2. Water…….
Water is a simple chemical molecule made of two
molecules of hydrogen and one molecule of oxygen.
Water splitting is a process in which water is splitted
into hydrogen and oxygen.
3. Why to split water???
Because 70% of the earth is made of water and water is
abuntantly available.
Hydrogen fuel production has gained increased
attention as oil and other nonrenewable fuels become
increasingly depleted and expensive.
Can be a key component of hydrogen economy.
By using the process of water splitting, the emission of
green house gases (especially Carbon di oxide) can be
reduced.
4. Methods of water splitting
Electrolysis
Photoelectrochemical water splitting
Photocatalytic water splitting
Radiolysis
Photobiological water splitting
Thermal decomposition of water
Nuclear thermal
Chemical production, etc
5. Electrolysis
If an electrical current is passed
through water between electrodes (the positive and
minus poles of a battery), the water is split oxygen and
hydrogen.
Used in industries especially in making aluminium.
Two types
High – pressure electrolysis
High – temperature electrolysis
6. Radiolysis: Radiolysis is the dissociation of molecules
by nuclear radiation. Here, it is a separation of water
via radioactive activity. The end result is the
production of hydrogen peroxide.
Thermolysis: Thermolysis is defined as a chemical
reaction whereby at elevated temperatures water
molecules split into their atomic components
hydrogen and oxygen.
7. Photoelectrochemical water
splitting
This is also called as artificial photosynthesis
Artificial photosynthesis is a chemical process that
replicates the natural process of photosynthesis, a
process that converts sunlight, water, and carbon
dioxide into carbohydrates and oxygen.
8. Photolysis…
In the first stage of
photosynthesis light
energy is absorbed by
chlorophyll in plant cells.
This light energy is then
used to produce ATP and
to split water into
hydrogen and oxygen.
The splitting of water is
referred to as photolysis
9. Water-plastoquinone
oxidoreductase is the protein
complex responsible for this
process.
Photosynthetic water splitting
(or oxygen evolution) is one of
the most important reactions on
the planet, since it is the source
of nearly all the atmosphere's
oxygen.
Moreover, artificial
photosynthetic water-splitting
may contribute to the effective
use of sunlight as an alternative
energy-source.
10. Photoelectrochemical water
splitting
The principle of
photoelectrochemical water
splitting is based on the
conversion of light energy
into electricity within a cell
involving two or three
electrodes immersed in an
aqueous electrolyte, of which
one is made of a
semiconductor, exposed to
light and is able to absorb
light. This electricity is then
used for water electrolysis.
11. Can be used on a large
scale to produce
hydrogen.
By 2050, around 10000
PEC plants will be
required to satisfy one
third of the world’s fuel
requirement.
12. Advantages
Artificial photosynthesis offers a strategy for replacing
fossil fuels with clean energy sources.
The ultimate goal of artificial photosynthesis is to
efficiently convert the sun’s energy into chemical
energy and store it as a fuel.
By splitting water, hydrogen molecules can be isolated
and then converted into electricity to power
everything from your fridge to a city.
13. Recent Research
Artificial photosynthesis is a research field that
attempts to replicate the natural process of
photosynthesis, converting sunlight, water and carbon
dioxide into carbohydrates (i.e. glucose which can be a
fuel) and oxygen.
Recently, this has been successful in splitting water
into hydrogen and oxygen using an artificial
compound called Nafion.
