304
U. S. Behera and J. S. Sangwai
2.2.5 Semiconductor Nanoparticles
A semiconductor nanoparticle behaves peculiarly due to the high energy gap between
the valence band and the conduction band. A significant change in the properties of
nanoparticles is observed with bandgap tuning, and hence they are considered as
vital material for photocatalysis, photo-optics, and electronic devices. They are also
used for making biosensor and metal sensor devices. These nanoparticles found
exclusively in water splitting application due to suitable bandgap and band edge
position (Hisatomi et al. 2014). These particles are usually charge stabilized.
2.3 Synthesis Process of Nanoparticles
Synthesis of nanoparticles involved various methods but all the synthesis methods
associated with the formation of nanoparticles either from bigger particle to smaller
(top-down) or from smaller to bigger one (bottom-up). If the preparation method
derives from the larger molecule, then the preparation method is called as top-down
process. Similarly, if the preparation method derives from molecular level to nanosize
particle, it is called as bottom-down method. Pictorial representation for production
of nanoparticles is given in Fig. 4.
Molecular
size
particle
Atomic
particle
Size
Bottom-up
Method
Nanoparticles
Top-down
process
Big size particles
Dust Particles
Fig. 4 Process involved for the production of nanoparticles
U. S. Behera and J. S. Sangwai
2.2.5 Semiconductor Nanoparticles
A semiconductor nanoparticle behaves peculiarly due to the high energy gap between
the valence band and the conduction band. A significant change in the properties of
nanoparticles is observed with bandgap tuning, and hence they are considered as
vital material for photocatalysis, photo-optics, and electronic devices. They are also
used for making biosensor and metal sensor devices. These nanoparticles found
exclusively in water splitting application due to suitable bandgap and band edge
position (Hisatomi et al. 2014). These particles are usually charge stabilized.
2.3 Synthesis Process of Nanoparticles
Synthesis of nanoparticles involved various methods but all the synthesis methods
associated with the formation of nanoparticles either from bigger particle to smaller
(top-down) or from smaller to bigger one (bottom-up). If the preparation method
derives from the larger molecule, then the preparation method is called as top-down
process. Similarly, if the preparation method derives from molecular level to nanosize
particle, it is called as bottom-down method. Pictorial representation for production
of nanoparticles is given in Fig. 4.
Molecular
size
particle
Atomic
particle
Size
Bottom-up
Method
Nanoparticles
Top-down
process
Big size particles
Dust Particles
Fig. 4 Process involved for the production of nanoparticles