- Titanium dioxide shells were deposited on zinc oxide nanorods using a hydrothermal method. Zinc oxide nanorods were first grown on a fluorine-doped tin oxide substrate via hydrothermal synthesis using zinc nitrate hexahydrate, hexamethylenetetramine, and deionized water at 80°C for 1-3 hours. Titanium dioxide shells were then deposited on the zinc oxide nanorods by another hydrothermal treatment using titanium isopropoxide as a titanium precursor at 150°C for 5 hours. The zinc oxide-titanium dioxide core-shell nanostructures were characterized using X-ray diffraction, scanning electron microscopy, UV-visible spectroscopy, and solar cell testing to analyze their structure, morphology

1. HA NOI UNIVERSITY OF SCIENCE AND TECHNOLOGY
**** ADVANCED TRAINING PROGRAM ****
OVERVIEWS OF INDEPENDENT STUDY:
SYNTHESIS OF ZnO-TiO2 CORESHELL
NANOSTRUCTURES BY HYDROTHERMAL
METHOD
Name : Hoàng Văn Tiến
Class : MSE-K54
ID Student : 20092697
Instructor : Dr. Nguyễn Duy Hùng-AIST

2. OUTLINE :
• Why i choose this topic?
• ZnO-TiO2 overviews
• Hydrothermal methods
• Process of researching
• Analysis method
• Results and discussions
• Summary

3. WHY I CHOOSE THIS TOPIC ?
Types of solar cell :
- Buried contact solar cell
• Cadmium telluride solar cell
• Copper indium gallium
selenide solar cells
• Dye-sensitized solar cell
• Gallium arsenide germanium
solar cell
• Hybrid solar cell
• - Organic solar cell
- Nanocrystal solar cell
- Plasmonic solar cell
- Plastic solar cell
- Polycrystalline solar cell
- Polymer solar cell
- Quantum dot solar cell
- Solid-state solar cell
- Thin film solar cell
- Monocrystalline solar cell
- Multijunction solar cell
- ……………………….

4. WHY I CHOOSE THIS TOPIC ?
• Harmful organic compounds in the ecological unit are the main concern
for the scientific society, which is causative agent of water pollution and
severe contamination of the environment. Waste-water containing organic
dyes (organicpollutants) inhibit sunlight penetration which
suppressesphotosynthetic reaction.
• Metal oxide semi-conducting nano materials have been proven to be very
efficient photocatalysts for the degradation of organic dye pollutants with
the help of solar light. In particular, TiO2 and ZnO are the most versatile
semiconductor oxides with applications across a wide range from
cosmetics to air purification.
• However, the poor consumption of solar energy and the short diffusion
length of photogenerated exciton are the two key factors restrictive to
further improvement of photocatalytic efficiency
develop new and efficient sunlight-sensitive
photocatalysts.
• 

5. FTO :Fluorine doped Tin Oxide

7. TiO2 (rutile )
- Pure titanium dioxide is colorless in the massive state, non-toxic, thermally stable, inert
versus acids, alkalis and solvents, and insoluble.
- Rutile is the most stable and the most abundant form
- Nanocrystalline TiO2 usually exhibits a wider band gap
than that of the bulk (3.03 eV for rutile and 3.20 eV for anatise)
Refractive index
Lattice Constants, Е
n=2.54 for anatise
or 2.75 for rutile at λ = 550 nm)
a = 4.593
c = 2.958
Brookite-orthorhombic
Anatise-tetragonal

10. HYDROTHERMAL METHODS
• The term “hydrothermal” usually refers to any heterogeneous reaction in
the presence of aqueous solvents or mineralizers under high pressure
and temperature conditions to dissolve and recrystallize materials that are
relatively insoluble under ordinary conditions.
• Uses : A large number of compounds belonging to practically all classes
have been synthesized under hydrothermal conditions: elements, simple
and complex oxides , tungstates , molybdates , carbonates, silicates ,
germanates etc. Hydrothermal synthesis is commonly used to grow
synthetic quartz , gems and other single crystals with commercial value.

12. EXPERIMENTALPROCEDURE
• Growth of ZnO nanorods array
• Deposition of TiO 2 shells on ZnO nanorods
• Materials characterization
• X‐ray diffraction (XRD) used to phase characterization and crystalline
size,
• Scanning electron microscopy (SEM) to morphology and
microstructure investigations.
• Diffusive UV‐visible‐NIR spectrometry to band gap calculations
• Solar cell fabrication and testing

13. GROWTH OF ZNO NANORODS ARRAY
• Process :
- Substrate preparation
- Growth ZnO nanorod
• Prepare :
-Zn(COOCH3)2.2H2O
- Zn(NO3)2 .6H2O
- DI water
-Dimethylformamide (DMF):
(CH3)2NC(O)H
-hexamethylenetetramine C6H12N4
-FTO substrate
-Powder coating gun

14. SUBSTRATE PREPARATION
• Clean substrate
• 0.44g Zn(COOCH3)2.2H2O + 20ml DMF
• Dry substrate to150 oC
• Coating
• Drying

15. GROWTH ZNO NANOROD
- temperatures : 80 0C
- Times : 1h -2h-3h
- Concentrations :
•
2 (Zn(NO3)2 .6H2O) :1 HTMA
- 0.75 g Zn(NO 3)2 .6H2O +150ml DI
• 0.35 g hexamethylenetetramine +100ml D
•
1 (Zn(NO3)2 .6H2O) :1 HTMA
- 0.45 g Zn(NO 3)2 .6H2O +150ml DI
• 0.42 g hexamethylenetetramine +100ml D
•
2 (Zn(NO3)2 .6H2O) :1 HTMA
- 0.75 g Zn(NO 3)2 .6H2O +150ml DI
• 0.35 g hexamethylenetetramine +100ml DI

16. 
∆t < 1 0C
Heat controllers

17. PHOTOLUMINESCENCE
381 nm

18. SEM ANALYSIS

21. DEPOSITION OF TIO 2 SHELLS ON ZNO
NANORODS
•
Preparations :
• ZnO nanorods on FTO substrate