Chapter 2
Water Splitting Reactions
and Nanotechnology
2.1 Water Splitting Reactions
Sustainable hydrogen can be produced from the water by splitting the molecule
directly into its elements. The process is known as water splitting reaction. The
general reaction is.
2H2O
2 H 2 + O2
The splitting of H-O-H bonds in the water splitting reaction can be achieved by a
variety of different methods, and each method fundamentally varies from the other
in the source of power, as energy is required to break the bonds. There are different
power sources involving in the splitting of the molecules like electrical energy,
thermal energy, or electromagnetic radiation, normally mentioned as electrolysis,
thermolysis, and photolysis.
Electrolytic splitting of water is obtained by the conversion of electrical energy to
chemical energy as the current is passed through the water. The conversion of energy
takes place at the water and electrode interface [1]. The redox reaction occurs, and the
hydrogen is obtained at cathode. 3.9% demand of the world hydrogen is fulfilled by
this process. The reaction has only oxygen as by-product and “zero” CO 2 emission,
and hence it is considered more environmental friendly as compared to the traditional
“steam methane reforming” (SMR). Electrochemical cells in which electrolysis of
water takes place are run by electricity which is primarily generated by coal or natural
gas combustion both of which involves the release of CO 2 . Hence, research nowadays
is focused on using renewable technologies like photovoltaics or wind turbines for
the operation of electrochemical/catalytic water splitting.
Photocatalytic or photochemical splitting of water is a remarkable alternative
for the generation of hydrogen. These processes are oriented toward the reduction
of CO 2 emission, as they involve the use of renewable sources like sunlight and
© The Editor(s) (if applicable) and The Author(s), under exclusive license
to Springer Nature Switzerland AG 2021
S. Farrukh et al., Nanotechnology and the Generation of Sustainable Hydrogen,
Green Energy and Technology, https://doi.org/10.1007/978-3-030-60402-8_2
13
Water Splitting Reactions
and Nanotechnology
2.1 Water Splitting Reactions
Sustainable hydrogen can be produced from the water by splitting the molecule
directly into its elements. The process is known as water splitting reaction. The
general reaction is.
2H2O
2 H 2 + O2
The splitting of H-O-H bonds in the water splitting reaction can be achieved by a
variety of different methods, and each method fundamentally varies from the other
in the source of power, as energy is required to break the bonds. There are different
power sources involving in the splitting of the molecules like electrical energy,
thermal energy, or electromagnetic radiation, normally mentioned as electrolysis,
thermolysis, and photolysis.
Electrolytic splitting of water is obtained by the conversion of electrical energy to
chemical energy as the current is passed through the water. The conversion of energy
takes place at the water and electrode interface [1]. The redox reaction occurs, and the
hydrogen is obtained at cathode. 3.9% demand of the world hydrogen is fulfilled by
this process. The reaction has only oxygen as by-product and “zero” CO 2 emission,
and hence it is considered more environmental friendly as compared to the traditional
“steam methane reforming” (SMR). Electrochemical cells in which electrolysis of
water takes place are run by electricity which is primarily generated by coal or natural
gas combustion both of which involves the release of CO 2 . Hence, research nowadays
is focused on using renewable technologies like photovoltaics or wind turbines for
the operation of electrochemical/catalytic water splitting.
Photocatalytic or photochemical splitting of water is a remarkable alternative
for the generation of hydrogen. These processes are oriented toward the reduction
of CO 2 emission, as they involve the use of renewable sources like sunlight and
© The Editor(s) (if applicable) and The Author(s), under exclusive license
to Springer Nature Switzerland AG 2021
S. Farrukh et al., Nanotechnology and the Generation of Sustainable Hydrogen,
Green Energy and Technology, https://doi.org/10.1007/978-3-030-60402-8_2
13