Abstract:
ZnO nanoparticles have been synthesized by precipitation method from zinc acetate dihydrate
and sodium hydroxide. The obtained precipitated compound was calcined at 4000 C for 2 hr and
then, the obtained product was dissolved in deionized water. The prepared solution was
characterized by UV-visible spectrophotometer and it was show absorption maxima at 380 nm
and particle size of 3.6 nm that was almost equal to 4 nm, not exhibiting band gap enlargement.
The band gap energy was lower for synthesized ZnO nanoparticles (3.263eV) than their bulk
counterparts (3.37 eV), indicating high conductivity than the bulk ZnO powder. Zn1-xLixO, Zn1-
xNaxO and Zn1-xKxO (where x= 0.005, 0.01, 0.015 and 0.02 M for all dopants) doped ZnO
nanoparticles was prepared and calcined at 4000C for 2 hr and their solution was then
characterized by UV-vis spectrophotometer. All concentration of Li+ doped ZnO nanoparticles
was more narrowing the band gap of the undoped ZnO nanoparticles than Na+ and K+ doped
ZnO nanoparticles. Both the size and concentration of dopants were affecting the band gap
energy of ZnO nanoparticles. As the concentration and ionic radii of the dopants increases the
optical band gap energy was also increasing. So the highest band gap energy was obtained by
0.015 and 0.02 M K+doped ZnO nanoparticles. The band gap narrowing was necessary to absorb
photons with a wide range of energies, so Li+ doped ZnO nanoparticles was used to absorb
photons in the portion of the solar irradiance with a high intensity than other dopants (Na+ and
K+).
