These slides provide the information about photocatalytic performance of TiO2 as a catalyst. This slides are arranged in a systematic and logical way.

1. Photocatalytic Performance of Dye Doped
Graphene Supported Titania Under Sunlight
Presented by: Muhammad Aamar Azam
M.Phil Physics - UAF

2. Problem
• Use of TiO2 as catalyst is solution of energy problem as it converts
solar energy into chemical energy.
• Due to large bang gap (3.2 eV) of TiO2 works in UV range spectrum
which is only 5 % of sunlight.
Objective
• The aim of this work is to improve its photocatalytic performance
by doping a suitable dye in it so that it works in visible range
spectrum.

3. Titanium Dioxide (TiO2) as a Catalyst
TiO2 is a white powder solid
It is most studied photocatalyst in field of photocatalysis
Atmospheric oxygen is used for reaction
It has strong oxidizing power
It is cheap, non-toxic, abundant
Chemically stable
High resistance to photo-corrosion
Found in three phases
i) Anatase
ii) Rutile
iii) Brookite

4. Why anatase

5. Photocatalysis
Photocatalysis is a reaction which
uses light to activate a substance
(catalyst) which modifies the rate
of a chemical reaction without being
involved itself.
Photosynthesis
Photosynthesis is a process by which
plants prepare their own food
(oxygen and glucose) by using
Chlorophyll (natural photocatalyst)
in the presence of carbon dioxide and water under sunlight.

6. holes and electrons breakdown the
organic matter to carbon dioxide and
water.
chlorophyll turn water and carbon
dioxide into oxygen and glucose
Opposite

7. Photocatalyst
o It is a substance that takes part in a chemical reaction and can alter the rate
of reaction, without being consumed at the end of the reaction.
Reaction Kinetics
o A catalytic reaction is compared to
a reaction which is not using catalyst.
o top curve=uncatalyzed reaction
o lower curve=catalyzed reaction
o Activation energy=energy difference
between energy of reactant and top
of energy curve
 Addition of a catalyst reduces the activation energy.

8. Principle of photocatalysis
• TiO2 absorbs light
• Electron-Hole pairs are
produced
• Electrons reduces
nearby oxygen
• Highly oxidizing Holes
oxidizes nearby water
• Both anion and radical
break organic
compounds

9. Improvement in Photocatalytic Activity
Photocatalytic activity of TiO2 can be improved by following
i) By increasing the electron-hole recombination time
ii) By decreasing energy band gap of catalyst
iii) By increasing light absorption level of catalyst
Surafce
Area
Carrier
Transport
Band
Gap
Controlling Factors

10. In 2001, Japanese chemist Asahi et al., Nitrogen doped titanium dioxide showed
effective visible light activity.
In 2003, Teruhisa et al., showed that S-doped TiO2 perform better under visible light
In 2003, Hiroshi et al., Carbon dopedTiO2 shows better activity under visible light
In 2005, Kim et al., showed Platinum-ion-dopedTiO2 showed good performance in
visible light
The reason for this activity was also
explained by other scientist by
describing that doping narrowed the
energy band gap of titania

12. Materials and Methods
Electric Furnace Dry Oven
It is used to calcinate samples
at high temperature
It is used for drying and
heating purpose.

13. Autoclave UV Visible Spectrometer
It is used for doping purpose It is used for UV analysis

14. Other materials and apparatuses
Magnetic Hot Plate Stirrer
pH paper
Pipet
China dishes
Titanium tetraisopropoxide
Distilled water
Sample bottles
Indigo dye
Flasks
Aluminum foil
Permanent magnet
Burette
Ethanol
Hydrochloric Acid
Reduced graphene oxide

15. Sol-gel Technique
Sol-gel technology is widely used and it is an effective process to
produce TiO2 nanoparticles. It involves the conversion of
precursor solution into nanostructured solid.
Advantages:
Low processing cost
Low processing temp.
High purity
Simple, economic, effective
Desired nanoparticle
Fine homogeneous powder

16. It states that x-rays reflected from
different parallel planes of a crystal
interfere constructively when path
difference is integral multiple of
wavelength.
nλ=2d sin θ
 This gives maximum intensity of
reflected beam.
 Bragg’s law is the fundamental principle of X-ray diffraction analysis (XRD)
 This law relates the wavelength of electromagnetic radiation to the
diffraction angle and the lattice spacing

17. UV-Vis Spectroscopy Principle
Beer-Lambert law
The Beer-Lambert law states that the quantity of light absorbed
by a substance dissolved in a fully transmitting solvent is directly
proportional to the concentration of the substance and the path
length
of the light through the solution.
A = a(λ) . b . c
A is the measured absorbance,
a(λ) is a wavelength-dependent
absorptivity coefficient
A = a(A = a( ) * b * c

18. Sample Preparation
80 ml of distilled water and 11 ml of
Hydrochloric acid (HCL) were taken
into a beaker and put into the
burette.
After that, 20 ml of Titanium
tetraisopropoxide was dissolved
into 220ml Ethanol solution.
After that Hydrochloric acid (HCL)
solution was allowed to add into
the milky solution then dried and
calcinated.
Sol-gel Method