Preparation and Characterization of g-C3N4/I-TiO2 Composite Photocatalyst and Application in Photodegradation

摘要

A novel g-C3N4/I-TiO2 composite photocatalyst was successfully designed and prepared by a simple hydrothermal method. The as-synthesized samples were characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD), fourier transform infrared spectroscopy(FT-IR), Brunauer Emmett-Teller(BET) surface area analysis, X-ray photoelectron spectroscopy(XPS), ultraviolet-visible(UV-Vis)spectroscopy. The photocatalytic activities of g-C3N4/I-TiO2 were evaluated by the oxidative degradation of target pollutants such as methyl blue(MB)and rhodamine B(RhB)under visible-lightirradiation(λ＞420nm). XRD results showed that all samples showed only anatse phase structure. 40wt％g-C3N4/I-TiO2 composite photocatalysts samples have aggregate semi-spherical particles.
　　Under optimal experimental condition,the 40wt％g-C3N4/I-TiO2 composites photocatalyst exhibited the highest photocatalytic activity.This g-C3N4/I-TiO2 composite photoactive component was incorporated in varying amounts in the g-C3N4,and the resulting composites proved to have improved photoactivity over composites containing the I-TiO2.
　　g-CaN4 could directly absorb the photons to induce the excitation of electrons from the highest occupied molecular orbital(HOMO)to the lowest unoccupied molecular orbital (LUMO)of g-C3N4.The excited state electrons could then transfer from the LUMO of g-C3N4to I-TiO2their interracial interaction.This can efficiently inhibit the recombination of photo-generated electrons and holes,and thus significantly improving the photocatalytic performance.This thesis proposes a novel g-C3N4/I-TiO2 compositephotocatalyst that can be used in waste water remediation.g-C3N4/I-TiO2 composite is a material of particular interest due to its chemical and photo-corrosion stability.

目录

声明

ABSTRACT

CONTENTS

Chapter 1 Literature Review

1．1 Introduction

1．2 TiO2Photocatalyst

1．2．1 Electronic Processes in Ti02Photocatalysis

1．2．2 Basic Principles of Heterogeneous Photocatalysis

1．3 (non-)metal-doped TiO2

1．3．1 Sulfur Doped TiO2

1．3．2 PhosphorusDoped TiO2

1．3．3 BoronDoped TiO2

1．3．4 Carbon Doped TiO2

1．3．5 Iodine-doped TiO2

1．3．6 Photoactive Mechanism

1．4 Graphitic Carbon Nitride(g-C3N4)

1．4．1 Modification of g-CaN4 for improved photocatalytic activity

1．4．2 Advantages and challenges of g-CaN4based photocatalysts

1．5 Dye Pollutants

1．5．1 Methylene blue (MB)

1．5．2 Rhodamine B (RhB)

1．6 Introduction of a New Research Topic and Statement on Topic Significance

Chapter 2 Experimental Part

2．1 Materials

2．2 Preparation of Graphitic Carbon Nitride g-CaN4

2．3 Preparation and Characterization of g-CsN4／I-TiO2 Composite

2．4 Characterization

2．4．1 X-Ray Diffraction (XRD)

2．4．2 Scanning Electron Microscopy (SEM)

2．4．3 Transmission Electron Microscopy (TEM)

2．4．4 Brunauer Emmett-Teller (BET) Specific Surface Area Analysis

2．4．5 Ultraviolet-visible (UV-Vis) spectroscopy

2．4．6 Fourier Transform Infrared Spectroscopy (FTIR)

2．4．7 X-ray Photoelectron Spectroscopy (XPS)

Chapter 3 Results and discussion

3．1 Phase Composition

3．2 Morphology

3．3 Binding Energies

3．4 Surface Area

3．5 Functional Groups

3．6 Light Absorption

Chapter 4 Photocatalytic Performance

4．1 Photocatalytic Activity

4．1．1 The Degradation of Methylene Blue (MB) and Rhodamine B (RhB)

4．1．2 Photocataytic Mechanism

Chapter 5 Conclusion

Refefences

Acknowledgements

Brief Introduction of the Author and Supervisor