Bromination of C-H Bond by In-situ generated Br2 over Tantalum Nitride based Photoanode
- 주제(키워드) Photoelectrochemical cell , C-H activation , Bromination
- 주제(DDC) 621.042
- 발행기관 아주대학교 일반대학원
- 지도교수 Eun Duck Park
- 발행년도 2024
- 학위수여년월 2024. 2
- 학위명 박사
- 학과 및 전공 일반대학원 에너지시스템학과
- 실제URI http://www.dcollection.net/handler/ajou/000000033409
- 본문언어 영어
- 저작권 아주대학교 논문은 저작권에 의해 보호받습니다.
초록/요약
(Photo)electrochemical catalysis, a developing discipline within the physical sciences, encompasses diverse processes across various domains. PEC cells have gained significant recognition as critical tools in energy and environmental application. Initially, PEC cells were employed for generating hydrogen fuel through water splitting, however, their utility extends to pollutant degradation, carbon dioxide reduction, and solar fuel production. Despite their established applications, their potential in organic synthesis is still in its nascent stages. Motivated by the desire for environmentally benign and sustainable synthetic routes, the integration of photochemistry and electrochemistry stands as an innovative paradigm, offering a promising approach to support new strategies of organic chemists. PEC cells are attractive due to their abundance and convenience, utilizing the affordable and environmentally friendly power of sunlight. They leverage a diverse selection of photoelectrode materials and redox mediators while operating effectively under gentle reaction conditions. They benefit from a wide range of photoelectrode materials and redox mediators, along with their capacity to operate under mild reaction conditions. In this study, a photoelectrochemical cell was used for tandem bromination of toluene within a unique two-phase electrolyte system. By incorporating a RuOx co-catalyst, the Ta3N5 photoelectrode demonstrated a remarkable selectivity for Br2 close to 100% without simultaneously generating O2. The kinetic study for charge carriers of photoelectrode reveals that the improved charge transfer at RuOx/Ta3N5 interfaces contributed to excellent photoelectrochemical Br2 evolution activity of RuOx decorated Ta3N5 photoanode. The photoelectrochemically produced Br2 was utilized for bromination of α-sp 3 carbon in toluene, (1-methyl)naphthalene, ethylbenzene, or cyclohexane by RuOx/Ta3N5 photoanode with 100% regioselectivity. The coupling of Ta3N5 photoanode and InP photocathode generated H2 and Br2 under light illumination conditions without external bias. This study provides systematic insights into the design of photoelectrodes for solar-driven tandem bromination systems within the unique environment of a two-phase electrolyte system.
more목차
Abstract i
List of Tables vi
List of Figure vii
CHAPTER 1 INTRODUCTION 1
1.1 Background of PEC organic synthesis 1
1.2 Important of C-H activation for organic synthesis 3
1.3 Basic Principles of photoelectrocatalysis 4
1.3.1 Fundamentals 4
1.3.2 Driving force for cell operation 5
1.4 Electrochemical reaction types 7
1.5 Green and sustainable chemistry 8
1.6 Aims and objectives 10
CHAPTER 2 LOW-TEMPERATURE CONVERSION OF METHANE 12
2.1 Electrochemical conversions of methane 12
2.1.1 Motivation for C-H activation in methane 12
2.1.2 Advantages of electrochemical conversions 13
2.2 Direct electrochemical conversion of methane 14
2.2.1 Methane to C2+ hydrocarbons 14
2.2.2 Methane to alcohols 24
2.3 Indirect electrochemical conversion of methane 32
2.3.1 Methane conversion highly active species 32
2.3.2 Methane conversion via halogens 34
2.4 Photoelectrochemical (PEC) methane oxidation 35
2.4.1 TiO2 40
2.4.2 WO3 41
2.4.3 ZnO 43
2.4.4 Potential semiconductor materials 44
2.5 Mechanistic insights for high selectivity during methane oxidation 45
2.5.1 Direct oxidation: co-catalyst approach 46
5.5.2 Indirect oxidation: PEC production of oxidant 51
2.6 Other factors that affect methane oxidation 53
2.7 Effect of catalyst structure on reaction selectivity 56
2.8 Activity evaluation for PEC methane oxidation 57
CHAPTER 3 EXPERIMENTAL 59
3.1 Materials 59
3.2 Preparing electrocatalytic anode and Ta3N5 photoanode 59
3.3 (Photo)electrochemical characterization 60
3.4 Photodiode configuration with Ta3N5 photoanode and InP photocathode 61
3.5 Quantifying (photo)electrochemical Br2 evolution 61
3.6 Tandem bromination of toluene 62
3.7 Other characterizations 63
CHAPTER 4 RESULTS AND DISCUSSION 65
4.1 Electrocatalyst characterization 68
4.2 Electrochemical BER 70
4.3 Electrocatalyst Bromination of Toluene 71
4.4 Photoelectrochemical Bromination of Toluene 73
4.5 Stability test 80
4.6 Post-stability XPS 81
4.7 Charge transfer dynamics 82
4.8 Photoelectrochemical tandem bromination of toluene 86
4.9 Bias-free photoelectrochemical BER 87
Conclusion 90
References 91
