Summary of chemistry doctoral thesis: Synthesis and characterization of doped Mn, Ce and C to ZnO nanoparticles and evaluation of their photo-oxidation potentiability

The objectives of the thesis: The thesis focused on the synthesis of Mn, Ce, C doped ZnO nanoparticles materials and doped ZnO with multi-layered carbon nanotube nanocomposite materials and assessed their photo-oxidative potentiality through photocatalytic reactions of methylene blue (MB) decomposition in aqueous solution under visible light.
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Summary of chemistry doctoral thesis: Synthesis and characterization of doped Mn, Ce and C to ZnO nanoparticles and evaluation of their photo-oxidation potentiability MINISTRY OF EDUCATION VIETNAM ACADEMY OF AND TRAINING SCIENCE AND TECHNOLOGY GRADUATE UNIVERSITY SCIENCE AND TECHNOLOGY ------------------------------------- LUU THI VIET HA SYNTHESIS AND CHARACTERIZATION OF NANOMATERIALS Mn, Ce AND C DOPED ZnO AND EVALUATION OF THEIR PHOTO-OXIDATION POTENTIAL Major: Inorganic chemistry Code: 9.44.01.13 SUMMARY OF CHEMISTRY DOCTORAL THESIS Hanoi - 2018 This thesis was completed at: Graduate University Science and Technology - Vietnam Academy of Science and Technology Adviser 1: Assoc. Prof. Dr. Luu Minh Đai Adviser 2: Assoc. Prof. Dr. Dao Ngoc Nhiem 1st Reviewer: 2nd Reviewer: 3rd Reviewer: The thesis will be defended at Graduate University of Science and Technology - Vietnam Academy of Science and Technology, at hour date month 2018 Thesis can be found in The library of the Graduate University of Science and Technology, Vietnam Academy of Science and Technology. 1 INTRODUCTION The urgency of thesis Today, the rapid growth of industries is in parallel with the level of serious environmental pollution, especially water pollution. The textile industry is one of the industries that causes bad water pollution due to direct discharge of wastewater into rivers. The World Bank estimated that from17 % to 20 % of industrial water pollution came from dyeing and fabric processing plants which cause alarming number for textile manufacturers, as well as environmental managers and scientists. So far, the methods of treating textile wastewater are used such as coagulation, sintering, biodegradation, adsorption by activated carbon, oxidation methods. Among these methods, the biodegradation is widely applied to treat textile wastewater on a large scale. However, under anaerobic condition, azo dye can be reduced to byproducts as the very toxic aromatic amines. Recently, we have found out advanced oxidation method which is a new and promising method for treating textile and dyeing wastewater. This method usually uses a catalyst as photocatalysts to generate OH radicals , under illumination which have strong oxidizing ability and can breakdown most organic chemicals. Photocatalysts are oxides such as TiO2, ZnO, SnO2, WO2 and CeO2, which are abundant in nature and are widely used by heterogeneuos processes. Among them, ZnO is considered to be a promising catalyst for decomposition of organic pigments as well as for water disinfection. The photocatalytic ability of ZnO is higher than that of TiO2 and some other semiconductor oxides on the basis of absorption of solar radiation energy. However, ZnO has a relatively large (3,27eV) bandgap energy, which corresponds to the ultraviolet light zone for optimum photocatalytic efficiency. Meanwhile, ultraviolet light accounts about 5 % radiation of solar. Therefore, practical application of ZnO has limited. In order to improve photocatalytic activity and expand application field, it is necessary to transform the electron properties in ZnO nanostructure and reduce bandgap energy and electron recombination dynamics and optical hole properties. DopedMetallic or non-metallic or co-doped metallic and non-metalic to the ZnO is one of the effective methods to increase photocatalytic activity of ZnO. Thus, the research topic of the thesis Synthesis and characterization of doped Mn, Ce and C to ZnO nanoparticles and evaluation of their photo- 2 oxidation potentiability was selected with the following objectives and contents: 1. The objectives of the thesis: The thesis focused on the synthesis of Mn, Ce, C doped ZnO nanoparticles materials and doped ZnO with multi-layered carbon nanotube nanocomposite materials and assessed their photo-oxidative potentiality through photocatalytic reactions of methylene blue (MB) decomposition in aqueous solution under visible light. 2. The content of the thesis: 2.1. The material synthesis: - Synthesis of Mn doped ZnO and Ce doped ZnO nanoparticle materials by combustion and hydrothermal method; - Synthesis of C, Mn and C, Ce co-doped ZnO nanoparticles by hydrothermal method; - Synthesis of C, Ce co-doped ZnO combined with multi-layer carbon nanotube composite materials. 2.2. Physical properties and characteristic studies of the synthesized materials: Synthesized materials were investigated using thermo-gravimetric and differential thermal analysis (DTA-TG), X-ray diffraction (XRD) analysis, Fourier-transform infrared spectroscopy (FT-IR), UV-Vis diffuse reflectance spectroscopy (UV-VIS), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscope (XPS), Brunauer-Emmett-Teller (BET)analysis and energy –dispersive x-ray spectroscopy (EDX). 2.3. Study of photo-oxidative potentiality of the materials: Synthesized materials were evaluated for photo-oxidative potentiality through photocatalytic reactions of methylene blue (MB) decomposition in aqueous solution under visible light. CHAPTER 1: OVERVIEW 1.1. ZnO materials 1.1.1. Introduction of ZnO 1.1.2. Application of ZnO 1.2. Methods of synthesizing ZnO materials 1.2.1. Hydrothermal method 1.2.2. Combustion method. 1.3. Doped ZnO materials 1.3.1. Doped ZnO materials 1.3.2. Reseaches of ZnO and doped ZnO photocatalytic materials 3 1.4. Photocatalyst 1.4.1. ZnO photocatalysis 1.4.2. Doped ZnO photocatalysis CHAPTER 2: EXPERIMENTS AND RESEARCH METHODS 2.1. Synthesis of materials 2.1.1. Synthesis of Mn doped ZnO and Ce doped ZnO 1.1.1.1. Synthe ...