. Kathik, and Dr. Debananda for their sharing of knowledge and research experience. I would
like to express my thanks to the past and present lab members: Dr. Marjorie, Dr. Toan, Mr.
Mostafa, Mr. Ganesh, Ms. Tensangmu, Mr. Abebaw, Mr. Chinh, Mr Tue, Ms. Lamiel, Mr.
Sarmad, Mr. Olvianas, Mr. Umer, Mr. Jinho, who shared their study experience and helped me
in the life in Korea.
I am also grateful to the Graduate School of Yeungnam University, which provided me with
full scholarship for my combined Master and Ph.D course, and the BK21+ Program for the
financial support during my stay in Yeungnam University.
Further, I would like to thank my senior staff from Building Material Division, Faculty of
Bridge and Road engineering, and close friends (Mr. Quang Hung, Mr. Minh Hoang, Ms. Minh
Tri, Mr. Van Thanh, Ms. Thi Phuong, Mr. Manh Hung ...) from Vietnam and (Mr. Van Dung,
Mr. Van Nam, Ms. Vinh Quy) in Korea for their company and encouragement during my stay in
Korea. Special thanks as well to Prof. Doan Quang Vinh (Rector of University of Science and
Technology-The University of Danang), Dr. Huynh Phuong Nam (Head of Department of
Personal Management-The University of Danang), Dr. Cao Van Lam (Dean of Faculty of Bridge
and Road Engineering, University of Science and Technology-The University of Danang) for
their unwavering support from Vietnam towards the completion of my doctoral degree. To
사모님,

Prof. Shim’s wife, for her best regards to me and great Korean meals.

Lastly, I am very grateful to my lovely family for special care, love, encouragement, and
supports. I would like to thank my parents (Dieu Nguyen, Thi Be Nguyen), my siblings (Hung

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Nguyen, Thi Nguyet Nguyen, Thi Nga Nguyen, Son Nguyen), my brothers and sisters-in-law
(Phu Trong Nguyen, Day Pham, Thi Nga Hoang, Thi Hang Vo) and all my nephews and nieces.

Thank you for beautiful memories with all of you in Korea.

Nguyen Van Quang
Yeungnam University
Republic of Korea
August 2021

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Abstract
Recently, the Z-scheme photocatalytic system has attracted more attention in
the photocatalyst designs for environmental remediation applications. Compared
with conventional designs of the photocatalysts, the Z-scheme-based design has
been selected as an ideal solution to improve the photocatalytic activity and
stability of the catalysts. This Z-scheme photocatalytic system not only reduces
the recombination of photoinduced electrons and holes but also maintains a
prominent redox ability. This dissertation builds up the story of various
photocatalytic systems from the simple construction of ZnO/graphene to the
Zscheme-based construction among semiconductors (TiO2, C-MoS2, BiPO4,
BiOCl, Ag/AgBr, BiOBr, and Bi2O3). For each photocatalytic system, the

synthesis method, characterization, and photocatalytic activities of the
photocatalysts in the degradation of organic pollutants, such as methylene blue
(MB), rhodamine B (RhB), and methyl orange (MO), tetracycline hydrochloride
(TCH), hydroxychloroquine (HCQ) in water are presented. In addition, the
mechanism of pollutant degradation at each photocatalytic system was also
discussed.

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In Chapter 2, the nanospherical ZnO/rGO composite synthesized by a twostep
method showed the high MB and RhB removal efficiencies and good
stability under UV light.
In Chapter 3, a Z-scheme heterojunction photocatalyst of C-MoS2/TiO2
nanocomposite was prepared by a two-step hydrothermal method (high
temperature and high pressure). The Z-scheme photocatalyst exhibited the
improvement of photocatalytic activity in the degradation of MB, RhB, and TCH
under solar light.
In Chapter 4, a facile and rapid microwave-assisted one-step method was
used to synthesize the Z-scheme ternary photocatalyst of silk cocoon-like BiPO4
on BiOBr/Bi2O3 nanosheets. The Z-scheme charge transfer mechanism among
three bismuth-based components resulted in a stronger enhancement of RhB
degradation under solar light. The photocatalyst also performed good
photocatalytic activity towards the TCH, HCQ, and MO pollutants under solar
light.
Following the same synthesis method as in Chapter 4, the Z-scheme ternary
photocatalyst of layer-structured BiOCl/BiOBr/Bi2O3 nanocomposite was

prepared and the excellent photocatalytic activity and good stability of the
catalyst were demonstrated in the degradation of RhB dye with high dye

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THƯ VIỆN TRƯỜNG ĐẠI HỌC BÁCH KHOA – ĐẠI HỌC ĐÀ NẴNG.

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concentration under visible and solar light. Moreover, this Z-scheme
photocatalyst also showed good photocatalytic activity for TCH and MO
pollutants.
Chapter 6 presents the synthesis of Z-scheme quaternary photocatalyst of
Ag/AgBr@BiOBr/Bi2O3 nanocomposite using the same method as described in
Chapters 4 and 5. This quaternary photocatalyst is highly efficient in degrading
the MO dye with high removal efficiency and excellent stability under visible
light. The photocatalyst also showed the good photocatalytic activity for RhB and
TCH under different light sources: Light-emitting diode (LED), halogen lamp
(from an overhead projector), and simulated solar light.
In addition, the rapid microwave-assisted one-step method could be used in
the large-scale processes for synthesizing the good Z-scheme photocatalysts for
the field of environmental remediation because the method is facile, fast, and
controllable.

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THƯ VIỆN TRƯỜNG ĐẠI HỌC BÁCH KHOA – ĐẠI HỌC ĐÀ NẴNG.

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