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Synthesis & Characterization of TiO2 & doped TiO2 Nanostructures for application in Dye Sensitized Solar Cell
Project Guide Project Student Dr.Tom Mathews Jose Martina PScientific Officer (G) 13PGN02SND Internal Project GuideIGCAR- Kalpakkam Dr.V. Sri Devi Co-ordinator Center for NanoScience Lady Doak College Madurai
Outline of the work
• Synthesis of TiO2 nanotube powders by Electrochemical
anodization Technique
• Modification of the synthesized TiO2 by Nitrogen doping
• Characterization of the synthesized TiO2 using XRD, HRTEM,
FESEM and DRS
IntroductionTitania is a wide band gap semiconductor metal oxide.
Nano structures of this material has widespread application
in solar energy conversion .
Electrochemical anodization was found to be the easiest and
cost effective method for the synthesis of TiO2 nanotubes
By this technique powder nanotubes of TiO2 were
synthesized
The bandgap was modified by N-doping
Biological and chemical inertnessNon-toxicityLow costAvailabilityLong term stability against photo and chemical corrosion
Advantages Titania
Applications
Photocatalysis (hydrogen generation and organic
destruction)
Sensors
Self cleaning properties
Antibacterial action
Photovoltaic devices
Motivation
To synthesize TiO2 nanotubes by electrochemical anodization technique and to study the crystalline and morphological stability for Dye Sensitized Solar Cell application
What is Solar Energy?
Energy produced by the sun
Clean, renewable source of energy
Harnessed by solar collection
methods such as solar cells
Converted into usable energy such as
electricity
• 26,126 kWh/CapitaEnergy
Generation
• 183,161 TWh/CapitaEnergy
Consumption
Energy Demand
To overcome the demand solar cell is used
Photovoltaic Solar Cells
Generate electricity directly from sunlight2 Main types:
Single-crystal silicon (traditional)• Widespread• Expensive to manufacture
Dye-sensitized (“nano”)• Newer, less proven• Inexpensive to manufacture• Flexible• High power conversion
efficiencies
Silicon-based solar cell
Dye-sensitized solar cell
Synthesis of one dimensional TiO2 architectures
Nano architectures – Nanotubes, rods and wires more active due to
directionality and large surface area. Hence nanotubular Architectures of
TiO2 were preferred
Nanotubular architectures
Nanotube powders
Electrochemical Anodization
Nanotube arrays
Rapid Breakdown anodization
Advantages of Electro chemical anodization
Cost effective
Simplest of all techniques
Aspect ratio tuning by changing the electrochemical
parameters
Chemical reaction involved…..2Ti + 2H2O 2TiO2 + 4e + 4H+
Working Electrode: Ti foil
Counter Electrode: Platinum foil Electrolyte : 0.1M
perchloric acid Applied voltage :11V
White powders of Titania ……
Synthesis of TiO2 powder nanotubes
Technique used … Rapid break down anodization
Synthesis of TiO2 nanotube arrays
Working Electrode: Ti foil
Counter Electrode: Platinum foil Electrolyte : 97 g of
ethylene glycol +0.5 g ammonium fluoride +2.5 g of DI water
Applied voltage :40V
Technique
used …
Electrochem
ical
Anodization
TiO2 Doping Dopants :Urea,
Hydrazine, Ammonia with different
concentrations….Voltage applied:
40 V
To overcome the disadvantage of tio2 dopants are usedDopants modify nano-TiO2’seffective range of light sensitivity
from the ultra-violet (UV) region to the visible light region due to band gap tuning
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1. Photovoltaic StudiesSolar Cell Fabrication and testing of DSSC fabricated using TiO2 nanotube arrays on
Ti foils and FTO coated glasses
Dye loaded TiO2 on FTO glass
Pt electrode
DSSC ready!!!!!!!
Taken for solar cell performance studies
•Dye-0.5mM N 719 dye in acetonitrile•Electrolyte- solaronix Iodolyte
Schematic of DSSCA sandwitch structure made of two conducting electrodes with a redox electrode filling the inter layer separation. Exposure of light - excitation of the dye - injects electrons to the CB of the oxide layerElectron hope through the semiconductor and collected at the collector electrode.Electrons flow through the external circuit and reach to the counter electrodeReduce the oxidized form of the electrolyte.
RBA Electrochemical synthesis routes provide an attractive alternative to the standard methods of synthesizingnanomaterials. Electrochemical anodic oxidation has been widely used to synthesize TiO2 nanotubes ontitanium metal surface. Recently, an anodization of Ti foil in an electrolyte containing chloride or perchlorateions can produce high aspect ratio TiO2 NTs in very short time (~ 50 µm in < 1 min), which the mainadvantage of this kind of anodization that known as “rapid breakdown anodization”
TiO2 Nanostructures – Energy Related Applications
Dye Sensitized Solar Cell Hydrogen Generation by water splitting
Counter Electrode Working electrode
Pt – Optimization
Electrochemical Characterization
Ammonia annealing
Electrochemical anodization
Electrochemical impedance spectroscopy
Mott Schotky plot Studies
Synthesis of 1. TiO2 nanotube powders2. N-doped TiO2 nanotube
powders3. TiO2 nanotube arrays4. N-doped TiO2 nanotube
arrays
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Scanning Electron MicroscopyTransmission Electron MicroscopyX ray DiffractionRaman SpectroscopyFourier Transform Infra Red Spectroscopy
X-ray Photoelectron Spectroscopy- compositional analysis
PhotoluminescenceUltraviolet and Visible Absorption Spectroscopy
Temperature Programmed Desorption Reduction OxidationBrunauer Emmet Teller adsorption methodApplication:Field EmissionContact AnglePhotocatalytic Hydrogen GenerationSolar Cell Fabrication and testing
Morphology and structural characterization
Optical characterization
Chemi & Physisorption surface area measurement
Characterization
Experimental Details
Synthesis of TiO2 nanotubes by electrochemical
anodization.
Annealing of the anodized samples at different
temperatures.
Characterization by FESEM and XRD
Surface wettability by studies by contact angle
measurements.
Conclusions
Self aligned TiO2 nanotube arrays were synthesized on Ti
substrates by electrochemical anodization technique.
The potentiostatic transients qualitatively revealed the
mechanism of nanotube formation
Structural and morphological stability were revealed from
XRD and FESEM analysis.
Shows very good surface wettability with solar cell indicates
its potential application in Dye sensitized solar cell.
Ongoing studies & Future plans……
Characterization of TNTA on Ti substrates, TNTA on FTO
coated glasses and N doped TNTA using FESEM, TEM, XRD,
XPS, Micro Raman, DRS, FTIR,UV visible spectroscopy
To investigate the DSSC performance of the synthesized TiO2
nanotube arrays photocat h2 gen by water splitting
Study the effect of crystallinity on the solar cell performance of
the material