가시광선 광촉매 효율 향상을 위한 결정성 바나듐 산화물/g-C_3 N_4 헤테로구조에서의 Z-스킴 전하 이동 = Z-Scheme Charge Transfer in Crystalline Vanadium Oxide/g-C_3 N_4 Heterostructures for Efficient Visible-Light Photocatalysis

다국어 초록 (Multilingual Abstract)

In recent years, graphite-like carbon nitride (g-C_3 N_4) has managed to attract considerable attention due to its narrow band gap and metal-free nature. While unlike titanium and zinc-based metal that have been extensively studied for decades, vanadium can be considered as an emerging field. Vanadium existed in multi oxidation states and various crystalline structures which potentially offer a more catalytic functionality. In this study, Crystalline Vanadium-Based Heterojunctions with g-C_3 N_4 composite had been synthesized via facile method for photocatalytic studies and had been employed in degradation of Congo Red (CR) and reduction of BPA under white light irradiation. The samples prepared were undergoing several characterization tests including SEM,EDS,TEM,FTIR, XPS and XRD. The synthesized photocatalyst demonstrated a high photocatalytic activity, achieving 95.43% degradation of Congo red (CR) and approximately 40% degradation of bisphenol A (BPA), with confirmed stability through repeated photocatalytic cycles. Nevertheless, the primary focus of this study was to develop a simple and cost-effective synthesis route for vanadium oxide–based photocatalysts, which has been successfully demonstrated through the proposed method.

목차 (Table of Contents)

• LIST OF FIGURES iii
• ABSTRACT vi
• 1 INTRODUCTION 1
• 2 MATERIALS AND METHODOLOGY 5
• 2.1 Chemicals 5
• 2.2 Synthesis of Conventional and Facile g-C3N4 nanosheets 5
• 2.3 Synthesis of Crystalline Vanadium 5
• 2.4 Synthesis of Crystalline Vanadium-Based Heterojunctions onto g-C3N4 nanosheet (Vc@g-C3N4) 6
• 2.5 Characterization 8
• 2.6 Photocatalytic Activity Test 8
• 2.7 Charged-carrier trapping experiment 9
• 3 RESULTS AND DISCUSSION 10
• 3.1 Characterization of the Photocatalysts 10
• 3.1.1 Fourier Transform Infrared Spectroscopy (FTIR) 10
• 3.1.2 Optical characterization 13
• 3.1.3 SEM, TEM, EDS 15
• 3.1.4 X-ray diffraction (XRD) 20
• 3.1.5 X-ray Photoelectron Spectroscopy (XPS) 22
• 3.2 Photocatalytic Performance 24
• 3.2.1 Degradation of Congo Red with Photocatalyst 24
• 3.2.2 Degradation of BPA with Photocatalyst 29
• 3.2.3 Comparison degradation performance with several dyes 32
• 3.3 Photocatalytic Mechanism 34
• 3.3.1 Scavengers test. 34
• 3.3.2 Proposed photocatalytic degradation mechanism. 35
• 3.4 Photocatalyst Stability 40
• 3.4.1 Recycle Test 40
• 3.5 Electrocatalytic Activity Evaluation 42
• 3.5.1 Cyclic Voltammetry (CV) 42
• 3.5.2 Electrochemical Impedance Spectroscopy (EIS) 44
• 4 CONCLUSION 46
• REFERENCES 49
• 요약 55
• ACKNOWLEDGEMENTS 57
• AWARDS 59